Membranes And Muscle Contraction

Question 1

What is voltage?

Answer 1

Electric potential difference

Question 2

What is resistance?

Answer 2

Opposition to the passage of electrical current

Question 3

Which way does sodium want to go?

Answer 3

In the cell

Question 4

Which way does potassium want to go?

Answer 4

Out of the cell

Question 5

What is the normal resting potential of a cell?

Answer 5

-70mV

Question 6

What is the absolute refractory state?

Answer 6

Time when another action potential cannot be generated

Question 7

What is the relative refractory period?

Answer 7

Time when a stronger than normal stimulus could trigger another action potential

Question 8

What ion ratio does the na-k pump, pump?

Answer 8

3 na out

2 k in

Question 9

What is hyperkalemia?

Answer 9

Increased extra cellular k+ resulting in cell being more excitable

Question 10

What is hypokalemia?

Answer 10

Decrease in extra cellular k+ leading to less excitable cell

Question 11

What affect does increasing the Ca++ have?

Answer 11

Makes cell less excitable

Question 12

What affect does decreasing the Ca++ have?

Answer 12

Makes cell more excitable

Question 13

What is the neuromuscular junction?

Answer 13

Site of innervation

Question 14

What does the sarcoplasmic reticulum primarily do?

Answer 14

Store and release Ca++

Question 15

What are terminal cisternae?

Answer 15

Enlarged portions of SR nearest t-tubules

Question 16

What are transverse tubules?

Answer 16

Tube through which action potentials propagate into muscle near SR

Question 17

What is the A-band?

Answer 17

Dark, myosin band

Question 18

What is the I-band?

Answer 18

Light actin filaments and z line

Question 19

What is the H-zone

Answer 19

Center of A band with just myosin

Question 20

What is the M-line?

Answer 20

Center or H-zone to which myosin anchors

Question 21

What are titins?

Answer 21

Proteins that anchor thick filaments to z-discs. Helps muscle spring back

Question 22

Which sections shorten during contraction?

Answer 22

I-band
H-zone
Sarcomere

Question 23

How do calcium, troponin and tropomyosin interact?

Answer 23

Calcium binds troponin which shifts and pulls tropomyosin over to expose binding sites on actin for myosin

Question 24

What are the 9 main events of skeletal muscle contraction?

Answer 24

1-AP initiates
2-AP triggers release of Ach
3-Ach diffuses to muscle fiber
4-Local depolarization occurs
5-EPP triggers AP in muscle
6-AP triggers release of Ca++ from SR
7-Ca++ binds troponin, shifting tropomyosin
8-Energized myosin binds actin and shortens
9-Cytoplasmic ca++ is pumped back to SR

Question 25

What are the 3 energy sources for muscle contraction?

Answer 25

``` Creatine phosphate- 1 ATP Anaerobic respiration (glycogen)- 2ATP Cellular respiration (aerobic)- 38ATP, heat water and CO2 ```

Question 26

What is isotonic contraction?

Answer 26

Tension force is greater than load and muscle shortens

Question 27

What is isometric contraction?

Answer 27

Load exceeds tension and muscle does not shorten

Question 28

What is type 1 motor units?

Answer 28

Slow twitch- always active

Question 29

What is type 2 motor units?

Answer 29

Fast twitch

Question 30

6 basic components of reflex?

Answer 30

``` 1-sensory receptor 2-sensory/afferent neuron 3-integration to CNS 4-interneuron 5-motor/efferent 6-an effector ```

Question 31

What is a stretch reflex?

Answer 31

Spindles sensitive to muscle length. Activated alpha motor neurons and Stimulates muscle to contract. Knee jerk

Question 32

What are the subtypes of muscle fibers?

Answer 32

Extrafusal-innervated by alpha motor neurons | Intrafusal- innervated by gamma motor neurons

Question 33

What is a Golgi (deep) tendon reflex?

Answer 33

Reflex sensitive to tendon tension causing muscle to relax by inhibiting alpha motor neurons

Question 34

What is current?

Answer 34

Flow of electrical force

Question 35

What do extrafusal muscle fibers do?

Answer 35

Provide force of contraction

Question 36

What do intrafusal muscle fibers do?

Answer 36

Detect fast (group Ia) and static changes (group II)