Ch 8 Test Materials

Question 1

Muscle Structure and Force Generation

Answer 1

Specialized cellular composition: Muscles are made of muscle fibers (cells) containing proteins like actin and myosin. These fibers contract, sliding past each other, generating force and movement.

Question 2

Types of Muscle Tissue

Answer 2

Skeletal muscle: Voluntary, striated, attaches to bones, and is responsible for body movement.
Cardiac muscle: Involuntary, striated, found in the heart.
Smooth muscle: Involuntary, non-striated, found in the walls of internal organs.

Question 3

Connective Tissue covering muscles

Answer 3

Epimysium: The outer layer of connective tissue that surrounds the entire muscle.

Question 4

Connective Tissue

Answer 4

Connective tissue consists of cells and extracellular matrix, and it supports, binds, and insulates organs and tissues.

Question 5

Actin

Answer 5

Actin is a thin protein filament involved in muscle contraction. It forms part of the sarcomere in muscle fibers.

Question 6

Myosin

Answer 6

Myosin is a thick protein filament that interacts with actin to produce muscle contraction.

Question 7

Striations in Skeletal Muscle

Answer 7

Striations are caused by the arrangement of actin and myosin filaments within the muscle fiber, creating alternating light and dark bands.

Question 8

Neuromuscular Junction

Answer 8

The site where a motor neuron meets a muscle fiber, transmitting nerve impulses for contraction.

Question 9

Motor Neurons

Answer 9

Nerve cells that transmit electrical impulses to muscles, causing them to contract.

Question 10

Neurotransmitter Secretion

Answer 10

Neurotransmitters (e.g., acetylcholine) are released from synaptic vesicles in the axon terminal, crossing the synapse to bind with receptors on muscle fibers.

Question 11

Muscle Fiber Contraction

Answer 11

A muscle contracts when the motor neuron releases acetylcholine, which triggers the muscle’s action potential and initiates the sliding filament mechanism between actin and myosin.

Question 12

Cross-Bridge Linkages

Answer 12

The connection formed when the myosin head binds to actin, allowing for muscle contraction.

Question 13

Force Generation in Muscular Contraction

Answer 13

The force of contraction comes from the repeated cross-bridge cycling between actin and myosin filaments.

Question 14

Acetylcholine (ACh)

Answer 14

A neurotransmitter that stimulates muscle contraction at the neuromuscular junction.

Question 15

Muscle Fiber Shortening

Answer 15

The interaction between actin and myosin causes the sarcomere to shorten, which in turn shortens the muscle fiber.

Question 16

Acetylcholinesterase

Answer 16

An enzyme that breaks down acetylcholine in the synaptic cleft, ending the signal and allowing the muscle to relax.

Question 17

ATP

Answer 17

ATP (Adenosine Triphosphate) is the energy source for muscle contraction. It provides the energy needed for the cross-bridge cycle and pumps calcium back into the sarcoplasmic reticulum.

Question 18

Creatine Phosphate

Answer 18

A molecule that helps regenerate ATP in muscles during short bursts of intense activity.

Question 19

Cellular Respiration

Answer 19

The process by which cells produce ATP from nutrients, typically involving glycolysis, the citric acid cycle, and oxidative phosphorylation.

Question 20

Aerobic Respiration

Answer 20

ATP production using oxygen, typically producing more ATP than anaerobic processes.

Question 21

Myoglobin

Answer 21

A protein that binds oxygen in muscle cells, aiding in oxygen storage and delivery during muscle activity.

Question 22

Oxygen Debt

Answer 22

The amount of oxygen required to restore muscle cells to their pre-exercise state (replenishing oxygen stores and removing lactic acid).

Question 23

Lactic Acid

Answer 23

Produced during anaerobic respiration when oxygen is insufficient, leading to muscle fatigue and soreness.

Question 24

Muscle Fatigue

Answer 24

Caused by prolonged activity, leading to a decrease in muscle’s ability to contract due to factors like depleted energy stores or lactic acid accumulation.

Question 25

Heat Generation

Answer 25

Muscle contractions produce heat as a byproduct, helping to maintain body temperature.

