3 - Heart and blood vessels

Question 1

Difference between atria and ventricles

Answer 1

-Atria has thing walls
- Atria contracts less forcefully
-Atria creates lower blood pressure to push blood short distance into ventricles

Question 2

What do tendinous chords do

Answer 2

Prevent AV valve from turning inside out as ventricular pressure increases

Question 3

What do AV valves do

Answer 3

Open to allow blood into relaxed ventricles then close when ventricles contract to prevent back-flow of blood into atria

Question 4

What do semi-lunar valves do

Answer 4

Open to allow blood into pulmonary artery and aorta then close when ventricles relax to prevent backflow of blood into ventricles

Question 5

How do you calculate cardiac output

Answer 5

Stroke volume X Heart rate

Question 6

What is the name of the blood vessel entering/leaving the liver

Answer 6

Hepatic vein- artery
- From gut to liver- hepatic portal vein

Question 7

What is the name of the blood vessel entering/leaving the kidneys

Answer 7

Renal vein/ artery

Question 8

Difference between artery and vein

Answer 8

Artery is narrow
-Artery wall is thick
-Middle layer of artery is thicker
-Arteries have no valves but veins do

Question 9

Elastic tissue in arteries

Answer 9

-Artery wall recoils due to elastic tissue- helps smooth out surges in blood flow and maintains high blood pressure in arteries when ventricles relax
- Contains higher ratio of elastic to smooth fibres to withstand high blood pressure

Question 10

Arterioles

Answer 10

• higher proportion of smooth than elastic tissue
• control flow of blood to different tissues or organs by contraction of smooth muscle - vasodilation/ vasoconstriction

Question 11

Formation and re- absorption of tissue fluid

Answer 11

• Hydrostatic pressure high at ateriole end coz of heart contraction which causes filtration of plasma through permeable capillary wall
• Blood cells/ large plasma proteins stay in capillary - reduces water potential so osmosis into venule end
• Filtered plasma forms tissue fluid - surrounds body cells and enters lymph capillaries - join to form lymph vessels - subclavian veins retuning tissue fluid into blood

Question 12

Why does blood pressure fall as blood flows through capillaries

Answer 12

• Frictional resistance- narrow lumen in capillary
• Loss of fluid from capillary