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125 Cards in this Set

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___________ is the common effector for all types of vascular control
Vascular smooth muscle
Vascular smooth muscle is Capable of ________ contraction
graded
Vascular smooth muscle is Capable of maintaining partial contractions for long periods of time. This gives rise to vascular ____ .
tone
__________________Is a property of the muscle cells.
Spontaneous tone:
2. Induced tone: e.g., neural tone is induced by ____________ released from sympathetic noradrenergic nerve endings.
norepinephrine
Vascular control depends upon the existence of a _______, upon which can be superimposed relaxation or further contraction of the vascular smooth muscle.
basal tone
__________ are independent of vascular innervation and circulating hormones.
Intrinsic Control Mechanisms:
Example of intrinsic control responses includes _________ where excess blood flow occurs after a period of reduced flow or zero flow, e.g. due to arterial constriction or occlusion.
reactive hyperemia:
Perfusion Pressure =
Arterial Pressure-Venous Pressure,
measured distal to occlusion.
Example of intrinsic control responses includes, ________ increased blood flow accompanies an increase in metabolic activity, even with a constant perfusion pressure
Functional hyperemia (or active hyperemia):
Autoregulation of blood flow in response to changes in perfusion pressure _______ blood flow tends to remain nearly constant over a wide range of arterial pressure.
steady state
A Possible mechanisms of intrinsic vascular control, includes the ______ mechanism. Where increased stretch of vascular smooth muscle cells causes contraction (e.g., following an increase in arterial pressure). This results in vascular constriction. Decreased stretch causes relaxation (e.g., following a decrease in arterial pressure). This results in vascular dilation.
Myogenic
A Possible mechanisms of intrinsic vascular control, includes the ______ mechanism. Where direct effects of vasoactive metabolites on have an effect on arterioles.
Metabolic mechanism:
Metabolic mechanism: increase in Tissue Cell Metabolic Rate leads to increase in Interstitial Fluid Concentrations of
K+, H+, CO2, inorganic phosphate, adenosine, ATP , ADP, AMP and increase in Total Osmolarity & a decrease in Interstitial Fluid O2 Concentration.
This produces _______ of Arteriolar Vascular Smooth Muscle, vasodialation, and increased blood flow.
An initial decrease in tissue cell metabolic rate would have effects opposite to those above.
Relaxation
Effects of vasoactive metabolites on _______ neurons innvervating arterioles:
increase Tissue Cell Metabolic Rate leads to increase in Interstitial Fluid Concentrations of
K+, H+, adenosine, ATP , ADP, AMP and increase in Total Osmolarity. This leads to decrease in Release of Norepinephrine from
Noradrenergic Neurons
Innervating Arterioles. Relaxation of Arteriolar Vascular Smooth Muscle, resulting in vasodilation & increased blood flow.
sympathetic
Both myogenic and metabolic mechanisms are probably involved to varying degrees in different organs. The normal ratio of ___________ determines which mechanism dominates.
blood flow to metabolic rate (BF/MR)
High BF/MR: usually associated with larger _____ component. (e.g., intestine, kidney, resting skeletal muscle).
myogenic
Lower BF/MR: usually associated with larger _______ component. (e.g., brain, heart, exercising skeletal muscle).
metabolic
Intrinsic mechanisms affect primarily the _______ side of the microcirculation. The venular side usually dilates or constricts passively following arteriolar dilation or constriction
arteriolar
Extrinsic Control Mechanisms are _____
Neural
Sympathetic Noradrenergic Innervation (Also commonly termed “Adrenergic” Innervation use the Neurotransmitter: ____________
norepinephrine (NE)
NE stimulates predominately _____ adrenergic receptors in vascular smooth muscle, which cause constriction.
alpha
Beta-2 adrenergic receptors are also present in some vessels, but increased sympathetic nerve activation normally causes ________
net constriction
The physiological importance of neural activation of any vascular _____ receptors is uncertain. They may be activated primarily by epinephrine from the adrenal medullae.
beta-2
Arterioles and venules receive sympathetic ________ innervation. Precapillary sphincters also may be innervated in some tissues.
noradrenergic
Sympathetic noradrenergic neurons are __________ at rest.
tonically active
Effects of increased activation of sympathetic noradrenergic neurons:

a. Arteriolar ________, with increased precapillary resistance and decreased blood flow to downstream capillaries.

b. Decreased capillary ______ downstream from innervated arterioles. This may increase absorption of fluid from surrounding tissue.

