Cardiovascular Physiology Part 3: Regulation of Systemic Arterial Pressure

Question 1

Mean Arterial pressure is the arithmetic product of two factors

Answer 1

• the cardiac output
• total peripheral resistance (TPR): combined resistance to flow of all sympathetic blood vessels; aka systemic vascular resistance (SVR)
  they determine the average volume of blood in systemic arteries over time

Question 2

MAP=

Answer 2

(Cardiac Output) *(Total Peripheral Resistance)

This equation is derived from
FR= change in P / R
change in P = F * R
can explain difference between systemic (higher) and pulmonary arterial pressure (lower)

Question 3

at any given pump input, a change in total outflow resistance must produce changes in the

Answer 3

volume and height (pressure) in the reservoir

Question 4

It is the (blank) that influences the systemic arterial blood pressure

Answer 4

• total arteriolar resistance
• distribution among organs is irrelevant in this regard

Question 5

Hemorrhage

Answer 5

blood loss causes decrease in blood volume which causes decreased venous return which decreases end diastolic volume which decreases Cardiac Output which decreases the MAP

Question 6

Arterial Baroreceptors

Answer 6

homeostatically regulate arterial pressure
- originate primarily with arterial receptors that respond to changes in pressure

Answer 7

2 receptors found on left and right carotid common arteries which then divide into 2 smaller arteries that supply the head with blood

Question 8

at the division between the left and right carotid artery

Answer 8

the wall of the artery is thinner and contains a lot of branching and sensory neuronal processes
CALLED THE CAROTID SINUSES–> sensitive to stretch, serve as pressure sensors aka BARORECEPTORS

Question 9

Aortic arch baroreceptor

Answer 9

function similarly to carotid sinuses
found at aortic arch

Question 10

the two carotid sinuses and aortic arch baroreceptor make up the

Answer 10

arterial baroreceptors
- afferent neurons travel from them to brainstem and provide input to the neurons of cardiovascular control from there

Question 11

The rate of discharge (AP) of the carotid sinus

Answer 11

is directly proportional to the mean arterial pressure

Question 12

at any given mean pressure, the larger the pulse pressure

Answer 12

the faster the rate of firing by the carotid sinus

Question 13

medullary cardiovascular center

Answer 13

-located in medulla oblongata
-neurons in this center receive input from various baroreceptors which determines the AP frequency to the heart and the parasympathetic neurons to the heart, arterioles and veins

Question 14

when arterial baroreceptors increase their rate of discharge

Answer 14

decrease in sympathetic neuron activity and an increase in parasympathetic neuron activity

Question 15

blank and blank are also altered by baroreceptor activity and help

Answer 15

• Angiotensin II generation
• Vasodilation
  altered and help restore Blood pressure

Question 16

if arterial pressure decreases, the discharge rate of

Answer 16

• baroreceptors also decreases
• fewer action potentials travel up the afferent nerves to the medullary cardiovascular system

Question 17

fewer APs traveling to medullary cardiovascular system causes

Answer 17

• increased heart rate (due to increased sympathetic activity to heart)
• increased ventricular contractility (increased sympathetic activity to the arterioles
• arteriolar constriction ( increased sympathetic activity to arterioles/ increased plasma concentration of angiotensin II and vasopressin)
• increased vasoconstriction (increased sympathetic activity to veins)

OPPOSITE OCCURS FOR INCREASE IN ARTERIAL PRESSURE

Question 18

net result of all of this (decreased arterial pressure)

Answer 18

increased cardiac output (increased heart rate and stroke volume)
increased total peripheral resistance (arteriolar constriction)
return of blood pressure towards normal

Question 19

baroreceptors as short term and long term regulator of arterial blood pressure

Answer 19

• short term: activated instantly by blood pressure changes
• if arterial pressure remains increased for more than a few days, baroreceptors adapt and decrease frequency of AP firing at any given pressure, they continue to oppose minute to minute changes in blood pressure but at a higher set point

Question 20

major mechanism for long term regulation of arterial pressure

Answer 20

is blood volume (baroreceptors are short term)

Question 21

Increased blood volume

Answer 21

increases arterial pressure

Question 22

when arterial pressure increases and negative feedback loop occurs

Answer 22

increased arterial pressure decreases blood volume (plasma component) by excretion of salt and water by kidneys (urine)

Question 23

Other cardiovascular Reflexes and Responses

Answer 23

apart from baroreceptors, arterial blood gas concentrations, pain , emotion, sexual activity

Question 24

ex for increased BP

Answer 24

decreased arterial oxygen, increased arterial CO2, decreased blood flow to the brain, pain originating in the skin

Question 25

pain originating in viscera or joints

Answer 25

may cause decreases in arterial pressure

Question 26

Cushing's Phenomena

Answer 26

elevated intracranial pressure (edema/trauma) leads to decreased brain blood flow and a large increase in arterial pressure. - increased brain interstitial CO2 levels to increased sympathetic output to vasculature, increased TPR, to large increase in arterial pressure