Blood and haemotopoesis Flashcards Preview

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Flashcards in Blood and haemotopoesis Deck (15):
1

Functions of blood

Transport- oxygen from lungs to tissues, carbon dioxde from tissues to lungs, nutrients, waste products, metabolites, hormones
Help protect from microorganisms
Regulation of body temperature
Repair of tissue damage

2

Blood composition

Red blood cells (erythrocytes) 45% of total blood
White blood cells (leucocytes) less than 1% of total blood
Platelets (thrombocytes) less than 1% of total blood
Plasma 55% of total blood

3

Plasma composition

Water
Organic solutes e.g. amino acids, glucose
Ions
Proteins
Enzymes
Hormones
Vitamins
Gases in solution

4

Plasma proteins (7.3g/dL)

General functions: buffers, transport
Albumin (60%)- colloid oncotic pressure, ~25mmHg
Globulins (35%)- immunity
Fibrinogen (5%)- clotting

5

Erythrocytes- morphology and composition

Bi-concave disk- flexible and maximum surface/volume ratio
Uniform size
65% Water
35% Haemoglobin
No nucleus or cell organelles

6

Erythrocytes

Red blood cell membrane is more permeable to water than to solutes
In hypertonic solution, becomes crenated
In hypotonic solution, cells swell and burst
Limits of tonicity determine fragility of cell

7

Erythropoiesis

Process of making RBCs
Haemocytoblast- stem cell directs ribosomes to make globin for Hb
Happens in red marrow
Takes 3-5 days

8

Erythrocyte elimination

Engulfed by reticulo-endothelial cells in the spleen, connective tissue, lungs, liver and lymphoid tissue
Porphorin from haem makes bilirubin (yellow colour)
Protein returned to amino acid pool
Iron retained

9

Blood transfusions and blood groups

Fatal haemolytic reactions may occur- antigen/antibody reactions
400 RBC antignes
Antibodies in serum- ABO are naturally occurring, rhesus are immune antibodies
At least 18 blood group systems

10

Incompatible transfusions cause:

Haemolysis of donor and recipient cells
Fall in blood pressure due to adenosine nucleotide release
Renal failure due to toxic substances released from haemolysing cells
Leakage of Hb through glomerular membranes

11

Rhesus factors

Subjects are Rh+ or Rh-
Rh antibodies do not occur naturally
Rh antibodies induced only after infusions of Rh+ blood or pregnancy
Antigen determined by dominant trait

12

Rh +ve transfusion in patient with Rh antibodies causes

Agglutination and haemolysis of red cells (erythoblastic)

13

Rhesus and pregnancy

Problems caused by Rh antibodies are only associated with Rh -ve mothers
Rh -ve mother carrying Rh -ve foetus is not a problem as no anti-Rh antibodies are generated
First Rh +ve baby carried by Rh -ve mother causes mother to generate anti-Rh antibodies
Second Rh +ve baby carried by Rh -ve mother is at risk of becoming erythroblastic due to attack from anti-Rh antibodies circulating in maternal bloodstream

14

Prevention of erythroblastic foetus

Delivered by caesarian
Immediate transfusion of Rh -ve blood to eliminate the Rh +ve antibodies and damaged cells
Give mum IV anti-globulin near time of delivery to mop up Rh antibodies

15

Platelet function

Play a vital role in cessation of bleeding
Have no nucleus and therefore cannot generate new proteins