Blood vessels and circulation Exam1 Flashcards
what are the characteristics of arteries
away from heart
- aorta
- arteries
- large, medium, small
- arterioles
What do capillaries do
exchange
what are the characteristics of veins
toward heart
- venules
- veins-large, medium, small
- vina cava -inferior and superior
what does the vessel wall consist of
tunica intima or tunica interna
-endothelium and underlying connective tissue
tunica media
-smooth muscle and elastic fibers
tunica externa or tunica adventitia
-connective tissuewhat is the smooth muscle in the tunica media responsible for?
vasoconstriction
does the tunica extera offer protection:
creates tough outer covering that resists puncture
what do large arteries tend to have?
what do medium/small arteries have?
very thick internal elastic layer while some medium/smaller arteries have a proportionally large muscular layer
why do veins have a larger radius relative to arteries at same distance from heart?
it allows for similar flow in veins with lower pressure and velocity than the matched artery
what is involved in controlling the perfusion of capillary eds, local and systemic?
local controls
- oxygen
- carbon dioxide
- K+
- nitric oxide
systemic control
- norepinephrine
- epinephrine
- vasopressin (ADH)
- angiotensin
define perfusion.
blood flowing into capillary beds
are precapillary sphincters involved in control of blood flow?
precapillary sphincters control the flow of blood into a capillary bed thus controlling the level of perfusion of that bed and the tissue it supplies.
what is a metarteriole?
a metarteriole is a more direct passage through the capillary bed
with less perfusion do you get more blood flow through the metarteriole?
with less perfusion more blood would flow through the metarteriole
an arteriovenous anastomosis is a direct connection that serves for a bypass for what?
an arteriovenous anastomosis is a direct connection between the arteriole and venule that serve as a bypass for the capillary bed
explain what regulates the level of perfusion at a local level?
the level of perfusion of capillary beds is under primarily local controls from chemical signals, through sympathetic signals (nerves and hormones) can regulate perfusion in some situations.
list the local effectors of vasodilation and vasoconstriction
vasodilators
- low O2 and or high CO2 - lactic acid - nitric oxide (NO) from endothelium - high K+ or H+ in interstitial fluid - local inflammation (e.g. histamine, NO)
vasoconstrictors
- prostaglandins - throwboxanes - endothelin
what is the endothelin and what produces it as well as releases it?
endothelin is a chemical messenger produced and released by endothelium
is adenosine a vasodilator?
adenosine is also listed as a vasodilator it may by an important local vasodilator for the heart
where are baroreceptors and chemoreceptors located?
baroreceptors and chemoreceptors in the arteries superior to the heart
specifically where are baroreceptors and what are their functions?
there are baroreceptors )fundamentally stretch receptors) in the aortic arch and carotid sinuses.
- they trach blood pressure for flow of blood to
the body (aortic arch) and brain (carotid sinus)
what do chemoreceptors form?
there are chemoreceptor cells clustered to form aortic bodies (where corotids branch from aorta) and carotid bodies (where internal and external carotids branch )
peripheral chemoreceptors in these blood vessels detect oxygen, carbon dioxide and PH levels in the blood
what do the peripheral chemoreceptors detect in the blood?
peripheral chemoreceptors in these blood vessels detect oxygen, carbon dioxide and PH levels in the blood
-the pressure, blood gas and PH information is
all transmitted to the brain stem via the vagus
(X) and glossopharngeal (IX) cranial nerves
what can these receptors affect? how does it affect it?
signals from these receptors can affect the ananomic nervous system drive to the heart to increase blood pressure (baroreceptors) and respiratory rythms (chemoreceptors) to keep blood gases and PH within normal reange
what are the 3 main types of capillaries?
continuous capillaries
fenestrated capillaries
sinusoids
describe continuous capillaries.
structure of a continuous capillary: small gaps between endothelial cells called intercellular clefts that let fluid in and out of the capillary
*specialized continuous capillaries in the brain have tight junctions between epithelial cells rather than clefts to form the blood-brain barrier
describe fenestrated capillaries
structure of fenestrated capillaries: capillaries with pores that span the epithelial cells
-these make these capillaries more porous than
continuous capillaries
-found in choroid plexus of brain, most classical
endocrine organs, intestines and kidneys
describe sinusoids
structure of sinusoids: flattened or irregularly shaped with large gaps between adjacent epithelial cells
-allows for greater exchange with surrounding
tissues
-found in liver spleen and bonemarrow
do arteries act as a reserve for pressure?
do veins act as a reserve for blood volume?
Arteries act as a reserve of pressure within the cardiovascular system, but veins act as reserve for blood volume
what has to happen for your blood to start circulating faster?
when you need to get blood circulating faster constriction of larger veins will greatly increase venous return helping to boost cardiac output
what portion of the nervous system controls vasoconstriction of veins?
sympathetic innervation controls the vasoconstriction of veins
do most tissues have a simple pathway?
most tissue have the simple pathway
is there a portal system in the hypothalamus and pituitary?
there is a portal system in the hypothalamus and pituitary
what is the portal system between the liver and intestine called?
the hepatic portal system
where are AV shunts most commonly found?
