exercise and the CV system - blood vessels
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Created by:
katttterinaaa on November 14, 2011
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53 terms
Terms | Definitions |
|---|---|
 arteries | the distributors of blood carry the blood to the tissues and away from the heart -3 types -in the systemic circulation carry oxygenated blood -in the pulmonary circulation carry deoxygenated blood -physically connected to SNS, no parasymp. innervation -tend to vasoconstrict with exercise |
| arterioles | smaller diameter arteris |
| capillaries | the exchange vessels allow diffusion of O2 and nutrients out of the blood and CO2 and waste into the blood to be carried away |
| venules | smaller diameter veins |
| veins | -the collectors of blood -carry blood away from the tissues and back to the heart -in the systemic circulation carry deoxygentaed blood -in the pulmonary circulation carry oxygenated blood -innervated by the SNS, but not parasymp. -w/exs, tend to vasoconstrict which pushes blood back towards heart, ^ in venous return |
| three layers (tunics) of blood vessels | -tunic intima -tunic media -tunic externae |
| tunic intima | found in all types of vessels single layer of endothelium critical for the integrity/health of the vessel |
| tunic media | not found in capillaries smooth muscle controlled by the SNS -when SNS is turned on, causes vasoconstriction of smooth muscl large amounts found in arteries and arterioles -gives arteries thicker walls compared to veins |
| tunic exertnae | not found in capillaries mostly fibrous connective tissue more seen in venules and veins |
| difference between blood vessel types | -walls of arteries are the thickest due to large tunica media allows blood to be carried under high pressue -lumens of veins are larger than the arteries but their walls are thinner -skeletal muscle "milks" blood in veins toward the heart -walls of capillaries are only one cell layer thick to allow for exchanges between blood and tissue |
| movement of blood through vessels | -most arterial blood is pumped by the heart --pressure moves blood towards the tissues -veins use the milking action of muscles to help move blood --also have one-way valves which help with directional flow |
| elastic arteries | -initial arteries of the body -very pliable, can stretch than snap back to their original shape -walls contain a great deal of elastic tissue -create the windkessel effect |
| windkessel effect | ejection of the blood out of the heart stretches the arteries, heart stop pushing blood out, arteries snap back and push the blood down stream. Maintains continual flow that a pump (the heart) can't do by itself |
| distributing arteries | -least important for exs phys -carry blood to specific organ or muscle |
| arterioles | -the smallest arteries and very critical to the vascular system -contain a great deal of smooth muscle in their walls -3 major characteristics: --help to control BP --control blood flow to specific tissue --*they are the site to most resistance to blood flow in the entire vascular tree |
| vasoconstriction | as sympathetic stimulation increases, the smooth muscle in the vessel wall contracts causing a decrease in the diameter of the lumen |
| vasodilation | as sympathetic stimulation decreases (or disappears), the smooth muscle relaxes and the diameter of the lumen increases |
| ateries (contd.) | -from the arterioles, the vessels branch off into capillaries -at this point, the last traces of smooth muscle are found, forming a sphincter around the start of the capillary- the PRECAPILLARY SPHINCTER -this smooth muscle is not connect to SNS. consequently, the muscle contracts by local control |
| local control | when the muscle contracts and relaxes on its own -regulates blood flow through the capillary bed |
| circulation through a capillary bed | -arterioles : deliver blood to capillaries -metaarterioles : emerge from arterioles and supplies a group of capillaries -throughfare channel : arise from metaarterioles and contains no smooth muscle; allow blood to bypass the capillary |
| how local control works | -the precapillary sphincters need O2 and nutrients delivered and CO2 & waste removed in order to contract -sphincter will contract an shut blood flow into capillary -- prevents O2 & nut. from being delivered & CO2/waste removed -this causes fatigue and sphincter relaxes -blood flows in, delivers O2/nut. & removes CO2/waste and the sphincter now contracts -cycle repeats itself -when skeletal muscle in the area starts to contract, they use up the O2/nut. & produce CO2/waste -- causes sphincter to stay relaxed and keeps blood flowing through the capillary bed "feeding" the skeletal muscle --more blood flows through cap. bed in same time frame. --> good regarding delivery of O2/nut & removal of CO2/waste but bad b/c now many precapillary sphincters are open at the same time which causes a drop in pressure which decreases perfusion ---this is the reason for arterial vasoconstriction |
| capillary beds | consist of two types of vessels: vascular shunt & true capillaries |
| vascular shunt | directly connects an arteriole to a venule |
| true capillaries | exchange vessels O2 & nutrients cross to cells CO2 & waste meta. waste products cross into the blood |
| capillary exchange | -substances exchanged due to concentration gradients through diffusion -pass through the capillary wall which is one cell layer thick -no energy is required only a concentration gradient -O2/but leave the blood due to their higher concentration in the blood vs the tissues -CO2/waste leave the cells and enter the blood due to their higher concentrations in the tissue vs the blood -just the opposite happens in the lungs. CO2 leaves the blood and enters the alveolar tissues of the lungs while O2 leaves the lungs and enters the tissue -the greater the gradient, the more sustance is diffused |
