Blood vessels, blood, and tissue fluid 3.1.2

Question 1

State three ways in which the wall of an artery is different from the wall of a vein. (3)

Answer 1

artery has smaller lumen;
artery has no valves;
artery endothelium / tunica intima, folded / AW;
more / thicker, muscle / elastic tissue / tunica media;
more / thicker, collagen / tunica externa;

Question 2

Blood in the arteries has a high hydrostatic pressure.

State how this hydrostatic pressure is generated in the heart. (1)

Answer 2

contraction of ventricle wall/ muscle;

Question 3

Explain why the hydrostatic pressure of the blood drops as blood moves away from the heart. (2)

Answer 3

more, (smaller) vessels / named vessels;
(vessels) have larger, total lumen / cross sectional area; reduced resistance to blood flow;
arteries, stretch / expand;
loss of, fluid / plasma, from capillaries;

   DO NOT CREDIT further from the heart

Question 4

Describe and explain what happens to the blood plasma in a capillary as hydrostatic pressure decreases (3)

Answer 4

plasma / fluid, moves out of, capillary / blood;
enters / forms, tissue fluid;
(plasma) proteins, remain in capillary / too large to pass through capillary wall / AW;
(fluid moves) down pressure gradient;
hydrostatic pressure greater than, water potential / Ψ;

Question 5

The majority of carbon dioxide is carried as ….. in the plasma.

Answer 5

hydrogencarbonate ions (HCO3–)

Question 6

Name of the enzyme which turns Co2 and H2o into carbonic acid

Answer 6

carbonic anhydrase

Question 7

State 5 reasons why most animals need specialised transport systems.

Answer 7

• high metabolic demands
• sa:vol ratio is smaller so larger diff. distances and smaller sa to absorb/ remove substances
• hormones/ enzymes made in one place,needed in another
• food needs to be transported to every cell for use in respiration and cell metabolism
• waster products of metabolism need to be removed from cells and transported to excretory organs

Question 8

haemocoel

Answer 8

• body cavity in an open circulatory system
• transport medium under low pressure
• comes into direct contact with tissues and clls

Question 9

open circulatory systems are found mainly in

Answer 9

invertebrate animals eg most insects & molluscs

Question 10

insect blood is called

Answer 10

haemolymph

Question 11

what does haemolymph do?

Answer 11

• carries food, nitrogenous waste products, and cells involved in defense against disease (immune)

Question 12

difference between lymph and plasma and tissue fluid

Answer 12

lymph has less oxygen and fewer nutrients

Question 13

carbonic acid breaks up into

Answer 13

H+ + HCO3-