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Hematology > 3: RBCs, Blood fxns, & Reticuloendothelial System > Flashcards

3: RBCs, Blood fxns, & Reticuloendothelial System Flashcards

0
Q

Shape of RBCs allows for what?

A

enables RBCs to have a large surface area for gas exchange & gives them flexibility when passing thru capillaries.

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1
Q

What is the Erythrocyte structure?

A

Biconcave discs with 7-8(micrometer) diameter and thickness (2.0-2.2 micrometer)

-Mature RBCs are non-nucleated and have no organelles.

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2
Q

Can mature RBCs reproduce or make proteins?

A

No, they have a limited capability to make ATP as well (via anaerobic metabolism)

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3
Q

Where is RBCs synthesized?

A

In RED BONE MARROW ( at a rate of 200 billion per day )

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4
Q

What is the location of red bone marrow?

A

1) Flat bones (sternum, ribs & cranial bones)
2) Irregular bones (coxal bones, vertebrae, & scapula)
3) Epiphyses of long bones (femur & humerus)

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5
Q

What are the types of bones

A

1) Irregular
2) flat
3) long
4) short

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6
Q

Where is yellow bone marrow found? What is a unique property of the yellow marrow?

A

-In the medullary cavity of the diaphysis

***In severe cases of blood loss it can be converted back to RED MARROW to increase blood cell production

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7
Q

In the fetus where is RBCs formed?

A

In the liver and the spleen (Extra-medullary erythropoiesis)

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8
Q

In adults when does Extramedullary erythropoiesis occur?

A

In diseases in which the bone marrow becomes destroyed or fibrosed

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9
Q

In children how does RBC formation differ?

A

Blood cells are actively produced in the marrow cavities of ALL BONES

***By the age of 20 the marrow in the long bones, except for the upper humerus & femur has become inactive.

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10
Q

What are pluripotential or multipotential stem cells?

A

Uncommitted stem cells that differentiate into one or another type of committed stem cell

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11
Q

What are progenitor or colony forming units?

A

Committed stem cells that differentiate into various types of blood cells.

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12
Q

What is the function of pluripotential stem cells?

A

*****Capable of replacing the bone marrow when injected into a host whose own marrow is completely destroyed
(few in number)

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13
Q

What can CFU colony forming (progenitor cells) be changed to?

A

1) CFU -Meg–> (Megakaryocyte) platelets

2) CFU-GM (Myeloid series) a) neuts b) Eosinophils c) basophils d) monocytes
3) BFU-E–>Red Cells

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14
Q

How do Lymphocyte progenitor (—>B cells, NK cells, & T cells) cells get made?

A

Pluripotent stem cell

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15
Q

What is Erythropoietin (EPO)?

A

A erythropoiesis growth factor which is released by the kidney (and to a smaller extent the liver)

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16
Q

What do the RBCs enter the circulation as?

A

Reticulocytes, which still contain some organelles :)

***They remain the bone marrow or spleen for a few days to mature into erythrocytes

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17
Q

What are the ingredients for making a normal RBC?

A

1) Amino acids
2) Iron
3) Folic acid
4) Vitamin B12

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18
Q

What is a the development pathway for a RBC?

A

Hemocytoblast (stem cell)–> Proerythroblast (Commited cell)–> Early erythroblast, late erythroblast, Normoblast, reticulocyte,–> Erythrocyte

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19
Q

How do Reticulocytes appear in staining?

A

Do to a very slight basophilic staining.

You see some organelles present in the cell

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20
Q

What kind of feedback loop does Erythropoietin production involve?

A

A NEGATIVE FEEDBACK LOOP

***as the # of RBCs increase, the red cell mass rises, oxygen is delivered more easily to tissues. Kidneys sense this increase in oxygen delivery and EPO levels drop

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21
Q

What happen to RBC production when oxygen levels are low (HYPOXIA)?

A

EPO levels rise, & RBC production increases until oxygenation return to normal

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22
Q

What is the RBC membrane like?

