Wednesday, February 21, 2024

Basic A&P for Karate

 



                Sometimes in class I get into the weeds talking about Anatomy and physiology. Sometimes I forget that while I took this in university and even worked in a field that required me to know basic physiology and a LOT about anatomy….most of the people in the Dojo don’t now this stuff.  This is a SUPER Simplified version of some of the stuff I talk about.

 

1)      The Human Body. Organization of the Human Body.

a)      The human body is organized based on the jobs that the different systems do. You have the:

i)       Circulatory system/Cardiovascular system:

(1)    Circulates blood around the body via the heart, arteries and veins, delivering oxygen and nutrients to organs and cells and carrying their waste products away, as well as keeping the body's temperature in a safe range.

ii)     Digestive system:

(1)    System to absorb nutrients and remove waste via the gastrointestinal tract, including the mouth, oesophagus, stomach and intestines.

iii)   Endocrine system:

(1)    Influences the function of the body using hormones.

iv)   Integumentary/exocrine system:

(1)    System that comprises skin, hair, nails, and sweat and other exocrine glands.

v)      Immune system/Lymphatic system:

(1)    Defends the body against pathogens that may harm the body. The system contains a network of lymphatic vessels that carry a clear fluid called lymph.

vi)   Muscular system:

(1)     Enables the body to move using muscles.

vii) Nervous system:

(1)    Collects and processes information from the senses via nerves and the brain and tells the muscles to contract to cause physical actions.

viii)          Renal system/urinary system:

(1)    The system where the kidneys filter blood to produce urine, and get rid of waste.

ix)    Reproductive system:

(1)    The reproductive organs required for the production of offspring.

x)      Respiratory system:

(1)    Brings air into the and out of the lungs to absorb O2 and remove Co2

xi)    Skeletal system:

(1)    Bones maintain structure for movement and to protect the body

2)      Cytology and histology: Cells and tissue


a)      


Cell types and cell membrane:

i)       Nucleus: The “brain” of the cell, directs most action and also houses the most DNA in the cells. Nucleus dictates the action of the cell.

ii)     Plasma Membrane: the protector and gatekeeper of the cell. Also the reception point or communication point for the cell. Also fastens cells together.

iii)   Cytoplasm: a jelly like fluid called Cytosol that helps protect the inner organelles of the cell.

iv)   Cytoskeleton: The inner “Scaffolding” that gives each cell its correct shape.

v)     Endoplasmic Reticulum: Helps with Cell movement and transports proteins in and across the cell itself.

vi)   Golgi Apparatus: the “Post office for the cells” this puts markers on the products of different cells to allow cells that need this product to identify it easier.

vii)Mitochondria: The “power house” of the cells. Takes ATP and makes energy for the body to work.  Also stores Calcium and catabolizes parts of the body to create ATP.

viii)          Ribosomes: Transcribe parts or segments of DNA into RNA to create new amino acids. The Ribosomes “Read” the RNA and create the Amino acids based on the blue prints that the RNA create.

b)     Tissue types

i)       Connective tissue:

(1)    Connective tissues bind structures together, form a framework and support for organs and the body as a whole, store fat, transport substances, protect against disease, and help repair tissue damage. They occur throughout the body. Connective tissues are characterized by an abundance of intercellular matrix with relatively few cells. Connective tissue cells are able to reproduce but not as rapidly as epithelial cells. Most connective tissues have a good blood supply but some do not.

ii)     Epithelial tissue:

(1)    Epithelial tissues are widespread throughout the body. They form the covering of all body surfaces, line body cavities and hollow organs, and are the major tissue in glands. They perform a variety of functions that include protection, secretion, absorption, excretion, filtration, diffusion, and sensory reception. The cells in epithelial tissue are tightly packed together with very little intercellular matrix. Because the tissues form coverings and linings, the cells have one free surface that is not in contact with other cells. Opposite the free surface, the cells are attached to underlying connective tissue by a non-cellular basement membrane. This membrane is a mixture of carbohydrates and proteins secreted by the epithelial and connective tissue cells. Epithelial cells may be squamous, cuboidal, or columnar in shape and may be arranged in single or multiple layers.

iii)   Muscle cells:

(1)    Muscle tissue is composed of cells that have the special ability to shorten or contract in order to produce movement of the body parts. The tissue is highly cellular and is well supplied with blood vessels. The cells are long and slender so they are sometimes called muscle fibers, and these are usually arranged in bundles or layers that are surrounded by connective tissue. Actin and myosin are contractile proteins in muscle tissue. Muscle tissue can be categorized into skeletal muscle tissue, smooth muscle tissue, and cardiac muscle tissue. Skeletal muscle fibers are cylindrical, multinucleated, striated, and under voluntary control. Smooth muscle cells are spindle shaped, have a single, centrally located nucleus, and lack striations. They are called involuntary muscles. Cardiac muscle has branching fibers, one nucleus per cell, striations, and intercalated disks. Its contraction is not under voluntary control.

iv)   Nerve Cells:

(1)    Nervous tissue is found in the brain, spinal cord, and nerves. It is responsible for coordinating and controlling many body activities. It stimulates muscle contraction, creates an awareness of the environment, and plays a major role in emotions, memory, and reasoning. To do all these things, cells in nervous tissue need to be able to communicate with each other by way of electrical nerve impulses. The cells in nervous tissue that generate and conduct impulses are called neurons or nerve cells. These cells have three principal parts: the dendrites, the cell body, and one axon. The main part of the cell, the part that carries on the general functions, is the cell body. Dendrites are extensions, or processes, of the cytoplasm that carry impulses to the cell body. An extension or process called an axon carries impulses away from the cell body. Nervous tissue also includes cells that do not transmit impulses, but instead support the activities of the neurons. These are the glial cells (neuroglial cells), together termed the neuroglia. Supporting, or glia, cells bind neurons together and insulate the neurons. Some are phagocytic and protect against bacterial invasion, while others provide nutrients by binding blood vessels to the neurons.

