Exam II: 3C Regulation of Arterial Blood Pressure

Question 0

What is the long term regulation for Mean Arterial Pressure (MAP)

Answer 0

• Occurs within hours to days
• Occurs primarily via endocrine pathways
• Targets the kidneys & blood vessels

Question 1

What is the short term regulation for Mean Arterial Pressure (MAP)

Answer 1

• Occurs within seconds to minutes
• Occurs primarily via neural pathways
• Targets the heart & blood vessels

Question 2

What are the short term regulation baroreceptors?

Answer 2

Neutral receptors located in the CAROTID SINUS & AORTIC ARCH

*** They participate in BARORECEPTOR REFLEXES

Question 3

What cranial nerves carry signals from the baroreceptors to the MEDULLARU CARDIOVASCULAR (or CARDIOREFULATORY CENTER) of the brainstem

Answer 3

CN 9 and CN 10

Question 4

What does the Medullary Cardiovascular Center consist of ?

Answer 4

Consists of individual “mini-centers” such as vasomotor area & cardioinhibitory area

Question 5

What does the Medullary cardiovascular center do?

Answer 5

Makes decisions about what to do about hypertension or hypotension and then employs the serves of the SNS and ParaNS to send those orders to various target tissues.

Question 6

What occurs if the BP increases with baroreceptor reflexes

Answer 6

Detection by barorecpetors in the carotids & aortic arch–>Cardio regulatory center informed–> SNS cardiac nerve activity & vasoconstrictor nerve active decreases. ParaNS cardiac nerve activity increases–> HR & SV Decreases (Vasodilation)–> CO and TPR decreases–> BP decreases to normal

Question 7

What occurs if BP decreases in barorecpetor reflexes?

Answer 7

Detection by barorecpetors in the carotids & aortic arch–>Cardio regulatory center informed–> SNS cardiac nerve activity & vasoconstrictor nerve active increases. ParaNS cardiac nerve activity decreases–> (Vasoconstriction) HR & SV increases–> CO and TPR increases–> BP increases to normal

Question 8

What is the pathway response to a hemorrhage in the parasympathetic system?

Answer 8

Acute hemorrhage–> Decreased Mean arterial pressure –> Decreased carotid sinus baroreceptors–>Decreased firing rate of carotid sinus nerve (Hering’s nerve)–> Decreased PARASYM outflow to heart –> Increased HR–> Increased arterial pressure toward normal

Question 9

What is the pathway response to a hemorrhage in the sympathetic system?

Answer 9

Acute hemorrhage–> Decreased Mean arterial pressure –> Decreased carotid sinus baroreceptors–>Decreased firing rate of carotid sinus nerve (Hering’s nerve)–> Increased SYMPATHETIC outflow to heart & Blood vessels –> Increased HR, Inc.. Contractility, Inc. Constriction of Arterioles (Inc TPR), Inc. Constriction of veins, inc. venous return, and Inc. mean systemic pressure –> Increased arterial pressure toward normal

Question 10

How can the sensitivity of the baroreceptors be altered?

Answer 10

By disease

Question 11

For example in hypertension how do the baroreceptors respond?

Answer 11

The baroreceptors do not see the elevated blood pressure as abnormal. The hypertension will be maintained rather than corrected by baroreceptor reflex.

Question 12

What is Long-term regulation–> RAA pathway ?

Answer 12

A decrease in renal perfusion pressure (blood pressure) causes kidneys to secrete the enzyme RENIN.

Question 13

What catalyzes the conversion of Angiotensinogen to Angiotensin I in the plasma ?
How does this affect the kidnet?

Answer 13

Renin

Kidney decreases Na+ excretion and decreases water excretion

Question 14

What does the ANGIOTENSIN CONVERTING ENZYME (ACE) ?

Answer 14

**Catalyzes the conversion of angiotensin I into Angiotensin II, the primarily in the LUNGS **

Question 15

How does the RAA pathway respond to a hemorrhage?

Answer 15

Arterial pressure is decreased–>Decreased Renal
perfusion pressure–>Renin–> Inc. Conv of Angiotensinogen to angiotensin I via ACE–>Increase conv. of angiotensin I to angiotensin II–> Increase Angiotensin II–> Increases Thirst, TPR, Na+-H+ exchange & resorption–>Increases Arterial pressure toward normal.

Question 16

What are other hormonal long term pathways–> ADH

Answer 16

Anti-diuretic hormone (ADH ) is also known as VASOPRESSIN

Question 17

What is the most important physiologic stimulus for increasing ADH secretion?

Answer 17

Increased plasma osmolarity

Question 18

What is another potent stimulus for ADH secretion?

Answer 18

Hypovolemia, or volume contraction (due to hemorrhage)

Question 19

What does decreases in extracellular fluid (ECF) volume of 10% (hypovolemic state) or more cause ?

Answer 19

A decrease in arterial blood pressure that is sensed by the baroreceptors in the left atrium, carotid artery, and aortic arch.

Question 20

What are the 4 things the primary effects of Angiotensin II ?

Answer 20

1) Affects the adrenals to secrete aldosterone (inc. BP, water retention, and conservation of salt)
2) Angiotensin directly affects the kidneys (decrease salt + H2O)
3) Goes straight to the blood vessels (vasoconstrictor)
4) Goes to the Blood Brain Barrier to activate ADH (retain water & increases BP)

Question 21

What are the 2 effects that tend to increase BP toward normal?

Answer 21

1) Increases water reabsorption via the kidneys by activation V2 receptors
2) It is a potent vasoconstrictor that increases TPR by activating V1 receptors on the Arterioles

Question 22

What is ANP? (Atrial Natriuretic peptide)

Answer 22

-Is a powerful vasodilator secreted by the Atria to help regulate & respond to high blood volume (decreases BP)
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Question 23

What are the 2 responses a increase in blood volume ?

Answer 23

1) Increased section of ANP (inc Na+ and H2O)

2) Decreased secretion of ADH \

Question 24

What effects do ANP have?

Answer 24

1) Causes relaxation of smooth muscle resulting in vasodilation and decreased TPR
2) In the kidney, this vasodilation leads to increased Na+ & water excretion –> decreasing total body Na+_ content, ECF volume, and blood volume.

Question 25

What else can effect venous return?

Answer 25

Skeletal muscle pump

Note: when skeletal muscle contracts they force blood back to the heart

Question 26

What do the venous valves do?

Answer 26

**Prevent the back flow of blood away from the heart.

Question 27

How does the skeletal muscle pump work?

Answer 27

When muscle contracts, upper valve opens, but lower closes, so that contraction muscle pushes blood up. After muscle relaxation, upper valve closes, preventing black flow and lower valve opens, allowing veins to fill.