Lec 18

Question 1

Cardiac muscle cells are

Answer 1

99% force-producing (myocardial cell/myocytes)
— striated muscle fibers

Question 2

1% autorhythmic/pacemaker

Answer 2

-generate spontaneous APs, signal for myocyte contraction
-Do not contribute to contractile force

Question 3

Both types of cells can generate AP

Answer 3

Memorize

Question 4

Autorhytmic cell

Answer 4

Spontaneously generate AP
Do not significantly contribute to contractile force

Question 5

Cardiac myocyte

Answer 5

Irregularly shaped striated muscle fiber with sarcomers
-actin & myosin
-cross-bridge cycling mirrors

Question 6

Connected in series by

Answer 6

Intercalated disks

Question 7

Desmosomes

Answer 7

Physical coupling, allow force to be transferred to neighbors

Question 8

Intercalated disk contains

Answer 8

Desmosomes
Gap junction

Question 9

Gap junction

Answer 9

Functional coupling
Electrical coupling

Question 10

Cardiac vs skeletal muscle fiber

Answer 10

1- smaller/ 1-2 nuclei per fiber
2- irregular, branching cell
3- t-tubules are larger
4- sarcoplasmic are smaller
5- mitochondria occupy one-third of cell

Question 11

Excitation-contraction coupling in cardiac muscle

Answer 11

1- Initially pacemaker produce AP
2- AP enter from adjacent cell (gap junction)
3- voltage-gated Ca channel open (L-type Ca channel [voltage-gated])
4- Ca enter from ECF
5- Ca bind to SR RyR (ligand gated)
6- Ca released from SR
7- Ca spark
8- Summed Ca sparks create Ca signal
9- Ca bind to troponin to initiate contraction
10- Relaxation happen when Ca unbind from troponin
11- Ca bumped back to SR for storage
12- Ca is exchanged with Na by NCX antiporter
13- Na gradient is maintained by Na/K ATPase

Question 12

For cardiac’s miscle Ca is

Answer 12

Critical

Question 13

In myocyte we have

Answer 13

CICR
Calcium induced calcium release

Question 14

Ca signal is

Answer 14

90% SR
10% ECF

Question 15

NCX antiporter

Answer 15

Up conc. Gradient
Active
Secondary

Question 16

Cardiac compare to skeletal

Answer 16

• no summation
• NCX available
• Ca trigger Ca

Question 17

Arterires

Answer 17

Take blood away from heart

Question 18

Veins

Answer 18

bring blood back to heart

Question 19

Pericardium

Answer 19

Fluid filled sac to minimize friction

Question 20

Artery/vein feeding the heart

Answer 20

Coronary

Question 21

Left side of heart is thicker why?

Answer 21

More power required for pumping to whole body

Question 22

Pathway from vena cava to aorta

Answer 22

1- superior/inferior vena cava
2- right atrium
3- Right AV- tricuspid valve
4- R V
5- pulmonary semilunar valve
6- pulmonary arteries
7- pulmonary veins
8- L A
9- Left AV- bicuspid valve
10- L V
11- Aortic ventricle valve
12- Aorta

Question 23

All valves are

Answer 23

One way flow

Question 24

Ventricular contaraction

Answer 24

AV valve close
Semilunar valve open

Question 25

Chordae tendineae

Answer 25

Heart string/anchoring ropes on AV valves
Make sure AV valve are close and don’t evert

Question 26

Ventricular Relaxation

Answer 26

AV valve open
Semilunar valve close
Chordae tendineae relax