3)      The Skeleton/Bone

a)      Bone tissue and development

i)        Intramembranous ossification involves the replacement of sheet-like connective tissue membranes with bony tissue. Bones formed in this manner are called intramembranous bones. They include certain flat bones of the skull and some of the irregular bones. The future bones are first formed as connective tissue membranes. Osteoblasts migrate to the membranes and deposit bony matrix around themselves. When the osteoblasts are surrounded by matrix they are called osteocytes. Bones grow in length at the epiphyseal plate by a process that is similar to endochondral ossification. The cartilage in the region of the epiphyseal plate next to the epiphysis continues to grow by mitosis. The chondrocytes, in the region next to the diaphysis, age and degenerate. Osteoblasts move in and ossify the matrix to form bone. This process continues throughout childhood and the adolescent years until the cartilage growth slows and finally stops. When cartilage growth ceases, usually in the early twenties, the epiphyseal plate completely ossifies so that only a thin epiphyseal line remains and the bones can no longer grow in length. Bone growth is under the influence of growth hormone from the anterior pituitary gland and sex hormones from the ovaries and testes. Even though bones stop growing in length in early adulthood, they can continue to increase in thickness or diameter throughout life in response to stress from increased muscle activity or to weight. The increase in diameter is called appositional growth. Osteoblasts in the periosteum form compact bone around the external bone surface. At the same time, osteoclasts in the endosteum break down bone on the internal bone surface, around the medullary cavity. These two processes together increase the diameter of the bone and, at the same time, keep the bone from becoming excessively heavy and bulky.

b)     Axial and Appendicular Skeleton

i)       You often here the terms Axial vs Appendicular or Axial and peripheral, this simply means the core part of the body and the limbs. The limbs mostly play a role in mobility and work while the axillary protects the organs and is less mobile, however it is also involved in movement and work as well.

c)      Classification of bones

i)       Long bones:

(1)    The bones of the body come in a variety of sizes and shapes. The four principal types of bones are long, short, flat and irregular. Bones that are longer than they are wide are called long bones. They consist of a long shaft with two bulky ends or extremities. They are primarily compact bone but may have a large amount of spongy bone at the ends or extremities. Long bones include bones of the thigh, leg, arm, and forearm.

ii)     Short bones:

(1)    Short bones are roughly cube shaped with vertical and horizontal dimensions approximately equal. They consist primarily of spongy bone, which is covered by a thin layer of compact bone. Short bones include the bones of the wrist and ankle.

iii)   Flat bones:

(1)    Flat bones are thin, flattened, and usually curved. Most of the bones of the cranium are flat bones.

iv)   Irregular bones:

(1)     Bones that are not in any of the above three categories are classified as irregular bones. They are primarily spongy bone that is covered with a thin layer of compact bone. The vertebrae and some of the bones in the skull are irregular bones.

d)     Movement

i)         Put simply the skeleton acts as a scaffolding and structure for the muscles to pull against to create movement and to do work.

4)      Integumentary system

a)      The skin:

i)       The integumentary system is the largest organ of the body that forms a physical barrier between the external environment and the internal environment that it serves to protect and maintain. The integumentary system includes the epidermis, dermis, hypodermis, associated glands, hair, and nails. In addition to its barrier function, this system performs many intricate functions such as body temperature regulation, cell fluid maintenance, synthesis of Vitamin D, and detection of stimuli. The various components of this system work in conjunction to carry out these functions—for example, body temperature regulation occurs through thermoreceptors that lead to the adjustment of peripheral blood flow, degree of perspiration, and body hair.

5)      Muscles of the body

a)      Muscle types:

b)      Skeletal Muscle:Skeletal muscle, attached to bones, is responsible for skeletal movements. The peripheral portion of the central nervous system (CNS) controls the skeletal muscles. Thus, these muscles are under conscious, or voluntary, control. The basic unit is the muscle fiber with many nuclei. These muscle fibers are striated (having transverse streaks) and each acts independently of neighboring muscle fibers.

c)       Smooth Muscle:Smooth muscle, found in the walls of the hollow internal organs such as blood vessels, the gastrointestinal tract, bladder, and uterus, is under control of the autonomic nervous system. Smooth muscle cannot be controlled consciously and thus acts involuntarily. The non-striated (smooth) muscle cell is spindle-shaped and has one central nucleus. Smooth muscle contracts slowly and rhythmically.

d)      Cardiac Muscle:Cardiac muscle, found in the walls of the heart, is also under control of the autonomic nervous system. The cardiac muscle cell has one central nucleus, like smooth muscle, but it also is striated, like skeletal muscle. The cardiac muscle cell is rectangular in shape. The contraction of cardiac muscle is involuntary, strong, and rhythmical.

e)     



