Muscular System

Question 1

What is the role of creatine phosphate in energy production of muscle cells? How long does it last?

Answer 1

It has an extra phosphate to give so it can donate one to ADP after ATP has depleted and this generates more ATP (energy). CP supplies only last 15 seconds.

Question 2

What are the major differences between aerobic and anaerobic glycolysis? How much ATP is formed and what by-products?

Answer 2

Aerobic requires oxygen and glucose and produces 36 ATP as well as carbon dioxide and water. Anaerobic happens when you don’t have extra oxygen so you just break down glucose. The glucose breaks down into pyruvic acid which converts to lactic acid which accumulates in muscle and stores in liver. Requires huge amounts of glucose and only produces 2 ATP, but very fast.

Question 3

How is myoglobin involved in energy production of muscle cells?

Answer 3

It is where oxygen is stored in your muscles

Question 4

What is meant by oxygen debt?

Answer 4

Oxygen must be repaid to tissue to remove deficit and create more ATP and CP. Oxygen is required to get rid of lactic acid.

Question 5

Name the 3 types of muscle tissue, where they are found in the body, and give a description of each type as seen under the microscope

Answer 5

Skeletal muscles move your body and are contracted voluntarily. They are striated (striped) with alternating light and dark bands. Cardiac muscle is the heart muscle and is involuntary. Looks similar to skeletal muscle with less striation. Smooth muscle is in hallow muscles that need to squeeze like your bladder, intestines, etc. Also involuntary. Looks more solid pink with little dots.

Question 6

What are the functions of muscles?

Answer 6

Produce movement, provide muscle tone, propel body fluids and food, and generate heat.

Question 7

List the parts of a muscle from smallest to largest

Answer 7

Myofilament, myofibril, sarcomere, muscle fiber, fascicles, muscle body

Question 8

What is the difference between a tendon and an apponeurosis

Answer 8

A tendon is a cord-like structure, mostly collagen fibers, often crosses a joint due to toughness and small size. Apponeurosis are sheet-like structures that attach muscles to each other and indirectly to bones, cartilage, or connective tissue coverings

Question 9

Define sarcomere

Answer 9

Basic contractile unit of muscle fiber. Composed of 2 main filaments - actin and myosin - which are responsible for muscular contraction

Question 10

Define sarcoplasmic reticulum

Answer 10

A complex network of specialized smooth endoplasmic reticulum that is important in transmitting the electrical impulse as well as in the storage of calcium ions. Necessary for muscle contraction and relaxation.

Question 11

Define sarcolemma

Answer 11

Fine transparent tubular sheath that envelopes the fibers of skeletal muscles

Question 12

Define sarcoplasm

Answer 12

Cytoplasm of a muscle cell

Question 13

Define t-tubule

Answer 13

Extension of the cell membrane that penetrate into the center of the skeletal and cardiac muscle cells

Question 14

Define a band

Answer 14

The area where contraction and relaxation of muscle occurs, darker

Question 15

Define I band

Answer 15

Contain only actin, lighter

Question 16

Define z line

Answer 16

Separation between sarcomeres, appears to look like a zigzag

Question 17

Define h zone

Answer 17

Contains only thick filaments

Question 18

Define thick filament

Answer 18

Myosin filament, 2 twisted strands of protein, have heads that project outwards

Question 19

Define thin filament

Answer 19

Actin, has binding sites for myosin, binding sites are covered by 2 proteins called tropomyosin and troponin

Question 20

Muscle contraction order of events

Answer 20

1. Nerve signal reaches the neuromuscular junction
2. Acetylcholine is released into the synaptic cleft
3. Acetylcholine binds to receptors on the sarcolemma
4. The action potential travels down the surface of the muscle fiber and goes down a t-tubule
5. The sarcoplasmic reticulum releases calcium
6. The calcium causes the troponin and tropomyosin to move and expose the myosin binding sites
7. The myosin heads bind to the actin
8. The myosin heads change shape and pull the actin filaments closer together and shorten the sarcomere

Question 21

What is the role of acetylcholinesterase?

Answer 21

It breaks down acetylcholine in the synaptic cleft, ending stimulation of the muscle fiber, resulting in relaxation of the muscle

Question 22

Define muscle fatigue and common causes as well as how it is resolved

Answer 22

A lack of ATP fatigues the muscle and doesn’t allow it to contract. Common cause is lack of oxygen, but can also be caused by drop in PH, electrolyte imbalance, and central fatigue. Resolved by repaying debt ie heavy breathing.

Question 23

Define threshold stimulus

Answer 23

Minimum amount of strength necessary to make a muscle contract

Question 24

Define twitch

Answer 24

Contractile response of a single muscle fiber to a nerve stimulator

Question 25

Define myogram

Answer 25

A graphic representation of the phenomena of muscular contractions

Question 26

Define latent period

Answer 26

Time from stimulus is received to muscle contracting, 2 milliseconds

Question 27

Define period of contraction

Answer 27

When the muscle fiber is actively contracting

Question 28

Define period of relaxation

Answer 28

When the muscle fiber is relaxing

Question 29

Define summation

Answer 29

One contraction is immediately followed by another. The muscle doesn’t completely return to resting, but is in a relaxed state in between

Question 30

Binding sites for myosin

Answer 30

Actin

Question 31

Blocks myosin binding sites

Answer 31

Tropomyosin

Question 32

Binding sites for calcium

Answer 32

Troponin

Question 33

Forms cross bridges

Answer 33

Myosin

Question 34

Site for calcium storage

Answer 34

Sarcoplasmic reticulum

Question 35

Threadlike bundles of thick and thin filaments

Answer 35

Myofibril

Question 36

Channel formed by invagination of plasma membrane

Answer 36

Transverse (T) tubule

Question 37

Plasma membrane of muscle fiber

Answer 37

Sarcolemma

Question 38

Cytoplasm of muscle fiber

Answer 38

Sarcoplasm

Question 39

Site of ATP production

Answer 39

Mitochondria

Question 40

Functional unit of contraction within muscle fiber

Answer 40

Sarcomere

Question 41

The point of communication between a motor neuron, and a muscle fiber is called a __________

Answer 41

Neuromuscular junction

Question 42

At this synapse, a ________ releases, a type of chemical called a neurotransmitter 

Answer 42

Motor neuron

Question 43

The chemical used at the synapse with a skeletal muscle cell is _________

Answer 43

Acetylcholine

Question 44

These chemical molecules diffuse across a small gap between the neuron and muscle fiber, called the _________

Answer 44

Synaptic cleft

Question 45

The chemicals, then bind to receptors located on the ________, a specialized area of the sarcolemma

Answer 45

Motor end plate

Question 46

The binding of the chemicals to the muscle cell causes an electrical impulse to travel across the sarcolemma and down the ______

Answer 46

Transverse tubules

Question 47

Muscle fiber, contractions called _____ result from a single stimulus to a muscle fiber. Each contraction generates the same force. These contractions aren’t physiologically useful. 

Answer 47

Muscle twitches

Question 48

Two mechanisms can be used to cause contractions of greater force. One involves increasing the ____ of stimulation. The result is _____ in which each successive contraction is a bit stronger.

Answer 48

Frequency, summation

Question 49

If the frequency of stimulation is fast enough, a _____ contraction results. This is called a ______ during which no relaxation occurs. 

Answer 49

Sustained, tetanic contraction

Question 50

Another way of increasing force of contraction is by the process of _____ during which an increasing number of _____ are stimulated to contract 

Answer 50

Recruitment, motor units