c. __________ of venules and veins.
a. constriction

b.pressure

c.Constriction
During vasoconstriction:

1) Venous _____capacity decreases.
2) Venous blood is displaced toward the _____.
3) Venous ______ and ventricular filling increase.

d. Vascular beds in different organs differ in degree of constriction by sympathetic noradrenergic stimulation. E.g.: skin > muscle > brain.
1. volume
2.heart
3.return
Most neurally mediated vaso- and venodilation results from ______ sympathetic noradrenergic activation ("passive dilation").
reduced
Sympathetic Cholinergic DILATOR Innervation Occurs primarily in _______vessels supplying skeletal muscle.
precapillary
Sympathetic Cholinergic DILATOR Innervation, Neurotransmitter is ________
acetylcholine (ACh)
Increased activation causes of Sympathetic Cholinergic DILATOR Innervation causes ________
vasodilation
Mechanism of dilation in Cholinergic DILATOR Innervation appears to involve prejunctional inhibition of ____ release from noradrenergic neurons innervating the same vessels.
NE
Sympathetic cholinergic dilator neurons are not _____ active, and innervate only precapillary vessels.
tonically
Sympathetic cholinergic dilator neurons may be activated at the beginning of ______ . Activation in highly emotional states could result in _______.
exercise
fainting
. In humans, some sympathetic dilator neurons may release ______ , which would stimulate vascular _____ receptors to dilate the vessels.
epinephrine
beta-2
"Active dilation" by beta-2 adrenergic receptors may result primarily from circulating ______ released by the adrenal medullae. Physiological importance is uncertain, but it may modulate alpha receptor mediated constriction. Beta-2 receptors are found on arterial and venous smooth muscle, but their importance appears greatest on the arterial vessels.
epinephrine
a. Genitals (erectile tissues; some fibers release nitric oxide as transmitter.)
b. Bladder
c. Large intestine
d. Heart
e. Brain

all have vessels that receive _________innervation (note: This is quite limited compared to sympathetic noradrenergic innervation)
parasympathetic
In most cases, the parasympathetic neurotransmitter is ____, which appears to inhibit release of NE from noradrenergic neurons innervating the same vessels, resulting in _________.
ACh
vasodilation
In erectile tissues of the genitals, ACh may cause endothelial release of ___
NO
. In salivary glands, ACh release appears to cause formation of ______ from a plasma protein. ______ then causes dilation of salivary gland vessels.
bradykinin
Bradykinin
“Nitroxidergic” Innervation: cerebral and other vessels may receive vasodilator fibers which release ______. These neurons may have tonic activity.
nitric oxide (NO)
__________ is the primary adrenal medullary hormone released in humans.
Epinephrine:
Epinephrine is released during increased _______ activity
sympathetic
the ______ mechanisms described above usually dominate over the effects of epinephrine released during increased sympathetic discharge
neural
Circulating levels of epinephrine are normally low. Increases in epinephrine cause dilation of vessels in _________ & constriction of vessels in the ____.
skeletal muscle
skin
Angiotensin II (ANG-II) is A powerful _________
vasoconstrictor
Formation of Ang II is initiated by low plasma _____ concentration and low blood _______
sodium
pressure
Formation of ANG-II continues when the kidney releases ______. This acts on a plasma protein to form __________. This converted to ANG-II by __________
renin
angiotensin I
(ANG-I)angiotensin converting enzyme (ACE)
ANG II is normally involved in ____and ____ balance rather than vascular control.
salt
water
Antidiuretic hormone (arginine vasopressin in humans) is a _________.
Vasoconstrictor
ADH is Released by _______ in response to lowered blood volume and increased extracellular osmolarity.
posterior pituitary
ADH May be important in the compensatory response to _______, and possibly in maintaining normal blood pressure
hemorrhage
Hormones of the adrenal cortex are ________
steroids
The role of steroids seems to be ________. Normal reactivity of vessels to neurotransmitters and hormones seems to depend upon normal levels of steroids.
"permissive"
Histamine ______ arterioles
dilates
Histamine eleased by _____ cells following injury and allergic reactions.
mast
histamine _______ capillary permeability
increases
histamine _____ edema formation
Promotes
Atrial natriuretic peptide (ANP, atriopeptin) and B-type natriuretic peptide (BNP, first found in the Brain Stored in and secreted from atrial (ANP) and ventricular (BNP) cells in response to increased _____ of the cardiac chambers.
distension
Additional stimuli for ANP release: cardiac ______ nerve activation, Angiotensin II, Endothelin, and possibly others. May also apply to BNP release
sympathetic
ANP and BNP cause ______ and reduce vascular resistance.
vasodilation
. ANP and BNP increase urinary excretion of ____ , which lowers blood volume.
Na+
ANP and BNP participate in the long-term regulation of ______ pressure and extracellular fluid volume, via additional mechanisms
arterial
ANP and BNP degradation is via neutral _______.
endopeptidase
Endothelium-Dependent Vasodilation. General Mechanism:

