Cardiac muscle

Question 1

How does the heart beat (mechanism)

Answer 1

spontaneous depolarization and triggering of the action potential via pacemaker

Question 2

Myocardium are broken down into

Answer 2

Nodal and contractile cells

Question 3

Function of nodal cells

Answer 3

Set rhythm and pace for the beating

Question 4

Contractile cell consist of

Answer 4

Tropomyosin, actin, myosin, troponin

Question 5

The pathway of impulses in the heart

Answer 5

Sa nodes -> av nodes

Question 6

How does the sa node impulse travel to the other side

Answer 6

Via backman bunder

Question 7

Bundle of his separates into

Answer 7

Right and left bundle branches

Question 8

The last bundle to receive an impulse is the

Answer 8

Purleinje fibers

Question 9

Sa nodes are

Answer 9

The pace makers

Question 10

What kind of wave are the impulses

Answer 10

Depolarisation waves

Question 11

Why does the av nodes takes 0.1 second slower (delay)

Answer 11

Cause of the lesser gap junction and smaller diameter

Question 12

What kind of cells can nodal cells send an impulse to

Answer 12

Other nodal or contractile cells

Question 13

What are intercalacted disk

Answer 13

The junction between each cell (the gap junction between desmosome)

Question 14

Desmosome function

Answer 14

Physically holding the cells together

Question 15

Intrinsic cardiac contraction steps (from nodal cell)

Answer 15

1. Na+ leak into the cells (-60 to -55)
2. T-type Ca+ channel open due to the depolarization (-55 to -40)
3. L-type Ca+ channel open which leads to excessive amount of Ca+ to flow in
4. K+ channel opens to repolarize

Question 16

Intrinsic cardiac contraction steps (contractile cells)

Answer 16

1. Cations from nodal flows in (-90 to -70)
2. Na+ voltage gated channel opens for Na+ to flow back in (reaches 10)
3. Ca+ channel open for it to enter, K+ channel open for it to exit (reaches 0) And this continues until back to -90

Question 17

Muscle contraction steps

Answer 17

1. ca+ calmodulin attaches to RYR-2 receptor (R2)
2. Ca+ then attaches to TnC to pull start the cross-bridge

Question 18

Down /”rest” period for the heart beat

Answer 18

1. Block Ca+ channel
2. Ca+ at tnC flow back out into the sarcoplasmic reticulum
3. Release Ca out of the cell
   Open K+ channel to repolarize

Question 19

Difference between cardiac and smooth muscles

Answer 19

Cardiac m. Has a longer refractory period (cool down since a tetanus cannot be achieved)

Question 20

What is the frank starling law

Answer 20

Stretching of heart increases force of contraction (elastic energy contribution)

Question 21

Concentric and eccentric

Answer 21

Con= force > resistance (better)
Ec = force < resistance

Question 22

Extrinsic cardiac contraction (nodal / sym. Cells)

Answer 22

1. Norepinephine /epinephrine stimulates b1-ar
2. Activates Gs -> stimulate G protein
3. Active adrenaline cyclase (ATP to be converted to cAMP)
4. CAMp -> pKA
5. PKA to open Ca+ channel and Ca+ flow in
6. Contraction via depolarization

Question 23

Extrinsic cardiac contraction (contractile/para. Cells)

Answer 23

1. Sym nerves connects to b1-ar and activate Gs
2. Activates acetyl-coa cyclase (convert to kPA)
3. Open Ca+ channel for Ca to flow into SR and cell to connect with tnC
4. Contraction via depolarization

Question 24

What is used to increase the HR

Answer 24

Positive Chronotropic action

Question 25

Positive inotropic causes

Answer 25

Increase in contractility

Question 26

Negative inotropic causes

Answer 26

Decrease in contractility

Question 27

What does the smooth muscle do not have

Answer 27

Sacromere

Question 28

Types of smooth muscles

Answer 28

Single unit and mutliunits

Question 29

Where are the mulitunit located

Answer 29

Iris

Question 30

Where are the single unit located

Answer 30

GI tract

Question 31

Function of single unit

Answer 31

Gross control

Question 32

Function of multiunit

Answer 32

Large arteries or goosebumps