Vessel Structure and Function
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What are the 5 main blood vessel types Arteries, Arterioles, Capillaries, Venules, Veins
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Vessel Structure and Function
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What is the job of veins? |
Regulation of BP and Flow
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How is control of BP and flow accomplished Control is accomplished through several negative feedback systems.BP controlled by adjusting HR, SV, TPR, and blood volume
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How do the fast-acting (short-term) systems work Counteract fluctuations in blood pressure by altering peripheral resistance and CO
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Give example keeps you from passing out from the drop in blood pressure in the brain when you get out of bed
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How do the slow-acting (long-term) systems work Counteracts fluctuations in blood pressure by altering blood volume
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Give an example of when distribution of BF is required when you exercise, a greater percentage of total flow is diverted to skeletal muscle
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Vessel Structure and Function
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List the three tunics of arteries and veins and their make-up Tunic Intima, Media, Externae
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Compare and contrast features between the two Arteries-endothelium, subendothelium, Internal elastic membrane, External elastic membrane, Vasa Vasorum
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Veins-Endothelium, subendothelial layer, Vasa Vasorum
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Capillary Exchange
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What is bulk flow Passive process in which large numbers of ions, molecules, or particles in a fluid move together in the same direction with the fluid
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What determines fluid movement Movement is from an area of high pressure to one of low pressure
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Why is it important Important for regulation of relative volumes of blood and interstitial fluid
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What forces determine bulk flow direction Hydrostatic and Osmotic forces
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Who are they named after Starling Forces
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Vessel Structure and Function
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How do capillaries differ structurally from arteries and veins Capillaries are different from other vascular structures in that they are made of only a single endothelial cell layer sitting on a very thin basement membrane - there are no other tunics, layers, or muscle.
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Why is their structure important The minimalist nature of capillaries allows them to be freely permeable to many substances (gases, fluids, and small ionic molecules).
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Capillary Exchange
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What is capillary exchange The movement of substances between the blood and interstitial fluid
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List three ways substances may pass to and from capillaries •Diffusion•Transcytosis•Bulk Flow (Filtration and Reabsorption)
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Capillary Beds: Two Types of Vessels
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What is the vascular shunt metarteriole
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What is its purpose Directly connects terminal arteriole and postcapillary venule
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What are the true capillaries 10 to 100 exchange vessels per capillary bed. Branch off metarteriole or terminal arteriole
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Vessel Structure and Function
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What structural feature of veins maintains blood flow to the heart despite the low pressure of blood in the veins Valves
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What type of patho can occur when the above fail Varicose Veins
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Vessel Structure and Function
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What is the job of arteries? carry blood away from the heart
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List the three types Large Elastic Arteries, Medium Muscular Arteries, Arterioles
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Neural Regulation
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What CNS structure is involved in neural control Cardio Vascular center
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What are the two parts of the vasomotor center •Vasoconstrictor center•Vasodilator center
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Through what neurons do they relay commands Sympathetic neurons
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What part of the ANS is this part of Sympathetic
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What is vasomotor tone and why is it important This sets the resting level for systemic vascular resistance
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Regulation of BP and Flow
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List and discuss the three methods of regulation of BP –Neural control–Hormonal control–Autoregulation
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Fluid Exchange - Starling Forces
–Filtration
•the movement of fluid (plasma) through the walls of the capillary and into the interstitial fluid.
•Two pressures promote filtration:
–Blood hydrostatic pressure (BHP) generated by the pumping action of the heart
–Interstitial fluid osmotic pressure (IFOP) is due to the presence of dissolved solutes in the interstitial fluid. |
Capillary Exchange
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What is diffusion The movement of a substance from an area of high concentration to an area of low concentration
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What chemical properties affect what can diffuse to and from capillaries Water-soluble substances and Lipid-soluble substances
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In all capillaries, excluding the brain, diffusion is the most important means in net solute exchange between the plasma and interstitial fluid
Vessel Structure and Function
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What is a anastomosis a union of vessels supplying blood to the same body tissue
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Why are they important Should a blood vessel become occluded, a vascular anastomosis provides collateral circulation (an alternative route) for blood to reach to and return from tissue.
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List example in the powerpoint A great example is the genicular anastomosis
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Where are anastomosis commonly found Common at joints, in abdominal organs, brain, and heart
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Where are they not found None in retina, kidneys, spleen
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Vessel Structure and Function
The body contains three types of capillaries:
-Continuous capillaries (least permeable)
The most common
Endothelial cells form a continuous tube, interrupted only by small intercellular clefts.
-Fenestrated capillaries (fenestra = windows)
Found in the kidneys, villi of small intestines, and endocrine glands
These are much more porous.
-Sinusoids (most permeable)
Form very porous channels through which blood can percolate, e.g., in the liver and spleen. |
Vessel Structure and Function
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What is the function of arterioles? Regulate blood flow to the capillaries
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Why are they important in regulating local blood flow and overall BP They are the primary "adjustable nozzles” across which the greatest drop in pressure occurs
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Vessel Structure and Function
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In what blood vessel type is the most percentage of the blood found? Systemic veins and venules
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Vessel Structure and Function
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What receives blood from the capillaries? Venules
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What do these structures empty into Veins
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Vessel Structure and Function
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What receives blood from the capillaries? Venules
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Blood Flow Through Capillary Beds
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What are the precapillary sphincters Precapillary sphincters are bands of smooth muscle that regulate blood flow into true capillaries
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What do they do to affect capillary exchange regulate blood flow
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What are two things that can affect their contractile state chemical conditions and vasomotor nerves
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Why is slow capillary flow important Slow capillary blood flow allows adequate time for exchange between blood and tissues
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Vessel Structure and Function
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Describe how arterioles feed blood into capillaries (list features) The terminal end of an arteriole tapers toward the capillary junction to form a single metarteriole
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At the metarteriole-capillary junction, the distal most muscle cell forms the precapillary sphincter which monitors and regulates blood flow into the capillary bed
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Capillary Exchange
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What is transcytosis Movement of a small quantity of material through the endothelial cell using a pinocytic vesicle
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How is it performed Small membrane enclosed bubble transporting substance within cell
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Why is it performed Used mainly for large lipid-insoluble (water-soluble) molecules that cannot cross capillary walls by other means
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List examples Insulin enters the blood stream this way
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Vessel Structure and Function
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What is the function of the large elastic arteries and give example storing mechanical energy during ventricular systole and then transmitting that energy to keep blood moving after the aortic and pulmonary valves close.
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Best exemplified by the garden hose-sized aorta
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Fluid Exchange - Starling Forces
–Reabsorption•the movement of fluid from the interstitial fluid back through the walls of the capillary and into the plasma.
•Two pressures promote reabsorption:
–Blood colloid osmotic (or oncotic) pressure (BCOP)
•due to the presence of plasma proteins too large to cross the capillary wall
–Interstitial fluid hydrostatic pressure (IFHP)
•The fluid pressure of the interstitial fluid |
–normally close to zero but can become a significant factor in states of edema.
Vessel Structure and Function
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What are tunics? Layers on the wall of a blood vessel
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Vessel Structure and Function
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What is the job of capillaries? site of nutrient and gas exchange
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Neural Regulation of BP
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List the two types of neural reflexes for control of BP and flow –Baroreceptor reflex–Chemoreceptor reflex
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