Structure of muscles

i)        A whole skeletal muscle is considered an organ of the muscular system. Each organ or muscle consists of skeletal muscle tissue, connective tissue, nerve tissue, and blood or vascular tissue. Skeletal muscles vary considerably in size, shape, and arrangement of fibers. They range from extremely tiny strands such as the stapedium muscle of the middle ear to large masses such as the muscles of the thigh. Some skeletal muscles are broad in shape and some narrow. In some muscles the fibers are parallel to the long axis of the muscle; in some they converge to a narrow attachment; and in some they are oblique. Each skeletal muscle fiber is a single cylindrical muscle cell. An individual skeletal muscle may be made up of hundreds, or even thousands, of muscle fibers bundled together and wrapped in a connective tissue covering. Each muscle is surrounded by a connective tissue sheath called the epimysium. Fascia, connective tissue outside the epimysium, surrounds and separates the muscles. Portions of the epimysium project inward to divide the muscle into compartments. Each compartment contains a bundle of muscle fibers. Each bundle of muscle fiber is called a fasciculus and is surrounded by a layer of connective tissue called the perimysium. Within the fasciculus, each individual muscle cell, called a muscle fiber, is surrounded by connective tissue called the endomysium. Skeletal muscle cells (fibers), like other body cells, are soft and fragile. The connective tissue covering furnish support and protection for the delicate cells and allow them to withstand the forces of contraction. The coverings also provide pathways for the passage of blood vessels and nerves. Commonly, the epimysium, perimysium, and endomysium extend beyond the fleshy part of the muscle, the belly or gaster, to form a thick ropelike tendon or a broad, flat sheet-like aponeurosis. The tendon and aponeurosis form indirect attachments from muscles to the periosteum of bones or to the connective tissue of other muscles. Typically a muscle spans a joint and is attached to bones by tendons at both ends. One of the bones remains relatively fixed or stable while the other end moves as a result of muscle contraction. Skeletal muscles have an abundant supply of blood vessels and nerves. This is directly related to the primary function of skeletal muscle, contraction. Before a skeletal muscle fiber can contract, it has to receive an impulse from a nerve cell. Generally, an artery and at least one vein accompany each nerve that penetrates the epimysium of a skeletal muscle. Branches of the nerve and blood vessels follow the connective tissue components of the muscle of a nerve cell and with one or more minute blood vessels called capillaries.

f)       Muscle terminology for beginers….how we named them:

i)        There are more than 600 muscles in the body, which together account for about 40 percent of a person's weight. Most skeletal muscles have names that describe some feature of the muscle. Often several criteria are combined into one name. Associating the muscle's characteristics with its name will help you learn and remember them. The following are some terms relating to muscle features that are used in naming muscles.

(1)    Size: vastus (huge); maximus (large); longus (long); minimus (small); brevis (short).

(2)    Shape: deltoid (triangular); rhomboid (like a rhombus with equal and parallel sides); latissimus (wide); teres (round); trapezius (like a trapezoid, a four-sided figure with two sides parallel).

(3)    Direction of fibers: rectus (straight); transverse (across); oblique (diagonally); orbicularis (circular).

(4)    Location: pectoralis (chest); gluteus (buttock or rump); brachii (arm); supra- (above); infra- (below); sub- (under or beneath); lateralis (lateral).

(5)    Number of origins: biceps (two heads); triceps (three heads); quadriceps (four heads).

(6)    Origin and insertion: sternocleidomastoid (origin on the sternum and clavicle, insertion on the mastoid process); brachioradialis (origin on the brachium or arm, insertion on the radius).

(7)   Action: abductor (to abduct a structure); adductor (to adduct a structure); flexor (to flex a structure); extensor (to extend a structure); levator (to lift or elevate a structure); masseter (a chewer).

g)     Relaxation and contraction

i)       Muscles can actually only do two things (Skeletal muscles specifically)…contract or expand/Relax.  A Muscle Contraction Is Triggered When an Action Potential Travels Along the Nerves to the Muscles. Muscle contraction begins when the nervous system generates a signal. The signal, an impulse called an action potential, travels through a type of nerve cell called a motor neuron.

ii)     Beyond Nerve action there is a chemo electric signal that will cause both contraction and relaxation of the muscle, you much have both to create the contract extend action of the muscle. Some nutrient deficiencies and illnesses or injuries to the brain and body can interfere with this signal and create systems issues like tetanus and other health issues less life threatening.

h)     Muscle action: movement and heat

i)       Part of the biproduct of the chemo electric contraction of a muscle is movement. The contraction pulls on the skeletal system and causes movement, or contraction based attempted movement. The other biproduct of the contraction of muscle is the creation of a thermogenic response, or heat. 

i)       Effects of tight muscles, what are triggers and why I cant relax.

i)       Tight muscles or muscle stiffness can be the result of many different things. Muscle stiffness most commonly arises after the overuse of skeletal muscles, which tends to happen after a long period of minimal motion (e.g., after extended bed rest) or after engaging in new exercises. These actions can cause temporary damage to the muscle cells, leading to stiffness. Muscle stiffness from overuse of the muscles occurs most frequently among people who do not exercise often or those that are trying a new type of exercise that they are not adapted too, or at a level of intensity they are not used to. Electrolyte imbalances may also cause muscle stiffness, especially after exercise. Electrolytes (e.g., sodium, potassium, etc.) are important minerals in the body that play a role in conducting nerve impulses and contracting muscles, among other functions. When a person exercises, electrolytes are lost with water (e.g., sweat), making it more difficult for the nervous system to facilitate muscle movement. Muscle stiffness can also develop due to an underlying myopathy, or a disease of the muscles, which can result from metabolic, inflammatory, endocrine, infectious, or medication-related causes. Metabolic disorders, such as mitochondrial disease and McArdle’s disease, disrupt the balance of nutrients and energy in the body. Inflammatory conditions, such as polymyalgia rheumatica, are characterized by increased inflammation in the body due to an overreaction by the body’s immune system. Endocrine disorders, like hypothyroidism and acromegaly, are caused by hormone imbalances in the body. Disruptions in metabolic processes, the immune system, and hormone levels can all produce muscle stiffness. Infections, such as the flu, COVID-19, and meningitis, are also often associated with muscle stiffness. Finally, muscle stiffness can occur as a side effect of certain medications, such as statins, which are prescribed to treat high cholesterol, or anesthetics, which are commonly given during surgery. Since muscle movement depends on communication between the nervous system and the muscles, muscle stiffness can also arise from issues with the nerves and muscles (i.e., neuromuscular disorders) or problems affecting only the nerves (i.e., neurologic disorders). Stiff-person syndrome, a rare cause of muscle stiffness, is a type of neuromuscular disorder in which motor neurons can cause involuntary muscle spasms. Other disorders, such as Parkinson’s disease, Myasthenia gravis, and Lambert Eaton syndrome, are characterized by progressively worsening muscle stiffness, or rigidity. Individuals with a history of stroke may also experience muscle stiffness.