Blood-Borne Vasoactive _____
V
Endothelial Membrane ______
V
Endothelial Cell Synthesis and Release
of ___________
V
Arteriolar Smooth Muscle _______
V
Vasodilation
Substances
V
Receptors
V
Endothelium-Derived Relaxing Factor(s)
(EDRFs)
V
Relaxation
Examples of vasoactive substances which appear to cause _____ release:

1. Acetylcholine (especially exogenous ACh injected into the bloodstream).
2. Vasopressin: (reduces constriction due to vasopressin.)
3. Bradykinin
4. Serotonin
5. Thrombin
6. ADP and ATP
EDRF
Increased rate of blood _____ also stimulates EDRF release and causes dilation (flow-induced vasodilation), which would enhance the flow increase.
flow
A major EDRF is _______.
nitric oxide (NO)
There appears to be a _______-dependent vasodilator tone existing in many, if not all, vascular beds.
nitric oxide
__________ is also a dilator released by endothelial cells.
Prostacyclin (PGI2)
________ is a powerful constrictor peptide released by endothelial cells. Other endothelium-derived constricting factors (EDCFs) appear to exist. Some may be released under pathological conditions such as anoxia and hypertension.
Endothelin
Hypertension and atherosclerotic damage to the vascular endothelium may reduce release of ___ and other EDRFs and enhance release of endothelin and other EDCFs, promoting arterial spasm. These possibilities are still being investigated.
NO
The _________ is the"Vasomotor Center":
Medulla Oblongata
The Medulla Oblongata contains the Vasoconstrictor ("Pressor") Area called area _____ in some books.
"C-1"
Activation of C1 results in vaso- and veno _______.
constriction
C1 neurons project to sympathetic preganglionic neurons in the spinal cord, and ______ their activities.
increase
Tonic activity of C1 at rest results in sympathetic noradrenergic neural ____ of blood vessels and heart.
tone
Spontaneous rhythmic changes in tonic activity produce oscillations in resting arterial blood ______
pressures
Vasodilator ("Depressor") Area is also called area ____ in some books.
"A-1"
A1 neurons project to and _____ the activity of the vasoconstrictor area. The pathways may involve more than one inhibitory interneurons.
inhibit
Nucleus Tractus Solitarius (NTS) Receives sensory input from the vagus and glossopharyngeal nerves, including afferent impulses from the _______
baroreceptors
________ interneurons project from the NTS to the vasoconstrictor area
Inhibitory
Increased activation of the NTS by increased afferent input from the baroreceptors ________ the vasoconstrictor area. (The vasodilator area may be simultaneously activated.) Diminished afferent input from the baroreceptors has the opposite effects.
inhibits
Medulla Oblongata: Nucleus Ambiguus and Related Areas Near the Dorsal Motor Nucleus of the Vagus Nerve.
These are called the _______ or "cardioinhibitory area" in many books.
"vagal area"
The vagal area is the origin of the vagal parasympathetic preganglionic neurons which innervate the heart. The area is ______ active at rest.
tonically
The VA receives _______ neurons from the NTS. May also receive afferent input from baroreceptors directly.
excitatory
Increased activation of the VA by increased afferent input from the baroreceptors _______ parasympathetic impulses to the heart. Diminished baroreceptor input has the opposite effect.
increases
Some books include the VA area as part of the of the __________ medulla.
"vasomotor center"
There is evidence that the vagal and pressor areas ______ the other when active E.g., increased pressor area activity inhibits vagal area activity.
inhibit
Hypothalamus is an important ________ center for body temperature control, and other functions
integrative
Activation of the anterior region of the hypothalmus causes ______blood pressure, vaso_______ , _____cardia.
decreased
dilation
brady
Activation of posterolateral region of the hypothalmus causes ____ blood pressure, vaso______ , ____ cardia
increased
constriction
tachy
The hypothalamus receives input from cutaneous temperature receptors. Causes reflex cutaneous vaso______ in response to heat, and vaso______ in response to cold.
dilation
constriction
Cerebral Cortex:
Activation of some regions results in vasodilation, while activation of others results in vasoconstriction.
It is involved in vascular actions producing _____ ,_____ and ______.
blushing
