Blood Vessels Flashcards
What are the 3 different kinds of capillaries? What is the order of leakyness?
continuous, fenestrated, sinusoid
least leaky > most leaky
Where are continuous capillaries located? What junction do they have to connect what? What do they also have?
- skin, muscles, blood brain barrier
- tight junctions connect endothelial cells
- allow passage of fluids and small solutes
What do fenesterated capillaries have? What is its function? Which organs are they found in?
- endothelial cells contain pores (fenestration)
- absorption/filtrate formation
- small intestine, endocrine glands, kidneys
What do sinusoid capillaires have? What is blood flow like? Where are they found? What kind of cells do they contain?
- large clefts/lumens
- blood flow sluggish
- found in liver, bone marrow, adrenal medulla
- macrophages
___ carry blood away from heart. It is de/oxygenated
___ carry blood toward heart.
arteries carry blood away from heart.
veins carry blood toward heart.
What do capillaries do?
contact tissue cells; directly serve cellular needs
What s a lumen?
Central blood-containing space
Characteristics of elastic arteries
Are they thick or thin walled? They have elastin in which tunics? What branches do they include? Its large lumen offers ___. Is it inactive or active in vasoconstriction? They act as ___ reservoirs.
Muscular arteries
What are they distal to? Delivers blood to where? What tunica is thick with more ___. Are they active in vasoconstriction?
Arterioles
They are the ___ arteries. They lead to ___. They control ___ with vasoconstriction/vasodialation?
Elastic arteries
- thick walled
- elastin in all 3 tunics
- includes aorta
- large lumen = low resistance
- inactive in vasoconstriction
- act as blood reservoirs
Muscular arteries
- distal to elastic arteries
- delivers blood to body
- *thick tunica media with more smooth muscle**`
- active in vasoconstriction
Arterioles
- smallest arteries
- lead to capillary beds
- control flow into capilary beds via vasoconstriction & vasodialation
Characteristics of venules
This is where ___ unite. It is the ___ venules. Are they porous? Which allow for what? Consists of ___ (tissue layer) and ___ (cell). It has how many layers of smooth muscle cells?
Veins
Veins are formed when ___ converge. Have thin/thick walls & small/large lumen in comparison to arteries. Blood pressure is ___ than arteries. It has a thin tunica ___ and a thick tunica___. Veins are also called ___, which is ___.
Venules
- where capillary beds unite
- smallest vein
- porous, allow fluids/WBC into tissues
- consists of endothelium & few pericytes
- has 1 or 2 layers of smooth muscle cells
Veins
- formed when venules converge
- thin walls & small lumen in comparison with arteries
- blood pressure lower than arteries
- thin tunica media and thick tunica externa
- called capacitance vessels (blood reservoir)
How do veins ensure return of blood to heart despite low pressure? (3)
- large diameter lumens off little resistance
- Venous valves prevent backflow of blood
- Venous sinuses: flattened veins with extremely thin walls
The longer the vessel, the more/less resistance
more
What is blood pressure? What does the pressure gradient do?
- Force exerted on wall of blood vessel by blood
- Pressure gradient (force) keeps blood moving from higher to lower pressure areas
What is resistance? What does it measure? What are the 3 sources of resistance? Which 2 are relatively constant? Which one has the greatest influence on resistance?
- Opposition to flow
- Measure of amount of friction blood encounters with vessel walls
Blood viscosity & Total blood vessel length (relatively constant)
Blood vessel diameter = greatest influence
What is blood viscosity? When viscosity increases, resistance ___,
-The “stickiness” of blood due to formed elements and plasma proteins
I-ncreased viscosity = increased resistance
Vasoconstriction increase/decrease resistance.
increase
___ are the major determinant of peripheral resistance. Disruption of laminar flow increase/decrease resistance.
small-diameter arterioles
-increases
As blood pressure gradient increases, blood flow increases/decreases.
As resistance increases, blood flow increases/decreases.
Which one is more important in influencing blood flow?
Δ P increases, blood flow speeds up
If R increases, blood flow decreases
R more important in influencing local blood flow because easily changed by altering blood vessel diameter
When do pressure result? Where is it the highest? Where does it drop?
- Pressure results when flow is opposed by resistance
Highest in aorta
Declines throughout pathway
0 mm Hg in right atrium
Steepest drop occurs in arterioles
Blood pressure is determined by these 2 things.
Elasticity (compliance or distensibility)
Volume of blood forced into them at any time
Aterial blood pressure
What is sytolic pressure? Diastolic pressure? Pulse pressure? Mean arterial pressure?
Pulse pressure/MAP increase/decrease with increasing distance from the heart.
Systolic pressure: pressure exerted in aorta during ventricular contraction
Diastolic pressure: lowest level of aortic pressure
Pulse pressure = difference between systolic and diastolic pressure
(Throbbing of arteries, called pulse)
MAP = pressure that propels blood to tissues
decreases
Why do we want low capillary blood pressure?
High BP would rupture fragile, thin-walled capillaries
True or false
venous blood pressure is the smallest pressure due to cumulative effects of peripheral resistance
true
What are 3 factors that aid venous blood return to the heart?
- Muscular pump: contraction of skeletal muscles
- Respiratory pump: pressure changes during breathing
- Venoconstriction under sympathetic control
cardiac output chart
Blood pressure increases when
- blood pressure gradient
- resistance
-large the pressure gradient,
