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74 Cards in this Set
- Front
- Back
what is hemodynamics |
the physiology of blood flow in the cardiovascular system |
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what is a pressure gradient |
the presence of a higher pressure in one area than in another area |
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where is pressure gradient for blood flow highest and lowest |
higherst in the left ventricle and lowest in the right ventricle |
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what is blood pressure |
the outward force that blood exerts on the walls of the blood vessels |
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what is blood flow and what is it determined by |
the volume of blood that flows per minute and is determined by blood pressure and resistance |
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is blood flow directly or indirectly proportional to the pressure gradient |
directly proportional; as pressure gradient increases so does blood flow |
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3 main factors that influence blood pressure |
resistance, cardiac output, and blood volume |
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what is peripheral resisistance |
the majority of resistance to blood flow takes place away from the heart in the periphery where the arteries brance and become smaller |
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3 things that contribute to peripheral resistance |
vessel size, viscosity and vessel length |
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what is blood viscosity |
refers to how thick blood is; as viscosity of a liquid increases, peripheral resisistance also increases |
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the longer the blood vessel, the greater the resistance to flow |
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what happens as cardiac output increases |
blood pressure will increase |
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what happens when blood volume increases |
blood vessels become fuller and blood pressure increases |
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what is blood volume directly related to |
the amount of water in the blood |
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what is systolic pressure |
pressure in the arteries during systole |
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what is normal systolic pressure |
120 mmHg |
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diastolic pressure is what? |
pressure in arteries during diastole |
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what is normal diastolic pressure |
80 mmHg |
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what is pulse pressure |
the difference between the systolic pressure and the diastolic pressure |
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what is blood pressure measured with |
a sphygmomanometer and a stethoscope |
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3 mechanisms that assist blood returning to the heart in the veins |
one way valves, skeletal muscle pump, respiratory movements |
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what do one way valves do |
function to keep blood from blowing backwards in the veins |
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what is a skeletal muscle pump |
when skeletal muscles contract they squeeze on the veins and propel the blood toward the heart |
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where do respiratory movements assist blood flow |
they help in the thoracic and abdominopelvic cavities |
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sympathetic effects of blood pressure |
the sympathetic nervous system releases the neurotransmitters norepinephrine and epinephrine in response to stressors in the body (does not have to be major stressors) -these neurotransmitters cause an increase in heart rate and contractility which increases cardiac output and thus increases blood pressure |
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parasympathetic effects on blood pressure |
opposite of the sympathetic nervous system -releases neurotransmitter aceytylcholine which causes heart rate to slow which decreases cardiac output thus loweering blood pressure |
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what are baroreceptors |
stretch receptors in the aorta and carotid arteries |
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what are cemoreceptors |
detect the presence or absence of certain chemicals |
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what are peripheral chemoreceptors |
chemoreceptors that regulate blood pressure and are located in the aortic arch and in the carotid artery close to the baroreceptors |
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3 main hormones that affect cardiac output |
epinephrine, norepinephrine and thyroid hormone |
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what does the thyroid hormone do |
acts in indirect manner to increase cardiac output |
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hormones that regulate resistance |
epi and norepinepherine cause vasoconstriction in many blood vessels in the body and thus increase resistance and blood pressure -angiotensin-II is a very powerful vasoconstrictor and will sharply increase peripheral resistance causing an increase in blood pressure |
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3 hormones that regulate blood volume |
antidiuretic hormone, aldosterone, atrial naturetic peptide (ANP) |
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antidiuretic hormone does what |
secreted by the posterior pituitary gland and acts in the kidney causing an increase in water reabsorption and decrease in urine production |
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what does aldosterone do |
released by the adrenal cortex and acts in the kidney causing an increase in the retention of sodium by the kidney; since water goes where sodium goes there is increase in total body water and thus an increase in blood volume |
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what does atrial naturetic peptide do |
causes the kidneys to invrease the elimination of sodium and water which decreases blood volume |
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what is hypertension |
"high blood pressure" |
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what is stage 1 hypertension |
systolic pressure is between 140-159 mmHg and diastolic is 90-99 |
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what is stage 2 hypertension |
systolic is greater or equal to 160 mm Hg and diastolic greater or equal to 100mmHg |
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what does hypertension cause |
increased risk or coronary artery disease, stroke, heart failure, kidney disease, vascular disease and more |
