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where does the heart lie?

2/3 to the left of the midline within the mediastinum

cardiovascular system

consists of pump (heart), blood, closed sytem in which blood is carried

heart

has four chambers

enclosed laterally by the_______

lungs

______ by the vertebral column

posteriorly

_______ by the sternum

anteriorly

pericardium

sac that covers the heart

visceral pericardium or epicardium

inner layer of the pericardium

parietal pericardium

outer layer of the pericardium

pericardial cavity

potential space between the visceral and parietal pericardium, contains serous fluid

wall of the heart

3 distinct layers supplied with blood vessels

epicardium

external layer of the wall

myocardium

middle layer of the wall

myocardium

contains cardiac muscle fibers, thickness varies in dif. sections according to function

endocardium

innermost layer of the wall

endocardium

lines the cavities of the heart, covers the valves and smooth muscle that opens and closes the valves

chambers of the heart

right and left halves with each half having 2 chambers

atria or atrium

upper chambers of the heart

ventricles

lower chambers of the heart

atrium

receive blood from veins

interatrial septum

separates the 2 atria

ventricles

recieve blood from the atria

interventricular septum

separates the 2 ventricles

ventricles

pumping chambers

upper and lower chambers

separated by valves

sulcus or sulci

2 grooves on the surface of the heart

R. atrium

recieves blood from all tissues except the lungs

coronary sinus

drains blood from the heart itself into the R. atrium

inferior vena cava

drains blood from the lower part of the body into the right atrium

superior vena cava

drains blood from the upper part of the body into the right atrium

tricuspid valve

valve between the RA and RV

chordae tendinae

cords of the tricuspid valve that extend into the ventricle and are attached to it

tricuspid valve

3 leaflets or cusps. allows blood to enter RV when RV relaxes and closes when RV contracts

R. ventricle

right inferior portion of the heart, pumps blood to the lungs

R. ventricle

walls are thinner that the LV

RV

contracts and closes the tricuspid valve, opens the pulmonary valve

pulmonary valve

lies at the entrance of the pulmonary trunk or artery

pulmonary valve

closes when the RV relaxes to allow it to fill with blood

arteries

always leave from the heart

veins

always come back to the heart

LA

receives oxygenated blood from the lungs

pulmonary veins

four veins that send blood to the LA from the lungs

mitral valve

between the LA and LV

mitral valve

stronger and thicker than the tricuspid valve

bicuspid valve

mitral valve

mitral valve

closes when LV contracts and opens when it relaxes

LV

left inferior portion of the heart, pumping chamber

aortic valve

between the LV and the aorta

semilunar valves

pulmonary and aortic valve

atrioventicular valve

tricuspid and mitral valves

coronary arteries

branch from the aorta as it leaves the heart and curl back across the chambers of the heart

coronary arteries

hearts blood supply rich in O2

cardiac cycle

when the atria contract as the ventricles relax, make up 1 heart beat

contractions

systole, part at the highest pressure

relaxation

diastole

heart sounds

caused by valves closing

cardiac output

stroke volume X number of beats per minute

stroke volume

volume of blood ejected per beat

normal cardiac output

5L per minute

cardiac muscle fibers

arranged end to end and side to side, intercalated disks

heart

contracts as a whole unit

heart muscles

need a constant supply of O2 and ATP

cardiac muscle tissue

has a higher number of mitochondria (power house)

1st sound of the heart beat

mitral and tricuspid valves closing

2nd sound of the heart beat

pulmonary and aortic valves closing

murmur

abnormal heart sound (valves)

stenosis

the narrowing of any body part

SA node

pacemaker of the heart

located in the floor of the RA, below the opening of the superior vena cava

SA node

SA node

sinoatrial node

SA node

responsible for rhythmic contractions of the heart

AV node

receives impulses from the SA node, it's delayed to allow the atria to empty and the ventricle to fill with blood

bundle of HIS

receives impulses from the AV node

bundle branches

receive impulses from the bundle of HIS

purkinje fibers

receive impulses from the bundle branches

purkinje fibers

spread out from the septum into the ventricles, causing the ventricles to contract

K and Ca

generate an electrical current as an impulse travels along the cardiac muscle fibers

EKG

place electrodes on skin, electrodes are connected to wires on EKG machine, which picks up the current and records it on special paper

graphy

procedure

graph

machine

gram

picture

P

action of the atrium

QRS

action of ventricles

T

action of ventricles regaining the electrical charge

depolarization

the loss of electrical charge

medulla oblongota

sends impulses to SA and AV node by way of the vegas nerve

pressoreceptors

located in the aorta and carotid arteries and are sensitive to changes in BP

what happens when your body temp increases

heart rate goes up

heart rate goes up when

increase in epinephrine, thyroxine, sodium or potassium increases

foramen ovale

hole in the heart of a fetus that connects the 2 atrium

ductus arteriosus

lies between the pulmonary artery and aorta in a fetus

ductus arteriosus

blood is bypassing the lungs, resp. system is not occuring at this point

when does the heart start pumping in a fetus

by the 4th week

ductus venosus

blood bypasses the liver in a fetus

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