Week 1: Physiology pt.1

main 4 functions of cardio system

circulation of blood, regulate body temp, remove of co2 and metabolites, maintenance of acid base balance (pH)

2 components of the cardiovascular system

pulmonary and systemic circulation

r ventricle pumps to

lungs

left ventricle pumps to

body

arteries and arterioles function

distributes blood throughout the region each pump supplies

network of capillaries function

gases and nutrients are exchanged with the tissue supplied

venules and veins function

Returns the distributed blood to the pump

p wave

atrial depolarization

QRS complex

ventricular depolarization

T wave

ventricular repolarization

what types of things do conduction

myocardial cells, SA, AV

Myocardial cells are capable of

spontaneous depolarization

what is close to the threshold of myocardial cells

resting membrane potentials, so it doesnt take a lot to hit the threshold and cause contraction

what causes automaticity and rhythmicity of the heart

All portions of the heart's conduction system contain automatic cells

ectopic pacemakers

conduction system cells outside of the SA node can assume the pacing roll when SA node function is depressed

what ions are needed for conduction

CA2 ions

cardiac output

volume of blood pumped by the heart per minute (CO=HRxSV)

normal cardiac output

4-5L/min but can increase to 5-7 x that amount during exercise

what is CO used for

indicator of how efficiently the heart can meet the demands of body

cardiac index formula

CO/BSA (body surface area)

stroke volume

amount of blood pumped with each heartbeat

intrinsic factors influencing SV

myocardial cell length, Frank-Starling mechanism (stretch)

extrinsic factors influencing SV

meds, hormones, disease

define frank-starling mechanism

force generated by contracting myocardium increases in direct proportion to its pre-contraction length, is related to end-diastolic volume and ventricular performance

Which ventricle is mainly stretching due to blood flow

Left ventricle

if stretch is too much or too little what happens to the performance

too much has more venous return, too little has less venous return

Sympathetic neural regulation of HR is done via which nerve

thoracic spinal cord

Sympathetic neural regulation of HR function

innervate conduction system and atria/ventricles, increases hr and conduction through AV node

Parasympathetic neural regulation of HR is done via which nerve

vagus n

Parasympathetic neural regulation of HR function

innervate the SA node, av node, atrial muscle. slow the HR and decrease the rate of conduction through the AV node

6 factors that control HR

Sa node, baroreceptors, chemoreceptors, body temp, concentration of ions (calcium), hormones