A comprehensive, all-encompassing guide that prepares you for final exams with detailed explanations across all major anatomical systems.
Complete Systems Overview: Covers musculoskeletal, cardiovascular, respiratory, digestive, and nervous systems, including neuron functions, muscle contraction...
● Anterior/Posterior:
○ Anterior: Refers to the front of the body (e.g., the chest is anterior to the
spine).
○ Posterior: Refers to the back of the body (e.g., the spine is posterior to the
sternum).
● Superior/Inferior:
○ Superior: Towards the head or upper body (e.g., the head is superior to the
abdomen).
○ Inferior: Away from the head, towards the lower part of the body (e.g., the
feet are inferior to the knees).
● Proximal/Distal:
○ Proximal: Closer to the origin of the body part or point of attachment (e.g.,
the shoulder is proximal to the hand).
○ Distal: Farther from the origin or attachment (e.g., the fingers are distal to
the elbow).
● Rostral/Caudal:
○ Rostral: Towards the nose or mouth, often used in the context of the head.
○ Caudal: Towards the tail or posterior part of the body.
Neurons and Neuroglial Cells
● Central Nervous System (CNS):
○ Neurons:
1. Multipolar neurons dominate, responsible for integrating and
transmitting signals.
○ Neuroglia:
1. Astrocytes: Support neurons, maintain the blood-brain barrier,
and regulate ion concentrations.
2. Oligodendrocytes: Form myelin sheaths in the CNS for faster
signal conduction.
3. Microglia: Act as immune cells, cleaning debris and protecting
against pathogens.
4. Ependymal Cells: Line the ventricles and produce cerebrospinal
fluid (CSF).
● Peripheral Nervous System (PNS):
, ○ Neurons:
1. Unipolar neurons for sensory input and multipolar neurons for
motor responses.
○ Neuroglia:
1. Schwann Cells: Produce myelin for axons in the PNS.
2. Satellite Cells: Support neurons in ganglia, similar to astrocytes
in function.
Skeletal Muscle Organization
● Structure Hierarchy:
1. Epimysium: Outer layer encasing the entire muscle.
2. Perimysium: Surrounds fascicles (bundles of muscle fibers).
3. Endomysium: Surrounds individual muscle fibers.
4. Muscle Fibers: Contain myofibrils made of actin and myosin filaments.
5. Sarcomere: The functional unit, responsible for contraction through the
sliding filament theory.
Neuromuscular Junction (NMJ) and Contraction
● Steps in Contraction:
1. Action Potential Arrival: A nerve impulse reaches the NMJ.
2. Acetylcholine Release: The neurotransmitter binds to receptors on the
sarcolemma.
3. Depolarization: Sodium channels open, triggering action potentials in
the muscle fiber.
4. Calcium Release: Action potentials cause the sarcoplasmic reticulum to
release calcium ions.
5. Cross-Bridge Formation: Calcium binds to troponin, moving
tropomyosin and allowing actin-myosin binding.
6. Power Stroke: Myosin pulls actin, shortening the sarcomere.
7. Relaxation: Calcium is reabsorbed, and the muscle relaxes.
Bone Ossification
1. Intramembranous Ossification:
, ○ Process: Bone develops directly from mesenchymal tissue. Occurs at 5-6
weeks in embryonic development.
○ Examples: Flat bones of the skull, clavicle.
2. Endochondral Ossification:
○ Process: Bone forms by replacing hyaline cartilage. Occurs from 2nd
month all the way to adulthood and is indirect.
○ Examples: Long bones like the femur and humerus.
Compact vs. Spongy Bone
● Compact Bone: Dense and strong; found in the diaphysis of long bones.
● Spongy Bone: Porous; contains red marrow and is found in the epiphyses of
long bones and flat bones like the sternum.
Location of Red Bone Marrow:
● Found in spongy bone, particularly in the pelvis, sternum, vertebrae, and ends of
long bones.
Clinical Conditions
1. Osteoporosis: Loss of bone density, increasing fracture risk.
○ Causes: Aging, reduced estrogen/testosterone, and low calcium intake.
○ Treatment: Calcium, vitamin D, weight-bearing exercise, and
medications (e.g., bisphosphonates).
2. Osteomalacia: Softening of bones due to vitamin D deficiency in adults.
3. Osteosarcoma: Aggressive bone cancer, commonly affecting the metaphysis of
long bones.
4. Arthritis: Inflammation of joints, categorized as osteoarthritis (wear-and-tear)
or rheumatoid arthritis (autoimmune).
Atherosclerosis
● Definition: Hardening and narrowing of arteries due to plaque buildup.
● Formation: Lipid deposition, immune response, and smooth muscle
proliferation.
● Clinical Significance: Can lead to heart attack or stroke.
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