AV shunts are most common in fingers and toes for conserving heart
does the blood supply to and from the brain have lots of anastomoses?
the blood supply to and from the brain has lots of anastomoses
what are the differences in arterial and venous systemic circulation?
Arterial
- conduit between heart and capillaries
- pressure reservoir
- damp oscillations in pressure and flow
- control distribution to capillary networks
Venous side
- conduit between capillaries and heart
- volume reservoir
- low pressure aided by various mechanisms
* one way valves
* skeletal muscle pumping
* respiratory pumping
Is TPR affected by arterial diameter?
Total Paripheral Resistance (TPR)
Arteriole diameter -big factor in TPR
why are baroreceptors called different things according to where they are found?
baroreceptors in the arterial side monitor blood pressure and sometimes are called high pressure baroreceptors while those in the venous side (primarily right atrium and a few large veins ) are called low pressure baroreceptors.
describe pressur flow and resistance
Blood flow (F)- is always from an area of higher pressure to lower pressure
Hydrostatic pressure (P)-is the pressure exerted by any fluid
resistance (R)- is the measure of forces tat impede flow
what is the equation fro flow?
F=^(greek delta)P/R
name and describe the different pressures that arise in the body?
blood pressure capillary pressure venous pressure pulse pressure mean arterial pressure (MAP)
how is blood pressure usually reported?
usually reported as arterial pressure at about level of heart
-systolic BP/diastolic BP
what is another name for capillary pressure and what is it a major factor in determining?
capillary pressure of capillary hydrostatic pressure (CHP)-is a major factor in determining the level of exchange of fluids with surrounding tissue
Is venous pressure usually low?
venous pressure is usually quite low; this is why there are additional mechanisms to help maintain good flow within the venous side of the systemic circuit
what is pulse pressure?
pulse pressure is the difference between systolic and diastolic pressure. It is a crude measure of total peripheral resistance and compliance (elasticity) of blood vessels.
what is MAP a measurement of?
mean arterial pressure is a measurement of the average force behind the blood flow withing the arterial side of the systemic circuit
Is MAP and indicator of something?
it is a good indicator of whether or not there is sufficient force to get a adequate brain blood flow and of the degree of stimulation of baroreceptors that signal blood pressure to the ANS
how is MAN equated?
MAP=DP + 1/3 (SP-DP)
MAP (mean arteriole pressure)
DP (diastolic pressure)
SP (systolic pressure)
when does BP fall?
when is BP the lowest?
- Pressure falls as blood flows through the circuit
- lowest pressure as blood re-enters the heart (superior vena cava)
what type of blood vessel has the greatest ability to change radius?
arterioles have the greatest ability to change radius of all the blood vessels, and thus, their changes usually determine the minute to minute changes in (TPR) total periperal resistance
is the blood flow the same at all points in the systemic system ?
does velocity slow at any point?
- blood flow same at all points in system
- velocity slows in capillaries
- small readius
- many capillaries
where is blood pressure the slowest?
blood flow is the slowest in the caillaries
do capillaries have a large cross section?
capillaries actually has the largest cross sectional area of any point within the circuit
flow is the result of differences in pressures at 2 points?
Flow (F)=P(point 1)——P(point 2)
P=pressure
is flow inversely related to resistance?
Flow(F) is inversely related t resistance
is there a positive correlation between viscosity and resistance?
yes, Resistance = viscosity ^ = Resistance ^
is there an inverse relationship with resistance and vessel diameter?
yes, Resistance ^ = vessel diameter down
what can affect cardiac output?
Cardiac output
-ANS (and epinephrine)
what affects blood volume?
Blood volume
- hormones
- ANS
what has a affect on arteriole diameter?
Arteriole diameter-local/systemic
- ANS
- hormones - vasopressin, angiotensin
- local signals and chemical messengers
what do the hormones vasopressin and angiotensin do?
vasopressin (AVP or ADH), and angiotensin are hormones that affect both blood voluje and directly alter blood pressure through vasoconstriction in some blood vessels
aldosterone and natriuretic peptides regulate what?
aldosterone and natriuretic peptides (ANP & BNP) are additional regulators of blood volume
adrenergic chemical messenger stimulate receptors that do what?
beta adrenergic receptors cause vasodilation
alpha adrenergic receptors cause vasoconstriction
cardio vascular regulation is controlled by what?
Neural mechanisms
endocrine
Autoregulation
how does the neural mechanisms affect cardio vascular regulation?
neural mechanisms - ANS
- systemically or - within specific tissues/organs
how does the endocrine system affect cardio vascular regulation?
endocrine
-direct via ANS (epiphrine) or other hormones (e.g.
thyroid hormone)
-indirect via regulation of blood volume
how does autoregulation factors affect cardio vascular regulation?
autoregulation
-with local factors e.g. 02 chemical messengers
where are the sensors found that mediate autoregulation?
