Anatomy & Physiology Study Notes: Cellular, Skeletal, Muscular, and Nervous Systems

Module 1: The Cellular Level of Organization

Macromolecules: Proteins

Proteins are essential macromolecules in cells, performing a wide range of structural and functional roles.

• Definition: Proteins are polymers of amino acids linked by peptide bonds.

• Functions: Enzymatic catalysis, structural support (e.g., collagen), transport (e.g., hemoglobin), signaling (e.g., hormones), and immune defense (e.g., antibodies).

• Structure: Four levels—primary, secondary, tertiary, and quaternary.

• Example: Actin and myosin are proteins involved in muscle contraction.

Plasma Membrane: Properties and Transport

The plasma membrane regulates the movement of substances into and out of the cell, maintaining homeostasis.

• Structure: Composed of a phospholipid bilayer with embedded proteins, cholesterol, and carbohydrates.

• Transport Mechanisms:

  • Passive Transport: Diffusion, osmosis, and facilitated diffusion (no energy required).

  • Active Transport: Requires ATP; includes pumps (e.g., sodium-potassium pump).

• Example: Glucose enters cells via facilitated diffusion through carrier proteins.

Labelled Cell: Structure and Function

Cells contain various organelles, each with specialized functions necessary for life.

• Nucleus: Contains genetic material (DNA); controls cell activities.

• Mitochondria: Site of ATP production via cellular respiration.

• Endoplasmic Reticulum (ER): Rough ER synthesizes proteins; smooth ER synthesizes lipids.

• Golgi Apparatus: Modifies, sorts, and packages proteins and lipids.

• Lysosomes: Contain digestive enzymes for breaking down waste.

• Example: Pancreatic cells have abundant rough ER for protein secretion.

Module 2: Bones and Bone Structure

Bone Types

Bones are classified based on their shapes and functions in the skeletal system.

• Long Bones: Found in limbs (e.g., femur, humerus); support weight and facilitate movement.

• Short Bones: Cube-shaped (e.g., carpals, tarsals); provide stability and support.

• Flat Bones: Thin and broad (e.g., skull, ribs); protect internal organs.

• Irregular Bones: Complex shapes (e.g., vertebrae, pelvis).

• Sesamoid Bones: Embedded in tendons (e.g., patella).

Calcium Homeostasis

Calcium levels in the blood are tightly regulated by hormonal control to support bone health and physiological functions.

• Key Hormones:

  • Parathyroid Hormone (PTH): Increases blood calcium by stimulating bone resorption.

  • Calcitonin: Lowers blood calcium by inhibiting bone resorption.

  • Vitamin D: Enhances calcium absorption from the gut.

• Equation: $\text{Ca}^{2+}_{\text{blood}} \xleftrightarrow{PTH,\ Calcitonin} \text{Ca}^{2+}_{\text{bone}}$

• Example: In hypocalcemia, PTH is released to increase blood calcium levels.

Module 3: Muscle Tissue and Muscular System

Muscle Compartments and Nerve Supply (Upper and Lower Limbs)

Muscle compartments are groups of muscles with similar functions and shared nerve and blood supply.

• Upper Limb Compartments:

  • Anterior Compartment: Flexors of the forearm; innervated by the median and musculocutaneous nerves.

  • Posterior Compartment: Extensors of the forearm; innervated by the radial nerve.

• Lower Limb Compartments:

  • Anterior Compartment: Extensors of the knee; innervated by the femoral nerve.

  • Posterior Compartment: Flexors of the knee; innervated by the tibial nerve.

  • Medial Compartment: Adductors of the thigh; innervated by the obturator nerve.

• Example: Injury to the radial nerve affects extension of the wrist and fingers.

Module 4: Nervous Tissue and Brain Vasculature

Action Potential

An action potential is a rapid electrical signal that travels along the membrane of a neuron.

• Phases:

  • Depolarization: Sodium channels open, Na+ enters the cell.

  • Repolarization: Potassium channels open, K+ exits the cell.

  • Hyperpolarization: Membrane potential becomes more negative than resting.

• Equation: $V_m = V_{rest} + \Delta V_{Na^+} - \Delta V_{K^+}$

• Example: Action potentials allow communication between neurons and muscle cells.

Neuroglial Cells

Neuroglial cells support and protect neurons in the central and peripheral nervous systems.

• Types:

  • Astrocytes: Maintain blood-brain barrier, provide nutrients.

  • Oligodendrocytes: Form myelin in the CNS.

  • Schwann Cells: Form myelin in the PNS.

  • Microglia: Act as immune cells in the CNS.

  • Ependymal Cells: Line ventricles, produce cerebrospinal fluid.

• Example: Multiple sclerosis involves damage to oligodendrocytes and myelin.

Vessels of the Brain

The brain receives blood through a network of arteries, ensuring oxygen and nutrient delivery.

• Main Arteries:

  • Internal Carotid Arteries: Supply anterior brain regions.

  • Vertebral Arteries: Merge to form the basilar artery, supplying posterior brain regions.

  • Circle of Willis: An arterial ring providing collateral circulation.

• Example: Stroke can occur if blood flow through these vessels is blocked.

Neuroglial Cell	Location	Function
Astrocyte	CNS	Support, blood-brain barrier
Oligodendrocyte	CNS	Myelination
Schwann Cell	PNS	Myelination
Microglia	CNS	Immune defense
Ependymal Cell	CNS	CSF production

Additional info: Academic context and examples have been added to expand on the brief points in the original file.