Lect. 13 - Heart and fetal circulation Flashcards
general charact. of the heart (3)
rests on diaphragm
approximately the size of a closed fist
2/3 of the mass lies L of the midline
general reference points of the heart (6)
apex base superior R point superior L point inferior R point inferior L point
what is pericardium
double-layered membrane that surrounds and protects the heart
what 2 layers of pericardium
fibrous layer (outermost) serous layer (innermost)
role of fibrous layer of pericardium
prevents overstretching of the heart
parts of serous layer of pericardium
outer parietal layer
inner visceral layer “epicardium”
pericardium (4 things)
pericardial cavity
pericardial fluid
pericarditis
cardiac tamponade
what is the pericardial cavity
space between visceral and parietal serous layers
what is pericardial fluid
fills the space
what is pericarditis
inflammation of the pericardium
what is cardiac tamponade
build up of fluid resulting on pressure on the heart
layers of the heart wall from ext. to int.
- epicardium
- myocardium
- endocardium
what is epicardium
visceral layer of the pericardium
what is myocardium
cardiac muscle tissue
what is endorcardium
inner smooth lining of the chambers
covers the valves of the heart
continuous with the endothelial lining of the large blood vessels
4 chambers of the heart
2 upper chambers = atria (and auricle)
2 lower chambers = ventricles
right atrium receives blood from three major veins
IVC, SVC, coronary sinus
parts of right atrium (4)
right auricle
pectinate muscle
interatrial septum (fossa ovalis)
tricuspid valve
what is the fossa ovalis
originally a foramen used for babies when they don’t use their lungs so the blood goes directly into the left atrium
parts of right ventricle (5)
trabeculae carneae cordae tendinae papillary muscles interventricular septum pulmonary semilunar valve
left atrium receives blood from
pulmonary veins
parts of left atrium (3)
left auricle
pectinate muscle
bicuspid “mitral” valve
parts of left ventricle (4)
trabeculae carneae
cordae tendinae
papillary muscles
aortic semilunar valve
what are the two atrioventricular valves (AV)
bicuspid and tricuspid valves
AV valves- when they are open
pointed end projects into ventricles
blood moves into ventricle
papillary muscles are relaxed
cordae tendinae are slack
AV valves- when the ventricles contract
pressure drives the cusps upwards
papillary muscles contract
cordae tendinae are tightened and prevent the cusps from opening into the atrium
semilunar valves allow ejection of blood into ___ and prevent backflow into ___
vessels, ventricles
semilunar valves charact. (3)
each consists of three cusps
outer border is attached to artery wall
valves are open when ventricular pressure exceeds arterial pressure
with each beat, blood is pumped into two circuits
pulmonary circulation and systemic circulation
t/f the entire body receives blood from the systemic circulation
false, except lungs that are supplied by the pulmonary circulation
coronary arteries originate where
at the base of ascending aorta
L. coronary artery supplies (2)
both ventricles & left atrium
R. coronary artery supplies (1)
both ventricles
name the 5 coronary veins
coronary sinus great cardiac vein middle cardiac vein small cardiac vein anterior cardiac vein
3 phases of the cardiac cycle
relaxation period
ventricular filling
ventricular systole
what is systole
phase of contraction
what is diastole
phase of relaxation
what happens at relaxation period (chambers, blood flow, pressure, valves)
all 4 chambers are in diastole
blood flow back towards ventricles closing the SL valves
pressure falls inside the ventricles
AV valves open and ventricle being filling
what happens at ventricular filling (% and valves)
75% occurs without atrial systole
25% occurs with contraction of pectinate muscle
AV valves are open while semi-lunar valves are closed
what happens at ventricular systole (blood flow, pressure, valves)
ventricular contraction pushes blood up against AV valves (forcing them to shut)
pressure inside ventricles rises sharply
when pressure exceeds that in arteries, both SL valves open
one heart cycle - 4 sounds are generated
s1 = lubb s2 = dupp s3 = rapid ventricular filling s4 = atrial systole
what happens at s1 lubb
closing of AV valves
beginning of ventricular systole
what happens at s2 dupp
closing of SL valves
end of ventricular systole
changes in maternal CV system - SV, CO, HR, blood volume
increase SV 30%
increase CO 20-30%
increase in HR 10-15%
increase in blood volume 30-50%
2 adjustments of the infant at birth
closure of foramen ovale
closing of ductis arteriosis (becomes ligamentum arteriosum)
