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
What does one single cardiac cycle on an EKG graph include ? & what do they indicate?
P wave: first wave form & it indicates atrial depolarization QRS complex: wave that represents ventricular depolarization T waves: wave that form that represents depolarization of the ventriclesand segments and intervals between them
T or F, there can be a mechanical response even if there is no electrical activity?
False
How is the heart’s mechanical activity determined?
By assessing the BP
What is assessed to determine whether or not the heart is pumping adequately?
BP, pulse, and other perfusion parameters
What is the difference between systole & diastole?
Systole: contraction/emptying of atria & ventricles, normally 1/3 of cardiac cycleDiastole: relaxation/filling of atria & ventricles & normally 2/3 of cardiac cycle
What is Cardiac Output, CO, the normal for an adult at rest, and how is it calculated & measured?
-It is the amount of blood that the heart pumps in 1 min ( a measure of mechanical efficiency)-normal is 4-7 L/min-it is calculated by multiplying the stroke volume to the heart rate and is measured in L/min.
What is stroke volume?
the amount of blood ejected with each contraction of the left ventricle (approx 60mL)
What influences stroke volume, SV ?
- Preload 2. Afterload2. Contractility
How does the preload influence SV & how is it determined?
-this is the stretching of muscle fibers in ventricles at the end of diastole just before contraction; the more the heart if filled during diastole within limits, the more forcefully it contracts.-it is determined by the amount of blood VOLUME returning to the heart and filling ventricles at the end of diastole
How does the afterload influence SV?
-the pressure or RESISTANCE the ventricles must overcome to eject its contents into the aorta during systole. -resistance is directly related to arterial BP and the diameter of the blood vessels
How does vasoconstriction (cold temperature, PVD, aortic stenosis, alpha stimulation) affect the afterload?
they are factors that increases the afterload
How does vasodilation (warm temp, alpha & beta blockers, calcium channel blockers) affect the afterload?
they are factors that decrease the afterload
How does Contractility influence SV?
Myocardial contractility is the force of cardiac contraction independent of preload
which inotropic agent affect the force of contraction?
Digoxin
What are 2 factors that increase contractility?
- sympathetic stimulation2. calcium release
what are 2 factors that decrease contractility?
- hypoxia2. decrease in pH
Whats does the vascular system consist of?
Arteries, arterioles, capillaries, venules, and veins
What is the arterial system consist of?
the arteries and arterioles
What are the large arteries (aorta/pulmonary artery) composed of?
thick walls, elastic tissue and some smooth muscle. The elastic quality cushions the impact of the force of the systemic BP and provides recoil that propels blood forward into the circulation
All arteries carry oxygenated blood, with the expection of the______ artery?
pulmonary
what is the major control of arterial BP?
arterioles (small arteries)
Fxn of arterioles?
Constrict or dilate in response to local conditions – e.g. blood can be directed to skin to promote heat loss or diverted away from the skin to conserve heat
What affects amount of blood flow to organs and tissues from arterioles?
the degree of constriction
arterioles are made up of smooth muscle? T or F?
true
What is the fxn of capillaries? & what type of cells are the made of?
Exchange of nutrients and wastes takes place in capillaries and they are made of endothelial cells
The venous system consist of?
Venules and veins
What is the fxn of venules?
Collect blood from the capillaries and terminal arterioles and channel it to larger veins
Venules are made up of?
small tubules made uo of small amount of muscle and connective tissue
Whats the fxn of veins?
Returns deoxygenated blood to the right atrium (except the pulmonary veins)
What are the 2 largest veins?
Superior and inferior vena cava
In veins, what prevents backward flow of blood ?
semi-lunar valves at intervals
If your pt. is sitting upright, it will delay venous return, why?
B/c gravity exerts an increase in hydristatic pressure which causes a delay in venous return
Having a patient lay down will do what to venous return?
decrease resistance to venous resistance because it will decrease hydristatic pressure.
How is BP in arterial system determined?
amount of blood flow and resistance in the arterioles. This is an indirect measure of BP
What effects does the ANS have on the heart?
-Stimulate sympathetic Receptors (Beta-adrenergic receptors) - Fight or Flight response -Inc, HR - Inc. Speed of conduction through AV node - Inc. Force of atrial and ventricular contraction-Stimulate Parasympathetic Receptors (Vagus Nerve) – Balancing System - Dec. HR - Dec. Speed of conduction through AV node
What effects does the ANS have on the blood vessels?
-Stimulate Sympathetic Receptors (Beta-adrenergic receptors) -Vasoconstriction - Inc. BP-Decrease Sympathetic Stimulation at Receptors (Beta-adrenergic receptors) -Vasodilation -Dec.BP-Stimulate Parasympathetic Receptors (Vagus Nerve) -Dilation of visceral blood vessels and increase activity of GI tract
What are the 5 locations of baroreceptors?
- Aortic arch2. Carotid sinus3.vena cava4.Pulmonary arteries5.atria
Fxn of baroreceptors?
Send info to vasomotor center in brain
What do barorecptors respond to?
- stretchor2. pressurewithin the arterial systemAn inc. in pressure causes dec. HR and peripheral vasodilation (parasympathetic response) A dec. in pressure causes HR and peripheral vasoconstriction (sympathetic response)
