Anatomy and Physiology Ch.19 The Heart Test 2

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What are the 2 major divisions of the cardiovascular system?

Pulmonary and systemic circuit

Pulmonary circuit

primarily the right side of the heart; pumps blood to the lungs

Systemic circuit

primarily the left side of the heart; pumps blood to the rest of the body

Mediastinum

centrally located between the lungs; contains the heart and great vessels (aorta, vena cava); contains the thymus and trachea

the base of the heart

on top of the heart; where main vessels located

apex

the bottom of the heart

pericardium

the parietal and visceral layers. has pericardial fluid between these.

pericarditis

inflammation of the pericardium

parietal pericardium

outside layer of the pericardium and is tough for protection

visceral pericardium or epicardium

inside layer of the pericardium and is very thin; it goes by different names with respect to different areas

myocardium

the involuntary muscles that pump the heart is thick and has spiral fibers which force more blood out of the heart

endocardium

the layer that lines the interior of the heart chambers and is very thin

atria

the chambers of the heart that receive blood from the vessels and are the top chambers

ventricles

the cambers of the heart that are on the bottom and receive blood from the atria; left wall is always thicker than the right

vena cavas

the major vein that brings all blood from the body to the right side of the heart

branches of the right pulmonary artery

the artery that is responsible for bringing blood to the lungs

pulmonary veins

the veins that bring blood in from the lungs

left atrium

the pulmonary veins bring blood into here

interatrial septum

the wall the is between the atria

interventricular septum

the wall that is between the ventricles

atrioventricular valves

tricuspid valves and bicuspid valves

tendon chords

anchor heart valve to the papillary muscles

semilunar valves

pulmonary valve and aortic valve

coronary arteries

supply blood to the inner tissue of the heart; these arteries are found through the valves

why the blood flows

the heart creates pressure gradients; blood always travels from high pressure to low pressure

how the blood flows

atria contracts and av valves open, blood flows into ventricles and atria relax as ventricles contract,av valves close, but semilunar valves open

coronary vessels

vessels that supply blood to the tissue of the heart

left coronary arteries

left circumflex branch>left marginal branch, anterior interventricular branch comes back by way of great cardiac vein

right coronary arteries

right marginal branch(supplies blood to the right atrium and ventricle), posterior interventricular branch, comes back by way of the middle cardiac vein

angina pectoris

partial blockage of blood vessel; causes chest pain; ischemia; part of the heart tissue dies

ischemia

oxygen not getting to the heart

myogenic

the fact that the signal for a heart beat originates in the heart itself

cardiomyocytes

the cells of the heart

intercalated discs

where the cardiocytes join end to end; has 3 features which are interdigitating folds, mechanical junctions, and electrical junctions

cardiac muscle

the cells have presence of sarcoplasmic reticulum where Ca is stored, Ca is required by the heart to contract; the have large t tubules, which allow propagation of signals deep into the tissues (this allow more Ca to flow in)

interdigitating folds

the plasma membrane of intercalated discs; interlock with eachother and increase the surface area of intercelluar contact

mechanical junctions

2 types: fascia adherens and desmosomes- these anchor the plasma membrane of the intercalated discs

electrical junctions

called gap junctions and allow ions to flow into a cardiocyte and allow the cells to electrically stimulate the others

sinoatrial node

pacemaker; initiates heart beat; determines heart rate

atrioventricular node

fires and sends signal to the right and left bundle of His

cardiac conduction system

the SA node fires, which makes the AV node fire, signal travels through bundle of His into the Purkinje fibers, which distribute the signal through the ventricles

vagus nerve

gives inhibitory signals to the heart

systole

contraction of the heart

diastole

relaxation of the heart

sinus rhythm

the normal heartbeat triggered by SA node

nodal rhythm

slower heartbeat that is triggered by the AV node; usually happens when the SA node has problems

ectopic foci

when the SA and AV node goes out this fires signals; in this case a pacemaker is artificially installed

arrhythmia

premature ventricular contractions; caused by stress and heart block

bundle branch block

a block due to damage to one or both bundle branches

total heart block

a block in which signals fail to reach the ventricles and ventricle beat at their own rhythm

pacemaker potential

sodium slowly leaks in channels, at threshold (-40) Ca channels open, then Ca and Na both rush in, this depolarization which causes K channels to open and the K leaves causing repolarization

action potential of a ventricular cardiocyte

stimulation from the SA node opens Na channels, Na flows in and depolarizes the cell to threshold and then opens more Na channels, when the potential peaks to +30 mV and the cell is depolarized the Na channels close. slow Ca channels open and prologue the depolarization and K leaks out and they go against eachother creating a plateau, Ca closes and K open all the way and repolarizes the cell

electrocardiogram

purley electrical measurements, consist of P wave QRS complex and T wave

P wave

firing of SA node and atrial depolarization

QRS complex

ventricular depolarization, atrial repolarization

T wave

ventricular repolarization

cardiac cycle

consist of one complete contraction and relaxation of all 4 heart chambers

pressure and flow

need pressure gradient to have flow, as pressure increases volume decreases; the higher the BP the more resistance the blood encounters

S1

the heart sound that comes from closure of AV valves "lubb"

S2

the heart sound that comes from the closure of semilunar valves "dubb"

quiescent phase

total relaxation of atria and ventricles; Av valves fully opened and blood flows through passively

ventricular filling

active filling of the ventricles;atrial systole and the ventricles fill with blood and have an end diastolic volume (EDV) of about 130 mL in them

Isovolumetric contraction

when the ventricles contract but do not eject blood because the pressure is greater in the aorta and pulmonary trunk than the ventricles

ejection

when the ventricular pressure exceeds the arterial pressure, it sends spurts of blood out rapidly then slows down when pressure lessens; ejects about 54% of the EDV- the SV

stroke volume

the amount of blood ejected during ventricular ejection; about 70 mL

end systolic volume

the amount of blood that was left behind in the ventricles after the ejection; about 60 ml

isovolumetric relaxation

when the semilunar valves close to prevent backflow and the ventricles diastole

cardiac output

the amount ejected by each ventricle in 1 mintue

CO

HR(beats per minute)xSV=

tachycardia

when the resting HR is greater than 100 beat per minute

bradycardia

when the resting HR is lower than 60 bpm

positive chronotropic agents

increase resting HR; epinephrine

negative chronotropic agents

lower resting HR; ACTH

preload

in terms of SV is the amount of tension found just before ventricles contract

Frank-starling law of the heart

SV is proportional to the EDV- the ventricles always pump out what they receive

contractility

refers to how hard the myocardium contracts for a given preload; factors that increase this are positive inotropic agents and those that reduse it are negative know table 19.2

afterload

the sum of all forces a ventricle must overcome before it can eject blood; significant contribution is the aorta and pulmonary trunk pressure ; it opposes the semilunar valve and limits SV

cor pulmonale

right ventricular failure due to obstructed pulmonary circuation

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