ii)      Trigger points: Trigger Point (TrP) is a hyperirritable spot, a palpable nodule in the taut bands of the skeletal muscles' fascia. Direct compression or muscle contraction can elicit jump sign, local tenderness, local twitch response and referred pain which usually responds with a pain pattern distant from the spot. Jump sign is the characteristic behavioural response to pressure on a TrP. Individuals are frequently startled by the intense pain. They wince or cry out with a response seemingly out of proportion to the amount of pressure exerted by the examining fingers. They move involuntarily, jerking the shoulder, head, or some other part of the body not being palpated. A jump sign thus reflects the extreme tenderness of a TrP. This sign has been considered pathognomonic for the presence of TrPs. Local twitch response - defined as a transient visible or palpable contraction of the muscle and skin as the tense muscle fibers contract when pressure is applied through needle penetration or by transverse snapping palpation. A local twitch response on stimulating active TrPs is a widely accepted diagnostic sign. Referred pain, also called reflective pain, is pain perceived at a location other than the site of the painful stimulus. Pain is reproducible and does not follow dermatomes, myotomes, or nerve roots. There is no specific joint swelling or neurological deficits. Pain from a myofascial TrP is a distinct, discrete and constant pattern or map of pain with no gender or racial differences able to reproduce symptoms - referred pain map. Trigger points develop in the myofascia, mainly in the center of a muscle belly where the motor endplate enters (primary or central TrPs)[6]. Those are palpable nodules within the tight muscle at the size of 2-10 mm and can demonstrate at different places in any skeletal muscles of the body. We all have TrPs in the body. Can be present even in babies and children, but their presence does not necessarily result in the formation of pain syndrome. When it happens, TrPs are directly associated with myofascial pain syndrome*, somatic dysfunction, psychological disturbance and restricted daily functioning. *Myofascial Pain Syndrome refers to regional pain of soft tissue origin and is associated with muscle tenderness that arises from TrPs, focal points of tenderness, a few millimeters in diameter, found at multiple sites in a muscle and the fascia of muscle tissue.

iii)    Causes - Usually, TrPs happen due to:

(1)    Ageing,

(2)    Injury sustained by a fall, by stress or birth trauma.

(3)    Lack of exercise - commonly in sedentary persons between 27,5-55 years, of which 45% are men[10],

(4)    Bad posture - upper and lower crossed pattern, swayback posture, telephone posture, cross-legged sitting,

(5)    Muscle overuse and respective micro-trauma - weightlifting,

(6)    Chronic stress condition - anxiety, depression, psychological stress trauma,

(7)    Vitamin deficiencies - vitamin C, D, B; folic acid; iron;

(8)    Sleep disturbance,

(9)    Joint problems and hypermobility.

6)      The Heart and circulatory system

a)       The heart is a pump, usually beating about 60 to 100 times per minute. With each heartbeat, the heart sends blood throughout our bodies, carrying oxygen to every cell. After delivering the oxygen, the blood returns to the heart. The heart then sends the blood to the lungs to pick up more oxygen. This cycle repeats over and over again. The circulatory system is made up of blood vessels that carry blood away from and towards the heart. Arteries carry blood away from the heart and veins carry blood back to the heart. The circulatory system carries oxygen, nutrients, and hormones to cells, and removes waste products, like carbon dioxide. These roadways travel in one direction only, to keep things going where they should.

b)      What Are the Parts of the Heart?

i)        The heart has four chambers — two on top and two on bottom: The two bottom chambers are the right ventricle and the left ventricle. These pump blood out of the heart. A wall called the interventricular septum is between the two ventricles. The two top chambers are the right atrium and the left atrium. They receive the blood entering the heart. A wall called the interatrial septum is between the atria. The atria are separated from the ventricles by the atrioventricular valves: The tricuspid valve separates the right atrium from the right ventricle. The mitral valve separates the left atrium from the left ventricle. Two valves also separate the ventricles from the large blood vessels that carry blood leaving the heart: The pulmonic valve is between the right ventricle and the pulmonary artery, which carries blood to the lungs. The aortic valve is between the left ventricle and the aorta, which carries blood to the body.

c)       What Are the Parts of the Circulatory System?

i)        Two pathways come from the heart: The pulmonary circulation is a short loop from the heart to the lungs and back again. The systemic circulation carries blood from the heart to all the other parts of the body and back again. In pulmonary circulation: The pulmonary artery is a big artery that comes from the heart. It splits into two main branches, and brings blood from the heart to the lungs. At the lungs, the blood picks up oxygen and drops off carbon dioxide. The blood then returns to the heart through the pulmonary veins. In systemic circulation: Next, blood that returns to the heart has picked up lots of oxygen from the lungs. So it can now go out to the body. The aorta is a big artery that leaves the heart carrying this oxygenated blood. Branches off of the aorta send blood to the muscles of the heart itself, as well as all other parts of the body. Like a tree, the branches gets smaller and smaller as they get farther from the aorta. At each body part, a network of tiny blood vessels called capillaries connects the very small artery branches to very small veins. The capillaries have very thin walls, and through them, nutrients and oxygen are delivered to the cells. Waste products are brought into the capillaries. Capillaries then lead into small veins. Small veins lead to larger and larger veins as the blood approaches the heart. Valves in the veins keep blood flowing in the correct direction. Two large veins that lead into the heart are the superior vena cava and inferior vena cava. (The terms superior and inferior don't mean that one vein is better than the other, but that they're located above and below the heart.) Once the blood is back in the heart, it needs to re-enter the pulmonary circulation and go back to the lungs to drop off the carbon dioxide and pick up more oxygen.

