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21 Cards in this Set
- Front
- Back
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Definition of the heart
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A muscular organ which pumps blood to the lungs and other parts of the body
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Description
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Cone shaped
10cm long size of your fist slightly to the left of midline |
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Structure
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Muscular organ made of three layers of tissue:
1.Pericardium 2.Myocardium 3.Endocardium Consists of 4 chambers: Right atrium left Atrium Right ventricle left ventricle Right and left side is divided by the septum their is no connection between the right and left side. the Tricuspid valve brings blood from the RA into RV and it ensures that blood flows in one direction only The Bi-cuspid Valve brings blood from the LA to LV, it also ensures that blood flows one direction only Chordae tendonae are attached tothe bottom of these valves and they help them to shut after blood has passed, the also maintain the direction of blood flow. Semi lunar valves guard the openings of the pulmonary artery and the aorta - not the pulm vein as this does not leave the heart. they are pocket like pouches |
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Pericardium
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Outer covering of the heart made of connective tissue
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Myocardium
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Middle muscular layer
myo = muscle |
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Endocardium
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Inner epithelial layer
Endo = inside |
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Position of the heart 9pts
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Lies in the thorasic cavity
dorsal to the ribs between the lungs superior to the diaphram it is more toward the left Base is above the apex Apex is near 5th intercostal space Base is near teh 2nd rib |
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Functions of chordae tendonae
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Maintaind direction of blood flow anad help shut the valve
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Blood flow through the heart
draw rough diagram 1st |
Deoxygenated blood brought into the RA via the Superior Vena Cava and Inferior VC
Passed through the tricuspid valve into RV then passes throught the Pulmonary Artery to the lungs, this artery divides to enter a lung each. Carbon dioxide is expelled in the lungs and blood is oxygenated. oxygenated blood then travels from each lung in 2 veins per lung in the pulmonary vein , these veins join before entering the LA blood is then passed throuth the bicuspid valve to enter the LV and it then passed through the Aorta which divides in two , upper body circulation and lower |
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Function of the heart
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Maintain constant circulation of blood throughout the body
acts as a pump it beats 74times per min |
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Sino atrial node is made of
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made of neurone cells, that conduct impulses which contract the cardiac muscle
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SA node location
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on the RA wall near the entrance of the SVC
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SA node - AV function
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It is called the pacemaker of the heart
it conducts impulses which are passed across the R + L atria causing it to contract, The AV node near the Septum picks up the impulses and and conveys them downwards between the ventricles to the bundle of his and then into perkunjes fibres which pearmeate the ventricular walls causing contraction |
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Cardiac cycle (in secsonds)
stage 1 Atrail Systole |
RA fills with do-ox blood from SVC & IVC and at the same time the LA fills with O2 blood form PV .SA node sends impulse and blood is pushed from atria to ventricles through tri and bicuspid valves.
This is arial systole and it takes .01 seconds both sides of the heart work at the same time |
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Cardiac cycle in secs
stage 2 Ventricular systole |
The contraction reaches the AV node near the septum which them emits a current which is sent into the bundle of his and purkunjes fibres to cause contraction and blood forced out of ventricles into PA and Aorta
This is called Ventricular systole and takes .03 seconds |
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Stage 3
Complete cardiac diastole |
The heart now rests for .04 seconds.
the cardiac cycle takes .08 seconds |
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Circulation of blood through body - Definition
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It is a continous process divided into three parts
1.Pulmonary circ 2.Systemic/general circ 3.Portal circ |
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Pulmonary circ
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Starts at the R ventricle - goes to lungs and back to L atrium.
in lungs carbon dioxide is excreted and O2 is absorbed De-ox blood leaves the RV and enters PA, it passes upwards and divides into R&L pulm A The RPA feeds into R lung and LPA into L lung. In the lungs, an interchange of gases between capillary blood and the air ocours in the alveoli The capilaries join to form 2 veins, 2 PV leave each lung and bring oxygenated blood into the RA of the heart. During arterial systole blood is passed into the LV ventricle systole forces blood into the AOrta. |
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Systemic or General circulation
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Circulation of blood to the tissues of the body
blood is pumped from the ventricle via V systole and is carried out via the aorta which brances out to all parts of the body |
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where is the bulk of the bodies blood carried
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Veins
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Blood supply to the heart is carried out by
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R&L coronary arteries
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