Skeletal Muscle (mod2)

Question 1

What is a Skeletal Muscle Fiber?

Answer 1

Multinucleated, striated cells responsible for voluntary movement

Question 2

What is the Sarcolemma?

Answer 2

Plasma membrane of a muscle fiber

Question 3

Define Sarcoplasm.

Answer 3

Cytoplasm of a muscle fiber containing organelles and myofibrils

Question 4

What are Myofibrils?

Answer 4

Contractile units containing sarcomeres

Question 5

What is a Sarcomere?

Answer 5

Repeating unit in a myofibril, the functional unit of contraction

Question 6

What is Actin?

Answer 6

Thin filaments; binding sites for myosin

Question 7

What is Myosin?

Answer 7

Thick filaments; heads bind to actin

Question 8

What does the Troponin-Tropomyosin Complex do?

Answer 8

Regulates actin-myosin interaction

Question 9

What is the immediate energy source for muscle contraction?

Answer 9

ATP

Question 10

What role does Creatine Phosphate play in muscle contraction?

Answer 10

Rapidly regenerates ATP

Question 11

What is Glycolysis?

Answer 11

Anaerobic metabolism of glucose

Question 12

Define Oxidative Phosphorylation.

Answer 12

Aerobic metabolism of glucose and fatty acids

Question 13

What is the Neuromuscular Junction (NMJ)?

Answer 13

Synapse between the axon terminal of a motor neuron and the muscle fiber membrane

Question 14

Describe the activation process at the NMJ.

Answer 14

An action potential leads to calcium influx and release of acetylcholine (ACh) into the synaptic cleft

Question 15

What occurs when ACh binds to receptors on the muscle cell membrane?

Answer 15

Opens ion channels allowing sodium ions (Na+) to enter the muscle cell

Question 16

What triggers the release of calcium ions (Ca++) from the sarcoplasmic reticulum?

Answer 16

Muscle cell depolarization generating an action potential

Question 17

What happens during the Cross-Bridge Cycle?

Answer 17

ATP is hydrolyzed by myosin, allowing myosin heads to pull actin filaments inward

Question 18

What is a power stroke?

Answer 18

Myosin pulling actin filaments toward the center of the sarcomere

Question 19

What is required for myosin to detach from actin?

Answer 19

ATP

Question 20

What is Myasthenia Gravis (MG)?

Answer 20

An autoimmune disorder where antibodies block or destroy ACh receptors at the NMJ

Question 21

What is Duchenne Muscular Dystrophy (DMD)?

Answer 21

A genetic disorder caused by the absence of dystrophin, leading to muscle weakness

Question 22

What role does Dystrophin play in muscle cells?

Answer 22

Stabilizes the sarcolemma and helps thin filaments bind to it

Question 23

What are early symptoms of DMD?

Answer 23

Loss of muscle mass and difficulty with balance and motion

Question 24

What is muscle fatigue due to?

Answer 24

ATP depletion, ion imbalances, and accumulation of metabolic byproducts

Question 25

What is the role of ATP in muscle contraction?

Answer 25

Required for sustained contraction and relaxation

Question 26

What is the effect of Curare?

Answer 26

Blocks ACh receptors, leading to paralysis

Question 27

What is Botulism?

Answer 27

Illness caused by a toxin that inhibits ACh release, leading to muscle paralysis

Question 28

Define Motor Unit.

Answer 28

A motor neuron and all the muscle fibers it innervates

Question 29

What is Muscle Tone?

Answer 29

Continuous low-level muscle activity

Question 30

What are Neurons?

Answer 30

Cells that transmit electrical signals in the nervous system

Question 31

What is the function of Dendrites?

Answer 31

Receive input from other neurons

Question 32

What does the Axon do?

Answer 32

Conducts action potentials

Question 33

What is the Resting Membrane Potential?

Answer 33

Maintained at -70 mV with voltage-gated channels closed

Question 34

What occurs during Depolarization?

Answer 34

Na⁺ channels open, causing membrane voltage to rise toward +30 mV

Question 35

What is Hyperpolarization?

Answer 35

Membrane potential temporarily below resting level (about -90 mV)

Question 36

What is Continuous Conduction?

Answer 36

Slow propagation of an action potential along an unmyelinated axon

Question 37

What is Saltatory Conduction?

Answer 37

Quick propagation of the action potential along a myelinated axon

Question 38

What is Synaptic Transmission?

Answer 38

Release of neurotransmitters from the presynaptic neuron to the postsynaptic neuron

Question 39

What are Excitatory postsynaptic potentials (EPSPs)?

Answer 39

Depolarize the membrane

Question 40

What are Inhibitory postsynaptic potentials (IPSPs)?

Answer 40

Hyperpolarize the membrane

Question 41

What is the Sensory Cortex?

Answer 41

Processes sensory information

Question 42

What do Chemoreceptors detect?

Answer 42

Chemicals (e.g., taste, smell)

Question 43

What do Exteroceptors interpret?

Answer 43

Stimuli from the external environment

Question 44

What do Proprioceptors sense?

Answer 44

Changes in body position and kinesthetic aspects

Question 45

What is the role of the Hypothalamus?

Answer 45

Controls the autonomic nervous system and regulates body functions

Question 46

What are Sympathomimetics?

Answer 46

Drugs that mimic sympathetic responses

Question 47

What are First-Class Levers?

Answer 47

Fulcrum is between the effort and resistance (e.g., neck extension)

Question 48

What are Third-Class Levers?

Answer 48

Effort is between the fulcrum and resistance (e.g., bicep curls)