d)      How Does the Heart Beat? The heart gets messages from the body that tell it when to pump more or less blood depending on a person's needs. For example, when we're sleeping, it pumps just enough to provide for the lower amounts of oxygen needed by our bodies at rest. But when we're exercising, the heart pumps faster so that our muscles get more oxygen and can work harder. How the heart beats is controlled by a system of electrical signals in the heart. The sinus (or sinoatrial) node is a small area of tissue in the wall of the right atrium. It sends out an electrical signal to start the contracting (pumping) of the heart muscle. This node is called the pacemaker of the heart because it sets the rate of the heartbeat and causes the rest of the heart to contract in its rhythm. These electrical impulses make the atria contract first. Then the impulses travel down to the atrioventricular (or AV) node, which acts as a kind of relay station. From here, the electrical signal travels through the right and left ventricles, making them contract. One complete heartbeat is made up of two phases: The first phase is called systole (SISS-tuh-lee). This is when the ventricles contract and pump blood into the aorta and pulmonary artery. During systole, the atrioventricular valves close, creating the first sound (the lub) of a heartbeat. When the atrioventricular valves close, it keeps the blood from going back up into the atria. During this time, the aortic and pulmonary valves are open to allow blood into the aorta and pulmonary artery. When the ventricles finish contracting, the aortic and pulmonary valves close to prevent blood from flowing back into the ventricles. These valves closing is what creates the second sound (the dub) of a heartbeat.

e)       The second phase is called diastole (die-AS-tuh-lee). This is when the atrioventricular valves open and the ventricles relax. This allows the ventricles to fill with blood from the atria, and get ready for the next heartbeat.

7)       The Brain:

i)        Three layers of protective covering called meninges surround the brain and the spinal cord.

ii)      The outermost layer, the dura mater, is thick and tough. It includes two layers: The periosteal layer of the dura mater lines the inner dome of the skull (cranium) and the meningeal layer is below that. Spaces between the layers allow for the passage of veins and arteries that supply blood flow to the brain.

iii)    The arachnoid mater is a thin, weblike layer of connective tissue that does not contain nerves or blood vessels. Below the arachnoid mater is the cerebrospinal fluid, or CSF. This fluid cushions the entire central nervous system (brain and spinal cord) and continually circulates around these structures to remove impurities.

iv)    The pia mater is a thin membrane that hugs the surface of the brain and follows its contours. The pia mater is rich with veins and arteries.

b)    



Gray vs white matter

i)         Gray and white matter are two different regions of the central nervous system. In the brain, gray matter refers to the darker, outer portion, while white matter describes the lighter, inner section underneath. In the spinal cord, this order is reversed: The white matter is on the outside, and the gray matter sits within. Gray matter is primarily composed of neuron somas (the round central cell bodies), and white matter is mostly made of axons (the long stems that connects neurons together) wrapped in myelin (a protective coating). The different composition of neuron parts is why the two appear as separate shades on certain scans. Each region serves a different role. Gray matter is primarily responsible for processing and interpreting information, while white matter transmits that information to other parts of the nervous system.

c)      Three main parts of the brain Cerebellum, Cerebrum, Brain stem.

d)     Cerebrum “latin for Bark” describes the outer gray matter covering the surface.

i)        Cortex is Latin for “bark,” and describes the outer gray matter covering of the cerebrum. The cortex has a large surface area due to its folds, and comprises about half of the brain’s weight. The cerebral cortex is divided into two halves, or hemispheres. It is covered with ridges (gyri) and folds (sulci). The two halves join at a large, deep sulcus (the interhemispheric fissure, AKA the medial longitudinal fissure) that runs from the front of the head to the back. The right hemisphere controls the left side of the body, and the left half controls the right side of the body. The two halves communicate with one another through a large, C-shaped structure of white matter and nerve pathways called the corpus callosum. The corpus callosum is in the center of the cerebrum.

e)      Brain Stem

i)        The brainstem (middle of brain) connects the cerebrum with the spinal cord. The brainstem includes the midbrain, the pons and the medulla.

  • Midbrain. The midbrain (or mesencephalon) is a very complex structure with a range of different neuron clusters (nuclei and colliculi), neural pathways and other structures. These features facilitate various functions, from hearing and movement to calculating responses and environmental changes. The midbrain also contains the substantia nigra, an area affected by Parkinson’s disease that is rich in dopamine neurons and part of the basal ganglia, which enables movement and coordination.
  • Pons. The pons is the origin for four of the 12 cranial nerves, which enable a range of activities such as tear production, chewing, blinking, focusing vision, balance, hearing and facial expression. Named for the Latin word for “bridge,” the pons is the connection between the midbrain and the medulla.
  • Medulla. At the bottom of the brainstem, the medulla is where the brain meets the spinal cord. The medulla is essential to survival. Functions of the medulla regulate many bodily activities, including heart rhythm, breathing, blood flow, and oxygen and carbon dioxide levels. The medulla produces reflexive activities such as sneezing, vomiting, coughing and swallowing.

The spinal cord extends from the bottom of the medulla and through a large opening in the bottom of the skull. Supported by the vertebrae, the spinal cord carries messages to and from the brain and the rest of the body.

f)       Cerebellum

i)         The cerebellum (“little brain”) is a fist-sized portion of the brain located at the back of the head, below the temporal and occipital lobes and above the brainstem. Like the cerebral cortex, it has two hemispheres. The outer portion contains neurons, and the inner area communicates with the cerebral cortex. Its function is to coordinate voluntary muscle movements and to maintain posture, balance and equilibrium. New studies are exploring the cerebellum’s roles in thought, emotions and social behavior, as well as its possible involvement in addiction, autism and schizophrenia.