A

Like most cell membranes with the lipid bilayer and both INTEGRAL AND PERIPHERAL PROTEINS.

  • Has uniquely expressed protein filaments in the cytoskeleton
  • **Protein content has only 10-15 major proteins and many minor
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23
Q

What are some examples of Integral proteins

A

1) Band 3
2) Glycophorins
3) Aquaporin-1
4) GLUT 1
5) Na+/K+ ATPase (pumps)
6) Ion Channels & Exchangers

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24
Q

What is Band 3? Function?

A

Constitutes about 25 % of total membrane proteins

Fxn: Anion transports. Exchanges bicarb for chloride across the membrane. Provides linkage of lipid bilayer to the memb skeleton

25
Q

What are Glycophorins?

A

Negatively charged proteins that reduce the interaction of RBC with one another and with other cells

26
Q

What is Aquaporin-1 ?

A

Serves as selective pores for water transport

27
Q

What is GLUT 1?

A

Facilitated diffusion of glucose into the cytosol of RBCs

28
Q

What is the Na/K+ pump

A

Active transport of Na+ out of the RBC and K+ into the RBC

29
Q

Ion channels & exchangers

A

For Na+, K+ and others

30
Q

What are the functions of Ankyrin, protein 4.1, protein 4.2m and spectrin?

A

These Peripheral/Cytoskeleton proteins provide the red cell w/ a FLEXIBLE, yet mechanically RESILIENT, and STABLE, membrane.

31
Q

What can the consequences be if the RBC lacks spectrin or ankyrin?

A

Hemolysis (increased RBC breakdown)

32
Q

What is Hereditary spherocytosis?

A

Disease caused by defects in the red cell proteins

***characterized by the production of RBCs that are sphere-shaped rather than bi-concave disc shaped

33
Q

Which disease is associated with abnormally small RBCs that lack the central pallor?

A

Hereditary Spherocytosis

34
Q

What happens to abnormally shaped RBCs?

A

They undergo hemolysis and suffer pre-mature destruction

35
Q

How is O2 in the blood transported?

A

1) dissolved in plasma (outside RBC 1.5%)

2) bound to hemoglobin ( inside RBC) 98.5%

36
Q

How is CO2 transported in the blood?

A

1) Hemoglobin transports 30% of the total amount of CO2 produced by the body this is = CARBAMINOHEMOGLOBIN or carboxyhemoglobin

37
Q

What is a hemoglobin molecule made up of?

A
  • 4 polypeptide chains with SH (sulfhydryl groups) ***in reduced form!
  • Each polypeptide chain contains a HEME RING
  • Iron in the reduced state FERROUS (Fe+2) which binds O2

NOTE: adult hemoglobin = alpha 2 beta 2

38
Q

At PO2 of 40 mmHg (mixed venous blood) and PO2 25mmHg how much of hemoglobin saturated?

A
  • 75% saturated, 3 heme groups on each hemoglobin molecule have O2 bound
  • 50% saturated, 2 heme groups of each hemoglobin molecule have O2 bound
39
Q

Why does Hemoglobin-Oxygen Dissociation curve sigmoid?

A

Result of the change in affinity of hemoglobin as O2 molecules bind to heme site

**POSITIVE COOPERATIVITY
Note: Flat part of graph = Loading of O2 in the lungs
steep portion= unloading of O2 at the tissues

40
Q

Does oxygen transport require energy?

A

No but in order to survive the 90-120 days the red cell requires regular maintenance that relies on energy

41
Q

What maintenance does the RBC rely on?

A

1) Red cell membrane integrity
2) Red cell shape
3) Hemoglobin sulfhydryl groups must be maintained in reduced form
4) Iron must be kept in reduced form
5) Iron gradients

42
Q

When does the RBC take on the spherical abnormal shape?

A

if there is insuffiencent energy, the red cell cant maintain these functions and it adopts a shape called SPHEROCYTE

43
Q

What is the main source of energy for the RBC? What does Erythrocyte metabolism depend on ?

