Control of blood pressure

Question 1

How is pressure calculated?

Answer 1

Pressure = flow x resistance

Question 2

How is blood pressure calculated?

Answer 2

maBP = CO x TPR

Question 3

What are the two timeframes that blood pressure is regulated during?

Answer 3

Short-term

Long-term

Question 4

What is the short-term regulation of blood pressure?

Answer 4

Baroreceptor reflex

Question 5

What are baroreceptors sensitive to?

Answer 5

Are sensitive to stretch

Question 6

Where are baroreceptors located?

Answer 6

Aortic arch

Carotic sinus

Question 7

How do baroreceptors detect an increase in pressure?

Answer 7

Arterial walls are stretched

Stretches nerve endings of baroreceptors

Question 8

What do baroreceptors do once stretched?

Answer 8

Increase frequency of action potentials fired

Question 9

Which nerve carries action potentials from baroreceptors in aortic arch?

Answer 9

Vagus nerve - cranial nerve 10

Question 10

Which nerve carries action potentials from baroreceptors in carotid sinus?

Answer 10

Glossopharyngeal nerve - cranial nerve 9

Question 11

Where are action potentials from the baroreceptors carried to?

Answer 11

Medulla oblongata

Question 12

How does the medulla oblongata relate to the cardiovascular system?

Answer 12

Is the cardiovascular control centre

Question 13

How does the medulla oblongata respond to the increased frequency of action potentials via afferent nerves?

Answer 13

Decrease in sympathetic output

Parasympathetic output is increased

Question 14

What is the result of decreased sympathetic output and increased parasympathetic output? What is the overall result?

Answer 14

Reduced CO - reduced heart rate, force of contraction, SV

Reduced TPR - vasodilation

Reduced maBP - reduced CO, TPR

Question 15

How do baroreceptors detect a decrease in blood pressure?

Answer 15

Less stretching of arterial walls

Less stretching of baroreceptor nerve endings

Question 16

What do baroreceptors do when they’re no lonnger being stretched?

Answer 16

Decrease frequency of action potentials to medulla oblongata via
vagus nerve - aortic arch
glossopharyngeal nerve - carotid sinus

Question 17

How does the medulla oblongata respond to the decreased frequency in action potentials via afferent nerves?

Answer 17

Increases sympathetic output

Decreases parasympathetic output

Question 18

What is the result of an increased sympathetic output and a decreased parasympathetic output? What is the overall result?

Answer 18

Increased CO - increased heart rate, force of contraction, SV

Increased TPR - vasoconstriction

Increased maBP - increased CO, TPR

Question 19

What type of feedback does the baroreceptor reflex involve? Explain how

Answer 19

Negative feedback loop

change in blood pressure results in blood pressure being restored back to normal

Question 20

Why are baroreceptor reflexes not involved in the long-term control of blood pressure?

Answer 20

Threshold for baroreceptor firing action potential is reset

to the new blood pressure

Question 21

What type of pathways are involved in the medium-long term control of blood pressure?

Answer 21

Neurohumeral pathways - ANS and circulating factors

Question 22

What are the four neurohumeral pathways involved in medium-long term control of blood pressure?

Answer 22

Renin-angiotensin aldosterone system (RAAS)

Sympathetic nervous system (SNS)

Anti-diuretic hormone (ADH)

Atrial natriuretic peptides (ANP)

Question 23

What do all the four neurohumeral pathways involved in medium-long term control of blood pressure have in common?

Answer 23

All affect sodium retention

Question 24

How does controlling sodium retention affect blood pressure?

Answer 24

Sodium retention affects water reabsorption
Extracellular fluid volume
Plasma volume
Blood volume
Affects filling of ventricle in diastole, EDV, SV, CO
And finally blood pressure

Question 25

What are the factors that cause the release of the renin?

Answer 25

Reduced perfusion pressure in kidneys Sympathetic stimulation of JGA Reduced NaCl deliverty to distal tubule, macula densa

Question 26

How do the kidneys detect reduced perfusion pressure?

Answer 26

Have baroreceptors | in afferent arterioles

Question 27

Where is renin released from in the kidneys?

Answer 27

Granular cells of afferent arteriole | of juxtaglomerular apparatus (JGA)

Question 28

What is the function of renin?

Answer 28

To cleave angiotensinogen to angiotensin 1

Question 29

Where is angiotensinogen released from?

Answer 29

Liver

Question 30

What does ACE stand for?

Answer 30

Angiotensin converting enzyme

Question 31

Where is ACE released from?

Answer 31

Epithelial cells in lungs

Question 32

What is the role of ACE?

Answer 32

Convert angiotensin 1 into angiotensin 2 Break down bradykinin protein into peptide fragments

Question 33

What does angiotensin 2 bind to?

Answer 33

Angiotensin 2 receptors - AT

Question 34

What are the types of angiotensin 2 receptors?

Answer 34

Type 1 - AT1 | Type 2 - AT2

Question 35

What type of angiotensin 2 receptor does angiotensin 2 mostly bind to?

Answer 35

AT1

Question 36

What type of receptor is AT1?

Answer 36

GPCR

Question 37

Where are AT1 receptors located

Answer 37

Arterioles Kidneys Adrenal cortex Sympathetic NS Hypothalamus

Question 38

What effect does angiotensin 2 binding to AT2 in the arterioles cause? How does this affect blood pressure?

