Control of Blood Pressure

Question 1

What does rapid short term control of blood pressure involve?

Answer 1

Nervous system’s effect on vascular smooth muscle

Question 2

What does long term control of blood pressure involve?

Answer 2

Dominated by the kidneys (renal-body fluid balance)

Question 3

Control of blood pressure is accomplished by either affecting one of what 2 things?

Answer 3

Vascular tone or blood volume

Question 4

What are baroreceptors and where are they located?

Answer 4

Spray type nerve endings in vessel walls

Abundant in carotid sinus and arch of aorta

Question 5

What stimulates baroreceptors?

Answer 5

Stretch

Question 6

Baroreceptors inhibit the pressor center via what?

Answer 6

CN IX, X and NTS

Question 7

What are the net effects of baroreceptors?

Answer 7

Vasodilation

Decreased cardiac output

Question 8

Are baroreceptors more sensitive to changing pressure or static pressure?

Answer 8

Changing pressure

Question 9

How do baroreceptors act as buffers?

Answer 9

Buffer change in BP to change in blood volume

Buffer change in BP to change in body position

Question 10

Where are low pressure baroreceptors located?

Answer 10

Artial walls and pulmonary arteries

Question 11

What do low pressure baroreceptors do?

Answer 11

Augment arterial baroreceptors

Minimize arterial pressure changes in response to blood volume changes

Question 12

What happens during a baroreceptor reflex-“low pressure?”

Answer 12

Decreased heart rate

Increased urine production

Question 13

How is urine production increased during the baroreceptor reflex?

Answer 13

Decreased SNS in renal nerves

Decreased secretion of ADH

Question 14

Stretch on the atrial wall stimulates what 3 things?

Answer 14

Baroreceptor reflex
Bainbridge reflex
Release of atrial natriuretic peptide

Question 15

What does the bainbridge reflex do?

Answer 15

Increase heart rate

Question 16

What are the functions of atrial natiuretic peptide?

Answer 16

Diuretic, natriuretic, vasodilator

Question 17

What does the renal-body fluid system do?

Answer 17

Arterial pressure control
Increased ECF will cause arterial pressure to rise
Kidneys excrete excess ECF

Question 18

What are some determinants of long term arterial pressure?

Answer 18

• The degree of shift of the renal output curve for water and salt
• The level of the water and salt intake line

Question 19

Will increased total peripheral resistance (TPR) create a long term elevation of BP if fluid intake and renal function do not change?

Answer 19

NO

Question 20

Where does filtration take place in the kidney?

Answer 20

Glomerular capillaries

Question 21

What can glomerular capillaries do?

Answer 21

• Filtration

- Constrict to autoregulate renal blood flow and glomerular filtration rate when arterial blood pressure is rising

Question 22

Where does reabsorption take place in the kidney?

Answer 22

Peritubular capillaries

Question 23

What are vasa rect?

Answer 23

Specialized peritubular capillaries associated with juxtamedullary nephrons

Question 24

What happens to arterial pressure as extracellular fluid levels rise?

Answer 24

Rise

Question 25

What is involved in an acute renal output curve?

Answer 25

Effect of arterial pressure alone

Question 26

What is involved in a chronic renal output curve?

Answer 26

Effect of arterial pressure plus: - SNS stimulation - Renin-angiotensin system - Aldosterone - ADH - ANP

Question 27

Juxtamedullary nephrons account for what percentage of all nephrons?

Answer 27

15%

Question 28

What do juxtamedullary nephrons do?

Answer 28

Concentrate urine

Question 29

Cortical nephrons account for what percentage of all nephrons?

Answer 29

85%

Question 30

What hormones decrease renal blood flow (RBF)

Answer 30

Norepinephrine Epinephrine Angiotensin II

Question 31

What hormones increase renal blood flow (RBF)

Answer 31

Prostaglandins (E & I)

Question 32

What does tubuloglomerular feedback monitor?

Answer 32

NaCl in macula densa of the distal tubule

Question 33

What does decreasing NaCl in the maucla densa stimulate?

Answer 33

Renin release from the juxtaglomerular (JG) cells & Dilation of afferent arteriole

Question 34

Increasing renin stimulates the increase in what hormone?

Answer 34

Angiotensin II

Question 35

Increasing angiotensin II causes what effect in efferent arterioles?

Answer 35

Resistance

Question 36

Where is renin synthesized, stored, and released from?

Answer 36

Smooth muscle cells in afferent arteriole (primary)

Question 37

What stimulates renin?

Answer 37

- Decreased perfusion pressure - SNS stimulation - Decreased NaCl delivery to macula densa - Hormonal stimulation - Thyroid hormone - Growth hormone

Question 38

What enzyme catalyzes the formation of angiotensin I from angiotensinogen?

Answer 38

Renin

Question 39

What enzyme catalyzes the formation of angiotensin II from angiotensin I in the lung?

Answer 39

angiotensin converting enzyme associated with pulmonary endothelium

Question 40

What are 4 functions of angiotensin II?

Answer 40

- Stimulates adrenal cortex to secrete aldosterone - Stimulates release of ADH - Stimulates kidney - Stimulates thirst/drinking behavior

Question 41

What is the net effect of angiotensin II?

Answer 41

Decrease Na and H20 secretion = Increasing blood pressure and tightening blood vessels

Question 42

What happens if one renal artery is tied off?

Answer 42

``` Systemic hypertension (increased renin & angiotensin II) No uremia ```

Question 43

What happens if one renal artery is tied off and the kidney is removed?

Answer 43

No hypertension or uremia

Question 44

What happens if both renal arteries are tied off and both kidneys removed?

Answer 44

Hypertension and uremia

Question 45

What is "Goldblatt hypertensive model?"

Answer 45

Hypertension generated by tying off a renal artery

Question 46

In the one kidney variety of the Goldblatt HTN model, what happens with renin?

Answer 46

Initially high

Question 47

In the two kidney model of Goldblatt HTN model, what happens with renin?

Answer 47

Renin from the restricted kidney causes fluid retention of the good kidney

Question 48

What are some beneficial effects of slow breathing (especially in CHF paitents)?

Answer 48

- Increased resting oxygen saturation - Improves ventilation/perfusion mismatching - Improves exercise tolerance by decreasing sense of dyspnea - Decreased chemoreflex activation - Decreased SNS activity (increased vagal tone?) - Decreased SBP and DBP

Question 49

What is the effect of increasing antioxidants on free radicals?

Answer 49

Reduces free radicals = nitric oxide can last longer, lowering BP

Question 50

What are some examples of antioxidants?

Answer 50

``` Glutathione Melatonin Superoxide dismustase Beta-carotene Lutein Lycopene Selenium Vitamin A Vitamin C Vitamin E ```

Question 51

What is serotonin's effect on SNS activation?

Answer 51

Inhibit (at CNS level)

Question 52

What is nitric oxide's effect on sympathetic nerve activity?

Answer 52

Inhibit it centrally

Question 53

Bradycardia and hypotension are promoted by what two humoral substances?

Answer 53

Serotonin and nitric oxide