8)      Respiratory anatomy

a)       When the respiratory system is mentioned, people generally think of breathing, but breathing is only one of the activities of the respiratory system. The body cells need a continuous supply of oxygen for the metabolic processes that are necessary to maintain life. The respiratory system works with the circulatory system to provide this oxygen and to remove the waste products of metabolism. It also helps to regulate pH of the blood. Respiration is the sequence of events that results in the exchange of oxygen and carbon dioxide between the atmosphere and the body cells. Every 3 to 5 seconds, nerve impulses stimulate the breathing process, or ventilation, which moves air through a series of passages into and out of the lungs. After this, there is an exchange of gases between the lungs and the blood. This is called external respiration. The blood transports the gases to and from the tissue cells. The exchange of gases between the blood and tissue cells is internal respiration. Finally, the cells utilize the oxygen for their specific activities: this is called cellular metabolism, or cellular respiration. Together, these activities constitute respiration.

9)      Digestive Anatomy

a)       The digestive system includes the digestive tract and its accessory organs, which process food into molecules that can be absorbed and utilized by the cells of the body. Food is broken down, bit by bit, until the molecules are small enough to be absorbed and the waste products are eliminated. The digestive tract, also called the alimentary canal or gastrointestinal (GI) tract, consists of a long continuous tube that extends from the mouth to the anus. It includes the mouth, pharynx, esophagus, stomach, small intestine, and large intestine. The tongue and teeth are accessory structures located in the mouth. The salivary glands, liver, gallbladder, and pancreas are major accessory organs that have a role in digestion. These organs secrete fluids into the digestive tract. Food undergoes three types of processes in the body:

i)        Digestion

ii)      Absorption

iii)    Elimination

b)      Digestion and absorption occur in the digestive tract. After the nutrients are absorbed, they are available to all cells in the body and are utilized by the body cells in metabolism. The digestive system prepares nutrients for utilization by body cells through six activities, or functions.

c)       Ingestion: The first activity of the digestive system is to take in food through the mouth. This process, called ingestion, has to take place before anything else can happen.

d)      Mechanical Digestion: The large pieces of food that are ingested have to be broken into smaller particles that can be acted upon by various enzymes. This is mechanical digestion, which begins in the mouth with chewing or mastication and continues with churning and mixing actions in the stomach.

e)       Chemical Digestion: The complex molecules of carbohydrates, proteins, and fats are transformed by chemical digestion into smaller molecules that can be absorbed and utilized by the cells. Chemical digestion, through a process called hydrolysis, uses water and digestive enzymes to break down the complex molecules. Digestive enzymes speed up the hydrolysis process, which is otherwise very slow.

f)        Movements: After ingestion and mastication, the food particles move from the mouth into the pharynx, then into the esophagus. This movement is deglutition, or swallowing. Mixing movements occur in the stomach as a result of smooth muscle contraction. These repetitive contractions usually occur in small segments of the digestive tract and mix the food particles with enzymes and other fluids. The movements that propel the food particles through the digestive tract are called peristalsis. These are rhythmic waves of contractions that move the food particles through the various regions in which mechanical and chemical digestion takes place.

g)      Absorption: The simple molecules that result from chemical digestion pass through cell membranes of the lining in the small intestine into the blood or lymph capillaries. This process is called absorption.

h)      Elimination: The food molecules that cannot be digested or absorbed need to be eliminated from the body. The removal of indigestible wastes through the anus, in the form of feces, is defecation or elimination.

10)  Endocrine system and the immune system/lymphatics

a)       The endocrine system, along with the nervous system, functions in the regulation of body activities. The nervous system acts through electrical impulses and neurotransmitters to cause muscle contraction and glandular secretion. The effect is of short duration, measured in seconds, and localized. The endocrine system acts through chemical messengers called hormones that influence growth, development, and metabolic activities. The action of the endocrine system is measured in minutes, hours, or weeks and is more generalized than the action of the nervous system.

b)      There are two major categories of glands in the body - exocrine and endocrine.

i)        Exocrine Glands: Exocrine glands have ducts that carry their secretory product to a surface. These glands include the sweat, sebaceous, and mammary glands and, the glands that secrete digestive enzymes.

c)       Endocrine Glands: The endocrine glands do not have ducts to carry their product to a surface. They are called ductless glands. The word endocrine is derived from the Greek terms "endo," meaning within, and "krine," meaning to separate or secrete. The secretory products of endocrine glands are called hormones and are secreted directly into the blood and then carried throughout the body where they influence only those cells that have receptor sites for that hormone. The endocrine system is made up of the endocrine glands that secrete hormones. Although there are eight major endocrine glands scattered throughout the body, they are still considered to be one system because they have similar functions, similar mechanisms of influence, and many important interrelationships.

d)      Some glands also have non-endocrine regions that have functions other than hormone secretion. For example, the pancreas has a major exocrine portion that secretes digestive enzymes and an endocrine portion that secretes hormones. The ovaries and testes secrete hormones and also produce the ova and sperm. Some organs, such as the stomach, intestines, and heart, produce hormones, but their primary function is not hormone secretion.

e)       Chemical Nature of Hormones: Chemically, hormones may be classified as either proteins or steroids. All of the hormones in the human body, except the sex hormones and those from the adrenal cortex, are proteins or protein derivatives.

f)        Mechanism of Hormone: Action Hormones are carried by the blood throughout the entire body, yet they affect only certain cells. The specific cells that respond to a given hormone have receptor sites for that hormone. This is sort of a lock-and-key mechanism. If the key fits the lock, then the door will open. If a hormone fits the receptor site, then there will be an effect. If a hormone and a receptor site do not match, then there is no reaction. All the cells that have receptor sites for a given hormone make up the target tissue for that hormone. In some cases, the target tissue is localized in a single gland or organ. In other cases, the target tissue is diffuse and scattered throughout the body so that many areas are affected. Hormones bring about their characteristic effects on target cells by modifying cellular activity. Protein hormones react with receptors on the surface of the cell, and the sequence of events that results in hormone action is relatively rapid. Steroid hormones typically react with receptor sites inside a cell. Because this method of action actually involves synthesis of proteins, it is relatively slow.

g)      Control of Hormone Action: Hormones are very potent substances, which means that very small amounts of a hormone may have profound effects on metabolic processes. Because of their potency, hormone secretion must be regulated within very narrow limits in order to maintain homeostasis in the body. Many hormones are controlled by some form of a negative feedback mechanism. In this type of system, a gland is sensitive to the concentration of a substance that it regulates. A negative feedback system causes a reversal of increases and decreases in body conditions in order to maintain a state of stability or homeostasis. Some endocrine glands secrete hormones in response to other hormones. The hormones that cause secretion of other hormones are called tropic hormones. A hormone from gland A causes gland B to secrete its hormone. A third method of regulating hormone secretion is by direct nervous stimulation. A nerve stimulus causes gland A to secrete its hormone.

