Erythrocytes + Porphyrin Metabolism

Question 1

How are aging blood cells removed?

Answer 1

By the reticuloendothelial system (mainly by marcophages in the spleen)

Question 2

Where does erythropoeis occur?

Answer 2

Bone marrow

Question 3

What is the major stimulus for RBC production? Where is it made?

Answer 3

Erythropoietin

Kidneys

Question 4

What stimulates the release of erythropoeitin?

Answer 4

Hypoxia

Question 5

What are RBCs reliant on for energy production?

Answer 5

Glucose

Question 6

What transporter is on RBC membranes that facilitate the diffusion of their main energy source?

Answer 6

GLUT1

Question 7

What two enzymes will be stimulated by hypoxia?

Answer 7

EPO and bisphosphoglycerate mutase

Question 8

List 3 categorical causes of Anemia

Answer 8

Blood Loss
Impaired RBC production
Increased RBC destruction

Question 9

What are the two types of polycythemia? describe them

Answer 9

Absolute -
-Overproduction of RBCs
-Reaction to chronic hypoxia
-Overtransfusion or blood doping
Relative
-Apparent rise in RBC concentration in the blood through loss of body fluids
-Dehydration, hypvolemic shock

Question 10

What is the most damaging free radical in biological systems?

Answer 10

Reactive oxygen species

Question 11

What protects against oxygen radical damage?

Answer 11

Antioxidants

Question 12

What 4 groups can have oxidative damage? What are the results if they do?

Answer 12

-DNA: in germ cells can cause heritable mutations, in somatic cells may result in the initiation of cancer
-Proteins: May lead to proteins being recognized as non-self by the immune system
-Membrane Lipids: Membrane structure and function disturbed
-Erythrocytes: Damage to cell membranes, Iron in heme can be oxidized causing methemoglobin

Question 13

What 4 enzymes reduce oxidative stress?

Answer 13

Superoxide dismutase
Catalase
Glutathione peroxidase
Cytochrome b5 reductase

Question 14

Where does heme biosynthesis primarily take place?

Answer 14

Bone Marrow and Liver
(Although all nucleated cells can synthesize)

Question 15

What is heme synthesized from?

Answer 15

Iron+ Porphyrins(Succinyl CoA + Glycine)

Question 16

Name 4 heme containing proteins

Answer 16

Hemoglobin
Myoglobin
Catalases
Cytochromes

Question 17

What is the biggest difference between myoglobin and hemoglobin?

Answer 17

Myoglobin is oxygen storage
Hemoglobin is oxygen transport

Question 18

What part(s) of the cell does heme synthesis take place?

Answer 18

Mitochondria and Cytosol

Question 19

What is the rate limiting step of heme biosynthesis?

Answer 19

Delta-ALA synthase

Question 20

What disorders can affect heme biosynthesis? (3)

Answer 20

-Genetic
-Acquired (lead toxicity)
-Porphyrias

Question 21

How do you regulate delta-ALA synthase?

Answer 21

-Heme is a negative regulator
-Induced by hypoxia

Question 22

What is unconjugated bilirubin?

Answer 22

Bilirubin that has not be glucuronidated by the liver yet

Question 23

What is conjugated bilirubin?

Answer 23

glucuronidated bilirubin (liver onward)

Question 24

What are 3 categorical causes of icterus?

Answer 24

-prehepatic (bloodstream events
-hepatic (liver diseases)
-posthepatic (bile duct obstructions)

Question 25

What are the 3 measurements of bilirubin in the serum?

Answer 25

Total bilirubin=conjugated bilirubin and unconjugated
Direct bilirubin= conjugated bilirubin
Indirect bilirubin= Total - direct= unconjugated

Question 26

What type of bilirubin is indicated in Bilirubinuria

Answer 26

Conjugated bilirubin

Question 27

Is it normal to have bilirubin in the urine of a dog? In a cat?

Answer 27

Dog- minimal (1+, 2+)
Cat- NO

Question 28

What RBC property does 2,3-BPG affect?

Answer 28

It’s affinity for oxygen

Question 29

What enzyme converts methemoglobin back to normal Hb?

Answer 29

Cytochrome-b5 reductase