Answer 38

Causes vasoconstriction | Increase in TPR, maBP

Question 39

What effect does angiotensin 2 binding to AT2 receptors in the kidneys cause? How does this affect blood pressure?

Answer 39

Stimulates sodium reabsoprtion Water follows Increased BV, filling of ventricles, EDV, SV, CO, maBP

Question 40

What effect does angiotensin 2 binding to AT2 receptors in the adrenal cortex cause?

Answer 40

Stimulates release of aldosterone

Question 41

What effect does angiotensin 2 binding to AT2 receptors in the sympathetic NS cause?

Answer 41

Increased release of NA

Question 42

What effect does angiotensin 2 binding to AT2 receptors in the hypothalamus cause?

Answer 42

Stimulates release of ADH

Question 43

Which cells does aldosterone affect?

Answer 43

Principal cells of collecting ducts | in kidneys

Question 44

What does aldosterone do?

Answer 44

Increases activity of Na+ K+ ATPase on basolateral domain Activates ENaC on apical domain

Question 45

What are the effects of aldosterone?

Answer 45

Increased Na+ efflux from cell into blood by Na+ K+ ATPase Sets up Na+ conc. gradient Na+ reabsorbed into cell through ENaC

Question 46

What effect does bradykinin have?

Answer 46

Vasodilation

Question 47

What is the purpose of ACE breaking down bradykinin?

Answer 47

Reduced vasodilation | Increase in TPR, maBP

Question 48

How does sympathetic activity affect renal blood flow?

Answer 48

Reduce renal blood flow | by vasoconstriction of arterioles

Question 49

How does reduced renal blood flow affect sodium retention?

Answer 49

Decreases GFR | Decreases Na+ excretion

Question 50

How does sympathetic activity affect ion transporters in cells?

Answer 50

Increases activity of Na+ K+ ATPase on basolateral domain Activates Na+ H+ exchanger on apical domain

Question 51

How does sympathetic activity affect sodium retention?

Answer 51

Increased Na+ efflux from cell into blood by Na+ K+ ATPase Creates Na+ conc. gradient Na+ is reabsorbed into cell by Na+ H+ exchanger

Question 52

Where in the kidney does the sympathetic nervous sytem affect ion transporter activity?

Answer 52

Proximal convoluted tubule

Question 53

How does sympathetic activity affect renin?

Answer 53

Stimulates renin release from granular cells of afferent arteriole in juxtaglomerular apparatus

Question 54

What is another name for ADH?

Answer 54

Arginine vasopressin

Question 55

What causes the release of ADH?

Answer 55

Increase in plasma osmolarity Severe hypovolaemia

Question 56

What are the functions of ADH?

Answer 56

Increase sodium retention Increase water reabsorption Cause vasoconstriction

Question 57

How does ADH increase sodium retention?

Answer 57

Stimulates Na+ K+ Cl- transporter | Na+ reabsorbed into cell

Question 58

How does ADH increase water reabsorption?

Answer 58

Through increasing Na+ retention Also by increasing aquaporin2 water reabsorbed through it

Question 59

Where does ADH stimulate the Na+ K+ Cl- transporter?

Answer 59

Thick ascending limb

Question 60

Where does ADH increase aquaporin2?

Answer 60

Distal nephron

Question 61

How are atrial myocytes related to ANP?

Answer 61

Atrial myocytes synthesise, store and release ANP

Question 62

What causes the release of ANP?

Answer 62

Stretch of atria | due to increased blood volume

Question 63

What is the effect of ANP?

Answer 63

Natriuresis - loss of sodium in urine

Question 64

How does ANP affect sodium retention?

Answer 64

Vasodilation of afferent arteriole Increased GFR Increased excretion of Na+ Inhibits Na+ reabsorption along nephron

Question 65

What type of receptors are located in the atria?

Answer 65

Volume receptors | are low-pressure baroreceptors

Question 66

How do atrial volume receptors detetch volume of blood?

Answer 66

Increased volume of blood causes stretching of atria | Stretching of baroreceptor nerve endings

Question 67

Is ANP released when blood volume is low?

Answer 67

No Reduced filling of heart Less stretching of atria Less ANP released

Question 68

What is an effect of prostaglandins?

Answer 68

Vasodilation

Question 69

How do prostaglandins affect sodium retention?

Answer 69

Local prostaglandins in kidney cause vasodilation of afferent arteriole increase GFR increased Na+ excretion

Question 70

How do prostaglandins have a protective function?

Answer 70

Buffer excessive vasoconstriction caused by RAAS, SNS | preventing damage to blood vessels

Question 71

How is dopamine formed in the kidneys?

Answer 71

From circulating L-DOPA

Question 72

Where are dopamine receptors present in the kidneys?

Answer 72

Renal blood vessels Proximal convoluted tubule cells Thick ascending limb cells

Question 73

What are the effects of dopamine binding to its receptor?

Answer 73

Vasodilation Reduced retention of sodium, water

Question 74

How does dopamine decrease sodium retention?

Answer 74

Inhibits Na+ H+ exchanger Inhibits Na+ K+ ATPase

Question 75

Which cells does dopamine affect?

Answer 75

Principal cells in proximal convoluted tubule | And thick ascending limb