Case 4- Blood

Question 1

Red blood cells (Erythrocytes)

Answer 1

Makes up 40-50% of male blood and 34-45% of female blood. Flexible to squeeze through narrow capillaries. Packed with haemoglobin which carries the oxygen, they have no nucleus and few organelles so more space for the oxygen. It is a flat disk with a concave surface (concave disk) increases surface area for oxygen diffusion

Question 2

White blood cells (Leukocytes)

Answer 2

A smaller number of them then red blood cells. There are many different types which have various roles in the immune system. They can perform phagocytosis, produce antibodies, destroy infected cell (T-killer)

Question 3

Platelets (thrombocytes)

Answer 3

Are fragments of cells called ‘megakaryocyte’, they are membrane bound but have no nuclei and are involved in blood clotting. Contains water, protein, inorganic solutes (K+, Na+) and non-organic solutes (glucose). The proteins have roles in maintaining oncotic pressure, buffers, blood coagulation and can carry other molecules (lipids)

Question 4

Plasma

Answer 4

The blood minus cells and platelets

Question 5

Serum

Answer 5

Plasma minus the coagulation factors

Question 6

Plasma proteins- Globulins

Answer 6

40% of plasma proteins, various different types like glycoproteins which carry sugar (alpha 1), prothrombonin (involved in blood clotting) and erythropoietin (makes new red blood cells) (both alpha 1). There are also globulins involved in transport, such as lipid carrier proteins e.g. LDL, or proteins which carry vitamins and metals (beta 1). The last category is immunoglobins (Y).

Question 7

Plasma proteins- Albumin

Answer 7

It is 60% of the plasma proteins. 80% of its function is its regulation of oncotic pressure. It also has roles in transporting substances such as drugs, hormones and fatty acids.

Question 8

Plasma proteins- fibrinogen

Answer 8

Blood clotting

Question 9

Electrolytes in the blood

Answer 9

Na+, K+, Ca+2, Mg+2, Cl-, HCO3- and phosphate. They help maintain osmotic pressure

Question 10

What is transported in the blood

Answer 10

• Glucose- nutrition, energy source
• Amino acids- protein synthesis
• Hormones- various roles as chemical messengers
• Dissolved gases- O2 for respiration, CO2 as a waste product.
• Vitamins, minerals- nutrition, various roles
• Urea, uric acid- waste product

Question 11

Oncotic pressure

Answer 11

The proportion of osmotic pressure du to proteins

Question 12

Gibbs-Donan effect

Answer 12

The proteins within the capillaries carry a negative charge which attracts the positively charged ions into the capillary. More water then enters the capillary.

Question 13

Starling forces in the capillaries

Answer 13

At the arteriole end the high hydrostatic pressure leads to a loss of fluid from the capillaries. The hydrostatic pressure then falls till it is below the oncotic pressure (due to loss of fluid). So, at the venous end of the capillary there is a gain of fluid due to the oncotic pressure being higher than the Hydrostatic pressure. The loss of fluid equals the gain. The fluid which is not returned to the venous system is taken up by the lymphatic system which will return the fluid. The interstitial hydrostatic pressure remains constant though the interstitial oncotic pressure rises slightly towards the venous end as fluid is absorbed.

Question 14

Causes of odema

Answer 14

Heart failure increases the hydrostatic pressure at the venous end, leading to less gain of fluid due to oncotic pressure. The loss of fluid is more then gain which can lead to oedema. In kidney nephrosis there is decreased oncotic pressure (less protein in the plasma) which leads to less gain of fluid at the venous end, leads to oedema.

Question 15

Minor odema

Answer 15

Lymphatic movement requires muscle contraction. If you dont use your muscles for a while you can get minor odema, i.e. in a flight

Question 16

Localised odema

Answer 16

After removal of lymph nodes, can’t remove excess fluid. When immune cells release chemical mediators which cause swelling so white blood cells can get into the tissue.

Question 17

Structure of spleen

Answer 17

It is in the left Hypochondrium and is supplied by the splenic artery and vein. Has the renal surface, gastric surface and hilum which is where the blood vessels enter. There is red and white pulp within the spleen. The red pulp removes old erythrocytes and the white pulp screens for pathogens, as it contains lots of white blood cells which can be secreted in response to an infection.

Question 18

Function of spleen

Answer 18

Lymphoid organ so has roles in the immune system. Stores platelets, also stores iron from the breakdown of RBC’s

Question 19

ABO blood group system

Answer 19

Everyone either has blood group A, B, AB, or O. Dependent on the antigens on the surface of the RBC and the antibodies in the plasma

Question 20

ABO blood group antigens

Answer 20

Antigens are short sugar chains, what differentiates them is the last sugar on the chains. People with O-antigens don’t have that extra sugar present, people with A-antigens have N-acetylgalactosamine, and people with the B-antigen have Galactose.

Question 21

Donating blood with ABO blood groups

Answer 21

Because the O group does not have any antigens on its surface it is a universal donor. The A group can be donated to blood group A and AB patients. Blood group B can be donated to B and AB patients. Blood group AB can not be donated to anyone as their antibodies would attack it. Best to give people the blood group that is the same as their blood.

Question 22

Haemolytic disease

Answer 22

When the wrong blood group is given and they have a reaction to the blood, the blood cells are destroyed

Question 23

Rhesus antigen

Answer 23

Patients are either rhesus positive (85%) or negative where they don’t have the antigen. It can be problematic is pregnancy, when a Rh- mother is carrying a Rh+ foetus. If there is mixing of blood between foetus and mother, the mother would have antibodies againts the foetus’s blood. This is known as Rhesus disease, prevented by an anti-Rhesus D injection. Without the injections there may be problems with future children and may cause Haemolytic disease within the newborn.

