Muscular System Flashcards Preview

ANPH 1105 > Muscular System > Flashcards

Flashcards in Muscular System Deck (40)
Loading flashcards...
1
Q

What are the three kinds of muscle?

A

Cardiac, skeletal, and smooth.

2
Q

What type of tissue connects muscles to bone?

A

Tendons.

3
Q

What is another name for cardiac muscle?

A

The myocardium.

4
Q

What two types of muscle are striated?

A

Skeletal and cardiac.

5
Q

Which two types of muscle are under involuntary control?

A

Cardiac and smooth.

6
Q

Where is smooth muscle found?

A

In the walls of blood vessels and internal organs.

7
Q

What are the functions of muscle?

A

To aid in motion, movement of substances through the body, to stabilize posture, and thermogenesis (shivering).

8
Q

What are the four key characteristics of muscle tissue?

A

It is excitable, able to contract, extensible, and elastic (can return to its original size after being stretched/contracted).

9
Q

Define fascia.

A

A sheet of connective tissue that surrounds the muscle to protect and separate it.

10
Q

What unit of muscle are the capillaries and motor neurons linked to?

A

The muscle fiber (which is an individual muscle cell).

11
Q

From largest to smallest, what are the units of muscle?

A

Muscle, fascicle (bundles), muscle fiber (muscle cell), myofibrils, filaments.

12
Q

Define a motor unit.

A

A motor neuron plus all the muscle fibers it stimulates (each ~150 fibers).

13
Q

Does a motor unit produce small or large movements?

A

Both. A motor unit may have only 2-3 fibers (ex. larynx) or up to 2000 fibers (ex. biceps).

14
Q

What is a fascicle?

A

A bundle of muscle fibers.

15
Q

What are myofibrils?

A

Rope-like structures made up of filaments that are bundled together within the sarcolemma to form a muscle fiber.

16
Q

What delineates a sarcomere?

A

It consists of everything within the z discs.

17
Q

What is the difference between thick and thin filaments?

A

The thick filaments are myosin and the thin filaments are actin.

18
Q

What is the A band?

A

The length of the thick filament.

19
Q

What molecule covers the myosin binding site?

A

Tropomyosin.

20
Q

Describe the steps of muscular contraction.

A

The active site on actin is exposed when Ca2+ binds troponin. The myosin head forms a cross-bridge with actin. During the power stroke the myosin head bends and ADP and phosphate are released. A new molecule of ATP attaches to the myosin head, causing the cross-bridge to detach. ATP hydrolyzes to ADP and phosphate, which returns the myosin the “cocked” position.

21
Q

What is the neuromuscular junction?

A

The synapse between the motor neuron and muscle fiber.

22
Q

Describe the release and action of ACh from a motor neuron.

A

ACh is released from a synaptic vesicle into the synaptic cleft. It diffuses across the cleft and binds to ACh receptors on the motor end plate, opening the cation channel. Cations (Na+) rush into the motor end plate and produce an action potential. After the action potential ACh is broken down and removed from the receptors by actelcholinesterase.

23
Q

How is calcium brought into the sarcoplasm?

A

A muscle action potential will travel along the muscle through transverse tubules causing Ca2+ release channels in the sarcoplasmic reticulum to flood the sarcoplasm with Ca2+.

24
Q

What are the three pathways of ATP regeneration?

A

The creatine phosphate system, glycogen-lactic acid system, and aerobic respiration.

25
Q

Describe the creatine phosphate system.

A

ATP gives one phosphate to creatine to make creatine phosphate. The creatine phosphate donates its phosphate to ADP in contracting muscle to produce ATP for energy.

26
Q

Describe the glycogen-lactic acid system?

A

Muscle glycogen is converted to glucose which is broken down in glycolysis to create 2 ATP and 2 pyruvic acid. The pyruvic acid is then converted into 2 lactic acid which builds up in the muscle and can increase the acidity and cause cell damage.

27
Q

Describe aerobic respiration.

A

Amino acids, fatty acids, pyruvic acid, and oxygen from the hemoglobin enter the mitochondria and engage in cellular respiration to produce heat, ATP, CO2, and H2O.

28
Q

List the methods of ATP production from short term to long term.

A

Creatine phosphate (15s), glycogen-lactic acid (30-40s), and aerobic respiration (>30s).

29
Q

What is myoglobin?

A

An oxygen binding protein inside muscle fibers which acts as an oxygen source for muscle tissue by releasing it as required.

30
Q

What causes muscle fatigue?

A

The inability to maintain muscle contraction because there is not enough ATP; may result from insufficiency of oxygen, glycogen depletion, or lactic acid build-up.

31
Q

Define isotonic muscle tone.

A

When tension remains constant; occurs when a constant load is moved through the possible range of motions at a joint (ex. picking up a book).

32
Q

Define isometric contraction.

A

The length of the muscle is constant but tension on the muscle increases during the contraction but no movement is produced (ex. holding a book at arms length for a long time).

33
Q

Define muscle tone.

A

Sustained partial muscle contraction; “firms” the muscle without producing movement (ex. maintaining posture).

34
Q

Which type of muscle has the most mitochondria and why?

A

Cardiac because it must have enough energy for continuous contraction or you will die.

35
Q

How does the contraction stimulus in cardiac muscle differ from other muscle?

A

The stimulus is intrinsic; it comes from within the heart from cells called autorhythmic cells. Nerves and hormones can alter the heart rate.

36
Q

Why does cardiac muscle have a long refractory phase?

A

The heart remains contracted longer because there is a longer influx of Ca2+ into the sarcoplasm.

37
Q

What are the two kinds of smooth muscle?

A

Visceral (single unit) and multi-unit.

38
Q

What joins smooth muscle networks?

A

Gap junctions which allows the smooth muscle to be arranged in sheets or layers.

39
Q

How does smooth muscle contraction differ from skeletal muscle contraction?

A

The duration of smooth muscle contraction is longer and produces more of an overall squeezing effect than skeletal muscle which contracts more quickly and shortens in length to produce movement.

40
Q

What is smooth muscle controlled by?

A

The autonomic nervous system as well as hormones and other factors.