CV lecture 1 Flashcards
How many chambers does heart have and what is its relative size?
There are 4 hollowed muscular chambers about the size of an adult fist.
What type of membrane covers the heart?
Pericardium: a 2layer thin, membranous, protective sac covers heart*there is 20-30ml of serous fluid in the space between the pericardial layers which protects the heart from friction or trauma
What are the 3 layers that the cardiac muscle tissues are compose of?
- Epicardium- thin, serous outer layer2. Myocardium-thick, muscular middle layer-responsible for contractile force3. Endocardium-smooth inner layer which comes in contact with blood
What divides the heart into 2 sides?
The septum: each side has an atrium and a ventricle
what is the fxn of the right atrium?
it receives deoxygenated venous blood from the superior vena cava, inferior vena cava, and coronary sinus and its a low-pressure chamber
what is the fxn of the right ventricle & location?
-it receives blood from the right atrium via the tricuspid valve (AV valve) during ventricular diastole-ejects deoxygenated blood via the pulmonic valve (semilunar valve) through the pulmonary artery into the pulmonary circulation during ventricular systole-it is a flat muscular pump located behind the sternum
what is the fxn the left ventricle?
-receives blood from the left atrium via the mitral valve (AV valve) during ventricular diastole-ejects oxygenated blood via the aortic valve (semilunar valve) through the aorta into the systemic circulation during ventricular systole -High-pressure chamber
what is the fxn of the left atrium?
-it receives oxygenated blood from the lungs via pulmonary veins-Low-pressure chamber
Fxn of the coronary arteries?
Coronary arteries supply the heart with blood- blood flow to the myocardium occurs primarily during diastole when coronary resistance is minimized
where does most of the coronary circulation empty and where does it return to?
it empties into the coronary sinus and returns to the right atrium near the inferior vena cava
Where does the right coronary artery supply blood to?
right atrium and ventricles and a portion of the posterior wall of the left ventricle
where does the left coronary artery (& its branches-left anterior descending and left circumflex arteries) supply blood to?
left atrium and ventricle
What results from Ischemia?
it results in :tissue hypoxiadecrease in energybuildup of toxic waste
Is cellular injury from Ischemia reversible?
Yes
What is an Infraction?
It is permanent loss of blood flow to the myocardium which results in cell death.
In an Infraction, what might develop if blood flow is reduced over months or years?
Collateral circulation or alternative routes
What are the 2 components for the heart to maintain adequate perfusion to organs and tissue systems?
- electrical impulses: tells the heart to beat2. mechanical beating of the heart in response to the electrical stimulation=pumping blood
What is the pathways of an electrical impulse in the heart?
from the SA node, impulse travels through the atria by way of intraatrial pathways and to the AV node by means of the internal pathways. After leaving the AV node, impulses go through the Bundle of His to reach the Right & left Bundle Branches ( RBB & LBB). At the terminal ends of the bundle branches, the Purkinje Fibers distribute the electrical impulses to the muscle cells to stimulate contraction.
What is the fxn of the SA Node?
it is located at the junction of the right atrium and superior vena cava and it initiates rhythmic electrical impulses at the rate of 60-100 bpm and it is the first impulse which starts the flow of electric current through the heart (pacemaker of the heart)
What must be present to initiate the contraction of the atria
Calcium- depolarize cells
What is the fxn of the AV node?
located in the right atrium near the tricuspid valve, it received the implies from the SA node, conduction of the impulses is delayed briefly- the delay allows the atria to contract completely before the ventricles are stimulated to contract
How is an impulse created?
it is created by the rapid inflow of sodium ions into the cells and the outflow of potassium ions out of the cells; this depolarizes the cells resulting in an impulse
What is the intrinsic rate of the Purkinje fibers?
20-40 bpm
What is an Electrocardiogram (ECG/EKG) designed for?
to give a graphic display of the electrical activity in the heart NOT the mechanical activity!
Whats is the heart rhythm on the EKG?
the pattern that is displayed