Blood IA %%+ COPY XXXXXXXXXXXXXXXX

Question 1

List the functions of blood

Answer 1

1. Carriage of physiologically active compounds
2. Clotting
3. Defence
4. Carriage of gas
5. Thermoregulation
6. Maintenance of ECF pH

Question 2

What is the average circulating volume in a typical adult male

Answer 2

Average 70kg

5 litres of blood:

–1L in lungs

–3L in systemic venous circulation

–1L in heart and arterial circulation

Question 3

Name the plasma proteins and describe their functions

Answer 3

Circulates biologically active molecules

1) Albumin: create and maintain oncotic pressure; transport insoluble molecules
2) Globulin - Subdivided into a, ß, g globulins: participate in immune system
3) Fibrinogen and other clotting factors:Blood coagulation

Question 4

Oncotic pressure

Answer 4

• Oncotic pressure, or colloid osmotic pressure, is a form of osmotic pressure exerted by proteins, notably albumin, in a blood vessel’s plasma (blood/liquid) that usually tends to pull water into the circulatory system, especially capillaries

Question 5

Fluid movement/forces

Answer 5

Net movement of fluid between capillary and interstitial space is subject to two forces:

i) Capillary Hydrostatic Pressure (CHP) favours movement of fluid out of capillary (bulging out)
ii) Plasma protein concentration (high) favours movement of fluid into capillary

Question 6

Composition of Blood 2

Answer 6

Erythrocytes (red blood cells)

• Most abundant blood cell
• 120 day lifespan.
• Highly flexible, biconcave, non-nucleated, diameter 7-8mm.
  *

Question 7

Erythropoiesis (Red Blood Cell Formation)

Answer 7

• Controlled and accelerated by erythropoietin.

Question 8

Composition of Blood 3

Answer 8

• Leukocytes (white blood cells)
• Nucleated, larger than RBC’s,
• Involved in defense against pathogens

Question 9

White Blood Cells

Answer 9

Question 10

Leukopoiesis (white blood cell formation)

Answer 10

• Cytokines are released from endothelial cells, fibroblasts and/or mature white blood cells.
• Stimulate both mitosis and maturation of leukocyte
• Bacterial - high in neutrophils

Viral - high in lymphocytes

Question 11

Platelets

Answer 11

• Platelets - membrane bound cell fragments . Rarely nucleated, 2-4mm diameter. Formation governed by Thrombopoietin
• Adhere to damaged vessel walls and exposed connective tissue to mediate blood clotting
• DO NOT adhere to healthy intact endothelium.

Question 12

Viscosity

Answer 12

Definition: How thick/sticky blood is compared to water.

Plasma - x 1.8 thicker than water

Whole blood - x 3-4 thicker than water

Factors that affect flow rate:

• Temperature: - increase in temp decreases viscosity and vice versa. 1oC changes viscosity by around 2%
• flow rate: - decreased flow rate increases viscosity and vice versa
• haemotocrit (ratio of RBC to total blood vol): 50% increase in haematocrit increases viscosity approx. 100%