Phys Unit 2 - Muscle Physiology

Muscle cells are capable of converting chemical energy to:

Mechanical energy

What are the three types of muscle tissue?

Skeletal, smooth, and cardiac muscle.

Muscle maintains length but produces internal tension

Isometric Contraction

Muscle changes in length with no change in tension

Isotonic Contraction

Muscle shortens

Concentric Isotonic Contraction

Muscle Lengthens

eccentric isotonic contraction

Type of muscle that is striated, voluntary, multinucleate, has parallel fibers

Skeletal muscle

Type of muscle that is striated, involuntary, has branching cells, is uninucleate, has intercalated discs, and is myogenic

Cardiac muscle

Type of muscle that is fat in the middle with tapered ends, uninucleate, non-striated, involuntary, and can be either myogenic or multiunit

Smooth muscle

First phase of muscle contraction

Excitation

second phase of muscle contraction

excitation-contraction coupling

third phase of muscle contraction

contraction

fourth phase of muscle contraction

relaxation

Staircase phenomenon with high stimulation

Treppe

No time to return to baseline between twitches (20-40 stim/sec)

Incomplete tetanus

No time to relax at all between stimuli (40-50 stim/sec)

Complete tetanus

Decreased ability of a fiber to produce tension despite continued stimulation

Fatigue

Produces greatest force when muscle contracts

Optimum resting length

A state of partial contraction maintained by the nervous system

muscle tone

Multi motor unit recruitment

spatial summation

AP triggered in the same muscle fiber consecutively, may lead to tetany

Temporal Summation

Initial sarcomere length = overly contracted

weak contraction

A form of spastic paralysis caused by toxin of Clostridium tetani

Tetanus (lock jaw)

Muscle is limp and cannot contract

Flaccid paralysis

Food poisoning caused by neuromuscular toxin of Clostridium botulinum

Botulism

Where calcium is stored in muscles

terminal cisternae

if too stretched before stimulated

a weak contraction results

stiffness in muscles after death, Actin-myosin cross-bridging can't be broken in absence of ATP

rigor mortis

Autoimmune disease in which antibodies attack neuromuscular junctions and bind ACh receptors together in clusters

myasthenia gravis

Group of hereditary diseases in which skeletal muscles degenerate and weaken, and are replaced with fat and fibrous scar tissue

Muscular dystrophy

Type of MD occurring in males

Duchenne muscular dystrophy

Type of MD that affects facial and shoulder muscles more than pelvic muscles (occurs in both sexes equally)

Facioscapulohumeral MD

Type of MD that affects shoulder, arm, and pelvic muscles

Limb-girdle dystrophy

Reflex testing function of corticospinal tract

Babinski reflex

"Jerk" reflex (as when falling asleep in class)

Myotaxic (stretch) reflex

nerve endings that respond to duration of stretch stimulus

secondary afferent fibers

Proprioceptors embedded in collagen fibers on tendons

Golgi Tendon Organ (GTO)

Stretch receptor inside of muscle that sends info to the cerebellum

muscle spindle

Starts at ventral horn, responds to tension; keeps muscle spindle fibers taut and responsive even when muscle shortens

Gamma motor neuron

nerve endings that respond to onset of stretch stimulus

primary afferent fibers

Number 1 on the diagram

Normal contraction

Number 2 on the diagram

Treppe

Number 3 on the diagram

Incomplete tetany

Number 4 on the diagram

complete tetany

Number 5 on the diagram

Fatigue

Contractile protein

myosin

Filament that blocks actin-binding site

Tropomyosin

Calcium-binding protein

Troponin (Tn)

Protein that links actin in outermost myofilaments to transmembrane proteins and fibrous endomysium

Dystrophin

Functional contractile unit of a muscle fiber

Sarcomere

One neuron and all the muscle fibers it innervates

motor unit

What are the only two electrically excitable cell types in the human body?

Nervous system and muscle cells

The amount of tension generated by a muscle + the force of contraction

Length-tension relationship

Type of twitch fiber that fatigues slowly, uses aerobic respiration, and is red in color

Slow twitch (Type I/Slow Oxidative)

Type of twitch fiber that fatigues slowly, contracts quickly, and is good for long periods of strenuous exercise

Fast Twitch - Oxidative

Type of twitch fiber that fatigues and contracts quickly, good for short periods of strenuous activity

Fast Twitch - Glycolytic

Type of muscle metabolism using creatine phosphate

Direct phosphorylation

Type of muscle metabolism with high ATP yield, CO2 and H2O byproducts

Oxidative phosphorylation

Type of muscle metabolism that has low ATP yield, lactic acid byproduct

Anaerobic fermentation (glycolysis)