Heart Ch. 20 Flashcards
In the pulmonary circuit the blood flows from which side of heart to where?
blood goes from right side of heart to lungs
In the pulmonary circuit the gas exchange occurs where and returns oxygen back to what?
gas exchange in lungs and returns oxynated blood back to heart
In the systamic circuit blood flows from which side of heart to where
blood goes from left side to organs
Where is the hear located?
mediastinum
How big is the heart?
about size of fist
Base of the heart is what?
superior
The Apex is where?
inferiorly and points to the left
The heart is enclosed in a double-walled sac called?
pericardium
What is the pericardial sac (parietal)
the outer wall of the heart that has a fibrous layer and a sereous layer.
The sereous layer of the pericardial sac turns inward at the base of the heart forming the what?
epicardium (visceral)
The space between the parietal and the visceral membranes is known as the what?
pericardial cavity
What 3 layers make up the heart wall?
epicardium, myocardium, endocardium
What is a serous membrane of the heart surface?
epicardium
What lines the interior of the heart chambers, covers the valves, and is continuous with the inner lining of the blood and is composed of simple squamous epithelium?
endocardium
What is composed of cardiac muscle and lies between the other two layers of the heart, composing the mass of the heart and has a vortex pattern that causes the heart to contract with a twisting or wringling motion that enhances the ejection of blood?
myocardium
Thin walled receiving chambers for blood returning to the heart by way of the great veins . Most of the mass is on the posterior side of heart.
Right and left atria
Each atrium has a small earlike extension called an _____ that slightly increases its volume
auricle
Thick walled, inferior pumping chambers that eject blood into the arteries and keep it flowing around the body.
right and left ventricle
What is the interventricular septum?
muscular vertical wall between the ventricles
When do atrioventricular (AV) valves close?
when ventricles contract
Which AV valve has three cusps and is therefor called the tricuspid valve?
right AV valve
What regulates the openings between the atria and ventricles?
atrioventricular (AV) valve
The left AV valve is known as the what valve?
mitral, formally called bicuspid valve
What connects the valve cusps to conical papillary muscles on the floor of the ventrical?
tendinous cords
What regulates the flow of blood from the ventricles into the great arteries?
semilunar valves
What makes up the semilunar valves?
pulmonary valve and the aortic valve
The valve that controls the opening from the right ventricle into the pulmonary trunk (exit of right ventricle)
pulmonary valve
The valve that controls the opening from the left ventricle into the aorta? (exit of left ventricle)
aortic valve
What is the first step of blood flow through heart?
Blood enters right atrium from superior and inferior venae cavae
2nd step of blood flow?
Blood in right atrium flows through right AV valve into right ventricle
3rd step of blood flow?
right ventricle contracts forcing pulmonary valve to open
4th step of blood flow?
Blood flows from pulmonary valve to pulmonary trunk
5th step of blood flow?
Blood is distributed by right and left pulmonary arteries to the lungs, where it unloads CO2 and loads O2
6TH step of blood flow?
Blood returns from the lungs via pulmonary veins to left atrium
7th step of blood flow
Blood in left atrium flows through left AV valve into left ventricle
8th step of blood flow
contraction of left ventricle forces aeortic valve open
9th step of blood flow
blood flows through aortic valve into ascending aorta.
10th step of blood flow
blood in aorta is distributed to every organ in the body where it unloads O2 and loads CO2.
11th step of blood flow
blood returns to heart via venae cavae.
The blood vessels of the heart wall constitute the?
coronary circulation
What can blockage of the coronary circulation cause?
myocardial infarction - death of the heart tissue
What travels through the coronary sulcus under the left auricle and divides into two branches?
left coronary artery (LCA)
Which branch of the LCA travels down the anterior interventricular sulcus to the apex, rounds the bend, and travles a short distance up the posterior interventricular branch.
anterior interventricular branch, clinically called left anterior descending
What is the branch of the LCA that continues around the left side of the heart in the coronary sulcus. It gives off a left marginal branch.
Circumflex branch
What artery supplies the right atrium and SA node, then continues along the coronary sulcus under the right auricle and gives off two branches of its own?
Right coronary artery
What branch of the RCA runs toward the apex of the heart and supplies the lateral aspect of the right atrium and ventricle?
The right marginal branch
What branch of the RCA travels down the corresponding sulcus and supplies the posterior walls of both ventricles as well as the posterior portion of the interventricular septum?
posterior interventricular branch
What is referred to as the route by which blood leaves an organ?
venous drainage
80% of blood returns back to the right atrium by way of: (3 veins)
Great cardiac vein
posterior interventricular vein
left marginal vein
Where do small thesbian veins drain to?
right ventricle
What is the order of the cardiac conduction system?
- SA node fires
- signals from SA node spread through the atria
- The AV node fires
- Excitation spreads through AV bundle
- Purkinje fibers distribute excitation through ventricular myocardium
cardiocytes are joined end to end by thick connections called?
intercalated discs
What are three distinctive features found in intercalated discs?
interdigitating folds - resemble egg cartons
mechanical junctions -fascia adherans and desmosomes
Electrical junctions - gap junctions
Nerve division that stimulates heart with cardiac nerves from cervical ganglia and increases force of contraction?
Sympathetic division
Nerve division that slows the heart with activity of vagus nerves?
Parasympathetic division
Electircal excitation of a heart chamber induces contraction
systole
The relaxation of any chamber is calle
diastole
1st step of the cardiac cycle?
All four chambers relaxed; AV valves open; ventricles filling
2nd step of the cardiac cycle?
Atrial systole completes ventricular filling
3rd step of the cardiac cycle?
Ventricles contract; AV valves close; semilunar valves open; blood ejected into arteries
4th cycle of cardiac cycle?
Heart returns to initial state of relaxation and refills
In fetal heart, foramen ovale and ductus arteriosus cause most blood to bypass what?
pulmonary circuit
What happens when lungs inflate at birth?
their resistance to blood flow decreases and flap seals foramen ovale which eventually becomes fossa ovalis
What happens to the ductus arteriosus several hours after birth?
becomes a permanentaly closed fibrous cord (ligamentum arteriosum)
What is an effect of aging on the cardiovascular system?
stiffening arteries
Leading cause of death in the US
heart disease
What is the most common form of heart disease?
coronary atherosclerosis often leading to myocardial infarction
Other heart diseases
congenital defects in anatomy myocardial hypertrohy or degeneration inflammation of pericardium or heart wall valvular defects cardiac tumors