Blood Circuits and The Heart

What are the two muscular pumps of the heart?

right pump and left pump

Which circuit does each side of the heart pump into?

right pump pulmonary circuit, left pump systemic circuit

What do ventricles do?

pump blood into arteries

What is the pulmonary circuit?

carries deoxygenated blood to lungs and returns oxygenated blood to the heart

What is the pathway through the pulmonary circuit?

right ventricle, pulmonary arteries, lungs, pulmonary veins, left atrium

What type of blood leaves the right ventricle?

deoxygenated blood

Where does gas exchange occur?

lungs

What is the systemic circuit?

sends oxygenated blood around the body and returns deoxygenated blood to the heart

What is the pathway through the systemic circuit?

left ventricle, systemic arteries, body tissues, systemic veins, right atrium

What type of blood leaves the left ventricle?

oxygenated blood

What are examples of systemic capillary beds?

limbs, kindeys, brain, gut and liver

What is the overall pathway of blood through the heart and circuits?

body, right atrium, right ventricle, lungs, left atrium, left ventricle, body

What is the unusual venous pathway associated with the gut?

gut, hepatic portal vein, liver, systemic veins, heart

What does the liver receive from the gut?

absorbed nutrients

Approximately how much blood is in a typical person?

5 litres

What is the approximate cardiac output stated in the lecture?

5 litres/min per pump

Where is most of the blood found?

84% in systemic circuit (3/4 in systemic veins)

How much blood is in the pulmonary circuit according to the lecturer's notes?

9%

How does cardiac output change during exercise?

increases

Which vessels are associated with high, medium and low pressure?

systemic arteries high, pulmonary arteries medium, pulmonary and systemic veins low

What are the four chambers of the heart?

right atrium, left atrium, right ventricle, left ventricle

What does the right atrium receive?

deoxygenated blood from the body

What are the main inlet vessels of the right atrium?

superior and inferior vena cava

What does the superior vena cava drain?

upper extremities

What does the inferior vena cava drain?

lower extremities

What does the left atrium receive?

oxygenated blood from lungs

Which vessels bring blood into the left atrium?

pulmonary veins

What is the function of the atria as reservoirs?

allow blood to keep flowing into the heart and accumulate before entering ventricles

What happens to the atria during ventricular ejection?

inlet valves close, blood accumulates

What happens during ventricular filling?

inlet valves open, blood enters ventricles quickly

What are auricles?

appendages of the atria that increase atria capacity

Where are the ventricular inlet valves located?

between atria and ventricles

What is the inlet valve on the right side?

tricuspid valve

What is the inlet valve on the left side?

mitral/bicuspid valve

What are the tricuspid and mitral valves also called?

atrioventricular valves

What are the AV valves made of?

two or three flaps of fibrous connective tissue

What are the free edges of the AV valve flaps attached to?

chordae tendineae

What are chordae tendineae?

chords that attach valve flaps to ventricles

What do papillary muscles do?

put tension on chordae tendineae

What is the function of the chordae tendineae during ventricular contraction?

prevent valve leaflets from being inverted/upturned into atrium

What happens to ventricular volume when the ventricle relaxes?

increases

What happens to pressure inside the ventricle when its volume increases?

pressure decreases

What causes the inlet valves to open during ventricular filling?

blood flow from atrium into ventricle pushes them open

Which valves are open during ventricular filling?

tricuspid and mitral

What happens to the outlet valves during ventricular filling?

closed

What happens to ventricular volume during ventricular ejection?

ventricle contracts and volume decreases

What happens to ventricular pressure during ejection?

increases

What happens to the inlet valves when ventricular pressure increases?

close, preventing blood from flowing back into atria

What are the two openings of each ventricle?

venous inlet where blood enters, aterial outlet where blood leaves

What is the shape of the left ventricular lumen?

dome shaped

What is the shape of the right ventricular lumen?

crescent shaped

Which is larger: the ventricular inlet or outlet opening?

inlet is larger

Why are ventricular inlets large?

allows blood to enter at low pressure

Why are the ventricular outlets smaller?

blood leaves ventricles under high pressure

What does the left ventricle form?

core/main muscular mass of the heart

Why does the left ventricle have thick muscular walls?

must generate the high pressure needed to pumped blood through systemic circuit

Where is the right ventricle positioned relative to the left ventricle?

sits on side of left ventricle

What is the right ventricle shaped like?

like a hip pocket on a pair of trousers

Why is the right ventricular wall thinner than the left?

only needs to pump blood through pulmonary circuit, so lower pressure

What is the approximate pathway through the ventricles?

v shaped

What are the two inlet valves associated with the ventricles?

tricuspid and mitral valves

What are the two outlet valves associated with the ventricles?

pulmonary and aortic valves

What is the outlet valve of the right ventricle?

pulmonary valve

What is the pathway out of the right ventricle?

right ventricle, pulmonary valve, pulmonary trunk

What is the outlet valve of the left ventricle?

the aortic valve

What is the pathway out of the left ventricle?

left ventricle, aortic valve, aorta

What are the outlet valves also called?

semilunar valves

How many cusps does each outlet valve have?

three cusps

What is the shape of the outlet valve cusps?

flat and pocket shaped

Do outlet valves have chordae tendineae or papillary muscles?

no

Why don't outlet valves need chordae tendineae and papillary muscles?

pocket shape allows them to close without them

What happens to the outlet valves during ventricular ejection?

high pressure causes cusps to open, allowing blood to leave ventricle

What happens to the outlet valves during ventricular filling?

close to prevent blood from returning to the ventricle

What is the peak pressure of the left ventricle?

120mmHg

What is the peak pressure of the right ventricle?

27mmHg

What is the approximate LV:RV peak pressure ratio?

5:1

What is the approximate LV:RV wall thickness ratio?

3:1

What are the peak atrial pressures stated in the lecturer's notes?

8mmHg in both atria

Which chambers are low-pressure chambers?

atria

Which chambers are high-pressure chambers?

ventricles, mostly left