Heart Flashcards
Location of Heart
from the second rib to the 5th intercostal space. 60% on the left side of the chest. Sits in the mediastinal cavity.
3 chambers of thoracic cavity
two pleural chambers with lungs and the mediastinal cavity
weight of the heart
300g
where is the apex of the heart and why
Apex of the heart is at the bottom left, has to do with how the heart is form
where is the base of the heart
posterior side of heart is the base
pericardium
serous membrane surrounding the heart
fibrous pericardium
not part of serous membrane, made of dense connective tissue
two layers of serous pericardium and their location
a. Parietal—the layer that lines the cavity
b. Viscera—the layer that lines the heart itself
what is pericardial fluid where does it hang out and how much of it is there
serous fluid between the parietal and visceral layers, 50ml
cardiac tamponade
- Excess fluid or blood in the pericardial sac prevents the heart from expanding fully, so it cannot adequately fill and pump blood
3 layers of the heart
epicardium
myocardium
endocardium
epicardium
Epicardium: outer layer. The same thing as the visceral pericardium
myocardium
middle layer, the cardiac muscle
endocardium
inner layer, made from simple squamous epithelium (endothelium)
auricles
right and left, purple fleshy structures at the top of the heart. Extra spaces for blood. The atria are deep to the auricles
Fossa Ovalis and PFO: function in utero, what happens when baby is born, what can happen when disease processes affect this on adults
When baby is still in uterus, lungs are filled with amniotic fluid which creates a lot of resistance. There is a hole between right and left article called Patent Foramen Ovale (PFO) where blood can move between RA and LA. Patent means open. When baby is born, pressure changes causes a “door” to shut across the PFO, this is referred to as the Fossa Ovalis. In 75% of people the fossa ovalis is sealed shut, but in 25% it is only closed, and being kept closed by the relatively higher pressure in the left atrium. Disease processes may cause the pressure to be higher in the right atrium, which may cause the fossa ovalis to leak which could lead to a stroke.
pectinate muscles
only in the right atrium. “Shaggy carpet” at the top left right atrium. Function unknown.
crista terminalis
C-shaped structure that divides atrium into posterior and anterior
Flow of blood through the heart
- Deoxygenated blood from the body enters the heart on the right side in the RA, exits through RV to go to the lungs, comes back from the lungs through the LA, exits from the LV through the aorta to the body.
atrioventricular (AV) valves location
between the atria and ventricles
tricuspid valve location and number of cusps
has three cusps, is on the right side b/w RA and RV
bicuspid valve location, number of cusps, common name
has two cusps, b/w LA and LV. Also commonly known as mitral valve
AV valves function
the atrioventricular valves are open most of the time, they only close as the ventricles contract.
stenosis
when an atrioventricular valve is too narrow, making it hard for blood to drain into the ventricle, making the heart have to work harder.
regurgitation
when the valves are too loose, causing blood to leak from the ventricle to the atrium. Also known as “incompetent valve”.
ventricles
chambers on the bottom of the heart
wall thickness atria vs ventricles
ventricles have Thicker walls than the atria because they work harder. Left ventricle is thicker than right for the same reason
Papillary muscles
attached to ligaments (chordae tendineae), which are attached to the cusps on the AV valves. These contract just before the ventricle contracts to anchor the valves in order to overcome the pressure of the ventricular contraction and prevent the valve from opening upwards into the atrium
carnae trabeculae
“cross-bars of flesh” inside the ventricles
5 great vessels
superior vena cava inferior vena cava pulmonary artery pulmonary veins aorta
superior vena cava function and valves
drains blood from the head, neck, certain parts of the thorax, into the RA. no valves.
inferior vena cava function and valves
drains blood from the rest of the body to the RA. No valves.
pulmonary artery function and valves
takes blood from the RV to the lungs. Semilunar valve: pulmonary valve
pulmonary veins number, function, valves
(4), two of them bring blood from left lung, two from right lunh, all to the LA. No valve.
aorta function, valves
biggest artery in body, attaches from LV. semilunar valves
semilunar valves
closed most of the time. Only open when ventricles contract. Like 3 tea cups together. They move away from each other when the ventricle contracts and the blood pushes past, but come back together as soon as the pressure subsides.
ligamentum arteriosum (PDA)
When baby is in uterus, there is a connection between pulmonary artery and aorta called patent ductus arteriosus (PDA) that serves to decrease pressure on the circulatory system (same as PFO). Eventually closes after birth, creating the ligamentum arteriosum
3 circulations/circuits
pulmonary
systemic
coronary
pulmonary circulation
deoxygenated blood leaving the right ventricle, going into the pulmonary system, becoming oxygenated in the lungs and then coming back to the heart via left atrium. low resistance.
systemic circulation
oxygenated blood leaving from left ventricle going out to the body and then returning as deoxygenated blood to the right atrium. high resistance.
coronary circulation function
delivers nutrients to cardiac muscle.
coronary circulation pathway
L and R coronary arteries come right off the aorta, travels behind the pulmonary trunk to the front of the heart.
L coronary a. descends anteriorly and becomes the anterior interventricular a., (aka anterior descending a.) and sits in the anterior ventricular sulcus. The anterior descending artery continues down and rounds the bottom of the heart and starts ascending on the posterior side, to form an anastomosis with posterior inter ventricular a.
c. R coronary a. travels from the aorta underneath the R auricle.
d. R marginal a. branches off from the R coronary a. to supply the right ventricle.
e. R coronary a. also continues down, rounds the bottom of the heart and ascends posteriorly and forms an anastomosis joining up with the circumflex artery.
f. Posterior interventricular artery travels down from the anastomosis between the R coronary a. and circumflex a. and forms the anastomosis with the anterior interventricular a.
g. All of the coronary veins drain to the coronary sinus which is on the posterior side of the heart. The coronary sinus drains straight into the right atrium.