Regulation of stroke volume & heart rate

Question 1

What do the sympathetic nerves release?

Answer 1

Noradrenaline

Question 2

Where is circulating adrenaline coming from?

Answer 2

Adrenal medulla

Question 3

What does noradrenaline act on?

Answer 3

• B1-receptors

- Sinoatrial

Question 4

What does noradrenaline do to the slope of the regulation of the heart?

Answer 4

Increases it

-meaning faster depolarisation

Question 5

What is the name for increased heart rate?

Answer 5

-Tachycardia

Question 6

What nerve in the parasympathetic system innervates the heart?

Answer 6

Vagus

Question 7

What does the vagus nerve release?

Answer 7

Acetylcholine

Question 8

What is a decreased heart heart rate called?

Answer 8

Bradycardia

Question 9

What is starlings law?

Answer 9

The energy of contraction is proportional to the intiail length of the cardiac muscle

Question 10

What is another way of thinking about preload?

Answer 10

length

Question 11

What determines preload?

Answer 11

EDV

Question 12

What happens if venous return is increased?

Answer 12

increase in EDV= Increase in stroke volume

Question 13

What does this reaction to preload mean in vivo?

Answer 13

Matches SV of left & right ventricles

Question 14

What is after load?

Answer 14

Load against which the muscle tries to contract

-in vivo against aortaic valve and peripheral resistance of arterioles

Question 15

What happens to stroke volume if total peripheral resistance is increased?

Answer 15

L ventricle has to work harder to open aortic valve and therefore has less energy to pump out blood. Lower stroke volume

Question 16

What kind of vessels affect preload?

Answer 16

-Capacitancy vessels ie venules and veins

Question 17

What vessels affect afterload?

Answer 17

Resistance vessels ie arteries and arterioles

Question 18

What happens if you constrict veins?

Answer 18

Lager EDV larger preload larger stroke volume

Question 19

What does inotopic mean?

Answer 19

Effecting strength

Question 20

What does Chronotopic mean?

Answer 20

Effecting rate

Question 21

What happens to contraction when sympathetic innervation takes over?

Answer 21

-Gives stronger and shorter contraction

Question 22

What is the effect of the parasympathetic system on the stroke volume of the heart?

Answer 22

-Little effect

Question 23

Why does the parasympathetic system have little effect on stroke volume?

Answer 23

Vagus nerve does not innervate the ventricle muscle

Question 24

What effect does hypercalcemia have on starlings curve?

Answer 24

-Shifts curve up and left

higher stroke volume with lower EDV

Question 25

What effect does hypocalcemia have on starlings curve?

Answer 25

Shifts curve down and to the right | lower SV and larger EDV

Question 26

What effect does ischaemia have on starlings curve?

Answer 26

Shirts curve down and right | lower SV and larger EDV

Question 27

How does heart react to lower SV?

Answer 27

Increases EDV if only left side is effected

Question 28

What numerical value tells you where youre working on starlings curve?

Answer 28

Ejection fraction | EDV/SV

Question 29

What effects do barbiturates have on starling curve?

Answer 29

Down and to the right

Question 30

How do you measure cardiac output?

Answer 30

Heart rate x stroke volume

Question 31

What does increasing heart rate with an electrical pacemaker do and why?

Answer 31

Small increase in CO but the SV decreases WHY? Shortening cardiac interval cuts into the rapid filling phase. Reduces EDV and reduces preload so lower SV

Question 32

What happens to HR and how when you exercise?

Answer 32

HR increases - Via decreased vagal tone - & Increased sympatheic tone

Question 33

What happens to Contractility and how when you exercise?

Answer 33

Contractility increases - via increased sympathetic tone - alters inotropic state & shortens systole

Question 34

What happens to venous return and how when you exercise?

Answer 34

Increases - Via venoconstriction - & skeletal/respiratory - maintains preload

Question 35

What happens to Total peripheral resistance and how when you exercise?

Answer 35

falls - Due to arteriolar dilation in muscle skin &heart - Reduces aterload

Question 36

CO increases by how much when exercising?

Answer 36

4-6 times