cardiology Flashcards
Blood flow of the heart
blood low in O2, high in CO2 enters the R side of the heart through the superior and inferior vena cava -> R atrium ->Tricuspid valve ->R ventricle-> pulmonic valve->pulmonary artieries->Lungs->pulmonary veins->L atrium->mitral valve->L ventricle->aorta-> body
excitability.
The ability of the cells to respond to electrical impulses
automaticity
Cardiac cells are able to generate an impulse to contract even with no external nerve stimulus
Cardiac conduction
SA node ->AV node->bundle of His->right and left bundle branches (which divide into the left anterior and posterior bundles) ->Purkinje network of fibers
Sinus rhythm
60 to 100 beats per minute
where is the AV node
in the right atrium adjacent to the septum
What is the intrinsic rate of the AV node and when does it initiate impulses
40-60 beats per minute, does not usually initiate impulses unless the SA node begins failing
P
atrial depolarization, which triggers atrial contraction
QRS
depolarization of AV node and conduction of electrical impulse through ventricles. Ventricular contraction begins at R.
T
repolarization of ventricles.
P to R interval
time required for impulses to travel from SA node to ventricles
ST segment
complete ventricular depolarization
Q to T interval
complete electrical systole
Cardiac cells require what to initiate and conduct electrical signals in addition to muscular contraction
sodium (Na+), potassium (K+), calcium (Ca+), and chloride (Cl-) ions
The medulla monitors and controls cardiac function through _____, ______ and ______
the autonomic nervous system, endocrine system and cardiac tissue
chronotropic effect
rate of contraction
dromotropic effect
rate of electrical conduction
inotropic effect
strength of contraction
what do Chemoreceptors detect
detect chemical changes in the blood
baroreceptors detect and are located
located in the carotid arteries, detect pressure in the heart and arteries
What happens when homeostasis is interrupted
receptors begin to fire, and neurotransmitters or hormones that activate either the sympathetic nervous system (SNS) or the parasympathetic nervous system (PNS) are released
What happens when the sympathetic nervous system is stimulated?
norepinephrine along with other catecholamines such as epinephrine is released by nerve endings on the heart ->bloodstream->bind with receptors on the heart
where are beta 1 receptors located
on the conduction system and myocardium
where are beta 2 receptors located
myocardium and smooth muscles
Beta 1 or 2? heart rate and contractility increase
both
Beta 1 or 2? blood vessels will vasodilate
Beta 2
what is the predominant receptor on the heart?
Beta 1
Beta 1 or 2? bronchodilation
Beta 2
Stimulation of Beta-3?
leads to reduced contractility
Alpha 1 or 2? vasoconstriction
Alpha-1
Alpha 1 or 2? centrally mediated vasodilation
Alpha-2 (keeps blood pressure in balance)
How do beta-adrenergic blocking agents work?
block beta-1 and beta-2 receptors thereby decreasing heart rate and contractility
Second generation beta blockers are
Cardioselective, blocking mainly beta 1 receptors
Parasympathetic nervous system stimulation, specifically the vagal nerve, causes
release of acetylcholine, which decreases heart rate and reduces contractile strength
Vagal nerve stimulation, which may occur with emotional distress from any situation like blood drawing, will cause
drop in heart rate and blood pressure referred to as a vagal or vasovagal reaction
heart’s blood is supplied by the
coronary arteries - Two main arteries arise from the root of the aorta and divide into the right (RCA) and left (LCA) coronary arteries.
anastomoses
multiple connections within and between the coronary arteries. . The flow through the anastomosis provides critical collateral circulation when it is not sufficient from the RCA or LCA for various reasons such as occlusions.
LCA supplies blood flow to where?
front of the heart, the left and right ventricles, and the interventricular septum
The second LCA division is the circumflex, which supplies the left atrium and lateral left ventricle wall.
RCA supplies blood flow to where?
right atrium and right ventricle and posterior part of the heart including the back of the interventricular septum.
what artery breaks the rules and carries oxygen depleted blood?
pulmonary arteries carry oxygen-depleted blood away from the right side of the heart to the lungs for gas exchange
what veins break the rules and carry oxygen saturated blood?
pulmonary veins
the oxygen-saturated blood returns to the left side of the heart through the pulmonary veins.
inner layer of the blood vessels known as
tunica intima
middle layer of the blood vessels known as
tunica media
what is the tunica intima comprised of
endothelium
what is the tunica media made of and what does it do?
smooth muscle that is responsible for the vessel’s ability to change diameter
Outer layer of the blood vessels known as
tunica adventitia
what is the tunica adventitia made of and what does it do?
consists of elastic and fibrous connective tissues that provide the necessary elasticity to accommodate the rush of blood with each cardiac contraction
what do some arteries also have to help accommodate the high pressures
Arteries also have a layer of elastic fiber in the tunica media and adventitia (externa) of some arteries
smooth muscle layer of arteries and arterioles is also much thicker than veins
vasa vasorum
Large veins and arteries also have blood vessels called vasa vasorum
Capillaries only have an _________ _________
endothelial layer
What is considered an overall average pressure in the arteries.
The average pressure in the arteries in one systole–diastole cycle is the mean arterial pressure considered an overall average pressure in the arteries
What can be a determinant of adequate perfusion
mean arterial pressure as opposed to blood pressure
Pulse pressure
the difference between the systolic and diastolic pressures and represents the force the heart generates each time it contracts
Cardiac output and systemic vascular resistance significantly affect _____ ______ . What is the equation that represents this?
Blood Pressure
BP = CO × SVR, where BP is blood pressure, CO is cardiac output, and SVR is systemic vascular resistance
Cardiac output
the amount of blood the heart pumps in one minute
Cardiac output is determined by what? what is the equation?
stroke volume and heart rate (CO = SV × HR, where SV is stroke volume, and HR is heart rate)
Stroke volume
the amount of blood ejected from the heart with each contraction
ejection fraction (EF),
Not all the blood in the heart is ejected. The amount pumped out with each cycle relative to how much blood volume there is at the end of diastole is called the ejection fraction (EF),
How can you measure EF
echocardiogram or computed tomography (CT)
The stroke volume is influenced by
preload, afterload, and contractility
preload
The pressure created in the left ventricle by the volume of blood at the end of diastole (left ventricular end diastolic pressure)
A key determinant of preload is
volume (measurements can be used as a gauge for ventricular volume)
Afterload
the pressure (resistance) the ventricle must overcome to eject blood (aortic pressure for the left ventricle and pulmonary pressure for the right ventricle).
The third variable affecting stroke volume and, in turn, cardiac output and ultimately blood pressure, is the
contractility of the heart
catecholamines that increases contractility
Norepinephrine, epinephrine and dopamine
catecholamines that depresses contractility
Acetylcholine
Frank-Starling law
explains the myocardial length–tension relationship and preload. The law states that the more the myocardial stretch, the greater the contraction.