Question 26

Threshold Stimulus

Answer 26

The minimum stimulus required to trigger a muscle contraction.

Question 27

Muscle Twitch

Answer 27

A brief, single contraction in response to a single stimulus.

Question 28

Myogram

Answer 28

A graphical recording of muscle activity, showing contraction time and force.

Question 29

EMG (Electromyography)

Answer 29

A technique used to measure the electrical activity of muscles.

Question 30

Summation of Twitches

Answer 30

The process by which twitches combine to produce a stronger contraction due to increased frequency of stimulation.

Question 31

Partial Tetanic Contraction

Answer 31

A muscle contraction that is not fully sustained but has a high frequency of stimuli.

Question 32

Complete Tetanic Contraction

Answer 32

A sustained muscle contraction with no relaxation between stimuli, leading to a smooth and continuous contraction.

Question 33

Motor Unit

Answer 33

A motor neuron and all the muscle fibers it innervates. The number of fibers in a motor unit varies depending on the precision of the movement.

Question 34

Muscle Recruitment

Answer 34

The process of activating more motor units to increase muscle strength during contraction.

Question 35

Muscle Tone

Answer 35

The constant, low-level contraction of muscles that helps maintain posture and stabilize joints.

Question 36

Isotonic Contraction

Answer 36

A muscle contraction in which the muscle changes length (either shortening or lengthening) while generating constant force.

Question 37

Isometric Contraction

Answer 37

A muscle contraction where the muscle generates force but does not change length.

Question 38

Similarities in Skeletal and Smooth Muscle Contraction

Answer 38

Both rely on actin and myosin filaments for contraction, but smooth muscle does not have striations.

Question 39

Norepinephrine

Answer 39

A neurotransmitter involved in smooth muscle contraction and the regulation of heart rate.

Question 40

Duration of Contraction: Skeletal vs. Smooth Muscle

Answer 40

Smooth muscle can maintain contraction longer due to slower cross-bridge cycling and less energy consumption compared to skeletal muscle.

Question 41

Intercalated Disks

Answer 41

Specialized connections between cardiac muscle cells that allow for synchronized contraction.

Question 42

Joint Movement and Skeletal Muscle

Answer 42

The type of movement depends on the arrangement of the muscle relative to the joint and the specific muscle action.

Question 43

Origin of a Muscle

Answer 43

The fixed attachment point of a muscle, typically closer to the body's core.

Question 44

Insertion of a Muscle

Answer 44

The movable attachment point of a muscle, typically located farther from the body's center.

Question 45

Agonist

Answer 45

The primary muscle responsible for a specific movement (e.g., biceps during arm flexion).

Question 46

Antagonist

Answer 46

The muscle that opposes the agonist, helping to control the movement (e.g., triceps during arm flexion).

Question 47

Facial Expression Muscles

Answer 47

Muscles like the orbicularis oculi, orbicularis oris, and zygomaticus

Question 48

Major Muscles of Mastication

Answer 48

Muscles like the masseter, temporalis, and pterygoid

Question 49

Muscles of the Pectoral Girdle

Answer 49

Muscles like the trapezius, pectoralis minor, and serratus anterior

Question 50

Muscles that Move the Arm

Answer 50

Muscles like the deltoid, biceps brachii, and triceps brachii

Question 51

Muscles that Move the Hand

Answer 51

Flexor and extensor muscles, such as flexor carpi radialis and extensor digitorum

Question 52

Muscles of the Abdominal Wall and Pelvic Girdle

Answer 52

Muscles like the rectus abdominis, external oblique, and diaphragm.

Question 53

Muscles of the Pelvic Floor

Answer 53

Muscles like the levator ani and coccygeus

Question 54

Muscles that Move the Thigh and Pelvic Girdle

Answer 54

Muscles like the gluteus maximus, iliopsoas, and adductors

Question 55

Muscles that Move the Leg

Answer 55

Muscles like the quadriceps and hamstrings

Question 56

Muscles that Move the Foot

Answer 56

Muscles like the tibialis anterior, gastrocnemius, and soleus