Kim - Regulation Of Vasculature Flashcards
________ do not play a significant role in the regulation of systemic vascular resistance and arterial blood pressure
Parasympathetic nerves
It does, however, play a role in the regulation of the heart
In blood vessels, ___——- released by sympatheic adrenergic nerves preferentially binds to α1-adrenoceptors to cause smooth muscle contraction and vasoconstrictionn
Norepinephrine
Norepinephrine binding to Beta-2 receptors in blood vessels causes?
Vasodilation
Explain vasomotor tone:
The vasoconstrictor area of the vasomotor center in the brain sends constant signals that tell the blood vessels to hold a baseline “sympathetic vasoconstrictor tone”, which maintain a partial state of contraction.
Sudden removal of sympathetic tone produces significant hypotension and vasodilation
What does standing with. Venous poolin in the legs do ?
Decreases venous return, central venous pressure, ventricular preload.
This leads to a decrease in cardiac output and in arterial blood pressure.
Stretch receptors in the heart are located at the _______ junctions and respond to atrial filling and contraction. An increase in firing of these, will lead to increased sympathetic activity. A decrease in central venous pressure will lead to a decrease in firing.
Venoatrial junctions
Antidiuretic hormone is released by the ?
Posterior pituitary
Specialized cells w/in the medulla and on arteries that monitor blood PO2, PCO2, or pH
Chemoreceptors
What causes an increase in firing of the chemoreceptor cells that are located in the aortic arch and the carotid sinus?
Hypoxia, hypercapnia (high CO2), or high H ion concentration (acidosis)
Examples of catecholamines
Epinephrine
Norepinephrine
During activation of the sympathetic nervous system, ________ are released from the adrenal medulla into the blood stream
Catecholamines
Moderately low levels of circulation epinephrine can cause vasodilation, but higher levels of circulating epinephrine will cause vasoconstriction. Why is this?
There are some B-2 receptors in the arterioles of a few specific organs which are more sensitive to epinephrine and promote vasodilation. With enough epinephrine, though, alpha 1 receptors become activated and cause vasoconstriction to take over.
The relative distribution of blood flow to the organs is regulated by the vascular resistance of the individual organs, which is influenced by ____ and ____ mechanisms
Neurohormonal
Local regulatory
A _______ in the availability of oxygen to the tissues increases blood flow
Decrease
A ______ in metabolism increases blood flow to the tissues
Increase
Vasodilator substances
Adenosine, carbon dioxide, potassium ions, hydrogen ions
The transient increase in organ blood flow that occurs following a brief period of ischemia, usually produced by temporary arterial occlusion
Reactive hyperemia
The increase in organ blood flow that is associated with increased metabolic activity of an organ or tissue
Active hyperemia
Releases in every tissue in the body if the tissue becomes damaged or inflamed.
Has vasodilator effect on the arterioles and ability to increase capillary permeability
Histamine
Formed in the blood and tissue fluids of some organs w/ tissue inflammation or by other similar chemical or physical effects on the blood or tissue
Causes both arteriolar dilation and increased capillary permeability
Normal role to help regulate blood flow to skin, salivary, and GI glands
Bradykinin
The vascular endothelium serves as an important ________ role in the regulation of smooth muscle tone and organ blood flow.
Paracrine
The intrinsic ability of an organ to maintain a constant blood flow despite changes in perfusion pressure
Autoregulation
Organs with a high degree of autoregulation:
Coronary circulation, cerebral circulation, renal circulation
Organs with a moderate degree of autoregulation of blood flow
Skeletal muscle circulation, gastrointestinal circulation
