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51 Cards in this Set
- Front
- Back
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Explain the workings of blood flow |
Constantly reconditions so composition remain relatively the same Can be adjusted according to metabolic needs Blood to brain is least disrupted supply |
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What happens with blood flow to reconditioning organ? |
They receive more blood than needed for metabolic needs They adjust extra blood to achieve homeostasis |
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What is flow rate through a vessel? |
directly proportionate to pressure gradient inversely proportionate to vascular resistant |
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What is the formula of blood flow through vessel? |
Blood flow equals Pressure gradient divided by Resistance |
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Define Pressure Gradient |
The pressure difference between the beginning and end of a vessel |
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Define Resistance |
Measure of opposition of blood flow through vessel |
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Resistance depends on what? |
Blood viscosity Vessel length Vessel radius (A MAJOR DETERMINENT)
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What is a Major Determinent for Resistence and why? |
Vessel Radius A slight change in vessel radius can greatly affect change in blood flow Resistance is proportionate to 1/r4 |
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What is a Vascular Tree? |
Closed System of Vessels |
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Vascular Tree consists of? |
Arteries Arterioles Capillaries Venules Veins |
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What do Arteries do and what are arterioles and capillaries? |
Arteries carry blood away from the heart. Arterioles are smaller branches of arteries and major resistant vessel Capillaries are smaller branches of arterioles (smallest vessels here all exchanges are made with surrounding cells)
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What are venules? |
Formed from the joining of capillaries Returns the blood to heart |
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What are veins and what do they do? |
Form when venules merge They return blood to heart |
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What is the function of Arteries |
a rapid-transit passageways for blod from heart to organs large radius off arteries offer them little resistance to blood flow a pressure reservoir to provide driving force for blood when heart is relaxing |
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What are in Arterial Connective Tissues? |
Collagen Fibers Elastin Fibers |
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What are collagen fibers? |
Within arterial connective tissues Provides tensile strength |
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What are elastin fibers? |
Within arterial connective tissues Provides elasticity to arterial walls |
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What is Blood Pressure? |
The force exerted by blood against vessel wall |
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What does blood pressure depend on? |
volume of blood contained in vessel compliance of vessel wall |
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What are two types of Blood pressure? |
Systolic and Diastolic |
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What is Systolic Pressure? |
Peak pressure exerted by ejected blood against vessel during cardiac systole (around 120 mm Hg) |
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What is Diastolic Pressure? |
The minimum pressure in arteries when blood is draining off in vessel downstream (around 80mm Hg) |
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How is blood pressure measured? |
Indirectly by a sphygmomanometer |
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What are Karotkoff Sounds? |
Sounds heard when determining blood pressure
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What do you hear Karotkoff Sounds? |
Karotkoff sounds are distinct during valve closure
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When is the first and last Karotkoff sound heard? |
The first sound is heard during peak of systolic pressure The last sound is heard at minimum diastolic pressure |
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What is pulse Pressure? |
The difference between systolic and diastolic pressure |
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You can feel a pulse at certain points, why? |
It is due to pulse pressure and is normally felt at artery closest to skin. |
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What is Mean Arterial Pressure? |
the average pressure driving blood forward into tissues throughout cardiac pressure |
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What is the formula for Mean Arterial Pressure |
diastolic pressure + 1/3 pulse pressure |
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What is the radius of Arterioles supplying individual organs able to adjust independently? |
To distribute cardiac output among systemic organ however, it also depends on the body's momentary needs. To regulate arterial blood pressure
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What mechanisms are involved in adjusting arteriolar resistance? |
Vasoconstriction Vasodilation |
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What is Vasoconstriction? |
The narrowing of a vessel |
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What is Vasodilation? |
The enlargement in circumference and radius of vessel
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What does vasodilation result from? |
It results from the relaxation of smooth muscle layer |
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What does the Vasodilation lead to? |
The decreased resistance and increase flow through the vessel |
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What blood supply is always steady? |
Blood supply to brain |
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What are local Chemical influences on arteriolar radius? |
Local metabolic changes Histamine release |
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What are Local Physical Influence on arteriolar radius? |
Local application of heat or cold Chemical response to sheer stress Myogenic response to stretch
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What are Local Vasoactive Mediators? |
Endothelial Cells |
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What do Endothelial Cells do? |
release chemical mediators that are key in locally regulating arterial callibar releases locally acting chemical messengers in response to chemical changes in their environment
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What is one of the best studied vasocative mediators? |
Nitric Oxide (NO) |
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How is extrinsic control of arterioles accomplished? |
Sympathetic Nerve Influences Hormonal influence over arteriolar smooth muscle |
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Where is the Cardiovascular Control Center? |
In the medulla of brain stem |
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What is the integrating center for blood pressure regulation? |
Cardiovascular Control Center in the Medulla |
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What other brain regions influence blood distribution? |
Hypothalamust |
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What does the hypothalamus doe to influence blood distribution? |
controls blood flow to skin to adjust heat loss to environment. |
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What are hormones that influence arteriolar radius? |
Adrenal Medullary Hormones |
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What are the Adrenal Medullary Hormones? |
Epinephrine and Norepinephrine
Vasopressin and Angiotensin III |
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What do Epinephrine and Norepinephrine do? |
Generally reinforce sympathetic nervous system in most organs. |
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What do Vasopressin and Angiotensin III do? |
Important in controlling fluid balance |
