Download Coronary Circulation

Coronary Circulation
 when blood supply to a region of the myocardium is reduced or cut
off for a prolonged period that part of the heart will be damaged or
die – called a myocardial infarction, a.k.a. heart attack
 the system of vessels that supply blood to the heart is called
coronary circulation – it is supplied to the heart by 2 main
arteries, the right and left coronary arteries
 these arteries branch off the aorta, which then divided multiple
times, supplying all regions of the myocardium with oxygenated rich
blood
 these arteries continue to branch into smaller vessels called
arterioles – then they become even smaller in diameter, one-celled
thick vessels called capillaries
 in the capillaries oxygen, carbon dioxide and nutrients are exchanged
between the blood and myocardium
 these vessels eventually become larger called coronary venules –
as blood moves through these venules they become together to form
larger vessels called coronary veins
 all of the coronary veins come together to form the coronary sinus
– which drains the right atrium of the heart – this completes
coronary circulation
Cardiac Cycle
 defined as a series of events that occurs through one heart beat
 during this cycle there is both a relaxation (diastole), where the
heart is filling with blood, and a phase of contraction (systole),
where the heart contracts and ejects the blood
 systolic blood pressure – pressure in the arteries during the
contraction phase (i.e. 120mmHg)
 diastolic blood pressure – pressure in the arteries during the
relaxation phase (i.e. 80 mmHg)
 normal blood pressure reading 120/80 mmHg
Blood
 main role: transport medium for oxygen, carbon dioxide and
nutrients
 made up of 2 main components: plasma and blood cells
 plasma:
 fluid component – composed mostly of water and other dissolved
substances such as nutrients, proteins and gases
 55% of blood
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blood cells:
RBC called erythrocytes – 45% of blood
transport oxygen and carbon dioxide in the blood
contains hemoglobin that binds oxygen and carbon dioxide – it gives
the blood the ability to transport and deliver oxygen to the tissues
and remove carbon dioxide to the lungs
 WBC called leukocytes – less than 1% of blood
 important for the body’s immune system – protecting the body from
disease and helps to regulate blood clotting