3.3.4 mass transport

Question 1

what is haemoglobin?

Answer 1

a large protein with a quaternary structure
made up of 4 polypeptide chains

Question 2

how is oxyhaemoglobin formed?

Answer 2

in the lungs, oxygen joins haemoglobin

Question 3

what does associating mean?

Answer 3

when oxygen joins to haemoglobin

Question 4

what does dissociating mean?

Answer 4

when oxygen leaves oxyhaemoglobin

Question 5

define affinity

Answer 5

the tendency a molecule has to bind with oxygen

Question 6

what is the relationship between partial pressure and haemoglobin affinity for oxygen?

Answer 6

as partial pressure increases haemoglobins affinity for oxygen also increasea

Question 7

why is a dissociation curve s shaped?

Answer 7

when haemoglobin first binds to an O2 molecule, its shape alters in a way that makes it easier for other O2 molecules to bind
the haemoglobin becomes saturated making it more difficult for O2 to bind

Question 8

how does partial pressure of carbon dioxide affect oxygen unloading?

Answer 8

haemoglobin gives up oxygen more readily at a higher partial pressure of CO2

Question 9

how are organisms in low oxygen environments adapted?

Answer 9

the have haemoglobin with a higher affinity for oxygen

Question 10

how are organisms that are very active adapted to that environment?

Answer 10

lower affinity for oxygen because they need their haemoglobin to easily unload

Question 11

how are smaller animals adapted?

Answer 11

they lose heat quickly due to a large surface area to vol ratio
so they have a high oxygen demand
they have haemoglobin with a lower affinity for oxygen they need oxygen to easily unload

Question 12

what is the structure of the circulatory system?

Answer 12

heart and blood vessels

Question 13

name all the vessels in the circulatory system

Answer 13

pulmonary artery
pulmonary vein
aorta
vena cava
renal artery
renal vein

Question 14

where does the pulmonary artery carry blood from and to?

Answer 14

from : heart
to : lungs

Question 15

where does the pulmonary vein carry blood from and to?

Answer 15

from : lungs
to : heart

Question 16

where does the aorta carry the blood from and to?

Answer 16

from : heart
to : body

Question 17

where does the vena cava carry the blood from and to?

Answer 17

from : body
to : heart

Question 18

where does the renal artery carry the blood from and to?

Answer 18

from : body
to : kidneys

Question 19

where does the renal vein carry blood from and to?

Answer 19

from : kidneys
to : vena cava

Question 20

what is the structure and function of the arteries?

Answer 20

carry blood from the heart to the rest of the body
they have thick and muscular walls with elastic tissue to stretch and recoil
endothelium is folded
they all carry oxygenated blood

Question 21

what is the structure and the function of the arterioles?

Answer 21

arteries are divided into smaller vessels called arterioles
blood is directed to different areas in the body by muscles inside the arterioles which contract to restrict blood flow

Question 22

what is the structure and function of the veins?

Answer 22

take blood back to the heart under low pressure
they have a wide lumen with very little elastic or muscle tissue
contain valves to stop the blood flowing backwards
all veins carry deoxygenated blood except pulmonary veins

Question 23

what is the structure and function of the capillaries?

Answer 23

arterioles branch into capillaries
they are always found very near cells in exchange tissues
walls are only one cell thick
network of capillaries are called capillary beds

Question 24

how is tissue fluid formed?

Answer 24

hydrostatic pressure inside capillary is greater than that in tissue fluid
difference in pressure means an overall outward pressure forces fluid out of the capillaries and into the spaces around the cell

Question 25

what differentiates the left and right side of the heart?

Answer 25

ride side pumps deoxygenated blood to the lungs left side pumps oxygenated blood to the whole body

Question 26

outline the key steps of the cardiac cycle

Answer 26

1. ventricles relax and atria contract 2. ventricles contract and atria relax 3. ventricles relax and atria relax

Question 27

outline pressure and volume changes and valve movement during atrial systole

Answer 27

ventricles are relaxed and atria contract decreasing volume inside chambers and increasing pressure pushes blood into ventricles atrioventricular valves open

Question 28

outline pressure and volume changes and valve movement during ventricular systole

Answer 28

atria relax and ventricles contract pressure increases in ventricles forces atrioventricular valves shut pressure in ventricles is higher than in aorta and pulmonary artery so semi lunar valves open

Question 29

outline pressure and volume changes and valve movement during atrial and ventricular diastole

Answer 29

ventricles and atria relax higher pressure in pulmonary artery and aorta closes semi lunar valves blood returns to heart atrioventricular valves open

Question 30

how do you calculate cardiac output?

Answer 30

stroke volume x heart rate

Question 31

explain how water from tissue fluid is returned to the circulatory system

Answer 31

plasma proteins remain so water potential gradient is created water moves to blood by osmosis it is returned to blood by lymphatic system

Question 32

what is pressure filtration?

Answer 32

the hydrostatic pressure inside the capillaries is higher than hydrostatic pressure in the tissue fluid difference in pressure results in overall outward pressure forces fluid out of the capillaries and into the space around cells forming tissue fluid

Question 33

how is the tissue fluid returned back to the circulatory system?

Answer 33

water potential at venule end of capillary is lower than water potential in tissue fluid, some re enters the capillaries from tissue fluid by osmosis excess is drained into the lymphatic system

Question 34

how does an atheroma form?

Answer 34

damage to the endothelium by high pressure white blood cells and lipids clump together to form fatty streaks over time, more clump together to form an atheroma it blocks the lumen and restricts blood flow causing blood pressure to increase

Question 35

what is an aneurysm?

Answer 35

swelling of the artery starting with the formation of an atheroma

Question 36

what is the function of the xylem?

Answer 36

transports waste and mineral ions in solution

Question 37

what is the cohesion tension theory?

Answer 37

water evaporates through transpiration this creates tension which pulls more water into the leaf water molecules are cohesive so when one is pulled into the leaf others follow

Question 38

what is translocation?

Answer 38

the movement of solutes to where they’re needed in a plant moves solutes from sources to sinks

Question 39

what is the mass flow hypothesis?

Answer 39

active transport is used to actively load the solutes from companion cells into sieve tubes this lowers the water potential inside sieve tubes so water enters tube by osmosis from xylem creating high pressure inside sieve tubes at the sink solutes are removed from phloem, this increases water potential so water also leaves by osmosis this lowers pressure inside sieve tubes

Question 40

what is evidence for the mass flow theory?

Answer 40

removing a ring of bark forms a bulge above the ring so the fluid in the bulge has a higher concentration of sugars than the fluid below the ring sugars can’t move past the area bark has been removed from aphids are used to prove pressure, they pierce the phloem and then sap seeps out quicker near leaves than further down stem radioactive trace can be used to track movements of organic substances