chapter 20 pt. 3

taking blood pressure

• at arm, close to where heart is in chest

• level with aorta, mimics __

• equipment can make a difference - hand better than automatic

cadiac output formula

CO = HR x SV

HR

• heart rate/pulse (BPM)

• @ neck, wrist

SV

• stroke volume

• everytime the heart beats is a stroke

  • means the amount of blood leaving the heart when it beats (mL/beat)

• different to measure, use ultrasound…, why we use HR

CO

• cardiac output

• mL/min.

mean arterial pressure (BP)

MAP = CO x PR

PR

• peripheral resistance (how tense they should be)

• at edge/outside of heart - muscle walls of arteries

• vessels need to maintain pressure to be continuous, so they don’t balloon up

• water hose: steady rate. thumb = stronger

• related to diameter of BV, volume that the CO will be filling as it leaves the heart (creates pressure)

venous return

• volume of blood coming back to heart

  • if impeded, SV is first affected

  • raises HR to maintain CO. PR may also go up

• pregnant women veins usually swell → high venous return

spleen in blood flow

• we have finite (limited) blood in circulation - i emergency, spleen can contract and release minimal blood

EDV (end diastolic volume)

• amount of blood in ventricles before they contract

• high HR, chamber has less time to fully open, decreases SV → + feedback

• where absolute refractory period is important, makes sure hearts have at least a little time to fill with blood before atria beat again

cardiac reserve

• difference between heart at worm and heart at work

• like skeletal muscle (trained) - can’t run a marathon out of nowhere b/c low cardiac reserve

• max cardiac output - cardiac reserve

regulation of the heart

intrinsic and extrinisc

intrinsic regulation

• internal feedback inside the heart → chambers, heart muscle, etc.

extrinsic regulation

• NS feedback → body gives feedback, NS tells heart what to do; HR, BP, work, etc.

  • sympathetic and parasympathetic

• vagus nerve provides most feedback (also cardiac nerve?)

endocrine input

• ex. adrenaline → F/F, person under perineal (constant stress)

• does put strain on their hard

baroreceptors

• cluster of cells monitoring and giving feedback to the brain

• monitor peripheral resistance → BP by giving signals to the brain

  • actually measuring stretch/diameter of BV → brain interprets that as pressure change

medulla oblongata

• where brain interprets what should be told to the heart

• info from baroreceptors goes here

chemoreceptors

• monitor chemicals, molecules (non-hormonal)

  • ex: O2, CO2, pH, H+, sodium, potassium, calcium

02 chemoreceptor

• if O2 down, more blood needs to be sent to lungs or need to breath more

C2 chemoreceptor

if high, brain freaks out, gets sleepy, harder to see whats happening

pH chemoreceptor

• actually monitors hydrogen ion

• higher the H+ = lower pH

sodium

• monitored to mantain BP

calcium

• APs releasing NTs, calcitonin/PTH - regulated by mineralcorticoids

potassium

if too high, heart block. heart will stop

temperature and heart fcn.

• if core is too cold/hot bad for heart

• too cold, slows down HR and metabolism, reducing stress on heart, growth of bacteria, release of wastes in (urea)

effect of aging on heart

• heart less prone to changes because of agin, more because of exercise or diet

• HR tends to increase (due to lifestyle)

• more about underlying diseases/lifestyle than aging

• increase in arrhythmia

• cardiovascular and coronary artery disease

hypertrophy/hyperplasia

• hypertrophy: increase in size of muscles

• hyperplasia: increase in number of cells

• can’t make more/regenerate heart cells - its permanent tissue

coronary artery disease

blockage of coronary arteries

arrhythmia

• not total lack of heart rhythm, but change in it

• one of PQRST