Integrated Control of the CVS

Question 1

what does mean arterial pressure depend on?

Answer 1

cardiac output and total peripheral resistance

Question 2

what does regulation of the entire cardiovascular system depend on?

Answer 2

the integrated action of multiple subsystem controls as well as non-cardiovascular controls

Question 3

what is preload?

Answer 3

how much of the blood comes back from the periphery to the heart

Question 4

what is afterload?

Answer 4

volume, work wise, in front of the heart

Question 5

what decreases preload?

Answer 5

anything pulling the blood in the periphery

Question 6

what increases preload?

Answer 6

anytime we have a higher peripheral resistance, it pushes blood toward the heart so that we can have a higher cardiac output so we can have a higher incoming stroke volume in the next cycle

Question 7

what are the subsystems of the cardiovascular system? what monitors them?

Answer 7

cardiac output
mean arterial pressure
total peripheral resistance 
blood volume
systemic circulatory reflexes
local vasomotor control

ANS
Respiratory system
hematopoietic organs and liver
urinary and GI systems
endocrine system
temperature control system

Question 8

How is part of the autonomic nervous system involved in cardiovascular control?

Answer 8

high-pressure baroreceptor response, also fight or flight response can affect the circulation

Question 9

how does the respiratory system affect the cardiovascular system?

Answer 9

• monitors pH changes which affect breathing
• the action of the respiratory muscles during inspiration causes intrathoracic pressure to become more negative, thereby increasing venous return
• a third example is that the evaporative loss of water during breathing reduces total body water and, ultimately, blood volume.

Question 10

how does the hematopoietic organs and liver affect the cardiovascular system?

Answer 10

control blood composition in terms of cell constituents and plasma proteins, which plasma proteins determine colloid osmotic pressure, therefore a major component of the starling forces affecting blood volume

hematocrit and large proteins are major determinants of blood viscosity and blood flow

Question 11

how does the GI system affect the cardiovascular system?

Answer 11

they determine the input and output of electrolytes and water and are responsible for controlling the volume and electrolyte composition of the ECF playing a role in blood pressure

Question 12

how does the endocrine system affect the cardiovascular system?

Answer 12

epinephrine release by the adrenal medulla and necessary in a function against norepinephrine in the act of maintaining homeostasis

Question 13

how does the temperature control system affect the cardiovascular system?

Answer 13

carrying blood from the body core to the skin where heat loss then occurs

Heat loss occurs as sweat glands secrete fluid that then evaporates
Loss of ECF volume reduces the effective circulating volume

Question 14

what does the overall fight or flight response involve?

Answer 14

Skeletal muscle blood flow
Cutaneous blood flow
Adrenal medulla
Renal and splanchnic blood flow
Veins
The heart
Mean arterial pressure

Question 15

how is skeletal muscle blood flow affected by the overall fight or flight response involve?

Answer 15

activation of sympathetic cholinergic vasodilator fibers directly causes a rapid and massive increase in blood flow to skeletal muscle.

Question 16

how is cutaneous blood flow affected by the overall fight or flight response involve?

Answer 16

The sympathetic response causes little change in blood flow to skin unless it stimulates sweating. The neural pathway involves sympathetic cholinergic neurons, which release acetylcholine and vasodilatory neurotransmitters (e.g., calcitonin gene - related peptide [CGRP], vasoactive intestinal peptide [VIP]).

Question 17

how is the adrenal medulla affected by the overall fight or flight response involve?

Answer 17

Preganglionic sympathetic neurons stimulate the chromaffin cells to release epinephrine, which causes vasodilation in muscle (via β2 adrenoceptors) and vasoconstriction in the kidney and splanchnic beds (via α1 adrenoceptors).

Question 18

how is the renal and splanchnic blood flow affected by the overall fight or flight response involve?

Answer 18

increased sympathetic output causes vaso-constriction and thereby decreases blood flow. The systemic release of epinephrine also vasoconstricts these vascular beds rich in α1 adrenoceptors.

