Module 11

Exam 3

HCN channels

cardiac pacemaker channels that open in response to hyperpolarization; AKA funny channels

afterload/ESV

amount of blood remaining in the ventricle following contraction

systemic circulation

blood flow to and from virtually all tissues of body

vein

any vessel returning blood to the heart

pacemaker potenial

spontaneous depolarization of the pacemaker region of the heart; SA node

cardiac cycle

repeating pattern of systole and diastole of the atria and ventricles

erythrocyte

red blood cell

agglutinate

clumping of cells as a result of chemical interactions between surface antigens and antibodies

isovolumetric ventricular relaxation

AV and semilunar valves are closed; early phase of ventricular diastole

cardiac output

volume of blood pumped by either the right or left ventricle each minute

sounds of karotkoff

turbulent flow of blood through the constricted artery creating sounds

stroke volume

amount of blood ejected from each ventricle at each heartbeat

preload/EDV

amount of blood in the ventricle just prior to contraction; in the ventricles of the heart the tension on the ventricular walls produced by filling w/blood

interstitial fluid

fluid outside the cells within organ; this plus plasma equals extracellular fluid

hemostasis

cessation of bleeding

osmoreceptor

sensory neuron that responds to changes in osmotic pressure of surrounding fluid

pulse pressure

difference between diastolic and systolic pressures

barorectpor

receptors for arterial blood pressure located in the aortic arch and the carotid sinuses

plasma

fluid portion of the blood

artery

thick walled elastic vessels that carry blood away from the heart

systole

phase of ventricular contraction in the cardiac cycle

fibrin

insoluble protein formed from fibrinogen by the enzymatic action of thrombin during blood clot formation

capillary

smallest blood vessels; most exchange of nutrients and waste occurs with interstitial fluid

Frank-Starling law of the heart

describes the relationship between EDV and stroke volume. a great amount of blood prior to contraction results in a greater stretch of the myocardium

pulmonary circulation

part of vascular system that includes pulmonary arteries and pulmonary veins. transports blood from right ventricle of the heart through the lungs and back to the left atrium of the heart

hemoglobin

protein in red blood cell that transports oxygen

atrioventricular valves

one way valves located between atria and ventricles

platelet plug

layers of platelets at the site of an injury

diastole

phase of ventricular relaxation which the heart fills with blood

sinoatrial node

pacemaker of the heart, bundle of cardiac tissue

circulatory/cardiovascular system function

• transport oxygen/CO2, products of digestion, waste

• regulate hormones and temperature

• clotting, immune

circulatory system cells

• myocardial cells

• node (pacemaker) cells

• erythrocytes

• endothelial cells

atria empty into

ventricles

tricuspid valve

permits blood flow from atrium to ventricles but not backward

left AV/mitral

bicuspid

right AV

tricuspid

pulmonary valve

right ventricle to pulmonary trunk

aortic valve

left ventricle to aort

conducting system

special cells are in electrical contact with cardiac muscle cells via gap junctions

conducting system function

initiates heartbeat and helps spread action potential

step 1 of electrical excitation of the heart

* signal starts in SA node located in right atrium
* both atria contract practically together
* discharge rate of SA node determines heart rate

step 2 of electrical excitation of the heart

AP jumps from cell to cell via gap junctions

step 3 of electrical excitation of the heart

AP passage through AV node is slow

step 4 of electrical excitation of the heart

after AV node is excited, AP moves down septum to the Bundle of His

AV node and Bundle of His

separates atrial and ventricular contraction

step 5 of electrical excitation of the heart

bundle of His divides left and right

step 6 of electrical excitation of the heart

Purkinji fibers spread potential quickly through out ventricles causing them to depolarize practically together

excitation of SA node

slow predictable depolarization called pacemaker potential

* maintained by ion channels

step 1 of excitation of SA node

K+ channels gradually closing from previous AP

step 2 of excitation of SA node

HCN channels open in response to hyperpolarization and Na+ enters causing spontaneous depolarization to start

step 3 of excitation of SA node

___ provide final depolarizing boost (Ca2+?)

step 4 of excitation of SA node

Ca2+ influx through _____, long AP

step 5 of excitation of SA node

K+ opens, causing repolarization

step 6 of excitation of SA node

cycle repeats, no stimulus needed, return to negative potentials activates the cycled to begin all over

step 1 of cardiac AP (myocardial cells)

voltage gated Na+ open, causing depolarization

step 2 of cardiac AP (myocardial cells)

opening of transient K+ channels

step 3 of cardiac AP (myocardial cells)

L type Ca2+ channels open slow and balance charge leaving through K+ (plateau phase)

step 4 of cardiac AP (myocardial cells)

L type Ca2+ close and K+ open, causing repolarization

long refractory period of the heart prevents

summation and tetanus

long refractory period of the heart allows

heart to refill with blood

* almost as long as contraction itself

electrocardiogram

electrical signals resulting from cardiac APs can be measured from fluid around the heart by placing electrodes on body to pick up movement of ions

P wave

atrial depolarization

QRS complex

ventricular depolarization

T wave

ventricular repolarization

atrial repolarization typically…

doesn’t register with electrocardiogram and happens at the same time as QRS complex

waves on ECG may vary depending on…

placement of electrodes

bradycardia

cardiac rate slower than 60 bpm

tachycardia

cardiac rate faster than 100 bpm

sinus

normal rhythm

cardiac cycle includes

all events involved with flow of blood through the heart in 1 beat

isovolumetric ventricular contraction

beginning of systole, all valves closed

isovolumetric ventricular relaxation

early diastole, all valves closed

increasing pressure in ventricles leads to

aortic and pulmonary valves opening and blood ejection

when AV valves open…

blood flows into ventricles from atria

normal heart sounds

“lub, dub”

first sounds (lub)

closing of AV valves, onset of systole

second sound (dub)

closing of pulmonary and aortic valves, onset of diastole

SV (stroke volume)

volume of blood ejected from each ventricle during systole or with each beat of the heart

SV equation

end diastole volume - end systole volume

most important factor causing stretch

amount of blood in ventricles

greater stretch means

more forceful contraction

increase in venous return forces

increase in CO by increasing EDV which increased SV

total peripheral resistance

combined resistance to flow of all systemic blood vessels

blood plasma function

carries blood cells, proteins, nutrients, metabolic wastes, etc being transported around the body

plasma volume

osmoreceptors in hypothalamus cause the release of ADH from the posterior pituitary gland if fluid is lost

erythrocyte function

shape allows for high surface area to volume ratios so O2 can diffuse quickly

erythrocytes produced in

bone marrow

erythrocyte struction

no nucleus, no organelles, don’t produce, don’t live long

dead erythrocytes

destroyed by spleen and liver

erythrocytes contain lots of

hemoglobin

antigen

found on surface of cells to help immune system recognize self cells

antibodies

secreted by lymphocytes in response to foreign cells

immediate response to bleeding

constrict vessels

ultimate stopping of bleed depends on

formation of platelet plug and clotting

platelet plug forms by

adhering to the surface of exposed collagen fibers

von willebrand factor

protein that holds the binding in place

clotting/coagulation

going from liquid to a solid gel (due to proteins fibrinogen and fibrin)

main hemostatic defense mechanism

clotting

blood clot function

support platelet plug

arteries act as

pressure reservoir that maintains blood flow through tissues