A

GLUCOSE is source of energy

***Depends EXCLUSIVELY on CYTOSOLIC PROTEINS

44
Q

What are the 3 important products of glucose metabolism?

A

1) ATP (main source of energy fo maintaing ion gradients)
2) NADH (required to maintain hemoglobin’s iron in the ferrous reduced state (Fe2+)
3) NADPH (required to maintain GLUTATHIONE on the red cell membrane in its reduced form; reduced glutathione essential for maintaining normal red cell structure and norm Hgb )

45
Q

How much energy does one molecule of glucose generate in Glycolysis?
What % of glucose is metabolized in this fashion?

A

2 ATP and 2 NADH

*** 90%

46
Q

What is the Pentose Phosphate Pathway?

What % of metabolism is generated here?

A
  • Also called Hexose Monophosphate Shut
  • Generates NADPH–> RBC energy

***10% of glucose is metabolized by RBCS in this fashion

47
Q

What is the Pentose Phosphate Pathway linked to Glycolysis through?

A

Glucose 6- Phosphate

Note:

  • if it is oxidized it enters the pentose phosphate pathway!
  • If it is isomersized to Fructose-6-phosphate it goes through Glycolysis
48
Q

What is the waste product of RBCs degradation?

A

BILIRUBIN

49
Q

What is reutilized during RBC degradation?

What is transported in plasma bound to albumin?

A

The Iron and Globin

Bilirubin is bound to albumin

50
Q

Where is the Spleen located? What is the removal of it called?

A

Located in LUQ; often injured

Splenectomy= removal

51
Q

RBCs shrink or swell with an osmotic pressure greater than that of normal plasma?

A

In hyperosmotic solution RBCs shrink!

52
Q

RBCs shrink or swell with an osmotic pressure LESS than that of normal plasma?

A

In hypotonic solution RBCs SWELL up and undergo hemolysis (Loose their hemoglobin)

53
Q

What happens to the hemoglobin of hemolyzed red cells ?

A

Dissolves in the plasma, coloring it red

54
Q

What % solution is isotonic with plasma ?

A

0.9% NaCl solution

55
Q

How can H+ ions affect extracellular fluid?

A
  • RBC operate at a certain pH and healthy individuals make 50-100 mEw/L of H+ a day via basic metabolic rxns
  • Body is sensitive to pH changes
56
Q

How is pH (H+ ) controlled in the RBC, LUNGS, and KIDNEYS

A

RBC: Converts the Co2 w/ Carbonic anhydrase into a bicarb product

LUNGS: Controls it by adjusting respiration rate and depth

KIDNEYS: Can excrete H+ in urine when low pH is sensed

57
Q

What are the 3 major chemical buffer systems in the blood?

A

1) Carbonic acid -bicarbonate (can soak up and relese H+ when needed)
2) Phosphate (can soak up and relese H+ when needed)
3) Protein (Hemoglobin, albumins)
- Amine portion Soaks H+ if excess H+ is present (acidosis)
- Carboxyl portion releases H+ (alkalosis ) if shortage of H+

58
Q

How does the Blood regulate the Temperature in cold temps?

A

Cold temperatures —>stimulate SNS fibers–> Vascular smooth muscle of skin blood vessels (alpha 1 mediated) –>VASOCONSTRICTION causes decrease in blood flow to surface of skin –>reduces heat LOSS

59
Q

How does the Blood regulate the Temperature in warm temps?

A

Warm temps–>inhibit SNS fibers–>Vascular smooth muscle of skin blood vessels (alpha 1 mediated)– VASODILATION (causes increase in blood flow to surface of skin) –> Warm blood from the body core is SHUNTED to the body surface; heat is then lost by radiation & convection

60
Q

What does shunting of blood to the surface cause ?

A

It is evidenced by redness and warmth of the skin :)

Hematology (8 decks)

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