intro to blood

Question 1

what is the average circulating volume of blood in a typical adult male (70kg)?

Answer 1

5L

1L - lungs
3L - systemic venous circulations (veins have a greater capacity to hold blood than arteries due to thinner walls)
1L - in heart and arterial circulation

Question 2

what are 5 functions of blood?

Answer 2

carriage of plasma
clotting - platelets
defence - white blood cells
carriage of gas - red blood cells
thermoregulation

Question 3

describe the composition of plasma

Answer 3

makes up 4% of body and contains 95% water

Question 4

what 3 categories of proteins is plasma subdivided into?

Answer 4

Albumin
- creates oncotic pressure
- transports fat-soluble vitamins and steroid hormones.

Globulins (3 types) :
a, ß, (alpha and beta transport like albumin)
while g, (gamma acts as antibodies)

Fibrinogen and other clotting factors

Question 5

what is colloid oncotic pressure?

Answer 5

a form of osmotic pressure induced by proteins in the blood because they displace water

which then favours the movement of water and solutes into the capillary.

Question 6

what is capillary hydrostatic pressure?

Answer 6

Capillary hydrostatic pressure (blood pressure) is an opposing pressure

it favours the movement of water and solutes out of the capillary into the interstitial space

Question 7

what is hypoproteinaemia?

Answer 7

low levels of circulating plasma proteins.

Question 8

what 4 things can hypoproteinaemia be caused by?

Answer 8

Live disease

Prolonged starvation

Intestinal disease

Nephrosis kidney disease

Question 9

what characteristic do all types of hypoproteinaemia share?

Answer 9

oedema/swelling (build-up of fluid) in the interstitial space due to loss of oncotic pressure because of the loss of plasma proteins.

Question 10

what is haematopoiesis?

Answer 10

process where all mature blood cells are produced from undifferentiated stem cells (pluripotent) found in bone marrow

Question 11

what type of blood cells do stem cells give rise to?

Answer 11

erythroblast
- reticulocyte (not mature RBC)
-> erythrocyte (mature RBC)

megakaryocyte - platelets

WBC - neutrophil, monocyte, basophil, eosinophil

Question 12

what are myeloid cells?

Answer 12

all blood cells except lymphocytes

Question 13

what are the most abundant blood cells?

Answer 13

erythrocytes 4-6x10^12/L with a 120-day lifespan

highly flexible
biconcave (increases surface area-to-volume ratio to carry more gas)
non-nucleated cells with a diameter of 7-8 micrometres.

They are densely packed with haemoglobin (protein for O2 transport).

Question 14

Why does arterial blood have a bright red colour while venous blood has a bluish/purplish colour?

Answer 14

when oxygen binds to the iron atoms on haemoglobin it becomes oxyhaemoglobin and takes on a brighter colour

when it loses oxygen it becomes deoxyhaemoglobin and takes on a darker bluish/purplish colour.

Question 15

what is erythropoiesis?

Answer 15

a process is controlled by the hormone erythropoietin

it gets increasingly secreted when oxygen delivery to kidneys is reduced (hypoxia).

Question 16

how is erythropoietin secreted?

Answer 16

85% kidney
15% liver

Question 17

Why is erythropoietin secretion increased when oxygen delivery to kidneys is reduced (hypoxia)?

Answer 17

the role of erythropoietin is to stimulate the maturation process of red blood cells in the bone marrow which takes about 2-3 days to mature.

increasing the amount of erythropoietin
-> speeds up growth of RBCs
-> an increase in the delivery of oxygen
-> restore oxygen delivery (negative feedback loop)

Question 18

Why is renal disease associated with anaemia (deficiency in the number of red blood cells)?

Answer 18

the kidney secretes 85% of the hormone erythropoietin which is responsible for stimulating the maturation process of red blood cells in the bone marrow.

So lack of kidney function = less erythropoietin secretion = less red blood cells.

Question 19

what are leukocytes (WBC)?

Answer 19

nucleated cells involved in defence against pathogens.

They are larger than red blood cells and are approximately 1 x 10^10/L

Question 20

what are neutrophils?

Answer 20

the most abundant white blood cells with a half life of 10 hours, and the body produces approximately 100bn of them per day.

Question 21

what are basophils

Answer 21

Basophils are the least abundant white blood cells

Question 22

what is the difference between a monocyte and a macrophage?

Answer 22

Monocytes (5%) are circulating cells in the plasma.

After they migrate to connective tissue

They become macrophages (live for 3 months) which phagocytose pathogens

Question 23

what is leukopoiesis?

Answer 23

the process by which white blood cells form.

Question 24

what is leukopoiesis controlled by?

Answer 24

a cocktail of cytokines such as:

Colony Stimulating Factors (CSF) - responsible for stem cell proliferation and differentiation.

Interleukins - mediates communication between cells.

Question 25

what are cytokines?

Answer 25

proteins or peptides released from mature white blood cells.

They stimulate both mitosis and maturation of leukocyte

Question 26

Why is the cytokine cocktail that is responsible for leukopoiesis considered dynamic?

Answer 26

it changes its composition in response to infection, which stimulates an increased formation of a specific type of white blood cell.

Question 27

Explain the differential stimulation of leukopoiesis in response to Bacterial and Viral infection.

Answer 27

In response to infection, all white blood cell production is increased.

Bacterial infection - there is a higher formation of neutrophils.

Viral infection - there is a higher formation of lymphocytes.

Question 28

what does a differential white cell count show?

Answer 28

the proportion of white blood cells in the blood to allow you to differentiate between infection types.

Question 29

what are platelets? lifespan, abundancy, function

Answer 29

membrane-bound cell fragments from megakaryocyte cells, rarely nucleated, are 2-4 microns in diameter.

10-day lifespan

least abundant in the composition of blood at 140-440 x 109/L.

They form the foundations of blood clotting, by adhering to damaged vessel walls and exposed connective tissue.

Question 30

what hormone governs the formation of platelets?

Answer 30

thrombopoietin

Question 31

what is a haematocrit?

Answer 31

a measurement of the percentage of red blood cells to the whole blood

it’s 40-50%, but it’s less in women and higher in men.

Question 32

what happens to the haematocrit in dehydration?

Answer 32

increases because the fluid component of blood decreases.

Question 33

what happens to the haematocrit under the influence of erythropoietin?

Answer 33

increases because it stimulates the growth of red blood cells.

Question 34

what is jaundice?

Answer 34

the condition caused by the build-up of bilirubin in the blood due to liver malfunction.

Question 34

what is bilirubin?

Answer 34

yellow substance in the blood

It forms as a product of red blood cell breakdown, which gets recycled under normal circumstances by the liver.

Question 35

what is viscosity?

Answer 35

how thick or sticky blood is compared to water

Question 36

what is the viscosity of plasma and whole blood compared to water?

Answer 36

plasma - 1.8x thicker than water

whole blood - 3/4x thicker than water

Question 37

what 3 factors does viscosity depend on?

Answer 37

Haematocrit - 50% increase in haematocrit = increase in viscosity by 100%

Temperature - increased temperature = decreased viscosity.
1 degrees changes viscosity by around 2%

Flow rate - decreased flow rate = increased viscosity