11)  The nervous system

a)      Cell types:

i)        Although the nervous system is very complex, there are only two main types of cells in nerve tissue. The actual nerve cell is the neuron. It is the "conducting" cell that transmits impulses and the structural unit of the nervous system. The other type of cell is neuroglia, or glial, cell. The word "neuroglia" means "nerve glue." These cells are nonconductive and provide a support system for the neurons. They are a special type of "connective tissue" for the nervous system.

ii)      Neurons: Neurons, or nerve cells, carry out the functions of the nervous system by conducting nerve impulses. They are highly specialized and amitotic. This means that if a neuron is destroyed, it cannot be replaced because neurons do not go through mitosis. The image below illustrates the structure of a typical neuron. Each neuron has three basic parts: cell body (soma), one or more dendrites, and a single axon.

iii)    Dendrites: Dendrites and axons are cytoplasmic extensions, or processes, that project from the cell body. They are sometimes referred to as fibers. Dendrites are usually, but not always, short and branching, which increases their surface area to receive signals from other neurons. The number of dendrites on a neuron varies. They are called afferent processes because they transmit impulses to the neuron cell body. There is only one axon that projects from each cell body. It is usually elongated and because it carries impulses away from the cell body, it is called an efferent process.

iv)    Axon: An axon may have infrequent branches called axon collaterals. Axons and axon collaterals terminate in many short branches or telodendria. The distal ends of the telodendria are slightly enlarged to form synaptic bulbs. Many axons are surrounded by a segmented, white, fatty substance called myelin or the myelin sheath. Myelinated fibers make up the white matter in the CNS, while cell bodies and unmyelinated fibers make the gray matter. The unmyelinated regions between the myelin segments are called the nodes of Ranvier. In the peripheral nervous system, the myelin is produced by Schwann cells. The cytoplasm, nucleus, and outer cell membrane of the Schwann cell form a tight covering around the myelin and around the axon itself at the nodes of Ranvier. This covering is the neurilemma, which plays an important role in the regeneration of nerve fibers. In the CNS, oligodendrocytes produce myelin, but there is no neurilemma, which is why fibers within the CNS do not regenerate. Functionally, neurons are classified as afferent, efferent, or interneurons (association neurons) according to the direction in which they transmit impulses relative to the central nervous system. Afferent, or sensory, neurons carry impulses from peripheral sense receptors to the CNS. They usually have long dendrites and relatively short axons. Efferent, or motor, neurons transmit impulses from the CNS to effector organs such as muscles and glands. Efferent neurons usually have short dendrites and long axons. Interneurons, or association neurons, are located entirely within the CNS in which they form the connecting link between the afferent and efferent neurons. They have short dendrites and may have either a short or long axon.

v)      Neuroglia: Neuroglia cells do not conduct nerve impulses, but instead, they support, nourish, and protect the neurons. They are far more numerous than neurons and, unlike neurons, are capable of mitosis.

b)     Peripheral nervous system

i)       The organs of the peripheral nervous system are the nerves and ganglia. Nerves are bundles of nerve fibers, much like muscles are bundles of muscle fibers. Cranial nerves and spinal nerves extend from the CNS to peripheral organs such as muscles and glands. Ganglia are collections, or small knots, of nerve cell bodies outside the CNS. The peripheral nervous system is further subdivided into an afferent (sensory) division and an efferent (motor) division. The afferent or sensory division transmits impulses from peripheral organs to the CNS. The efferent or motor division transmits impulses from the CNS out to the peripheral organs to cause an effect or action. Finally, the efferent or motor division is again subdivided into the somatic nervous system and the autonomic nervous system. The somatic nervous system, also called the somatomotor or somatic efferent nervous system, supplies motor impulses to the skeletal muscles. Because these nerves permit conscious control of the skeletal muscles, it is sometimes called the voluntary nervous system. The autonomic nervous system, also called the visceral efferent nervous system, supplies motor impulses to cardiac muscle, to smooth muscle, and to glandular epithelium. It is further subdivided into sympathetic and parasympathetic divisions. Because the autonomic nervous system regulates involuntary or automatic functions, it is called the involuntary nervous system.


c)     


Central nervous system:

i)        The brain and spinal cord are the organs of the central nervous system. Because they are so vitally important, the brain and spinal cord, located in the dorsal body cavity, are encased in bone for protection. The brain is in the cranial vault, and the spinal cord is in the vertebral canal of the vertebral column. Although considered to be two separate organs, the brain and spinal cord are continuous at the foramen magnum.

d)     Sympathetic and parasympathetic nervous system:

i)        Sympathetic Autonomic Nervous System: It is the part of the autonomic nervous system located near the thoracic and lumbar regions in the spinal cord. Its primary function is to stimulate the body’s fight-or-flight response. It does this by regulating the heart rate, rate of respiration, pupillary response and more.  Parasympathetic Autonomic Nervous System: It is located in between the spinal cord and the medulla. It primarily stimulates the body’s “rest and digest” and “feed and breed” responses. The sympathetic nervous system prepares the body for the “fight or flight” response during any potential danger. On the other hand, the parasympathetic nervous system inhibits the body from overworking and restores the body to a calm and composed state. The sympathetic and parasympathetic nervous systems are differentiated based on how the body responds to environmental stimuli.

