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24 Cards in this Set
- Front
- Back
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What is a baroreflex? |
Autonomic, negative feedback mechanism in response to blood pressure through the use of baroreceptors.
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What does a baroreflex do? |
Inhibits the SNS - Cardiac Center - Vasomotor Center Excites Vagal Fiber |
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What effects do baroreceptors have? |
- Reduces heart rate - Reduces Cardiac output - Dilates vessel - Reduces Blood pressure |
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Vagus Nerve stimulate parasympathetic nervous system |
This causes a reduction in heart rate and control force and cardiac output- all caused from baroreceptors |
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parasympathetic discharge - BP goes down sympathetic discharge - BP goes up |
Note |
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What are chemoreflexes and how do they work? |
Autonomic response to chemical change through chemoreceptors - will respond to a decrease in pH and O2 or increased Co2 - primary role is to adjust respiration - secondary roles are vasomotor vasoconstriction and increased perfusion
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What is the medullary ischemic reflex and how does it work? |
Autonomic response to drop in brain perfusion - Cardiac and vasomotor centers increase increase HR contraction and cause widespread vasoconstriction
Input from higher brain center due to stress, arousal, and anger |
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How does Angiotensin II affect act on vascular smooth muscle? |
vasoconstriction |
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How does aldosterone act on vascular smooth muscle? |
Sodium retention by kidneys |
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How does Atrial Natiurtic Peptide act on vascular smooth muscle? |
Increases Sodium Excretion - come from heart hence the atrial part - release peptide when volume of atria are stretched more than normal |
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How does antidiuretic hormone act on vascular smooth muscle? |
water retention |
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How does epinephrine and norepinephrine act on vascular smooth muscle? |
- Norepinephrine - Vasoconstriction on most vessels - Epinephrine - general vasoconstriction and increase in CO but Vasodilation in coronary and skeletal muscle blood vessels which increases blood to skeletal muscle and heart |
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What happens during localized vasoconstriction of an artery? |
- Pressure downstream decreases - Pressure upstream increases - Blood takes the path of least resistance |
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Pay attention to graphs which show changes in systemic blood flow during rest and exercise |
Note: Exercise greatly increases the blood flow to many parts of the body, including the brain and muscular tissue. - The percentage of blood now within the muscle tissue is much higher. |
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What is the cardiac output at rest during the cardiac output during exercise? |
At rest: 5 L/min. Exercise: 17 L/min. |
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What is the two way moment of materials and fluids? |
Delivery and Removal
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Can you describe the delivery part the movement of materials and fluids? |
Blood - capillary - interstitial space - tissue - oxygen, glucose, AA, lipids, minerals, hormones
Velocity of blood slows into capillary bed -increase in cross sectional area of blood - increases time for exchange
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Can you describe the removal part of movement of materials and fluids? |
tissue - interstitial space - capillary - blood - Co2, ammonia, other wastes |
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What are the 3 modes of capillary exchange? |
1. Diffusion 2. Vesicular transport - pincytosis - exocytosis 3. Bulk flow - filtration - reabsorption |
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What are the characteristics of simple diffusion? |
Requires concentration gradient Lipid - soluble materials - through plasma membrane Water - soluble substances - Fernestrations - pores in capillary cells - intercelluarl clefts - gaps in tight junctions between cells |
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What are the characteristics of transcytosis vesicular transport? |
- Vesicles pick up fluid by pinocytosis or receptor mediated endocytosis - transport across cell - discharge on other side (exocytosis) - accounts for small percentage of transportation -fatty acids, albumins, insulin |
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What is Bulk Flow and how does it work? |
Balance of filtration and osmotic forces - filtration at arterial end of capillary - reabsorption at venous end of capillary - fluid from interstitial pace to capillary Two forces involved - hydrostatic and osmotic - Net Filtration Pressure (NFP) |
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Blood hydrostatic pressure is the pressure of the fluid against the walls of the capillary - about 30 mmHg in the proximal end - venous distal end - about 10 mmHG - artery |
Inerstitial fluid pressure is the pressure against the outside walls of the capillary beds. |
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What are some critical mechanism of venous return? |
Pressure gradient - Central Venous Pressure Gravity Skeletal Muscle Pump - Contraction squeezes or "milks" veins Respitory Pump - Thoracic pressure Cardiac Suction
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