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
cardiac output chart
