circulatory system

Question 1

why do multicellular organisms need a specialised transport system and what is it called

Answer 1

they have a low surface area to volume ratio, so they need a specialised transport system to carry raw materials from specialised exchange organs to their body cells

called the circulatory system

Question 2

what is the circulatory system made up of

Answer 2

the heart and blood vessels

Question 3

what happens in the circulatory system

Answer 3

the heart pumps blood through blood vessels to reach different parts of the body

there are two circuits:
one circuit takes blood from the heart to the lungs, then back to the heart
the other loop takes blood around the rest of the body

the heart has its own blood supply - the left and right coronary arteries

Question 4

what does blood transport

Answer 4

blood transports respiratory gases, products of digestion, metabolic wastes and hormones

Question 5

name all types of blood vessels

Answer 5

arteries
arterioles
veins
capillaries

Question 6

what takes blood into the kidneys

Answer 6

renal artery

Question 7

what takes blood out of the kidneys

Answer 7

renal vein

Question 8

what takes blood out of the gut, into the liver

Answer 8

hepatic portal vein

Question 9

what takes blood directly into the liver

Answer 9

hepatic artery

Question 10

what takes blood away from the liver

Answer 10

hepatic vein

Question 11

what takes blood into the lungs

Answer 11

pulmonary artery

Question 12

what takes blood away from the lungs

Answer 12

pulmonary artery

Question 13

taking oxygenated blood to body

Answer 13

aorta

Question 14

taking deoxygenated blood to the heart

Answer 14

vena cava

Question 15

how are arteries adapted

Answer 15

they carry blood from the heart to the rest of the body

walls are tick and muscular and have elastic tissue to stretch and recoil as the heart beats - maintains high pressure

inner lining (endothelium) is folded, allowing the artery to stretch - maintains high pressure

all arteries carry oxygenated blood except for the pulmonary arteries, which take deoxygenated blood to the lungs

Question 16

what are arterioles

Answer 16

arteries divide into smaller vessels called arterioles

these form a network throughout the body

blood is directed to different areas of demand in the body by muscles inside the arterioles, which contract to restrict the blood flow or relax to allow full blood flow

Question 17

how are veins adapted

Answer 17

veins take blood back to the heart under low pressure

have wider lumen with very little elastic or muscle tissue

contains valves to stop the blood flowing backwards

blood flow through the veins is helped by contraction of body muscles surrounding them

all veins carry deoxygenated blood, except for the pulmonary veins which carry oxygenated blood to the heart from the lungs

Question 18

how are capillaries adapted

Answer 18

always found very near cells in exchange tissues (eg alveoli) so there’s a short diffusion pathway

their walls are only one cell thick, which also shortens the diffusion pathway

there are a large number of capillaries, to increase surface area for exchange - networks of capillaries in tissue are called capillary beds

Question 19

tissue fluid - first stage

Answer 19

at the start of the capillary bed, nearest the arteries, the hydrostatic pressure inside the capillaries is greater than the hydrostatic pressure in the tissue fluid

Question 20

tissue fluid - second step

Answer 20

the difference in the hydrostatic pressure means an overall outward pressure forces fluid out of the capillaries and into the spaces around the cells, forming tissue fluid

Question 21

tissue fluid - third step

Answer 21

as fluid leaves, the hydrostatic pressure reduces in the capillaries - so the hydrostatic pressure is much lower at the venule end of the capillary bed

Question 22

tissue fluid - fourth step

Answer 22

due to the fluid loss, and an increasing concentration of plasma proteins, the water potential at the venule end of the capillary bed is lower than the water potential in the tissue fluid

Question 23

tissue fluid - fifth stage

Answer 23

this means that some water re-enters the capillaries from the tissue fluid at the venule end by osmosis