Physiology Lecture 4

Question 1

ICU patients can lose up to _% every __ hours.

Answer 1

1% every 24 hours

The sooner they are mobilized, the less muscle mass lost

Question 2

Difference between exercise and physical activity

Answer 2

Exercise is planned, structured, repetitive and purposeful activity.

Physical activity is any movement of the body that requires energy expenditure

Question 3

7 functions of muscle

Answer 3

• Produces body movement
• Helps to maintain posture
• Powers respiration
• Produces body heat (shivering)
• Communicates with other organs and organ systems
• Constricts organs and blood vessels (smooth muscle)
• Produces cardiac contraction (cardiac muscle)

Question 4

What is contractility?

Answer 4

Ability of a muscle to shorten or attempt to shorten.

Question 5

What is excitability?

Answer 5

Capacity of muscle to respond to a stimulus.

Question 6

What is extensibility?

Answer 6

Muscle can be stretched to its normal resting length and beyond to a limited degree

Question 7

What is elasticity?

Answer 7

Ability of a muscle to recoil to original resting length after stretched

Question 8

What are contractures?

Answer 8

A condition of shortening and hardening of muscles, tendons, or other tissue, often leading to deformity and rigidity of joints.

Too much internal scar tissue.

Reduces extensibility

Question 9

Explain skeletal muscle

Answer 9

• Attached to and causes bones to move
• Multiple nuclei
• Striated
• Voluntary and involuntary

Question 10

Explain cardiac muscle

Answer 10

• Found in heart
• Single central nucleus
• Striated
• Involuntary

Question 11

What is a functional syncytium?

Answer 11

intercalated disks and gap junctions

Question 12

Does every muscle cell in the heart have to be innervated?

Answer 12

No, but skeletal muscle cells do

Question 13

Explain smooth muscle

Answer 13

• Lines walls of hollow organs
• Single nucleus
• Lacks striation
• Involuntary
• Fatigue resistant

Question 14

Does every smooth muscle cell have to be innervated?

Answer 14

No

Question 15

What is an isotonic contraction?

Answer 15

muscle changes length under a constant load

Question 16

Concentric vs Eccentric

Answer 16

Conc- muscle shortens while contracting

Ecce- muscle lengthens while contracting

Question 17

What is an isometric contraction?

Answer 17

Muscle length does not change while contracting

Question 18

What is an isokinetic contraction?

Answer 18

Muscle shortens at a constant speed

Question 19

Epimysium and perimysium

Answer 19

Epi- covers the surface of muscle and has a role in force transmission and insulation

Projects into muscle itself

Peri- divides the muscle fibers into functional groups called fascicles

Continuous with the epimysium

Question 20

Individual muscle fibers are surrounded by what?

Answer 20

Endomysium

Question 21

What is the endomysium connected to?

Answer 21

Basement membrane, which plays a role in force production

Question 22

What is the Myotendinous Junction?

Answer 22

Weak point in the muscles, where muscle connects to tendon

Question 23

Where is force generated?

Answer 23

By the cross-bridges in the sarcomere

Force is then transmitted to the costamere

Question 24

What happens with rigor mortus?

Answer 24

there is no ATP to release crossbridging and calcium ions cant be pumped out of the cell

Question 25

When does force production go down?

Answer 25

When thin filaments overlap, crossbridges cant attach to thick filament

Question 26

List the order in which force gets to the tendon.

Answer 26

``` Sarcomere Costomere Endomysium Perimysium Epimysium Tendon ```

Question 27

Increased force production comes from what?

Answer 27

Increase in sarcomeres

Question 28

Difference between Type I and Type II muscle fibers

Answer 28

Type I- slow twitch, more mitochondria for aerobic Type II- fast twitch, glucose storers for anaerobic capacity

Question 29

What is the longest muscle in the body?

Answer 29

Sartoris

Question 30

What do the I,A and H band consist of

Answer 30

I band has the thin filaments only A band contains thick filaments with some thin filament overlap H band is within the A band and only has the thick filament

Question 31

What forms the boundary of a sarcomere?

Answer 31

Z disc

Question 32

Thick filaments are composed of? | Thin filaments are composed of?

Answer 32

Myosin Actin

Question 33

What prevents myosin from binding at rest?

Answer 33

Tropomyosin and troponin

Question 34

General movement of AP to a muscle cell

Answer 34

L5S4 -Presynaptic nerve cell synapses with a muscle cell -ACh is released and binds with receptors on motor end plate of muscle cell -AP propogates down t-tubule -Binds to a receptor in the tubule that induces the release of calcium from the sarcoplasmic reticulum -Calcium seeks binding sites on thin filaments Crossbridges can now bind to the thin filaments

Question 35

What reabsorbs calcium so crossbridges can relax?

Answer 35

Sarcoplasmic reticulum