fainting
sexual arousal
The Cerebral Cortex is the origin of neurons which project to the sympathetic postganglionic dilator neurons innervating vessels in _______.
skeletal muscle
Baroreceptors are sensory nerve terminals which respond to stretch by ________ action potential generation.
increased
Major baroreceptors involved in continuous, short-term adjustments of _____ pressure.
arterial
Major baroreceptors include, the _______; afferent fibers in the sinus nerve and glossopharyngeal nerves. And the _______ ; afferent nerve fibers in the vagus nerves.
Carotid sinus
Aortic arch
The afferent fibers of baroreceptors have terminals in the __________
nucleus tractus solitarius (NTS).
Baroreceptors adapt to sustained stretch, so they respond more to _____ changes in pressure than to slow or sustained changes.
rapid
Baroreceptors respond to changes in _______ as well as mean arterial pressure
pulse pressure
The normal range of pressures they respond to is about 50 to 200 mm Hg. This can be altered by disease states such as ______ .
hypertension
The __________ results when changes in arterial mean and/or pulse pressure elicit reflex responses which attempt to return pressure toward normal (may not actually reach normal).
Baroreceptor Reflex
Since mean arterial pressure (MAP) = cardiac output (CO) x total peripheral resistance (TPR), MAP can be altered by adjustments in CO (stroke volume x heart rate) and/or TPR. All these are under control of the ________.
autonomic nervous system
An initial increase in arterial pressure results in _________ of carotid and aortic baroreceptors (increased action potential frequency).
Vasodilator area may also be activated.
Stimulation
An initial increase in arterial pressure results in increased frequency of afferent impulses to the _____.
medulla
An initial increase in arterial pressure results in Inhibition of ________ area of medulla and activation of "______ area".
vasoconstrictor
vagal
An initial increase in arterial pressure results in decreased tone in sympathetic fibers to blood vessels and heart, resulting in:
1) Vaso-______(decreases TPR)
2) Cardiac _____ 3) Decreased cardiac ________(decreases SV and CO)
1. dilation
2. slowing
3. contractility
An initial increase in arterial pressure results ine. Increased tone in _______ fibers to heart decreases HR.
parasympathetic
An initial increase in arterial pressure results in _____ being decreased toward the original value (may not actually reach original value).
MAP
The ________ involves Carotid and aortic body sensors for changes in arterial PO2, PCO2, and pH. It has afferents in glossopharyngeal and vagus nerves, respectively. It is stimulated by hypoxia, hypercapnia and acidosis.
Chemoreceptor reflex
Primary reflex activity of chemoreceptors is in regulation of ________
ventilation
Chemoreceptor stimulation sends impulses to vasomotor center, resulting in reflex vaso-_________ .
constriction
Chemoreceptor stimulation potentiates baroreceptor reflex in response to decreased _____ (it then increased toward normal).
pressure
When chemoreceptor stimulation and increased pressure occur simultaneously, the _______ dominates (pressure is reduced toward normal).
baroreceptor reflex
______ and _______pressoreceptors are also called cardiopulmonary baroreceptors
Atrial
pulmonary
Increased volume of the atria causes reflex vasodilation and decreased blood pressure. Atrial pressures are normally much lower than those in systemic arteries, so these are low pressure receptors responsive to ______ changes.
volume
Collapse of lungs causes reflex vaso______ , via stretch receptors in the lungs
constriction
Direct stimulation of the vasomotor center by increased arterial PCO2 and decreased pH, results in vaso__________ .
constriction
_________ decreases in arterial PO2 may activate vasomotor center by releasing neurotransmitters.
Moderate
_____ decreases in arterial PO2 depress vasomotor center activity.
Large
_______, resulting in strong vasoconstriction is probably due to local increases in PCO2 and decreases in PO2, which transiently stimulate the vasomotor center of the medulla.
Cerebral ischemic response
Distension of viscera often causes diffuse pain and vaso______ .
dilation
Cutaneous pain usually causes vaso______ , but deep cutaneous pain may cause vaso_______ .
constriction
dilation