RBC Structure

Question 0

What does a cytoskeleton do for a RBC?

Answer 0

Provides RBCs with strength & flexibility needed to survive in circulation

Question 1

What are three things that are crucial to normal RBC survival & function?

Answer 1

1. RBC membrane
2. hemoglobin structure & function
3. RBC metabolic pathways

Question 2

What is deformability in a RBC?

Answer 2

Highly elastic

Can distort to traverse small capillaries

Question 3

What does the RBC membrane let in?

Answer 3

Selectively sequesters vital components

Question 4

What does the RBC membrane let out?

Answer 4

Allows escape of metabolic waste products

Question 5

How does the RBC membrane regulate metabolism?

Answer 5

Reversibly binding & inactivating many glycolytic enzymes

Question 6

How does the RBC membrane exchange bicarbonate & chloride ions?

Answer 6

Aids in transfer of carbon dioxide from tissues to lungs

Balances cation & water concentrations to maintain RBC ionic composition

Question 7

What are the components and their percentages of the phospholipid bilayer-protein complex?

Answer 7

40% lipids
52% proteins
8% carbohydrates

Question 8

What functions does the membrane control?

Answer 8

Transport
Durability/strength
Flexibility

Question 9

The membrane composition determines the membrane’s what?

Answer 9

Antigenic properties

Question 10

Defects in the membrane can alter function and lead to what?

Answer 10

Cell death

Question 11

What are two major proteins of RBCs?

Answer 11

Glycophorin

Spectrin

Question 12

What type of protein is glycophorin?

Answer 12

Integral protein

Question 13

What type of protein is spectrin?

Answer 13

Peripheral protein

Question 14

What does glycophorin account for?

Answer 14

Most of the negative net charge of RBC causing them to repel each other

Question 15

What do glycophorins function as?

Answer 15

Anion exchange channels & glycophorins anchor the bilayer to the cytoskeleton

Question 16

What is the major component of red cell skeleton?

Answer 16

Spectrin

Question 17

What does spectrin do?

Answer 17

Attaches to other components such as ankyrin to form a network of microfilaments on the inner surface of the RBC

Question 18

What does the network of microfilaments on the inner surface of the RBC do?

Answer 18

Strengthens the membrane & control biconcave shape & deformability of the cell

Question 19

Spectrin is phosphorylated by a protein kinase in what kind of fashion?

Answer 19

ATP dependent

Question 20

What are other types of peripheral proteins that are components of the cytoskeleton?

Answer 20

Ankyrin
Adducin & Band 4.1
Band 3

Question 21

What does ankyrin do?

Answer 21

Couples lipid bilayer to the cytoskeleton

Question 22

What does Adducin & Band 4.1 do?

Answer 22

Promotes the association of spectrin with F-actin

Question 23

What is Band 3 and what does it do?

Answer 23

Integral protein

Catalyzes chloride-bicarbonate exchange & contains binding sites for ankyrin, band 4.1, etc.

Question 24

RBC's deformability is due to what?

Answer 24

Biconcave shape Viscosity of it's internal contents Viscoelastic properties of the erythrocyte membrane

Question 25

Deformability is necessary for what?

Answer 25

Small vessel transit

Question 26

How does the loss of ATP affect spectrin?

Answer 26

Loss of deformability

Question 27

Increased calcium deposists make RBC what?

Answer 27

Rigid

Question 28

When RBCs are rigid what kind of cells do they become?

Answer 28

Bite cells & spherocytes

Question 29

Where are bite cells & spherocytes removed prematurely?

Answer 29

In the spleen

Question 30

Skeletal proteins are not what?

Answer 30

Static

Question 31

Proteins are in equilibrium with each other and attachment sites through what two aspects?

Answer 31

Association & disassociation

Question 32

Skeletal proteins are not static in response to what?

Answer 32

Various physical & chemical stimuli as RBCs travel through the body

Question 33

What dimeric cell membrane protein is important in deformability & requires ATP?

Answer 33

Spectrin

Question 34

RBCs are permeable to what compounds or elements?

Answer 34

Water Cl- HCO3- Glucose

Question 35

RBC are relatively impermeable to what?

Answer 35

Na & K

Question 36

What are the exchange numbers for the ATPase Na/K pump?

Answer 36

2 K into cell & 3 Na out

Question 37

When ATP depleted cells build up excess Na & lose water & K what happens?

Answer 37

Increased intracellular monovalent cations & water | Cell swelling & osmotic hemolysis

Question 38

What is pumped out by the Ca-ATPase cationic pump?

Answer 38

Ca2+

Question 39

Why is Ca2+ is pumped out?

Answer 39

To maintain low levels of intracellular Ca2+

Question 40

Elevated Ca2+ induces membrane protein cross-linking how?

Answer 40

Acting as a fixative | Causing less shape changes & a loss of deformability

Question 41

What are some RBC membrane lipids?

Answer 41

Phospholipds Glycolipids Cholesterol

Question 42

An altered arrangement of phospholipids can result in activation of clotting & can lead to what?

Answer 42

Extravascular hemolysis

Question 43

Where are glycolipids located in the RBC membrane?

Answer 43

Outer half of lipid membrane

Question 44

What do glycolipids do in the RBC membrane?

Answer 44

Interact with glycoproteins to form many RBC antigens

Question 45

When there is excess cholesterol in the RBC membrane what happens?

Answer 45

There is less fluidity in the cell membrane

Question 46

What two deficiencies may produce acanthocytes & cell hemolysis?

Answer 46

Abetalipopprteinemia & LCAT deficiency

Question 47

Excess cholesterol does what to RBCs?

Answer 47

Changes morphology - target cells & acanthocytes | RBC membrane damage

Question 48

Excess cholesterol can cause red blood cells to become what?

Answer 48

Target cells & acanthocytes

Question 49

Cholesterol accumulation in the RBC membrane causes what RBC morphology?

Answer 49

Target cells

Question 50

Abetalipoproteinemia with cholesterol accumulation causes what type of RBC morphology?

Answer 50

Acanthocytes

Question 51

LCAT deficiency causes what RBC morphology?

Answer 51

Hemolysis with red cell fragmentation

Question 52

Decreased phosphorylated spectrin or altered spectrin causes what type of RBC morphology?

Answer 52

Bite cells & spherocytes

Question 53

What protein is a heterodimer that is important in RBC cytoskeleton?

Answer 53

Spectrin

Question 54

What shape is an acanthocyte cell?

Answer 54

Helmet shape