Structure and function of RBC's

Question 1

do rbcs contain a nucleus

Answer 1

no making them more deformable and more room for hb molecules

Question 2

do rbcs contain mitochondira

Answer 2

no

Question 3

surface area to volume ratio

Answer 3

high to allow for gas exchange

Question 4

consequences of rbcs strtucture

Answer 4

Full of haemoglobin
High oncotic pressure, oxygen rich environment (oxidation risk)

No nucleus Can’t divide, can’t replace damaged proteins - limited cell lifespan

No mitochondria Limited to glycolysis for energy generation (no Krebs’ cycle)

High Surface area/volume ratio Need to keep water out

Flexible Specialised membrane required that can go wrong

Question 5

red cell membrane structure

Answer 5

complex
not just a lipid bilater
flexible
maintains fluidity and deformability allowing rbcs to squeeze through capillaries
protein spars

Question 6

why do rbcs require energy

Answer 6

to maintain specific ion concentration gradients and keep water out

Question 7

what pump is used

Answer 7

sodium potassium pump

keeps water out
needs atp
keeps ion concs right
keeps system working in the cell

Question 8

structure of haemoglobin

Answer 8

tetrameruc globular protein

adult has two alpha and 2 beta chains

Question 9

what is a heme group

Answer 9

prosthetic group responsible for biding and transporting oxygent

Question 10

structure of heme group

Answer 10

iron containing porphyrin ring structure

ferrous iron fe2+ at centre of ring

Question 11

does oxygen bind to fe3+

Answer 11

no

Question 12

how many o2 moleculels bind to one fe2+ molecule

Answer 12

one

Question 13

function of haemoglboin

Answer 13

deliver o2 to tissues

act as buffer for h+

co2 transport

Question 14

what is red cell production regulated by

Answer 14

erythropoietin- growth factore which stimulates bone marrow to make rbcs

Question 15

red cell destruction

Answer 15

Normally occurs in spleen (and liver) -

Aged red cells taken up by macrophages

Red cell contents are recycled

Globin chains recycled to amino acids

Heme group broken down to iron and bilirubin

Bilirubin taken to liver and conjugated
Then excreted in bile (colours faeces and urine)

Question 16

energy source of rbcs

Answer 16

only glycolysis as no mitochondira no krebs cycle

low energy yielding procwss

Question 17

red cell challenges

Answer 17

Lots of oxygen about - oxygen free radicals are easily generated

Free radicals are dangerous

Can oxidise Fe2+ to Fe3+ which doesn’t transport oxygen

Free radicals damage proteins ~(remember we can’t repair/replace proteins as no machinery to do so -so once they’re damaged that’s it)

Question 18

what does a red cell need

Answer 18

A way of generating energy i.e. ATP
A way to keep Fe2+ from becoming Fe3+ (ie stop it oxidising)
A way to prevent oxidative damage to cellular enzymes and Hb from free radicals
A way of buffering CO2 for transport
A way of holding onto oxygen in transport and dumping it in hypoxic environments
A way of improving tissue oxygen delivery when it needs it most (when anaemic or when high demand for oxygen - metabolic acidosis, high CO2 concentrations, anaemia)

Question 19

what prevents oxidation of fe2 to fe3

Answer 19

nadh acting as an electron donor

Question 20

reactive oxyxgen species assoc

Answer 20

such as superoxide and hydrogen peroxide are free radicals so can interact with other molecules damaging their structure

Question 21

role of glutathione

Answer 21

protects us from hydrogen peroxide by reacting with it to form watter and an oxidised glutathione product

Question 22

how does co2 get from tissues to lungs

Answer 22

dissolved in plasma so transported in dissolved form

bound to haemoglobin to form carbaminohaemoglobin

as bicarb ions through a reaction facilitated by the enzyme carbonic anhydrase

Question 23

how many o2 molecules per hb

Answer 23

4

Question 24

dissociation curve for haemoglobin

Answer 24

sigmoidal

Question 25

cooperative binding haemoglobin

Answer 25

first oxygen binds to a haem in one subunit the hb shape changes altering how easy it is for the next o2 to bind and so on

Question 26

foetal haemoglobin

Answer 26

2 alpha 2 gamma

Question 27

what is increased in chronic anaemia

Answer 27

2.3 BPG

Question 28

CO2 AND BOHR EFFECT

Answer 28

co2 indirectly lowers haemoglobins affinity for 02

Question 29

what is cooperative bindings modulated by

Answer 29

several allosteric effectors that influence its affinity for oxygen

Question 30

allosteric effectors and their role

Answer 30

2,3 biphosphoglycerate , protons, c02

stabilisize the t tense state reducing oxygen affinity and promoting oxygen release

Question 31

mechanism of 2,3 bpg

Answer 31

binds to deoxygenated form haemoglobin stabilizing it and reducing its affinity for oxygen

Question 32

when does haemoglobin shift to the r state - relaxed

Answer 32

in the lugs where co2 and h+ levels are lower increasing oxygen affinity for efficient oxygen uptake

Question 33

r state

Answer 33

High oxygen affinity.
More stable when oxygen is bound.
Occurs when oxygen is bound to hemoglobin, leading to a conformational change

found in oxygen rich environment s- lungs

Question 34

t state

Answer 34

Low oxygen affinity.
More stable when oxygen is not bound.
Predominates in deoxygenated hemoglobin.
The heme group is slightly distorted, and the interactions between subunits are stronger.
Found in tissues where oxygen needs to be released.

found in oxygen poor environments- muscles