| venules and veins | -the collecting vessels; often referred to as the blood reservoirs -alls are very distensible, they can stretch and do regain their inital diamter, but if kept stretched out for long they tend to stay stretched, creating varicose veins - veins hold about 2/3 of the blood volume in the body -veins larger than 2 mm contain 1-way valves that help to maintain proper flow of blood back to heart |
| varicose veins | stretched out veins that haven't snapped back to their original shape |
| venous return | volume of blood moving in the veins as it returns to the heart -increases w/ vasoconstriction, decreases w/vasodilation |
| blood pooling | -may occur when one stops exercising -result of: --vasodilation --decreased SBP --decreased muscle pump --along with blood in the exercised muscle that now isn't "pushed" to return to the heart --decreased venous return -if this occurs there is a possibility you won't get enough blood to the brain -- not getting enough blood back to <3 so not able to pump enough blood out |
| actions of skeletal muscle in venous return | -while standing at rest venous valves are open -contraction of the muscles pushes blood upward through the proximal valve, back-pressure closed the distal valve -as muscle relaxes, pressure drops closing the proximal valve. higher blood pressure in the foot opens the distal valve allowing blood to flow into section of the vein |
| anastomosis | -a unique connection b/w two large vessels, specifically arteries & veins -3 types: --vein to vein --artery to vein --artery to artery |
| vein to vein anastamosis | -connects two veins, either two superficial or one superficial and one deep - when you're cold, blood goes to deep vein to keep warm, when warm blood goes to superficial vein to cool off |
| artery to vein anastamosis | bypasses the capillary bed only really in kidney & liver not important to exs phys |
| artery to artery | -very important** -in the heart they are called collateral channels and allow the bypass of a blockage in one artery -exs is thought to enhance or stimulate the growth of collaterals |
| velocity of blood | -affects circulation -measured as the volume of blood that flows through any tissue in a given time period -inversely related to cross-sectional area -more cross-sectional area when we add all the capillaries together than the c-s area of the aorta -capillaries are where exchange takes place --> want to slow down flow in capillaries so that the exchange is more efficient |
| pulse | -the expansion and recoil of the arterial wall as a bolus of blood moves through it -reflects the pumping action of the heart and therefore the heart rate --palpation can give an individual information regarding the HR and the strength of the heart's contractions -attenuated at the level of the arterioles -- not in veins or capilalries -typically measured with ones fingers up can also be sensed by machines |
| BP | the force or pressure exerted against the walls of the arterial blood vessels by the blood; two parts -normal = 120/80 -high is > 140/90 |
| SBP | -reflects the pressure generated by the heart as it forces blood out of its ventricles -gives a good estimate of the heart's work -pressure generated during ventricular contraction (systole) |
| DBP | -reflects the tension within the arterial walls during diastole -good indication of peripheral resistance -pressure in the arteries during ventricular relaxation (diastole) |
| hypotension | low systolic BP (below 110 mm Hg) often associated with illness |
| hypertension | -high systolic = above 140 mmHg -high diastolic = above 90 mm Hg -can be dangerous if it is chronic |
| BP & exercise | -SBP goes up due to the increased force needed to perfuse the muscle tissue as more and more blood vessels dilate. if it goes down by more than 10 mmHg, this is potentially dangerous and exercise should be terminated. -DBP remains unchanged or goes down due to the vasodilation which decreases peripheral resistance. if it goes up by more than 10 mm Hg this is potentially dangerous and exercise should be terminated immediately |
| taking BP | -use a sphygmomanometer or BP cuff --cuff stops blood flow by increasing pressure around arm -- pressure is slowly released while placing stethoscope on an artery --1st sound heard is SBP, when all sound goes away is DBP |
| BP - neural factors | - autonomic NS adjustments by the sympathetic division -neural control of BP is done by the baroreceptors and chemoreceptors. these baroreceptors relay information back to the brain which then uses the autonomic nervous system to correct or maintain the situation -* when SNS kicks in, BP goes up |
| BP - renal factors by hormonal control | -regulation by altering blood volume & vessel diameter - Aldosterone -- causes sodium to be retained which, in turn retains water which increase pressure -Renin-angiotension system -- renin is released which converts angiotensinogen to angiotension I which converts to angiotension II. Ag II is a very potent vasoconstrictor which can result in elevated BP |
| BP- Temperature | heat has a vasodilation effect, decrease BP cold has a vasoconstricting effect, increase BP |
| BP- chemicals | various substances can cause increase or decrease in BP |
| BP- diet | salts help to retain water which increases volume & therefore increases BP |
| BP formula | =CO x TPR (cardiac output x total peripheral resistance) |
| pulse pressure | = systolic - diastolic BP (wont be on test?) |
| Mean Arterial Pressure (MAP) | = [SBP + (2 x DBP)]/3 *multiple DBP by 2 b/c heart is in diastole twice as long as it is in systole |
| Poiseuille's equation | -measures resistance to flow R or TPR = ( 8 x h x l) / pi x r^4 h= viscosity l = length of tubes r = radius of blood vessel --MOST IMPORTANT FACTOR R is inversely proportional to r^4 -- if r goes up, TPR goes down; if r goes down, TPR goes up |
| resistance to flow | -arterioles are the site of greatest resistance due to both their small diameter and the large amount of muscle tirrue within their walls that allows a lot of vasoconstriction -while capillaries are small in diameter, they are so numerous that their total cross-sectional area is greater than the arterioles, therefore radius is larger and resistance is lower |
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