PHYS20008 Lecture 17: PHYS20008 Lecture 17
10 May 2018
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Lecture 17
- Blood pressure is important and regulated around a setpoint, too high ⇒ rupture
vessels, atherosclerosis in old age, too low ⇒ not perfusing vessels adequately; tight
setpoint; setpoint changes during exercise; maintain it around a steady setpoint
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- Movement of blood is regulated by heart (main source of energy pumping things
around circulatory system)
- Skeletal muscle contraction: more blood goes to working skeletal muscle (reflexive
vasodilation within working skeletal muscle), skeletal muscle pump → when muscle
contract, squeeze blood vessel in the muscle → helps with venous return, push blood
back up into heart; in exercise when contract muscle → helps move blood
rhythmically around system
- Movement of diaphragm: breathing in and out changes pressure in thorax, rhythmic
pressure changes in thorax also helps move blood around system
- Elastic tissue: within arteries, expand to accommodate blood that heart pumped into
them, recoil to push around system
find more resources at oneclass.com
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- When heart is actively contracting pushing blood into artery: high pressure in artery
at that point
- When ventricle is relaxing blood pressure in that artery is going to decrease
- Blood pressure is variant with each cardiac cycle, looks like a wave, parts contracting
and relaxing
- Systolic BP: The top with high blood pressure occurring during ventricular systole
- Diastolic BP: Blood pressure during relaxation of ventricles or ventricular diastole
- Systolic pressure over diastolic pressure (120/80; 110/70)
- Pulse pressure: Difference between values is the pressure exerted by heart
- Mean arterial pressure (MAP): summary of diastolic and systolic pressure; diastolic
BP + ⅓ Pulse pressure
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- In arteries: diastolic blood pressure increases because the smooth muscle within
arteries maintaining vasomotor tone, smooth muscle in arterial walls never
completely relaxed → maintain some form of pressure
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- Lose wave form as resistance increases, moving through smaller and smaller
vessels → by time reach capillaries, steady flow of blood, no more wave form →
return to right atrium at steady pressure
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- Pressure at arterial end of system
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- How to increase blood pressure: put more blood in from heart, higher cardiac output;
resistance of arterioles (total peripheral resistance) , overall all arterioles are
constricting → increase blood pressure, inhibiting ability of blood to flow out
- MAP proportional to (cardiac output x total peripheral resistance)
- Cardiac output: litres of blood pumped out of heart per minute, heart rate (more beats
per minute means more blood pumped out), heart rate (how many beats per minute)
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Blood pressure is important and regulated around a setpoint, too high rupture vessels, atherosclerosis in old age, too low not perfusing vessels adequately; tight setpoint; setpoint changes during exercise; maintain it around a steady setpoint. Movement of blood is regulated by heart (main source of energy pumping things around circulatory system) Movement of diaphragm: breathing in and out changes pressure in thorax, rhythmic pressure changes in thorax also helps move blood around system. Elastic tissue: within arteries, expand to accommodate blood that heart pumped into them, recoil to push around system. When heart is actively contracting pushing blood into artery: high pressure in artery at that point. When ventricle is relaxing blood pressure in that artery is going to decrease. Blood pressure is variant with each cardiac cycle, looks like a wave, parts contracting and relaxing. Systolic bp: the top with high blood pressure occurring during ventricular systole. Diastolic bp: blood pressure during relaxation of ventricles or ventricular diastole.
