Structure and Function of the heart

Question 1

the heart

Answer 1

The heart is the pump that pushes blood around the body
Located in the middle of the chest cavity between the lungs.
Surrounded by a membrane (pericardium) which holds it in place whilst allowing it to move, and prevents it from overstretching
Pericardial fluid reduces friction.
Heart is composed of cardiac muscle.

Question 2

how many chambers of the heart? what are their names?

Answer 2

4
atria - upper chambers
ventricles - lower chambers
left and right is separated by the septum

Question 3

What are atria

Answer 3

the upper chambers which receive blood (atrium = singular).
Have thin walls as they pump blood to ventricles

Question 4

what are ventricles?

Answer 4

lower chambers which pump blood out of the heart (pumping chambers).
Have thicker walls than atria as they pump blood to lungs and rest of body.
Wall of left ventricle is thicker because blood is travelling further, and pressure needs to be maintained

Question 5

circulation

Answer 5

Blood loses pressure as it is pumped around the body  Has to return to heart to be re-pumped.
The heart is therefore a double pump  Right side pumps to lungs, left side around the body

Question 6

direction of blood flow

Answer 6

Deoxygenated blood from body -> superior / inferior vena cava -> right atrium -> right ventricle -> pulmonary artery -> lungs -> oxygenated blood -> pulmonary vein -> left atrium -> left ventricle -> aorta -> Body

Question 7

the pulmonary circuit

Answer 7

The pulmonary circuittakes deoxygenated blood from the right ventricle to the lungs and returns oxygenated blood to the left atrium.
The right ventricle is the pump for the pulmonary circulation.

Question 8

systemic circuit

Answer 8

The systemic circuit takes oxygenated blood from the left ventricle to all the tissues of the body and returns deoxygenated blood to the right atrium.
The left ventricle is the pump for the systemic circulation.

Question 9

what do valves do

Answer 9

ensure blood can only flow in one direction

Question 10

what are atrioventricular valves

Answer 10

between atria and the ventricles
Tri-cuspid on right & bi-cuspid (mitral) on left
Thin flaps of tissue held by strong tendons (chordae tendinae)
Seal the opening between the atria & ventricles when ventricles contract

Question 11

what are semilunar valves?

Answer 11

at base of arteries where blood leaves the heart.
Each has three cusps  flat against artery wall, but fill up if blood flow goes backwards, seals the artery
Stop blood flowing back into ventricles when they relax