The Heart and Heart Disease (UNIT 1) Flashcards
Describe the pump system in the human heart.
Two separate pumps lying side by side.
Pump on left deals with oxygenated blood from lungs.
Pump on right deals with deoxygenated blood from body.
Each pump has two chambers-
The atrium and the ventricle
Describe the structure and function of the atrium.
Thin walled and elastic- stretches as it collects blood.
Only has to pump blood a short distance to ventricles and therefore only has a thin muscular wall.
Describe the structure and function of the ventricle.
Much thicker muscular wall than atria because it has to pump blood further
- Left ventricle thicker than right because has to create enough pressure to pump blood around whole body whereas right only has to pump it to the lungs.
Why does blood return to the heart after being oxygenated by the lungs?
So the pressure can increase before it’s distributed to the rest of body.
Speed up blood flow to rest of body.
What do the atrioventricular valves do and describe the two different ones.
Prevent backflow of blood into the atria when the ventricles contract.
Left atrioventricular (BICUSPID) valve has two cup shaped flaps.
Right atrioventricular (TRICUSPID) valve has three cup shaped flaps.
What are pulmonary vessels?
Vessels connecting the heart to the lungs
Describe the Aorta.
Connected to the left ventricle carries oxygenated blood to all parts of the body except lungs.
Describe the Vena Cava.
Connected to the right atrium and brings deoxygenated blood back from the tissues of the body.
Describe the pulmonary artery.
Connected to the right ventricle and carries DEoxygenated blood to the lungs, where its O2 is replenished and CO2 removed.
Describe the pulmonary vein.
Connected to the left atrium and brings oxygenated blood back from lungs.
How is the heart muscle supplied with oxygen?
Supplied by its own blood vessels, called CORONARY ARTERIES.
Branch off aorta shortly after it leaves the heart.
Blockage of theses arteries lead to myocardial infarction (heart attack) because area of heart muscle is deprived of oxygen so therefore dies.
Describe diastole.
RELAXATION- Blood returns to ATRIA through PULMONARY VEIN(lungs) and the VENA CAVA (body).
As ATRIA fill, pressure in them rises, pushing open ATRIOVENTRICULAR VALVES and allowing blood to pass into VENTRICLES.
Walls of ATRIA and VENTRICLES are relaxed at this stage.
Relaxation of VENTRICLE wall reduces pressure within VENTRICLE which causes pressure to be lower than in AORTA and PULMONARY ARTERY so SEMI LUNAR VALVES close.
DUB SOUND.
Describe atrial systole.
Muscle of atrial wall contracts, forcing remaining blood that they contain into the ventricles.
Blood only pushed v. short distance so muscular walls of atria are v. thin.
VENTRICLE RELAXED.
Describe ventricular systole.
(SHORT DELAY AFTER ATRIAL SYSTOLE TO ALLOW VENTRICLES TO FILL WITH BLOOD)
Ventricle walls contract simultaneously.
This increases the blood pressure within them, forcing atrioventricular valves shut and preventing backflow of blood.
LUB SOUND
With AV valves closed, pressure rises further, forcing open the semi-lunar valves and pushing blood into pulmonary artery and aorta.
Ventricle walls much thicker than those of atria because have to pump blood further.
Left ventricle thicker than right.
How is blood flow controlled?
Mainly controlled by the pressure created by the heart muscle.
Blood moves from an area of higher pressure to an area of lower pressure.
However also controlled by valves- prevent unwanted backflow.