Question 24

Erythropoiesis

Answer 24

Making erythrocytes

Question 25

Thrombocytopoiesis

Answer 25

Making platelets

Question 26

Granulopoiesis

Answer 26

Making granulocytes which have multiple nuclei (majority of white blood cells, neutrophils, eosinophils and basophils)

Question 27

Mononuclear cells

Answer 27

Have one nuclei, inside monocytes which are a macrophage precursor and lymphocytes (B and T cells)

Question 28

Primitive haematopoiesis

Answer 28

In the developing embryo you have the yolk sac which contains the blood forming islands which give rise to primitive erythrocytes. Don’t give rise to definitive haematopoiesis

Question 29

Definitive haematopoiesis

Answer 29

In the foetus definitive stem cells arise in the AGM (aorta-gonad mesonephros). These populate the liver and then the bone marrow to give rise to blood cells

Question 30

Adult haematopoiesis

Answer 30

The erythrobasts are formed around an erythroblast island in the bone marrow. It contains a central macrophage which contains an iron store, it also takes the nucleus out of the developing red blood cell. Haematopoiesis is present in cord blood and all trabecular bone of the infants. This retreats to the axial skeleton and proximal ends of the long bones of adults. The Haematopoietic tissue is intergrated between the trabecular bone and fat globules. This can be mobilised into the peripheral blood of adults.

Question 31

Stem cells- case 4

Answer 31

The most primitive cell which all other cells are derived from.They are self-renewing and pluripotent, meaning they can replicate many times and differentiate into multiple different cell types. Can be called HSC/HSPC

Question 32

Committed progenitors- case 4

Answer 32

Cells which dvide to form one type of cell. Can be called CMP/GMP (common myeloid progenitor and granucyte macrophage progenitor). Can be CFU-X (colony forming unit then the cell it produces)

Question 33

Precursors- case 4

Answer 33

The undeveloped form of a cell

Question 34

Lineage prime model of Haematopoieses

Answer 34

Each stem cell is primed to make either a common myeloid progenitor or a common lymphoid progenitor. If there is an infection the stem cells may change to give rise to more common lymphoid progenitors

Question 35

Branching model of lineage commitment

Answer 35

1) The immediate environment keeps stem cells pluripotent, they receive signals to stay in this niche, when a daughter cell leaves this environment they become DIFFERENTIATED PROGENCY.
2) An increase in a transcription factor will stimulate more of them to be produced as well as inhibit the production of the other transcription factor. This will cause it to become a MULTIPOTENT PROGENITOR as it divides.
3) The transcription factors produce the the growth factor receptors, the cell is now a COMMITED PROGENITOR.
4) The growth factors bind to the receptor they are complimentory for. The growth factors drive expression of specialised genes and expansion of PRECURSORS, allowing the cell to differentiate more.
5) The cell then divides rapidly to expand and becomes a precursor and then develops into a mature cell, this is driven by growth factors. As expansions decreases, development increases. In red blood cells a macrophage destroys the nucleus.

Question 36

Transcription factors for white and red blood cells

Answer 36

The transcription factors for red blood cells are GATA1 and for white blood cell PU.1

Question 37

The growth factors receptors for red and white blood cells

Answer 37

Epo R (red blood cells) and GCSF R (granulocytes- will becomes white blood cells)

Question 38

The growth factors for red and white blood cells

Answer 38

G-CSF in granulocytes and Epo in erythrocytes

Question 39

Growth factors- case 4

Answer 39

Extrinsic signals that influence what the cell will become, produced by stromal cells. Also called colony stimulating factors (CSF’s)

Question 40

Regulation of erythropoiesis- Hypoxia

Answer 40

Hypoxia is detected by the kidney which causes renal perivascular fibroblasts to make Erythropoietin (EPO), which stimulates the uptake of iron in the bone marrow, and stimulates the production of globin and haem. This leads to more red blood cells being produced. EPO production is regulated by negative feedback through increased oxygen delivery to the kidney

Question 41

Regulation of erythropoiesis- reticulocytosis

Answer 41

When you have a sudden need for red blood cells, more reticulocytes are produced, potentially due to bleeding, haemolysis or restoration of a deficiency. They tend to be a larger size. This is a left shift as more immature cells are in the blood.

Question 42

Regulation of granulopoeses

Answer 42

In infection, inflamation or immunity. The macrophage in the bone marrow release more G-CSF. This promotes progenitor expansion, ‘toxic granules’ and a left shift with mobilisation of immature cells. So there will be increased Leukocytosis, neutrophilia, left shift and toxic granulation.

Question 43

The monuclear phagocyte system

Answer 43

Blood monocytes, mobile issue macrophages, fixed tissue macrophages and dendritic cells.

Question 44

The monuclear phagocyte system- function

Answer 44

Macrophages help with the deveopment of the blood, brain and bone. They recycle blood cells and form a storage of iron. They clear debris (lung, liver and spleen). The detect pathogens (lungs, liver, spleen, GI tract). They prime the immune system (antigen presentation) and help with immune response (phagocytosis, giant cells and granulomata).

Question 45

Specialised mononuclear tissue macrophages

Answer 45

Microglion (brain), red pulp macrophage (spleen), osteoclast (bone) and bone marrow macrophages