Chapter 21 - Blood Vessels and Circulation - Part 2 Flashcards
What is tissue perfusion?
blood flowing through tissues
What are 3 factors that affect tissue perfusion
- Cardiac output
- Peripheral resistance
- Blood pressure
Explain how autoregulation works to restore adequate blood flow after blood pressure drops
-precapillary sphincters open and close in response to chemical changes in interstitial fluids
Explain how neural mechanisms work to restore adequate blood flow after blood pressure drops
the cardiovascular centers of the autonomic nervous system ajust cardiac output and peripheral resistance to maintain blood pressuer and ensure adequate blood flow
explain how endocrine mechanisms work to restore adequate blood flow after blood pressure drops
the endocrine system releases hormones that enhance short term adjustments and direct long term changes in cardiovascular performance
What promotes the dilation of precapillary sphincters?
vasodilators
what are local vasodilators?
act at the tissue level to accelerate blood flow through their tissue of origin
give some examples of local vasodilators
-decreased tissueO2 levels or increased CO2 levels
-lactic acid or other acids generated by tissue cells
-Nitric Oxide released by endothelial cells
-rising concentrations of potassium or hydrogen ions in the interstitial fluid
-chemicals released during inflammation (histamine and NO)
-elevated local temo
local vasodilators and vasoconstrictors control blood flow within….
a single capillary bed
in high concentrations, these factors could also affect arterioles
what are the 2 control centers responsible for regulatory activities of maintaining adequate blood flow to vital tissues and organs?
-cardiac centers
-vasomotor center of the medulla oblongata
what do cardioaccelatory centers do?
increase cardiac output through sympathetic stimulation
what do cardioinhibitory centers do?
reduce cardiac output through parasympathetic innervation
the most common vasodilator synapses are “cholinergic” meaning what?
their synaptic terminals release acetylcholine
OTHER vasodilator synapses are “nitroxidergic” meaning what?
their synaptic terminals release NO as a neurotransmitter
NITRIC OXIDE HAS AN IMMEDIATE AND DIRECT RELAXING EFFECT ON THE VASCULAR SMOOTH MUSCLES IN THE AREA
what does “adrenergic” mean
they release the neurotransmitter norepinephrine, which causes VASOCONSTRICTION
