Blood

Question 1

Components of blood

Answer 1

1. Plasma
   - small solutes
   - larger molecules ( albunin, globulins (fibrinogen + serum), clotting factors)
2. Cellular component
   - rbc, wbc, paltelets

Question 2

How many RBC’s per ml

Answer 2

5000 million

Question 3

In anaemia

Answer 3

Capacity of blood to carry O2 is reduced

• no. RC’s reduced
• Iron folic acid / vit.b12 deficiencies
• defective hb (sickle cell)

Question 4

Haematocrit ratio

Answer 4

Proportion of blood made of cells

Question 5

Normal Ht

Answer 5

0.42-0.47

Question 6

Normal Hb

Answer 6

13.5 - 15g dl-1 (larger in men)

Question 7

Normal Ht depends on ____ then ____

Answer 7

age, sex

Question 8

A lower than normal Ht causes

Answer 8

1. loss of blood
2. nutritional deficiency
3. bone marrow problems
4. abnormal haemoglobin

Question 9

A higher than normal Ht causes

Answer 9

1. high altitudes
2. chronic smoker
3. dehydration
4. erthropoicten use in athletes

Question 10

Pc

Answer 10

Capillary hydrostatic pressure - force fluid out from capillary

Question 11

Pi

Answer 11

Intestital hydrostatic pressure - force fluid from interstital space

Question 12

Pi c

Answer 12

Capillary oncotic pressure - force pushes fluid from I.S. space to capillary ( 25mmHg)

Question 13

Pi i

Answer 13

Intestital oncotic pressure - caplilary to I.S. space

Question 14

Jv

Answer 14

Net fluix flux, = Kf [(Pc-Pi) - ó (pic - pi i )]

Question 15

Kf

Answer 15

Filtration coefficient

Question 16

ó

Answer 16

Reflection coefficient -> different for diff. capillary beds but same proteins from blood able to cross vessel wall into interstitum

Question 17

If Jv = +ve

Answer 17

Fluid wants to leave capillary

Question 18

Kf based on

Answer 18

how large + leaky capillary wall is

Question 19

Oedema

Answer 19

When filtration forces significantly exceed absorption forces, an accumulation of extravascular fluid occurs

Question 20

Consequences of Oedema

Answer 20

1. Primary increase of hydrostatic pressure gradient
2. Congentive heart failure
   - primary decrease of oncotic pressure gradient
3. Liver failure, rephotic syndrome, extensive tissue trauma

Question 21

Normally hydrostatic pressure within blood vessels

Answer 21

cause water to filter out into tissue + oncotic pressure in plasma -> water back into blood

Question 22

Haemostasis

Answer 22

When a blood vessel is damaged

Question 23

Vasoconstriction in response to haemostasis

Answer 23

Contraction of smooth muscle around damaged blood vessel due to physical stimulation of muscle

Question 24

Platelet aggregation

Answer 24

• platelet produced by megakaryocytes
• bind to injury site forming platelet plug
• > accelerated by platelets releasing ADP, thromboxane A2 which promotes further platelet aggregation (modulated by aspirin)

Question 25

How does ADP promote further platelet aggression?

Answer 25

Activate phospholipases in platelet membrane to form archanidenic acid. Cyclo-oxygenase activates endoperoxidases -> platelet + endothelium

Question 26

Coagulation

Answer 26

Conversion of plasma protein from fibrinogen to fibrin

Question 27

Coagulation activating factors 10 and 5 pathways

Answer 27

1. Intrinsic pathway - exp. of blood to damaged tissue

2. Extrinsic pathway - substances released from damaged tissue

Question 28

Factors 10 and 5 cause

Answer 28

Prothrombin to thrombin which promotes fibrinogen to convert to fibrin which forms a fibrin mesh

Question 29

Functions of blood

Answer 29

1. Maintenance of cellular function
2. Gaseous exchange
3. Nutrients
4. Hormones
5. Protection against invading organisms
6. Thermoregulation