BP regulation

Question 1

How do arterioles modify resistance?

Answer 1

They have lots of smooth muscle which

Question 2

What is mean arterial blood pressure?

Answer 2

mean pressure over the entire cardiac cycle (average is about 95 mmHg not mean between SBP and DSP due to being in Systole for longer)

Question 3

What is systolic BP?

Answer 3

Maximum arterial BP during heart contraction

Question 4

What is diastolic BP?

Answer 4

Min arterial BP during heart relaxation

Question 5

What is the formula for mean arterial pressure?

Answer 5

CO x TPR

P = QR

Question 6

What controls cardiac output?

Answer 6

sypathetic and parasympathetic nerves that affect heart rate and stroke volume

Question 7

What does SVR get affected by?

Answer 7

constriction or dilation of the arterioles and venules (due to preload effect)

Question 8

What things manipulate Mean Arterial Pressure?

Answer 8

CO

SVR

Blood Volume (more volume = more pressure)

Question 9

What is chronotropy?

Answer 9

Heart rate effects

Question 10

What are the excitatory affects on heart rate caused by?

Answer 10

Sympathetic innervation

Question 11

What are the slowing effects on heart rate caused by?

Answer 11

Parasympathetic innervation

Question 12

What is the intracellular response of muscarinic ACh binding?

Answer 12

opens potassium channels causing potassium to leak out of the cell to make the cell more negative making gaps between heartbeats longer

No effect on contractility

Question 13

What does beta adrenergic innervation result in?

Answer 13

More calcium flows into the cell making the heart cells more contractile and contract more often

Question 14

What is beating harder described as?

Answer 14

Inotropy

Question 15

What factors affect MAP?

Answer 15

Female M>F

Age Elderly > Children

Emotions Increases due to increases due to secretion of adrenaline and noradrenaline

Exercise increases due to increased venous return

Hormones increases MAP

Gravity increases MAP due to pooling of blood in lower limbs

Sleep decreases MAP due to decrease in venous return

Pregnancy increases MAP due to increased metabolism

Question 16

What factors affect systemic vascular resistance?

Answer 16

Blood viscosity (ratio of RBCs to plasma and protein concentration)

Total blood vessel length (resistance directly proportional to length of vessel)

Size of lumen (vasoconstriction makes lumen smaller meaning greater resistance)

Question 17

What happens in blood vessels when responding to noradrenaline binding to alpha receptors?

Answer 17

They narrow with the exception of arteries going to muscles and coronary arteries

Question 18

How is BP measured?

Answer 18

Short term: Baroreceptors

Long term in kidneys via the tubuloglomerular feedback

Question 19

How is BP controlled?

Answer 19

Short term controlled by baroreceptor reflex.

Long term controlled by RAAS, ADH, and ANP

Question 20

What 3 centers are present within the CV center in the medulla?

Answer 20

Cardiostimulatory center (Increase heart rate and heart contractility)

Cardioinhibitory center (Decrease HR)

Vasomotor center (Vasoconstriction)

Question 21

What part of the brain is the CV center a part of?

Answer 21

The solitary tract

Question 22

Where are baroreceptors located?

Answer 22

Carotid sinus

Aortic reflex

Question 23

What fires the baroreceptors?

Answer 23

stretch of the mechanoreceptors

Question 24

Which receptors cause arteriolar smooth muscle to contrict?

Answer 24

Alpha receptors

Question 25

Which receptors cause the ventricles to contract harder?

Answer 25

Beta - 1

Question 26

Which receptors cause the SA node to depolarize more frequently?

Answer 26

Beta - 2

Question 27

Are there other important receptors that the heart reacts to?

Answer 27

Yes, for example lung stretch receptors will elevate HR

Question 28

What does the Frank-Starling curve show?

Answer 28

The effect of the venous system on preload. Increasing venous pressure elevates CO.

Question 29

What happens to venous pressure when cardiac output is elevated?

Answer 29

It drops because blood is being removed from venous circulation

Question 30

What happens when Venous pressure drops as a result of elevated CO?

Answer 30

the CO drops This goes back and forth until equilibrium is reached at what is known as a goldilocks zone There is an optimal cardiac output for an optimal preload

Question 31

What happens to goldilocks zone with the effect of sympathetic stimulation?

Answer 31

Venous Pressure drops due to increase in tone and an elevation of CO. Increase in preload results in a higher point

Question 32

What does nitroprisside do?

Answer 32

Elevates heart rate without influencing preload

Question 33

What does increasing blood volume do to the venous preload?

Answer 33

Elevates both CO and venous pressure. More fluid means venous pressure is higher due to presence of more fluid and CO increases due to higher preload

Question 34

If CO & CVP are low how can this problem be fixed?

Answer 34

Increasing the amount of fluid in the system.

Question 35

If CO is low but CVP is raised what can be done?

Answer 35

Use a cardiac stimulant