Integrated Control of the CVS Flashcards
what does mean arterial pressure depend on?
cardiac output and total peripheral resistance
what does regulation of the entire cardiovascular system depend on?
the integrated action of multiple subsystem controls as well as non-cardiovascular controls
what is preload?
how much of the blood comes back from the periphery to the heart
what is afterload?
volume, work wise, in front of the heart
what decreases preload?
anything pulling the blood in the periphery
what increases preload?
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
what are the subsystems of the cardiovascular system? what monitors them?
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
How is part of the autonomic nervous system involved in cardiovascular control?
high-pressure baroreceptor response, also fight or flight response can affect the circulation
how does the respiratory system affect the cardiovascular system?
- 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.
how does the hematopoietic organs and liver affect the cardiovascular system?
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
how does the GI system affect the cardiovascular system?
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
how does the endocrine system affect the cardiovascular system?
epinephrine release by the adrenal medulla and necessary in a function against norepinephrine in the act of maintaining homeostasis
how does the temperature control system affect the cardiovascular system?
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
what does the overall fight or flight response involve?
Skeletal muscle blood flow Cutaneous blood flow Adrenal medulla Renal and splanchnic blood flow Veins The heart Mean arterial pressure
how is skeletal muscle blood flow affected by the overall fight or flight response involve?
activation of sympathetic cholinergic vasodilator fibers directly causes a rapid and massive increase in blood flow to skeletal muscle.
how is cutaneous blood flow affected by the overall fight or flight response involve?
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]).
how is the adrenal medulla affected by the overall fight or flight response involve?
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).
how is the renal and splanchnic blood flow affected by the overall fight or flight response involve?
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.
how are veins affected by the overall fight or flight response involve?
Most veins constrict in response to sympathetic output.
how is the heart affected by the overall fight or flight response involve?
Increased sympathetic output and decreased vagal output cause a rise in heart rate and contractility, so that cardiac output increases.
how is the mean arterial pressure affected by the overall fight or flight response involve?
cardiac output increases, the net result of an increased cardiac output and a resistance change is an increase in arterial pressure.
what is vagovasal syncope?
- 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
how does the vasovagal response affect Total peripheral resistance?
massive vasodilation occurs, fall in BP is not corrected by a baroreceptor response, which decreases cardiac output
how does the vasovagal response affect Cardiac output?
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
