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Anatomy & Physiology: Muscle and Nervous System Study Guide

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  • Connective tissue layers of muscle from outside to inside
    Epimysium surrounds entire muscle, Perimysium surrounds fascicles, Endomysium surrounds individual muscle fibers.
  • Types of fascicle arrangements
    Parallel: fibers run parallel (e.g., sartorius), Pennate: feather-like (uni-, bi-, multipennate), Convergent: broad origin to narrow insertion, Circular: surrounds openings (e.g., orbicularis oris).
  • Order of skeletal muscle organization from largest to smallest
    Muscle → Fascicle → Muscle fiber (cell) → Myofibril → Sarcomere → Myofilaments.
  • Sarcomere regions and their filament composition
    Z disc: sarcomere boundary, A band: thick filaments, I band: thin filaments only, H zone: thick filaments only, M line: center of sarcomere.
  • What happens to sarcomere bands during muscle contraction?
    I band shortens, H zone shortens, A band stays the same length.
  • Main proteins in thick and thin filaments
    Thick filament: Myosin. Thin filament: Actin, Troponin, Tropomyosin.
  • Role of tropomyosin and troponin in muscle contraction
    Tropomyosin blocks actin binding sites; Troponin binds calcium and moves tropomyosin to expose active sites.
  • Sequence of events in the sliding filament theory
    Calcium released → binds troponin → tropomyosin moves → myosin binds actin → power stroke → ATP binds myosin → myosin detaches → ATP hydrolyzed → head resets.
  • Why is ATP needed in muscle contraction?
    ATP is required for myosin detachment from actin, re-cocking the myosin head, and powering the calcium pump.
  • Role of calcium in muscle contraction
    Calcium binds to troponin, causing tropomyosin to move and expose active sites on actin, enabling contraction.
  • Steps at the neuromuscular junction to initiate muscle contraction
    Action potential arrives → calcium enters neuron → acetylcholine released → ACh binds receptors → sodium channels open → depolarization → muscle action potential → calcium released from SR → contraction.
  • Function of acetylcholine and acetylcholinesterase at NMJ
    Acetylcholine stimulates muscle contraction; acetylcholinesterase breaks down ACh to stop stimulation.
  • Difference between isometric and isotonic muscle contractions
    Isometric: tension changes, length stays same (e.g., holding dumbbell still). Isotonic: muscle length changes; concentric shortens, eccentric lengthens.
  • Components of a lever system in the body
    Fulcrum: pivot point, Effort: force applied, Load: resistance.
  • Functions of the masseter and sternocleidomastoid muscles
    Masseter: chewing. Sternocleidomastoid: rotates and flexes neck.
  • Muscles involved in breathing
    Diaphragm and intercostals.
  • Four rotator cuff muscles (SITS)
    Supraspinatus, Infraspinatus, Teres minor, Subscapularis.
  • Muscle adaptation: hypertrophy
    Increase in muscle size due to increased workload, resistance training, and increased myofibrils/protein synthesis.
  • Neuron parts and their functions
    Dendrites: receive signals, Cell body: control center, Axon: conducts impulse, Synaptic terminal: releases neurotransmitter.
  • Myelin-producing cells in CNS and PNS
    CNS: oligodendrocytes. PNS: Schwann cells.
  • Resting membrane potential and ion distribution
    About -70 mV; more sodium outside, more potassium inside the cell.
  • What occurs during depolarization and hyperpolarization?
    Depolarization: membrane becomes less negative (sodium enters). Hyperpolarization: membrane becomes more negative (potassium leaves or chloride enters).
  • Threshold potential for triggering an action potential
    Usually around -55 mV.
  • Saltatory conduction
    Impulse jumps from node to node along myelinated axons, increasing conduction speed.
  • Difference between absolute and relative refractory periods
    Absolute: neuron cannot fire again. Relative: neuron can fire if stimulus is strong enough.
  • Inhibitory neurotransmitter example
    GABA is an inhibitory neurotransmitter.
  • Functions of the frontal, temporal, parietal, and occipital lobes
    Frontal: motor, personality, planning. Temporal: hearing, memory. Parietal: somatosensory. Occipital: vision.
  • Primary motor and somatosensory cortex functions
    Primary motor cortex controls voluntary movement; primary somatosensory cortex processes touch sensation.
  • Functions of the hypothalamus
    Regulates temperature, hunger/thirst, endocrine control, and autonomic nervous system.
  • Role of the cerebellum
    Coordinates movement, balance, and motor learning.