LEC 23: Heart I (Vessels, Blood, Microstructure)- Part II - 09.03.14

Question 1

hematopoiesis

Answer 1

• formation and development of blood cells
• very few starting cells produce massive numbers of mature cells
• ~10 trillion blood cells are lost and replaced every day

Question 2

Starting cells for hematopoiesis and their survival times

Answer 2

1. red blood cells (4 months)
2. leukocytes (10 hours)
3. platelets (1 week)

NB: leukocytes = WBC (can be divided into granulocytes and agranulocytes)

Question 3

Describe this slide of bone marrow

Answer 3

A. Red marrow

B. Yellow marrow

Bone marrow sample is usually taken from iliac crest, like coring an apple

Question 4

Composition of blood

Answer 4

1. cells

• red blood cells (RBC): carry oxygen
• leukocytes (WBC): fight infection
• thombocytes (platelets): hemostasis (control bleeding)

2. plasma

• electrolytes: maintain tonicity
• proteins: albumin, globulins (antibodies), clotting factors
• lipids: serum

Question 5

What percentage of blood is plasma? Cells?

Answer 5

• plasma (55%)
• cells (45%)

Question 6

characteristics of blood cells

Answer 6

• short life span (except lymphocytes and macrophages)
• multiplicity of cell types
• widely distributed throughout the body
• bone marrow must respond quickly to emergency needs for additional cells
• stem cells must be maintained in adequate numbers through life (e.g. self-renewal)

Question 7

What are the structures in this peripheral blood smear

Answer 7

A. Platelet

B. Red blood cell (RBC)

C. Neutrophil (WBC)

Question 8

Erythroblasts vs. Erythrocytes

Answer 8

Erythroblasts = young/immature RBC found in bone marrow

• polychromatophilic erythroblasts = nucleated
• orthochromatic erythroblasts = as differentiate, nucleas gets smaller and is eventually extruded

Erythrocytes = mature RBC found in blood

• reticulocytes = immature RBC; count of reticulocytes used to check anemic patients

Question 9

Size and shape of RBC

Answer 9

• nucleus of small mature lymphocytes are approximately same size as RBC
• biconcave disc (Surface Area important for gas exchange)
• structure important for deformability

Question 10

Normal Red Cell Membrane

Answer 10

1. lipid bilayer (slippery exterior impedes adherence to capillaries or aggregation)
2. integral membrane proteins (chloride-bicarbonate exchange)
3. cytoskeleton proteins (maintain cellular shape, deformability, tensile strength)

Question 11

Characteristics of RBC

Answer 11

• anucleate
• lack organelles (cannot replenish enzymes or cytoskeletal proteins)
• anaerobic respiration
• 120 day life span

Question 12

hemoglobin

Answer 12

• most abudant protein in blood
• transports oxygen from lungs to tissues
• transports CO2 from tissues to lungs
• Importance of Fe (Iron) molecule for binding

Question 13

Types of RBC deformities

Answer 13

1. elliptocytes (too flat)
2. spherocytes (no concave disc)
3. Sickle cells (inherited defect in structure)
4. microcytes (RBC smaller than should be)

Question 14

megakaryocytes

(mega- = large; karyo- = nucleus; cyte- = cell)

Answer 14

• can draw from bone marrow
• largest cell in bone marrow
• undergoes special division (only nucleus divies, not cell)
  
  • multiple lobes
• cytoplasm breaks off, leaves marrow, becomes platelets

Question 15

Characteristics of platelets

Answer 15

• anuclear
• 7-10 day life span
• all organelles
• electron dense granules
• contractile proteins (actin, myosin)

Question 16

Platelet function

Answer 16

• first line of defense in hemostasis at site of vessel injury
  
  • adhesion, activation, aggregation
• platform for fibrin formation (clot)
• mediate inflammation
• mediate vascular contriction (serotonin)
• mediate fibroblasts proliferation

Question 17

thrombocytopenia

Answer 17

too few platelets

Question 18

What are the 5 kinds of leukocytes (white blood cells)

Answer 18

GRANULOCYTES

1. neutrophil
2. eosinophil
3. basophil

AGRANULOCYTES

4. monocyte
5. lymphocyte

Question 19

Neutrophils

Answer 19

• polymorphonuclear leukocyte
• 6 hour lifespan in blood
• 1-5 day life span in tissue
• multilobed nucleus
• contractile proteins (actin, myosin)
• endocytosis/phagocytosis function
• 55-65% of WBC

Question 20

Eosinophils

Answer 20

• biloped nucleus
• circulate for several hours after leaving marrow, then enter skin, pulmonary, or GI mucosa
  
  • may migrate into local secretions
• phagocytize antigen-antibody complexes
• increased numbers in allergy and parasitic infections
• 2-5% of WBC

Question 21

Basophils

Answer 21

• bilobed nucleus
• basophilic granules contain heparin and histamine
• mediate allergic responses
• precursors of tissue mast cells
• 1% of WBC

Question 22

Monocytes

Answer 22

• eccentric, horeshoe-shaped nucleus
• phagocytize antibody or complement coated cells/organisms
• differentiate into tissue macrophages, living for months to years
• 3-8% of WBC

Question 23

Lymphocytes

Answer 23

• effectors of immune response
  
  • T cells: cell mediated immunity
  • B cells: humoral immunity
• 20-25% of WBC