CARDIOVASCULAR 6

Question 1

Main functions of the Circulatory system: four main functions

Answer 1

1) Transport and distribute essential substances to the tissues
2) Remove metabolic by products
3) Adjustment of oxygen and nutrient supply in different physiologic states
4) Regulation of body temperature
5) “Humoral” communication

Question 2

Cardiovascular system anatomy:
How pumps does the heart contain
Function of:
1) Arteries 
2) Veins

Answer 2

The heart contains 2 pumps
Function of:
1) Takes blood away from the heart
2) Brings blood back to the heart

Question 3

1) Pulmonary circuit:

2) Main function

Answer 3

1) Right ventricle to pulmonary trunk to pulmonary arteries to lungs to pulmonary veins t to left atrium
2) Brings O2 rich blood back to the heart

Question 4

1) Systemic Circuit
2) Blood vessel to Blood vessel?
3) Main function

Answer 4

1) Left ventricle to Aorta carrying O2 rich blood from the left ventricle with an artery to each organ
2) Artery to arteriole to capillaries to venules to vein
3) Circulate blood back and forth form the rest of the body

Question 5

What is the heart mainly composed of?

The heart is encased within a membranous fluid-filled sac?

Answer 5

Myocardium muscle

Pericardium

Question 6

Main function of the four valves in the heart

Answer 6

One-way blood flow

Question 7

Semilunar valves:

1) Between RV and pulmonary trunk
2) Between LV and Aorta

Answer 7

1) Pulmonary valve

2) Aortic valve

Question 8

Atrioventricular valves
Location?
Names of the valves?
1) Left 
2) Right 
How are these valves re-enforced

Answer 8

Between atria and ventricles 1) Bicuspid (mitral) valve
2) Tricuspid valve
by Chordae tendinae attached to muscular projections within ventricles

Question 9

Passage of blood through the heart:

Answer 9

Superior and inferior vena cava to right atrium to tricuspid valve to right ventricle to pulmonary valve to trunk and arteries to the lungs to veins to left atrium to bicuspid valve to left ventricle to arotic valve to the body

Question 10

Myocardial muscle cells

Attached to each other by specialized junctions called?

Answer 10

Branched with a single nucleus

Intercalated disks

Question 11

Cardiac Muscle Properties

1) Syncytial network
2) Connected by intercalated disks containing

Answer 11

1) Branched myocyte connections

2) Desmosomes

Question 12

1) Desmosomes

2) Occupy one-third of cell volume?

Answer 12

1) To allow force transfer, and gap junctions for electrical connectivity
2) Mitochondria

Question 13

Excitation-contraction coupling

steps: 1 to 10

Answer 13

1) AP from adjacent cell
2) Voltage-gated Ca2+ channels open
3) Ca 2+ induces Ca2+ release through ryanodime receptor-channels (RyR)
4) Local release causes Ca2+ spark
5) Summed Ca2+ sparks Ca2+ signal
6) Ca2+ ions bind to troponin to initiate contraction
7) Relaxation occurs when Ca2+ unbinds from troponin
8) Ca2+ is pumped back into the sacroplasmic reticulum for storage
9) Ca2+ is exchanged with Na+ by the NCX antiporter
10) Na+ gradient is maintained by the Na+ K+ -ATPase

Question 14

What is the main difference between action potential in the neural and skeletal muscle cells?

Answer 14

Main difference is duration

1) Nerves = about 1ms
2) Skeletal muscle cells = 2-5ms
3) Cardiac AP : 200 to 400 ms

Question 15

Myocardial Contracile Cell Action potential

Answer 15

1) Na + channels open
2) Na+ channels close
3) Ca2+ channels open:fast K+ channels close
4) Resting potential

Question 16

Refractory period:

1) Cardiac muscle
2) Skeletal muscle

Answer 16

1) Lasts as long as the entire muscle twitch

2) The refractory period is very short compared with the amount of time required for the development of tension

Question 17

1) Skeletal muscles stimulated repeatedly.

2) Cardiac muscle fiber

Answer 17

1) Exhibit summation and tetanus

2) Long refractory period in a cardiac muscle prevents tetanus

Question 18

Cardiac NA+ channel: inactivation and resetting upon repolarization

Answer 18

Closed/primed by repolarized state to depolarization to inactivation to repolarization

Question 19

Action potential in Cardiac muscle:

1) Membrane potential
2) Events leading to threshold potential
3) Rising phase of AP
4) Repolarization phase
5) Hyperpolarization
6) Duration of AP
7) Refractory period

Answer 19

1) 70mV
2) Net Na+ entry through ACh- operated channels
3) Na+ ENTRY
4) Rapid caused by K+ efflux
5) Due to excessive K+ efflux at high K+ permeability when K+ channels close: leak of K+ and Na+ restores potential to resting state
6) Short:1 -2ms
7) Generally brief

Question 20

Action potential in Skeletal muscle:

1) Membrane potential
2) Events leading to threshold potential
3) Rising phase of AP
4) Repolarization phase
5) Hyperpolarization
6) Duration of AP
7) Refractory period

Answer 20

1) 90mV
2) Depolarization enters via gap junctions
3) Na+ entry
4) Extented plateau cuased by Ca2+ entry: rapid phase caused by K+ efflux
5) Resting potential is -90Mv, the equilibrium potential for K+
6) Extended: 200+ ms
7) Long because resettling of Na+ channel gates delayed until end of AP