Hematopoiesis Nutrition

Question 1

Enzyme used in the rate limiting step converting dUMP to dTMP

Answer 1

Thimidylate synthase

Question 2

Both of these nutrients are required for DNA synthesis

Answer 2

Folate and Vitamin B12

Question 3

Cobalmin

Answer 3

Vitamin B12

Question 4

Vitamin B9

Answer 4

Folate

Question 5

What is the structural change when converting RNA dUMP to DNA dTMP

Answer 5

addition of one methyl grop

Question 6

Source of methyl groups

Answer 6

Folate

Question 7

Also involved in purine biosynthesis

Answer 7

Folate

Question 8

Co-enzyme for recycling folate

Answer 8

Vitamin B12

Question 9

After folate is taken in from diet, what are the two successive reduction steps?

Answer 9

Folate»DHF»THF

Question 10

THF trap

Answer 10

If don’t have B12, can’t convert N5 methyl THF back to THF

Question 11

The name of B12 or folate deficiency which results in fewer, but larger blood cells

Answer 11

Megaloblastic anemia

Question 12

3 important consequences of B12 or folate deficiency

Answer 12

1. DNA synthesis impaired
2. Cell division impaired
3. Cytoplasm matures faster than nucleus (cytoplasm can still undergo maturation so can make hemoglobin, gets larger, but won’t divide)

Question 13

What are visual signs of megaloblastic anemia?

Answer 13

Multilobed PMNs (normal are 3-4), macrocytic RBCs

Question 14

Why are fortified foods with folic acid more stable?

Answer 14

Doesn’t contain/form a polygluconate conjugate

Question 15

Why can hemolytic anemia cause an increased demand and use of folate?

Answer 15

Hemolytic anemia is due to RBC destruction, have to keep up with loss of RBCs, so requires a lot of cell division

Question 16

Term for reduction of all types of blood cells (RBC, WBC, platelets)

Answer 16

Pancytopenia

Question 17

Why is neural tube defect a symptom of folate deficiency?

Answer 17

Highest proliferation during embryogenesis, need high folate levels. Neural tube defect

Question 18

Major component of VB12 structure

Answer 18

Corrin ring

Question 19

Source of VB12

Answer 19

Made by bacteria, found in meats/animal biproducts

Question 20

Two direct steps involving VB12 that are important in neuronal function

Answer 20

Homocysteine —*—->Methionine (—>SAM)

Methylmalonyl CoA —*—> Succinyl CoA

Question 21

This breakdown product of methylmalonyl CoA will accumulate if B12 deficient

Answer 21

methylmalonic acid (MMA)

Question 22

What produces haptocorrin?

Answer 22

Salivary glands in the mouth

Question 23

2 other names for haptocorrin

Answer 23

Transcobalamin I, R factor

Question 24

Vitamin B12 is not readily available because it is bound to proteins. Where does VB12 get digested and liberated from proteins?

Answer 24

Stomach

Question 25

After liberated from proteins, VB12 binds to this molecule to protect it from the hydrochloric acid found in stomach

Answer 25

Haptocorrin

Question 26

Instrinic Factor (IF) is made by?

Answer 26

Parietal cells (stomach epithelial cells)

Question 27

VB12 disassociation from haptocorrin occurs where? What chews up haptocorrin?

Answer 27

Duodenum, pancreatic enzymes

Question 28

When released from haptocorrin, VB12 binds to what? Where?

Answer 28

Intrinsic factor in the dudodenum

Question 29

Where is B12/IF absorbed?

Answer 29

Terminal Ileum by ileal cells

Question 30

Storage of B12

Answer 30

liver and muscle

Question 31

This glycoprotein binds and transport VB12 through the blood once it has been absorbed by terminal ileum

Answer 31

Transcobalamin II (TC-II)

Question 32

List 4 conditions that prevent VB12 absorption

Answer 32

1. Loss of intrinsic factor (IF) 2. Achlorhydria (not making enough HCL that maks up gastric acid) 3. Pancreatic insufficiency 4. Malabsorption in terminal ileum

Question 33

Gastric acid in the stomach favors binding to?

