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ZA - Science for Medicine > Blood > Flashcards

Flashcards in Blood Deck (28):
1

What is the average circulating volume in an adult male?

5L overall

1L in lungs

3L in systematic
venous circulation

1L in heart and arterial circulation

2

What are the 6 functions of blood?

Carrying physiologically active compunds - hormones enzymes nutrients

Clotting

Defence

Carrying gas

Thermoregulation

Maintenance of ECF pH

3

What % water is plasma?

95%

4

What is plasma used for?

Used to circulate biologically active molecules and compounds

5

What are the 3 plasma proteins sub-categories?

Albumin

Globulins

Fibrinogen

6

What does albumin do?

Transports lipid and steroid hormones

Helps create colloid oncotic pressue

7

What does Globulins do?

Alpha/beta transports lipids and fat-soluble vitamins

Gamma type are antibodies

8

What is fibrinogen ?

Clotting factor

9

What is causes the colloid oncotic pressure?

Plasma proteins do not readily cross the capillary wall.

These proteins displace water and create an osmotic potential. This creates a pressure that can pull water from the interstitial space into the lumen/plasma.

When the water moves, chemicals and nutrients move to, however this only changes the volume, not the concentration.

10

What are erythrocytes and what is its lifespan? Function? Normal circulating levels?

Red blood cells
120 days
Carries O2
Levels between 4 and 6x10^12/L

11

What is erythropoiesis

Red blood cell formation
Controlled and accelerated by protein erythropoietin

12

What does erythropoietin do? What factors cause its secretion to be enhanced?

Speeds up differentiation of pluripotent stem cells to Erythroblasts (immature RBC)

Secretion is enhanced when O2 delivery to kidneys is reduced due to either a hemorrhage, anemia, cardiac dysfunction or lung disease

13

What are leukocytes?

White blood cells - several types of them

14

Neutrophils - function and half life? Normal levels?

Phagocytic function - entraps bacteria and forms the 1st line of defense

has a 6 hour half life

Normal levels are 68% of WBC population (2.5-2.7x10^-9/L)

15

Eosinophils - function - normal levels?

Attacks pathogens too large for neutrophils such as parasites

Numbers increase rapidly during allergenic response

Normal levels are 1.5% of population (0.1-0.44x10^-9/L)

16

Basophils function? Normal levels?

Relases histamine and heparin - triggers inflammation

Normal levels are 0.5% of population (0.1x10^-9/L)

17

Monocytes - function and life span? Normal levels?

Largest white blood cell
72 hours life span

Are "pre" macrophages that migrate to spleen, liver, lungs and lymph nodes

Normal levels are 5% (0.2-0.8x10^-9/L)

18

What are macrophages? Life span?

Mature monocyte that has migrated from the blood to the connective tissue

Can reside for up to 3 months.

Is phagocytic.

19

Lymphocytes - normal levels? Function?

25% (1.3-3.5x10^-9/L)

Are key componants of immune system - respond to viruses - have B and T cells

20

What is Leukopoiesis?

White blood cell formation

21

How does Leukopoiesis occur?

More complex than erythropoiesis

Controlled by a cocktail of cytokines - growth stimulating factors and interleukins

Cytokines released by endothelial cells, fibroblasts and mature white cells, and stimulate mitosis and maturation of leukocytes

The cocktail is dynamic and changes its composition to suit which specific cell type is needed at any given moment.




22

What are platelets? Are they nucleated? What governs formation? Life span?

Membrane bound cell fragments (from megakaryocytes)

Rarely nucleated

Formation governed by Thrombopoietin

Has life span of 10 days

23

What do platelets adhere to and function of them?

Adhere to damaged vessel walls and exposed connective tissue to mediate blood clotting

DO NOT adhere to healthy intact endothelium.

24

What is the haematocrit?

% of RBC to whole blood content

25

What colour is plasma and why?

Yellow due to bilirubin - which is the breakdown part of RBC

26

What is the normal haematocrit ranges?

Male - 40-54%
Female - 37-47%

27

What is blood viscosity?

The thickness of blood in comparison to water. Plasma is 1.8x thicker, whole blood is 3-4x thicker.

28

What can change blood viscosity?

Haematocrit range, temperature and flow rate.