(1)    Sympathetic: Involved in the fight or flight response, The sympathetic system prepares the body for any potential danger, Has a shorter neuron pathway hence a faster response time, Increases heartbeat, muscles tense up, the pupil dilates to let in more light, salivation is inhibited, In “fight and flight” situations, Adrenaline is released by the adrenal glands; more glycogen is converted to glucose.

(2)    Parasympathetic: Involved in maintaining homeostasis and also permits the rest and digest response, Aims to bring the body to a state of calm, Compatibly longer neuron pathways, hence a slower response time, Reduced heartbeat, muscles relaxes, the pupils contract, saliva secretion increases and digestion increases. No such functions exist in fight or flight situations.

e)      Autonomic vs Somatic nervous system

i)        The somatic nervous system is a component of the peripheral nervous system associated with the voluntary control of the body movements via the use of skeletal muscles. It is responsible for all the functions we are aware of and can consciously influence, including the movement of our arms legs and other parts of our body. A substantial portion of the peripheral nervous system is the 43 different segments of nerves- 12 pairs of cranial and 31 pairs of spinal nerves, which help us perform daily functions. The somatic nervous system consists of both afferent (sensory) and efferent (motor) nerves. It is also responsible for the reflex arc, which involves the use of interneurons to perform reflexive actions. Besides these, there are thousands of other association nerves in the body. Cranial nerves are responsible for carrying information in and out of the brain. Ten of the cranial nerves originate from the brain stem and mainly control the voluntary movement and structures of the head with some exceptions. The nucleus of the olfactory and optic nerve are located in the forebrain and thalamus, respectively, and are not considered true cranial nerves. The others originating from the brainstem include oculomotor, trochlear, trigeminal, abducens, facial, vestibulocochlear, glossopharyngeal, vagus, spinal accessory, and hypoglossal. Of note, the accessory nerve innervates the sternocleidomastoid and trapezius muscles, neither of which control muscles used exclusively in the head. Spinal nerves carry somatosensory information into and motor instructions out of the spinal cord. They arise from the spinal cord as nerve roots and merge to form a web (plexus) of interconnected nerve roots and once again branch to form nerve fibers. The formation of nerve plexuses rather than a direct continuation of the nerve roots to peripheral nerves serves as an essential safety measure so that injury at one site or body region may not affect the vital functions of our body. The spinal nerves help to control the function and movement for the rest of the body. The 31 pairs of spinal nerves include 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal. Their names match the adjacent spinal vertebra from which they exit. In the cervical region, the nerve root exits above the corresponding vertebrae (the nerve root between the skull and C1 vertebrae is the C1 spinal nerve). In the thoracic to the coccygeal region, the spinal nerve root originates below the corresponding vertebrae. The reason for this difference is due to the naming and location of the spinal root between C7 and T1 vertebrae (C8 spinal nerve root). In the lumbar region, the spinal cord ends at L1 from the region named conus medullaris, but the spinal nerve roots travel within the dural sac below the L2 level, this region is known as the cauda equina. Information in the form of electrical impulses is relayed to and from the CNS (brain and spinal cord) to the neuromuscular junction (NMJ), which converts electrical signals into chemical signals allowing for muscle contraction. Information from the periphery is detected by sensory receptors and coveted as electrical signals back to the central nervous system.

ii)      Structure and Function

iii)    The somatic nervous system contains both afferent nerves traveling from the periphery towards the CNS and efferent nerves that are responsible for sending signals from the CNS to the periphery. The brain and spinal cord are responsible for processing and integrating the various sources of information to allow us to develop a response. Therefore the main function of the somatic nervous system is to connect the CNS with organs and striated muscle to perform our daily functions. The basic motor pathway involves the upper motor neurons located in the precentral gyrus (primary motor cortex), which sends signals through the corticospinal tract via axons in the spinal cord to the lower motor neurons. These signals travel through the ventral horn of the spinal cord and synapse with the lower motor neurons and send their signals through peripheral axons to the NMJ of skeletal muscle. UMN release neurotransmitters acetylcholine, which binds to nicotinic acetylcholine receptors of the alpha-motor neurons creating a stimulus that propagates towards the NMJ, which innervates muscles. The peripheral(outside of the CNS) processes of the somatic nervous system form the somatic peripheral nerves, which are structurally and functionally different from the autonomic nervous system. The somatic peripheral nervous system is a single neuron system with the motor neurons lying inside the brainstem or spinal cord and the sensory neurons lying in the dorsal root ganglia. The autonomic peripheral nervous system is a two neuron system with a neuron lying outside of the CNS in the autonomic ganglia. The nerve fibers have different sizes with different conduction velocities. The size depends on the actual size of the axons and, more importantly, the degree of myelination, which provides electrical insulation and fast conduction seed through the so-called "saltatory conduction." The fastest conducting fibers are, therefore, the most heavily myelinated. They are the motor fibers from the motor neurons and sensory fibers serving discriminative touch, joint position, and vibratory sensations. The small fibers are mainly sensory fibers serving pain and temperature sensations. 

iv)    Somatic Reflex Arc: These are neural pathways that are responsible for the automatic response between a sensory and motor neuron. The sensory input generates a specific motor output. The simplest spinal reflex is mediated by a single synaptic process called the monosynaptic reflex. It contains only one synapse between the two neurons involved in the arc (sensory and motor). An example to illustrate this is the patellar reflex- Striking the patellar ligament just below the patella with a reflex hammer leads to automatic contraction of the quadriceps, this results in knee extension. The next order of a simple reflex involves two or more synapses termed the polysynaptic reflex (one or more interneurons). For example, the sensory neuron becomes stimulated, which activates the interneuron, which then directly stimulates the motor neuron, causing a movement.


If you made it this far....Im going to have to put you through more in the coming post, I hope you enjoyed it. 

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