Sensors tat mediate autoregulation are found locally within blood vessel walls
what are the sensors that regulate neural control?
sensors that regulate neural control are baroreceptors (detect pressure) and chemoreceptors (detect oxygen, carbon dioxide and PH levels)
what is the process involved in the negative feedback control of blood pressure?
high blood pressure activates baroreceptors in the aortic arch and corotid sinus.
this triggers decreased sympathetic activity at the sinoatrial node ( SA node AKA pacemaker cell) of the heart and increased parasympathetic activity at the SA node. The resulting decrease in cardiac output reduces blood pressure.
what is the sequential order of lowering BP?
1.Elevated BP
2.Causes arteries to stretch
3.baroreceptors detect pressure change and begin increasing their firing rate
4.cardioinhibitory neurons are stimulated
5.increased vagal tone
6.reduced heart rate
7. reduced BP
Simultaneously starting at 4.
4.vasomotor center is inhibited
5.reduced sympathetic tone
6.reduced vasomotor tone
7.Vasodilation
8.reduced BP
is redirection of blood flow in response to changing metabolic needs typically mediated by local and systemic changes?
typically changes in blood flow are mediated by both local and systemic factors
does digestion increase blood flow primarily through local signals leading to vasodialation?
digestion would increase blood flow to the intestines primarily through local signals leading to vasodilation as food and chyme moved through the digestive track.
does increased sympathetic activity as well as local changes affect blood flow to muscles?
increased sympathetic activity as well as local changes in oxygen and carbon dioxide levels around muscles will increase blood flow to skeletal muscles during exercise
which muscles have higher levels of blood perfusion?
typically those muscles being used the most would have a greater level of blood perfusion.
what are the responses in vasodilation, venous return, cardiac output and stress response with light exercising?
- light exercise
- extensive vasodilation of skeletal muscle (O2)
- venous return increases
* skeletal muscle pumping
* respiratory pumping - cardiac output increases
* frank starling
* sympathetic stimulation
what are the responses in vasodilation, venous return, cardiac output and stress response with heavey exercise?
- Heavy exercise
- stress response
- blood flow shifts
- large increase in heart rate and BP
- stress response
will light exercise cause some sympathetic activity?
light exercise will cause some sympathetic activity, but not into the range of stress levels of sympathetic hormone.
will heavier exercise cause big increases of stress hormones?
heavier exercise, however can cause much bigger increases of stress hormones depending on the intensity of the exercise. Intensity activity will trigger stress levels of hormones and the attendant stress responses
where are chemoreceptors found around on and extended from the aortic arc of the heart?
chemoreceptors
-external carotoid artery
-aortic bodies (between right commoncarotoid
artery and left common carotid artery and bet
ween left subclavian artery and left common
common carotid artery
where are baroreceptors found around on and extended from the aortic arc of the heart?
Baroreceptors
- aortic arch
- carotid sinus (internal carotoid artery)
what hormonal controls control BP up and BP down?
angiotensin II aldosterone ADH/AVP (vasopressin) epinephrine/norepinephrine natriuretic peptides (ANP/BNP)
how does angiotensin II raise BP?
vasoconstrictor and through aldosterone
how does aldosterone raise BP?
causes Na+ retention, water stays with Na+
how does ADH/AVP (vasopressin) raise BP?
causes water retention
how does epinephrine/norepinephrine raise BP?
cardiac output; venous constriction; increased TPR
what are some routes of capillary fluid exchange?
filtration pores
trancytosis
diffusion through endothelial cells
intercellular clefts
how does capillary filtration and reabsorption occur?
exchange of fluids and dissolved substances occurs in capillary beds because of capillary hydrostatic pressure pushing fluid out and colloidial osmotic pressure pulling fluid into the capillary
what is the term for the difference in osmotic pressure and hydrostatic pressure?
the difference between these 2 pressures is called the net filtration pressure
is the net filtration pressure positive on the end of arterials?
the net filtration pressure is positive on the arterial end of the capillary causing fluid to move out
is the net filtration pressure negative on the venous side?
it is negative on the venous side causing fluid to come into the capillary
what is colloidal osmotic pressure usually generated by? what is this pressure sometimes called?
colloidal osmotic pressure is the osmotic pressure of blood generated by large blood proteins, primarily albumins. It is sometimes called on oncotic pressure
do valves in the legs and lympahtic veins need the help of skeletal muscles for return of fluids to counter gravity and the length of the vessels?
valves in the legs in blood and lympahtic veins really need the help of skeletal muscle activity around the viens to counter gravity and resistance generated by long blood vessels
waht are the mechanisms aiding venous blood flow
one way valves
skeletal muscles pumping
respiratory pumping
can deep breathing help bring blood from the legs back to the heart?
the peristaltic pumping action on the outside of the inferior vena cava caused by the pressure changes inside the thoracic cavity as you breathe can help to draw blood up form the legs and return it to the heart (deep breathing)
