blood + blood vessels

Question 1

what is the role of blood?

Answer 1

transport medium
distributes heat
buffer
defence
provides pressure for some organs functions

Question 2

what dissolved substances are in plasma?

Answer 2

oxygen
carbon dioxide
glucose
fatty acids
amino acids
hormones
plasma proteins

Question 3

what is the structure of arteries/arterioles?

Answer 3

thick layer of elastic muscle fibres
narrow lumen
smooth lining layer
connective tissue

Question 4

what are the properties of arteries/arterioles?

Answer 4

narrow lumen to maintain high pressure
thick walls to resist high pressure

Question 5

what does elastic tissues do in arteries/arterioles?

Answer 5

stretch to accommodate surge of blood
recoil to maintain pressure

Question 6

what does the smooth endothelium do in arteries/arterioles?

Answer 6

reduce friction

Question 7

what is the structure of veins/venules?

Answer 7

wide lumen
thin muscle and elastic fibres

Question 8

what are the properties of veins/venules?

Answer 8

thinner walls as blood pressure reduced
wider lumen to decrease friction
valves to prevent backflow
outer layer of collagen to resist stretching

Question 9

what is the structure of a capillary?

Answer 9

wall made of single layer of cells
no elastic tissue
small lumen
small gaps to allow solutes and ions to leak out

Question 10

what is the flow of blood like in a capillary?

Answer 10

slow as small lumen causes friction

Question 11

how does low speed of blood flow benefit the capillaries?

Answer 11

enhances ability to exchange materials with surrounding tissues by diffusion

Question 12

what is the structure of a general blood vessel?

Answer 12

tunica intima
tunica media
tunica externa
lumen

Question 13

what is the tunica externa?

Answer 13

made of collagen
helps with high pressure

Question 14

what is the tunic media?

Answer 14

smooth muscle
elastic tissue for stretch and recoil for blood pressure

Question 15

what is the tunic intima?

Answer 15

single layer of endothelial cells
smooth and flat to reduce friction

Question 16

what is the pressure like in arteries/arterioles (systemic circulation)?

Answer 16

pressure maintained due to elastic fibres
blood at high pressure as just pumped out of left ventricle
fluctuations due to contractions and relaxation of left ventricle

Question 17

what is the pressure like in capillaries (systemic circulation)?

Answer 17

lower pressure as further away from the heart
greater total cross sectional area which pressure can be spread over
pressure drops further as loss of fluid from blood to tissues

Question 18

what is the pressure like in veins/venules (systemic circulation)?

Answer 18

some residue pressure left from the heart
contraction of skeletal muscles aids in returning blood to the heart

Question 19

what is tissue fluid?

Answer 19

bathes all cells
plasma without plasma proteins and RBCs
formed by leakage from capillaries

Question 20

what does tissue fluid do?

Answer 20

transports oxygen and nutrients from blood to cell

Question 21

what happens at arteriole end of capillary (tissue fluid)?

Answer 21

hydrostatic pressure is high
water potential of blood is lower than tissues so water moves into blood
hydrostatic pressure is higher than osmotic pressure so net movement of fluid out of blood into tissue fluid
tissue fluid high in oxygen and nutrients (from diffusion)

Question 22

what do cells do with oxygen and nutrients?

Answer 22

aerobic respiration to e.g. make new proteins
ensure a concentration gradient

Question 23

what happens at venous end of capillary (tissue fluid)?

Answer 23

hydrostatic pressure is low due to loss of fluid to capillary
water potential of blood is lower than tissue fluid (due to retention of large plasma proteins) so water enters blood
osmotic pressure is higher than hydrostatic so net movement of fluid into capillary (contains waste)

Question 24

what is lymph?

Answer 24

remaining tissue fluid removed by drainage into the lymphatic system
(10%)

Question 25

how is lymph different to tissue fluid?

Answer 25

more carbon dioxide less oxygen and nutrients

Question 26

what do lymph nodes do?

Answer 26

produce lymphocytes which intercept bacteria and viruses

Question 27

what is haemoglobin?

Answer 27

complex protein at quaternary structure 4 polypeptide chains (each contain a haem group)

Question 28

what does haemoglobin do?

Answer 28

oxygen binds with Hb in lungs to form oxyhaemoglobin oxygen unbinds with Hb in respiring tissues

Question 29

what does the ability of Hb to take up and release oxygen depend on?

Answer 29

partial pressure of oxygen (like concentration)

Question 30

what is cooperative binding (Hb)?

Answer 30

1st oxygen molecule binds with one haem group and changes shape of Hb molecule 2nd oxygen molecule attaches and changes shape 3rd molecule attaches but doesn't change shape 4th molecule only if there is a large increase in ppO2

Question 31

why is cooperative binding hard for oyxgen molecules and Hb?

Answer 31

haem groups are in the centre of haemoglobin so difficult for oxygen to bind to them (especially if small diffusion gradient)

Question 32

why does the oxygen dissociation curve never reach 100% saturation?

Answer 32

because 4th oxygen molecule cannot bind

Question 33

what happens at low partial pressure on the oxygen dissociation curve?

Answer 33

haemoglobin does not easily bind with oxygen Hb has a low affinity for oxygen Hb releases/dissociates oxygen in tissues with low oxygen levels

Question 34

what happens at high partial pressure on the oxygen dissociation curve?

Answer 34

Hb binds with oxygen easily to form oxyheamoglobin in tissues with high oxygen levels Hb has a high affinity for oxygen oxyhaemoglobin does not release its oxygen

Question 35

what happens when the bohr shift occurs?

Answer 35

concentration of CO2 increases haemoglobin releases more 02 curve shifts to the right

Question 36

why does foetal Hb shift to the left on the oxygen dissociation curve?

Answer 36

Hb has slightly different structure to adult Hb has greater affinity for oxygen than mothers at same partial pressure of oxygen

Question 37

what are the properties of myoglobin?

Answer 37

much higher affinity for oxygen than Hb more saturated at any partial pressure oxyhaemoglobin does not dissociate unless partial pressure is low

Question 38

where is carbon dioxide in the body?

Answer 38

5% dissolved in plasma 10% combined with Hb 85% transported in form of hydrogen carbonate ions

Question 39

what happens in carbon dioxide transport (simple)?

Answer 39

CO2 diffuses into RBC CO2 + H20 -> H2C03 (carbonic acid) by carbonic anhydrase catalyst carbonic acid is unstable dissociates into H+ ions and HCO3- ions (hydrogen carbonate ions) THE CHLORIDE SHIFT - chloride ions diffuse into cell to maintain correct charge H+ ions lower pH and effect enzyme activity Hb comes to the rescue Hb acts as buffer by binding to H+ forming haemoglobinic acid (HHb) H+ ions have a higher affinity for Hb than oxygen so oxygen is pushed off into tissue fluid to dissolve into cells

Question 40

how does the bohr shift and carbon dioxide transport relate?

Answer 40

H+ ions cause Hb to be less saturated with oxygen than normal at a specific partial pressure graph shifts to the right