Question 19

how are veins affected by the overall fight or flight response involve?

Answer 19

Most veins constrict in response to sympathetic output.

Question 20

how is the heart affected by the overall fight or flight response involve?

Answer 20

Increased sympathetic output and decreased vagal output cause a rise in heart rate and contractility, so that cardiac output increases.

Question 21

how is the mean arterial pressure affected by the overall fight or flight response involve?

Answer 21

cardiac output increases, the net result of an increased cardiac output and a resistance change is an increase in arterial pressure.

Question 22

what is vagovasal syncope?

Answer 22

• Fainting episode
• Response to emotional stress, phlebotomy, sight of blood, acute pain
• Loss of consciousness is due to a transient fall in perfusion pressure to brain

Question 23

how does the vasovagal response affect Total peripheral resistance?

Answer 23

massive vasodilation occurs, fall in BP is not corrected by a baroreceptor response, which decreases cardiac output

Question 24

how does the vasovagal response affect Cardiac output?

Answer 24

intense vagal output to heart causes bradycardia and decreased stroke volume= decrease in cardiac output.

Atropine (muscarinic receptor blocker) does not reliably prevent syncope, decreased sympathetic tone to the heart may also play a role in the bradycardia

Question 25

how does the vasovagal response affect arterial pressure?

Answer 25

fall in mean arterial pressure due to decrease in total peripheral resistance and decreased cardiac output

Question 26

how does the vasovagal response affect cerebral blood flow?

Answer 26

global cerebral ischemia develops, which results in dizziness and faintness

• If lasts for 10 seconds results in loss of consciousness
• Stress may also provoke hyperventilation= lowers arterial PCO2
• Cerebral blood flow is impaired due to constriction of cerebral blood vessels

Question 27

Other manifestations of altered ANS activity due to vasovagal syncope?

Answer 27

pallor of skin and sweating
○ Intense vagal stimulation of the GI causing epigastric pain/ nausea
○ Miosis (pupil constriction) and visual blurring from parasympathetic stimulation

Question 28

what happens following hemorrhage?

Answer 28

Fall in arterial pressure

Four major receptors: high-pressure baroreceptors, low-pressure baroreceptors, peripheral chemoreceptors, and central chemoreceptors

Question 29

what are the four major receptors affected following hemorrhage?

Answer 29

high-pressure baroreceptors
low-pressure baroreceptors
peripheral chemoreceptors
central chemoreceptors

Question 30

how are the high pressure baroreceptors affected following hemorrhage?

Answer 30

decrease in the firing rate of afferents from the carotid and aortic baroreceptors
○ Enhanced sympathetic output and diminished vagal output
○ Increase HR and cardiac contractility
○ Produce venoconstriction and selective arteriolar constriction
○ Cooperate to re-establish the arterial pressure

Question 31

how are the low pressure baroreceptors affected following hemorrhage?

Answer 31

○ Decreases effective circulating volume
○ Lessens the activity of low-pressure stretch receptors
○ Increased sympathetic outflow causes vasoconstriction in a number of vascular beds, particularly the kidney, reducing glomerular filtration rate and urine output
○ Divergent effects on HR
○ Atrial stretch receptors also project to the hypothalamus, enhancing release of AVP, which reduces water excretion by the kidneys

Question 32

how are the peripheral chemoreceptors affected following hemorrhage?

Answer 32

○ BP drops causing perfusion of the carotid and aortic bodies decline
○ Hypoxia near the glomus cells and increase in firing rate of the chemoreceptor afferents
○ Increased chemoreceptor discharge leads to increased firing of the sympathetic vasoconstrictor fibers and ventilatory chances that indirectly increase HR

Question 33

how are the central receptors affected following hemorrhage?

Answer 33

○ Severe hypotension results in brain ischemia
○ Fall in the PO2 of brain ECF
○ Rise in PCO2 and fall in pH
○ Acidosis has a profound effect on the central chemoreceptors in the medullar= greatly enhanced sympathetic vasoconstrictor output