Anatomy and Physiology Unit 6 Cardiovasvular

pulmonary circuit

carries blood to and from gas exchange surfaces of lungs

systemic circut

carries blood to and from the rest of the body

arteries

blood vessels that carry blood away from the heart

veins

blood vessels that carry blood towards the heart

capillaries

networks between arteries and veins

right atrium

collects from systemic circuit; anterior portion is smooth-walled, posterior portion contains ridges formed by pectinate muscles; posterior and anterior units are separated by crest terminalis

what are the three veins that empty into the right atrium

superior vena cava, inferior vena cava, and coronary sinus

superior vena cava

returns blood from body regions above the diaphram

inferior vena cava

returns blood from body regions below the diaphram

coronary sinus

returns blood from coronary veins

right ventricle

pumps to pulmonary circuit

left atrium

collects from pulmonary circuit; the pectinate muscles are only found in the auricles; collects blood from the four pulmonary veins which returns blood from the lung

left ventricle

pumps to systemic circuit

papillary muscles

project into ventricular cavity and anchors chordae tendinae that are attached to the valves

trabecular carneae

irregular ridges of muscle on ventricular walls

pericardial sac

the fibrous sac surrounding the heart, providing protection and reducing friction during heartbeats.

where does the heart sit

mediastinum

mediastinum

space between lungs

what are the three layers of the heart wall

epicardium, myocardium, endocardium

epicardium

outer layer that covers the heart

myocardium

the muscular middle layer responsible for heart contractions.

endocardium

the innermost layer lining the heart chambers; made up of epithelial tissue

coronary sulcous

atrioventricular groove that encircles junction of atria and ventricles

anterior interventricular sulcus

a groove on the heart's surface that separates the left and right ventricles and contains blood vessels.

atria

small thin walled chambers which contributes little to propulsion of blood.

tricuspid valve

made up of three cusps and its between right atria and ventricle

bicuspid valve

made up of two cusps and lies between left atria and ventricle

chord tendinaeae

anchor sups of av valves to papillary muscles

semilunar calves

pulmonary and aortic tricuspid valves; functions to prevent back flow from pulmonary trunk and aorta into ventricles. three cups support like tripod

what are some structural differences between the left and right ventricles

right ventricle wall is thinner, develops less pressure than left ventricle; right ventricle is pouch shaped and left ventricle is round

pathway through the heart

superior vena cava, or inferior vena cava, or coronary sinus, to right atrium, to tricuspid valve, right ventricle, to pulmonary semilunar valve, to pulmonary trunk, to pulmonary arteries, to lungs, to the pulmonary veins, to the left atrium, to the mitral valve, to the left ventricle, to aortic semilunar valve, to aorta, to the systemic circulation

right coronary artery

supplies blood to right atrium and portions of both ventricles

left coronary artery

supplies blood to the left ventricle, left atrium, and interventricular septum

great cardiac vein

drains blood from area of anterior interventricular artery into coronary sinus

sinoatrial node

wall of right atrium (structure of conducting system)

atrioventricular node

junction between atria and ventricles (structure of the conducting system)

conducting cells

(structures of the conducting system) interconnect sa and av nodes; distributes stimulus through myocardium

what are the conducting cells in the atrium

internodal pathways

what are the conducting cells in the ventricles

the av bundle and the bundle branches

prepotential

aka pacemaker potential; the resting potential of conducting cells (gradually depolarizes toward threshold); when the sa node depolarizes first and establishes heart rate

av bundle

in the septum, carries impulse to left and right bundle branches and to the moderator band

the conducting system

1. sa node activity and atrial activation begins

2. stimulus spreads across the atrial surface and reaches the av node

3. there is a 100-msec delay at the av node. atrial contraction begins

4. the impulse travels along the interventricular septum within the av bundle and the bundle branches to the perking fibers and, via the moderator band, to the papillary muscles of the right ventricle

5. the impulse is distributed by prkinje fibers and relayed throughout the ventricular myocardium. atrial contraction is completed, and ventricular contraction begins

electrocardiogram

electrical events in the cardiac cycle can be recorded on an ecg

features of the ecg

p wave, qrs complex, and t wave

p wave

atria depolarize

qrs complex

ventricles depolarize, precedes ventricular contraction

t wave

ventricles depolarize

interval between p-r wave

from start of atrial depolarization and contraction to start of qrs complex

interval between q-t wave

from ventricular depolarization to ventricle repolarization

the cardiac cycle

begins with the action potential at sa node; the period between the start od one heartbeat and the beginning of the next (includes both contraction and relaxation)

two phases of the cardiac cycle

systole(contraction) and diastole (relaxation)

what are the 8 steps in the cardiac cycle

atrial systole, atria eject blood into ventricles, atrial systole ends, ventricular systole, ventricular ejection, ventricular pressure falls, ventricular diastole, atrial pressure is higher than ventricular pressure

atrial systole

atrial contraction begins; right and left av valves are open

atrial systole ends

av valves close, ventricles contain maximum blood volume, known as end-diastolic volume

ventricular systole

isovolumetric ventricular contraction, then pressure in ventricles rise, and av valves shut

ventricular ejection

semilunar valves open, blood flows into pulmonary and aortic trunks, stroke volume = 60% of end diatonic volume

ventricular pressure falls

semilunar valves close, ventricles contain end systolic volume about 40% of end diastolic volume

ventricular diastole

ventricular pressure is higher than atrial pressure, all heart valves are closed, ventricles relax

atrial pressure is higher than ventricular pressure

av valves open, passive atrial filling, passive ventricular filling, cardiac cycle ends

hypertension

abnormally high blood pressure

hypotension

abnormally low blood pressure

systolic pressure

peak atrial pressure during ventricular systole

diastolic pressure

minimum arterial pressure during systole

pulse pressure

difference between systolic pressure and diastolic pressure

mean arterial pressure

diastolic pressure plus 1/3 of pulse pressure