Transcript File

CV system – function is to distribute oxygen and
nutrients/remove wastes from the body’s tissues
Made up of 2 parts: systemic [body] Left side and pulmonary
[lungs] Right side
Heart is the main organ of the system
size of your clenched fist, 14 cm long by 9 cm wide
located in the mediastinum (b/w the lungs laterally, spinal column
and sternum, posteriorly and anteriorly respectively);
apex points to the left and inferior (5th intercostal space, touching
diaphragm),
base is superior (beneath 2nd rib)
Coverings – contained within a triple-layered membrane (pericardium)
outer layer is fibrous pericardium (tough, dense)
deep to that is the parietal pericardium
covering the surface of the heart is the visceral pericardium.
space b/w fibrous and visceral is pericardial cavity, filled with serous fluid lubricates the heart.
If pericardium becomes inflamed (pericarditis – can’t secrete fluid –
membranes stick together- heart can’t move properly, severe chest pain,
may require surgery)
The Heart Wall - 3 layers
epicardium (aka visceral pericardium)– the outermost layer
– usually has fat deposits along the surface
myocardium – thick cardiac muscle – large blood supply,
large nerve supply
endocardium – elastic and collagen fibers
Heart Chambers – 4 chambers double pump
2 atria (“entrance room”) – superior - receive blood from veins then push it to
the ventricles – not much myocardium, thinner walls than ventricles; only
generate about 5 mm Hg pressure (each), smaller than ventricles, positioned
superior to ventricles, pump blood to the ventricles.
Contain ear-like projections – auricles – hollow, hold xs blood
2 ventricles - inferior to atria– thicker myocardium, pump blood out of the heart.
Right vent – sends deoxyg, blood to lungs, generates about 25 mm Hg
pressure; Left vent. – sends oxygenated blood to entire body, generates about
120 mm Hg pressure
interventricular, interatrial septum – walls that divide the heart into R & L halves
* Valves [4]- regulate blood flow through the heart
* ATRIOVENTRICULAR [A-V] valves- control blood flow
from atria to ventricle
* Right A-V valve- TRICUSPID [3 cusps]
* Left A-V valve- BICUSPID/MITRAL [2 cusps]
* SEMILUNAR valves- control blood flow out of the heart
* Pulmonary valve- allows blood to leave RIGHT Ventricle to
go to the lungs
* Aortic valve- allows blood to leave LEFT Ventricle to go to
aorta and to the body
*Chordae tendonae- chords attached
to the AV valves and anchor to walls
of ventricle.
*Papillary muscle- chordae tendonae
attached and pulled by papillary
muscle [cardiac muscle].
*Trabeculae carnae- muscular ridges
on inside of heart, especially
ventricles. Increase surface area.
*
*Rt and Lt coronary arteries branch off
the Aorta and feed the Myocardium.
*Deox blood from Myocardium drain
back to coronary sinus [back of heart
by way of cardiac veins] into Rt
Atrium
*
* ISCHEMIA- partial blockage of coronary arteries
* Decrease in blood flow/ oxygen to heart muscle
* ANGINA PECTORIS-pain radiates from neck, jaw,
left arm and shoulder
* Diaphoresis [increased sweating] and dyspnea
[difficulty breathing], nausea and vomiting
* Damage to cardiac cells
* MYOCARDIAL INFARCTION [MI- heart attack]cardiac cells DIE
* Usually caused by a clot in the coronary arteries.
Atherosclerosis – big factor in MI b/c it narrows the
arteries. Cholesterol, smoking, obesity high risk
factors.
* Cardiac Cycle-cycle of atrium and then
ventricles contracting
* SYSTOLE= to contract
* DIASTOLE= to relax
ATRIAL SYSTOLE:
*Blood flows into the atria – both contract
at the same time increasing the pressure
and forcing blood out through the AV valves
into the ventricles
*Ventricles relax, increasing their volume
and decreasing pressure, drawing blood in.
*VENTRICULAR SYSTOLE:
*Then the ventricles contract, pushing the
AV valves closed – chordae tendonae
prevent backflow into atrium.
*Increased pressure pushes the blood out
through the SL valves.
* DIASTOLE:
* When ventricles relax, pressure drops, pulling
the SL valves closed. Their structure prevents
them from opening inward.
*
Heart sounds – two sounds repeated – “lub- dub” valves opening
and closing
First sound – “lub” = ventricular contraction (systole) and AV valve
closure
Second sound – “dub” = ventricular relaxation (diastole) and SL
valve closure
*when ventricles relax, they expand and create a partial vacuum –
forces SL valves to swing back and shut.
Murmurs – incomplete closure of valves (valve prolapse) – may get
backflow of blood into atria
Can detect murmurs by listening:
lub swish dub – AV valve damage
lub dub swish – SL Valve damage