Lecture 12 - Blood

Question 1

What is the typical pH range of blood?

Answer 1

7.35-7.45

Question 2

What is blood plasma?

Answer 2

-blood minus the formed elements

Question 3

What is blood serum?

Answer 3

-plasma without blood clotting-proteins

Question 4

What are the different layers of centrifugated blood and what do they contain?

Answer 4

• supernatant (plasma)
• buffy coat (leukocytes)
• precipitate (sedimented red blood cells

Question 5

What is the average blood volume, % of formed elements, and hematocrit of males and females?

Answer 5

Blood volume:

• males: 5-6
• females: 4-5

Formed elements:

• males: 44-54%
• females: 38-48%

Hematocrit:

• males: 47%
• females: 42%

Question 6

What are the different types of blood proteins?

Answer 6

Fibrinogen:

• made in liver
• function in blood clotting
• target for thrombin

Albumins:

• made in liver
• exert osmotic pressure on blood vessel walls

Globulins:
-immunoglobulins

Question 7

What are the characteristics of an erythrocyte?

Answer 7

Red blood cells

• biconcave shape
• devoid of granules and organelles
• contains: lipids, ATP, carbonic anhydrate, and hemoglobin
• protein contents: ~50% integral membrane proteins; spectrin, ankyrin, and actin

Question 8

What is the average concentration of erythrocytes in males and females?

Answer 8

Males:
-4.3-5 x 10^3 / μL

Females:
-3.5-5 x 10^3 / μL

Question 9

What is responsible for the biconcave shape of erythrocytes?

Answer 9

• spectrin tetramers (two dimers of α and β spectrin) bind actin
• actin-spectrin network is bound to cell membrane by ankyrin which is connected to transmembrane protein band 3
• protein 4.1 binds at actin-spectrin junctions and also binds to transmembrane glycophorin

Question 10

What are characteristics of neutrophils?

Answer 10

-polymorphonuclear leukocytes (PMNs)

• 7-9μm
• 3-5 nuclear lobes
• amoeboid phagocytes
• small, numerous granules (lysozymes and protease)
• larger, less numerous azurophilic granules (elastase and myleoperoxidase)
• circulate for 10-12 hours
• 1-2 day life span after circulation
• release enzymes which destroy bacteria such as lysozyme, lactoferrin, and free radical forming enzymes

Question 11

What are characteristics of basophils?

Answer 11

• 7-9μm
• loculated nucleus (bilobed)
• large, basophils granules: contains serotonin, heparin, and kallikerin (attracts eosinophils)
• can produce leukotreines which increase vascular permeability and slow contraction of smooth muscle

Question 12

What are characteristics of eosinophil?

Answer 12

• 9-10μm
• BILOBED nucleus
• GRANULES containing major basic protein (MBP)(disrupts parasite membranes), peroxidase, and cationic protein (neutralizes heparin)
• respond in ALLERGIC and PARASITIC infections
• PHAGOCYTIZE antibody-antigen complexes and parasites

Question 13

What are characteristics of lymphocytes?

Answer 13

• large round, indented nucleus
• small (6-8μm), medium (10-12 μm), and large (up to 18 μm)
• B lymphocytes: precursor of plasma cells
• T lymphocyte

Question 14

What are characteristics of monocytes?

Answer 14

• 9-12 μm
• largest leukocyte
• eccentrically located, kidney-shaped nucleus
• granular cytoplasm due to small lysosomes
• precursor of macrophages

Question 15

What are characteristics of platelets?

Answer 15

• derived from megakaryocytes
• 2 μm
• 200,000-400,000 per microliter of blood
• enhance aggregation (secretion of thromboxane),
• promote clot formation, retraction, and dissolution

Question 16

What is hemostasis? What is the sequence of events that results in hemostasis?

Answer 16

-elimination of bleeding

• constriction of smooth muscles around vessels
• constriction of vessels
• slowing of blood
• promotion of platelet plug
• blood coagulation

Question 17

Describe the process of platelet plug formation.

Answer 17

• injury of endothelium exposes collagen fibers
• platelets bind to collagen; secrete ADP and convert arachidonic acid to thromboxane (stimulates further aggregation)
• aggregation causes plug formation
• Von Willebrand factor is secreted from Wiesel-Palade bodies in endothelium which facilitates adherence of platelets to wall

Question 18

What are the steps of the common pathway?

Answer 18

• PROTHROMBIN is activated by FACTOR X, FACTOR V, and C++
• activated prothrombin is converted into THROMBIN
• thrombin and Ca++ activate FIBRINOGEN and FACTOR XIII
• activated fibrinogen converts into FIBRIN
• fibrin forms a MESH in the presence of activated factor XIII
• erythrocytes and other cells are TRAPPED by mesh

Question 19

What is the intrinsic pathway?

Answer 19

• clotting initiated by injury to the endothelium and exposure of collagen fibers
• all components for clotting are present in the blood

Question 20

What is the extrinsic pathway?

Answer 20

• blood clotting initiated by release of thromboplastin (factor III) entering the bloodstream
• thromboplastin produced in cell membranes or organelle membranes of damaged tissue

Question 21

What are the steps of the intrinsic pathway?

Answer 21

• factor XII is activated by collagen and kallikrein
• factor XII activates factor XI along with thrombin factor II
• factor XI activates factor IX
• thrombin factor II additionally activates factor VIII
• factor X is activated by factor IX and factor VIII in the presence of calcium
• factor X activates the common pathway

Question 22

What are the steps of the extrinsic pathway?

Answer 22

• TISSUE INJURY occurs and tissue release THROMBOPLASTIN
• thromboplastin activates FACTOR VII
• activated factor VII and Ca++ activate FACTOR X
• factor X activates common pathway

Question 23

How does the formation of a blood clot regulate the dissolution of the blood clot?

Answer 23

• tissue plasminogen activator (t-PA) activity is strengthened by fibrin and converts PLASMINOGEN to plasmin
• PLASMIN dissolves clot

Question 24

What is leukocyte extravasation and what are the two main steps through which it occurs?

Answer 24

-leukocytes leave the laminar flow of a blood vessels and undergo transendothelial migration

Phases:

• selectin phase
• integrin phase

Question 25

What occurs during the selectin phase of extravasation?

Answer 25

• P-selectin is expressed on the surface of endothelial cells when inflammatory signals are present
• Sialyl Lewis-x antigens are oligosaccharides present on the leukocyte membrane which bind P-selectin
• binding of antigens to carbohydrate recognition (CRDs) domain on P-selectin causes the leukocyte to roll

Question 26

What happens during the integrin phase of extravasation?

Answer 26

• occurs after integrin phase
• integrin receptors are activated on leukocyte membrane and bind to ICAM-1 and ICAM-2 (Ig superfamily) on endothelial cell
• integrin receptors are activated on leukocyte membrane and bind VCAM and ICAM on endothelial cell
• binding of integrins with ligand promotes transendothelial migration

Question 27

What is erythroblastosis fetalis?

Answer 27

• antibody induced hemolytic disease
• occurs when fetal blood type (ABO/Rh) varies from the mothers and the mother develops antibodies to the fetal blood
• occurs after first pregnancy as IgG is produced which can cross the placenta