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treatment for hypertension |
lifestyle modificaitons, dietary modifications like low salt and decrease cholesterol intake and drug therapy that is aimed at one or more of the three factors controlling blood pressure |
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what is hypotension |
abnormally low blood pressure; systolic less than 90mm and diastolic less than 60mmhg |
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what is hypotension caused by; 3 things |
reduced blood volume: from dehydration, vomiting, diarrhea, overuse of diuretics decreased cardiac output: caused by medications that lower heart rate or a decreased stroke volume caused by heart failure vasodilation: septic shock resulting from a severe bacterial infection can cause vasodilation |
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what is tissure perfusion |
blood flow through a capillary bed to a tissue and takes into account the mass of the tissue |
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how is perfusion calculated |
taking blood flow and dividing it by the mass in grams of tissue |
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what is capillary exchange |
capillaries have extremely thin walls which allows them to function as exchange vessels for nutrients, gases, ions, water, hormones and waste between blood and the tissues. |
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3 was materials are exchanged in capillaries |
diffusion and osmosis diffusion through the endothelial membrane transcytosis |
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what are fenestrations |
small openings between the endothelial cells |
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what moves through fenestratioins when there is a concentration gradient |
small substances such as monosaccharides and amino acids |
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diffusion through the endothelial membrane |
lipid soluble substances such as exygen, carbon dioxide and ertain lipids can generally enter and exit the capillary by diffusing through the endothelial cells; diffusion always takes place down the concentration gradient |
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what is transcytosis |
transcytosis is a process in which the molecules are taken into the cell by endocytosis and then moved out the other side by exocytosis |
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3 types of capillaries |
continuous capillaries; fenestrated capillaries; sinusoidal capillaries |
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what are continuous capillaries |
the least "leaky" and permit the fewest substances to enter or exit the blood. their endothelial cells are joined by tight junctions |
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fenestrated capillaries |
contain fenestrations or openings in the enothelial cells whcih makes them more leaky than continuous capillaries |
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siunusoidal capillaries |
have discontinuouis sheets of enothelium and very large pores in the enothelial cells; leakiest of all capillaries |
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what is autoregulation |
ensures that the correct amount of blood is delivered to match the tissue's activity level |
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2 mechanisms for control by autoregulation |
myogenic mechanism and metabolic controls |
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what is myogenic mechanisms of regulation |
relies on properties inherent in the smooth muscle of the arteriole vessel supplying the capillary beds; increases in blood pressure in the arterioles activates stretch sensors which result in vasoconstriciton. the reverse is true if there is a decrease in blood pressure |
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metobolic controls |
cellular metabolism generates chemicals that can act to regulate tissue perfusion |
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tissue perfusion in the heart |
because of the contraction forces in the ventricular muscle, blood only flows through the coronary circulation during diastole; the main regulatory mechanism of the coronay circulation is the metabolic control |
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tissue perfusion of the brain |
the brain is more intolerant of ischemia than any other tissue in the body; a loss of conciousness will occur within secons of a sudden decrease in perfusion pressure |
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what maintains cerebral blood flow |
autoregulatory mechanisms including myogenic and metabolic controls |
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tissue perfusion in skeletal muscle |
when exercise begins metabolic conditions in the skeletal mescle cause casodilation resulting in an increase in blood flow to the muscle |
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what is one of the mechanisms behind autoregulation of blood flow to the skin |
temperature: warm conditions will cause vasodilation while cold conditions will cause vasoconstriction |
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how does what move in and out of blood |
by passing through small pores and fenestrations as well as moving via osmosis and filtration |
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what is filtration |
the movement of a fluid driven by a force such as pressure or gravity |
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what is hydrostatic pressure (HP) |
the force that a fluid exerts on the wall of its container |
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blood pressure is a hydrostatic pressure which will force water out of a capillary. this movement of water is an example of |
filtration |
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what is osmosis |
movement of water from low solute concentration to area of high solute concentration |
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what is osmotic pressure |
the solute particles in a solution exert a pulling force on water |
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a solution with a higher solute concentration will have a higher Osmotic pressure than a solution with a lower solute concentration |
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what is oncotic pressure (colloid osmotic pressure) |
the difference in osmotic pressure between the capillary and the interstitial space |
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what is edema |
excessice water in the intersitial fluid |
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2 causes of edema |
an increase in capillary hydrostatic pressue and a decrease in the oncotic pressure (caused by liver failure as a result of chronic alcoholism, viral infection, or cancer) |