Answer 33

Haptocorrin

Question 34

How would pancreatic insufficiency affect VB12 absorption?

Answer 34

Need pancreatic enzymes to chew up haptocorrin and release B12

Question 35

How would gastritis, gastrectomy, or antibodies to parietal cell antigens affect VB12 absorption?

Answer 35

Loss of intrinsic factor= pernicious anemia | Pareital cells in stomach make intrinsic factor, haptocorrin hands off VB12 to IF in duodenum

Question 36

Blind loop, bacterial overgrowth, fish tape worm, and IBS all would affect

Answer 36

VB12 absorption in terminal ileum

Question 37

How does B12 deficiency specifically cause neurological impairment?

Answer 37

Affect myelination

Question 38

Where is folic acid absorbed?

Answer 38

Duodenum/jejunum (middle section of small intestine)

Question 39

Synthesis of heme and hemoglobin occur in these two cites

Answer 39

Mitochondria and cytoplasm (heme is made in mitochondria and joins with globin chains in the cytoplasm to make hemoglobin)

Question 40

What is the rate limiting step in heme synthesis? What enzyme?

Answer 40

``` ALA synthetase (aminolevulinic acid) converts succinyl CoA---> dALA ```

Question 41

Iron deficiency only affects

Answer 41

RBCs

Question 42

size of RBCs when iron deficient

Answer 42

microcytic, small because not enough hemoglobin

Question 43

Iron deficiency shows these three signs

Answer 43

1. microcytic 2. hypochromic (less hemoglobin, expanded area, thinner hemoglobin, pale looking) 3. Insufficient hemoglobin

Question 44

Why does iron cause insufficient hemoglobin?

Answer 44

Fe2+ gets incorporated into heme to make hemoglobin; incorporation is complex

Question 45

What is the most common cause of iron deficiency? Rare cause?

Answer 45

Bleeding bleeding bleeding. Rare cause is renal/pulmonary syndrome (kidney failure)

Question 46

Why might pulmonary syndrome cause iron deficiency?

Answer 46

Kidney responsible for EPO synthesis, so no reticulocyte response, and red blood cell survival decreases

Question 47

Eating, craving weird things; a symptom of iron deficiency

Answer 47

Pica

Question 48

Are platelets and WBCs affected by iron deficiency?

Answer 48

NO, ONLY RBCs

Question 49

4 iron parameters for deficiency diagnosis

Answer 49

1. Serum Iron 2. Transferrin saturation 3. TIBC (total iron binding capacity) 4. Ferritin

Question 50

Type of anemia in B12 and folate

Answer 50

Hypoproliferative

Question 51

Type of anemia in Iron

Answer 51

hypoproliferative (if don't have enough heme, body sense that and slows down proliferation)

Question 52

Size of RBCs in B12 and folate deficiency

Answer 52

macrocytic (large, because not enough DNA synthesis but still can make hemoglobin)

Question 53

Size of RBCs in iron deficiency

Answer 53

microcytic (small, because not enough hemoglobin)

Question 54

Most common cause of deficiency in B12 and folate

Answer 54

Reduced absorption or intake

Question 55

2 key points about deficiency treatment

Answer 55

1. should be rapid and complete | 2. folate will partially correct the hematologic manifestations of B12 deficiency but NOT the neurologic

Question 56

This metal is involved in iron transport, heme synthesis, and RBC membrane

Answer 56

Copper

Question 57

This metal is involved in DNA synthesis, and in excess inhibits copper absorption

Answer 57

Zinc

Question 58

This metal is the corrin core of cobalamin

Answer 58

Cobalt

Question 59

This metal blocks iron absoprtion and heme synthesis

Answer 59

Lead

Question 60

This vitamin is involved in iron absorption

Answer 60

Vitamin C (ascorbic acid)

Question 61

This vitamin is involved in heme synthesis

Answer 61

Vitamin B6, pyridoxine

Question 62

This vitamin is involved in iron absorption and mobilization

Answer 62

Vitamin A

Question 63

Autoimmune version of VB12 deficiency

Answer 63

pernicious anemia