Physiology Exam 3

homeostatic function

maintain adequate blood flow to deliver materials between cells and the environment, and between cells in different parts of the body

cardiovascular system duties

CV system works with all organ systems to maintain the ECF composition compatible with cell survival

CV system delivers oxygen and nutrients to and it removes the waste products generated by cellular metabolism from EVERY cell in the body

blood composition

55% plasma

45% blood cells

erythrocytes (red blood cells)

carry gases (O2 and CO2)

leukocytes (white blood cells)

defend the body against foreign invaders (part of immune system)

platelets

form blood clots to prevent bleeding when damage to vessels occurs

pulmonary circuit

blood vessels to and in the lungs

systemic circuit

blood vessels to the rest of body

coronary arteries

supply the heart tissues and heart muscle with blood

atrioventricular valves

separate the atria and ventricles

semilunar valves

separate the ventricles and the outflow vessels (pulmonary artery and aorta)

Q

flow = cardiac output = heart rate x stroke volume

P

pressure = change of pressure = mean arterial pressure (MAP)

R

resistance = total peripheral resistance

the cardiac cycle

all events the occur in one heartbeat

diastole

blood returns to the heart from systemic circuit via the vena cava and from the lungs via the pulmonary vein

systole

blood is pumped out into the systemic circuit via the aorta and into pulmonary circuit via the pulmonary artery

cardiac cell types

nodal cells

conducting cells

contractile cells

automaticity

depolarize to threshold spontaneoulsy

pacemaker potential

fastest to reach threshold

Pf (funny Na+)

open when Vm hyper polarizes and close when Vm depolarizes.

PCa+2 (T-type)

open briefly (transiently) when Vm depolarizes, then close

Pca2+ (L-type)

open for long time when Vm reaches threshold, then inactivated.

responsible for the upstroke and plateau of the action potential

K+ channels

open slowly when Vm depolarizes and close when Vm repolarizes after an action potential

responsible for the repolarization of the action potential

pacemaker potential in nodal and conducting cells

generated by the combination of K+channels closing, funny Na+ channel opening, T-type Ca+2 channel opening

PNa+ (fast Na+ channels):

open very quickly when Vm reaches threshold

responsible for the upstroke of the action potential

action potential is generated in the SA node via…

gap junctions

rapid and coordinated conduction means that the heart contracts like…

functional syncytium

action potentials generated in the SA node are conducted through the heart via specific pathways

conduction system

conduction velocity

determined by the steepness of the upstroke of the action potential

electrocardiogram (EKG)

non-invasive way to examine heart electrical activity in the clinic

P wave

atrial muscle depolarization

P-Q interval

AV nodal delay; time during which the atria are depolarized

QRS complex

ventricular depolarization

Q-T interval

time during which the ventricles are depolarized

T wave

ventricular repolarization

P-P = R-R = T-T intervals

heart rate

magnitude of each EKG wave

the mass of tissue that is undergoing depolarization/repolarization

direction of each EKG wave

whether the wave of depolarization/repolarization of the tissue mass is traveling toward or away from the lead

calcium induced calcium release

Ca2+ entering from extracellular fluid via voltage-gated Ca2+ channels in the plasma membrane

Ca2+ ATPase pumps and Na/Ca Exchanger proteins in the plasma membrane

cardiac muscle also pumps Ca2+ out of the cell

healthy heart valves

one-way

open and close based on pressure gradient across the valve

lubb

closure of AV valves

dupp

closure of SL valves

ventricular filling

phase of the cardiac cycle (during diastole) when blood flows from the atria into the relaxed ventricles through open atrioventricular (AV) valves

consists of rapid filling

isovolumetric ventricular contraction

early phase of ventricular systole where the ventricles contract with all heart valves closed, causing a rapid rise in pressure while the blood volume remains constant

ventricular ejection

the phase of the cardiac cycle when ventricular pressure exceeds arterial pressure, forcing the semiluar (aortic and pulmonary) valves to open and pumping blood out of the heart into the aorta and pulmonary trunk

diastolic arterial pressure (DP)

minimum pressure in the aorta at the beginning of this phase

mean arterial pressure (MAP)

average aortic pressure

systolic arterial pressure (SP)

maximum pressure in the aorta during mid-way through

isovolumetric ventricular relaxation

early phase of ventricular diastole where the ventricles relax, intraventricular pressure drops sharply, and all heart valves are closed, resulting in no change in blood volume

end disastolic volume (EDV)

maximum volume in the ventricle

end systolic volume (ESV)

minimum volume in the ventricle

stroke volume

(SV = EDV - ESV)

urinary system maintains adequate MAP on a…

long-term basis by regulating blood volume

CV system maintains adequate MPA on a…

second-to-second basis by regulating heart (CO) and blood vessel (TPR) functions

arteries

strong, muscular blood vessels that carry oxygen blood away from the heart to tissues (except pulmonary arteries, which carry deoxygenated blood to the lungs)

arterioles

smallest branches of the arterial system that extend from arteries and connect directly into capillary beds “blood flow traffic controllers”

endothelium

smooth, one-cell-thick inner lining found in all blood vessels (connects directly to the inside of the heart and ensures blood flows smoothly without friction)

large arteries

body’s pressure reservoirs (use smooth muscle to squeeze and maintain high pressure)

capillaires

“exchange zones” made of only one layer of endothelium with tiny holes between cells, allows nutrients, waste, and fluids to easily pass between blood and body tissues

large veins

body’s “blood reservoirs” to hold massive volumes of blood, and smooth muscle to squeeze the blood back into the arterial system when your bloood pressures needs a boost

venous valves

“one-way-gates” inside veins to keep blood traveling in only one direction

hemodynamics

dynamics of blood flow through the vascular system

sphygmomamotery

measurement of blood pressure

intrinsic or local current of arteriolar vasoconstriction

(smooth muscle contraction): designed to meet local needs

extrinsic control of arteriolar vasconstriction

designed to regulate mean arterial pressure and therefore meet whole body needs

veins

the vessels that return blood to the heart and as a reservoir to hold blood volume

hydrophobic or lipid soluble substances

can diffuse across the capillary endothelial cell membrane

hydrophilic or water soluble substances

diffuse through the pores between the capillary endothelial cells

transcytosis

special transport system used for large substances (like proteins) that cannot fit through normal capillary pores (combination of endocytosis and exocytosis)

baroreceptors

constantly sense blood pressure

aortic arch baroreceptors

monitor blood pressure where blood is entering the arterial tree from the heart

carotid bifurcation baroreceptors

monitor blood pressure in the vessels that provide the brain with blood