Muscle Physiology

Question 1

Skeletal Muscle

Answer 1

Skeletal muscle fibers are long, multinucleated cells. Blood vessels and nerves enter the connective tissue and branch in the cell. Muscles attach to bones directly or through tendons or aponeuroses. Function: maintain posture, stabilize bones and joints, control internal movement, and generate heat

Question 2

Smooth Muscle

Answer 2

Nonstriated involuntary muscle in the wall of many visceral organs.

Question 3

Cardiac Muscle

Answer 3

performs coordinated contractions that allow your heart to pump blood through the your circulatory system

Question 4

Sarcolemma

Answer 4

The plasma membrane of a muscle cell. It acts as a barrier between the extracellular and intracellular compartments, defining the individual muscle fiber from its surroundings.

Question 5

Sarcoplasm

Answer 5

the cytoplasm of a muscle containing ATP and phosphagens, as well as the enzymes and intermediate and product molecules involved in many metabolic reactions

Question 6

Sarcoplasmic Reticulum (ER)

Answer 6

membrane-bound structure found within muscle cells that is similar to the endoplasmic reticulum in other cells. The main function of the SR is to store calcium ions (Ca2+) regulates the cytoplasmic calcium ions (Ca2+) concentration of skeletal muscle cells, and thereby controls muscular contraction and relaxation.

Question 7

Sarcomere

Answer 7

The smallest contractile unit of a striated cell. composed of two main protein filaments—actin and myosin—which are the active structures responsible for muscular contraction.

Question 8

Terminal Cisternae

Answer 8

One of the areas of the sarcoplasmic reticulum of striated muscle cells, surrounding T tubules, that are able to store calcium and release it when an action potential courses down the T tubules.

Question 9

Triad

Answer 9

the structure formed by a T tubule with a sarcoplasmic reticulum (SR) known as the terminal cisterna on either side. Each skeletal muscle fiber has many thousands of triads

Question 10

Myosin (Think Filaments)

Answer 10

a protein that converts chemical energy in the form of ATP to mechanical energy, generating force and movement

Question 11

Fascicle

Answer 11

a bundle of skeletal muscle fibers surrounded by perimysium, a type of connective tissue. affects the muscle’s range of motion

Question 12

Troponin

Answer 12

Globular muscle protein that binds to
tropomyosin. a calcium-regulatory protein for the calcium regulation of contractile function in skeletal and cardiac muscles

Question 13

Tropomyosin

Answer 13

Fibrous muscle protein that covers
active sites on G actin and prevents actin-myosin
interaction.

Question 14

Acetylcholine (ACh)

Answer 14

A chemical neurotransmitter in the brain and peripheral nervous system; the dominant neurotransmitter in the peripheral nervous system, released at neuromuscular junctions and synapses of the parasympathetic division.

Question 15

Acetylcholinesterase (AChE)

Answer 15

An enzyme found in the synaptic cleft, bound to the postsynaptic membrane, and in tissue fluids; breaks down and inactivates acetylcholine molecules; also called cholinesterase

Question 16

Action Potentials

Answer 16

A propagated change in the membrane potential of excitable cells, initiated by a change in the membrane permeability to sodium ions

Question 17

Cross Bridges

Answer 17

The binding of a myosin head that projects from the surface of a thick filament at the active site of a thin filament in the presence of calcium ions.

Question 18

Titin

Answer 18

A large protein that is a bundle of skeletal muscle fibers surrounded by perimysium, a type of connective tissue

Question 19

Neuromuscular Junction

Answer 19

a chemical synapse between a motor neuron and a muscle fiber. It allows the motor neuron to transmit a signal to the muscle fiber, causing muscle contraction

Question 20

Motor End Plate

Answer 20

specialised chemical synapses formed at the sites where the terminal branches of the axon of a motor neuron contact a target muscle cell

Question 21

Repolarisation

Answer 21

The movement of the membrane
potential away from a positive value and toward
the resting potential

Question 22

Relaxation Phase

Answer 22

The period after a contraction when the tension in the muscle fiber returns to resting levels

Question 23

Excitation-contraction coupling

Answer 23

the physiological process of converting an electrical stimulus to a mechanical response…

Question 24

Contraction Cycle

Answer 24

muscle contraction is a cycle of molecular events in which thick myosin filaments repeatedly attach to and pull on thin actin filaments, so the filaments slide over one another. The actin filaments are attached to Z discs, each of which marks the end of a sarcomere

Question 25

Contraction Phase

Answer 25

when the muscle is generating tension and is associated with cycling of the cross bridges

Question 26

Wave Summation

Answer 26

when another stimulus is applied to a muscle before the previous relaxation period is complete, resulting in a stronger contraction

Question 27

Power Strokes

Answer 27

As the actin is pulled, the filaments move approximately 10 nm toward the M line.

Question 28

Isotonic Contraction

Answer 28

generate force by changing the length of the muscle and can be concentric contractions or eccentric contractions. A concentric contraction causes muscles to shorten, thereby generating force. Eccentric contractions cause muscles to elongate in response to a greater opposing force

Question 29

Isometric Contraction

Answer 29

the muscle is activated, but instead of being allowed to lengthen or shorten, it is held at a constant length e.g. ...

Question 30

Muscle Tension

Answer 30

muscles of the body remain semi-contracted for an extended period

Question 31

Length-tension Relationship

Answer 31

he observation that single muscle fibers do not produce the same amount of isometric force when they are activated at different static lengths