Lab 1

Question 1

What are the functions of blood?

Answer 1

Transporting gasses to/from lungs and tissue Transporting nutrients from digestive organs to cells. Transports waste products from cells to kidneys, sweat glands and lungs. Transports hormones from endocrine glands to cells Regulate pH, temperature and water content. Prevents body fluid Protects against toxins and microbes.

Question 2

How much of our body weight does blood make up?

Answer 2

8%

Question 3

What is the composition of blood?

Answer 3

55% plasma 45 % Formed elements ( Buffy coat(this makes up less than 1%) + erythrocytes)

Question 4

What is blood plasma?

Answer 4

91.5% water 8.5% solutes ( plasma proteins,fibrinogen,hormones, nutrients,dissolved gasses, waste products, electrolytes)

Question 5

What are key features of erythrocytes (Red blood cell)?

Answer 5

No nucleus Biconcave shape Carry oxygen via their haem groups. (280 million haemoglobins in total roughly)

Question 6

What is haemopoiesis/Haematopoiesis?

Answer 6

Formation of new blood cells.

Question 7

What are the three types of leukocytes?

Answer 7

Granulocytes ( cells containing large granules) Agranulocytes (cells that do not contain large granules) Thrombocytes (platelets)

Question 8

What are the three types of granulocytes?

Answer 8

Eosinophils Basophils Neutrophils

Question 9

What are the two types of agranulocytes?

Answer 9

Lymphocytes Monocytes

Question 10

What is the buffy coat?

Answer 10

A mixture of leukocytes and platelets.

Question 11

What are the two ways of stem cells giving rise to other blood cells?

Answer 11

Monophyletic- one stem cell gives rise to all blood cells Polyphyletic- each blood cell has its own stem cell.

Question 12

What type of system is haemopoiesis?

Answer 12

A limited polyphyletic system.

Question 13

What are the five phases of development of every blood cell?

Answer 13

1. Commitment of the stem cell 2. Proliferation 3. Differentiation 4. Maturation 5. Release

Question 14

What is erythropoiesis?

Answer 14

Formation of red blood cells

Question 15

How many days can erythrocytes survive in the blood?

Answer 15

120 days

Question 16

How is the process of erythropoiesis stimulated?

Answer 16

Hypoxia occurs due to decreased RBC count thus there is a decreased availability of O2. Therefore tissue demand for O2 increases. This causes erythropoietin to be released by the kidneys. This stimulates bone marrow for enhanced erythopoiesis to occur.

Question 17

How is blood type determined?

Answer 17

By the antigens (agglutinogens) on the surface of the red blood cell.

Question 18

How does Blood typing work and who can donate and receive from who?

Answer 18

The body of a person carries the antibody (agglutinin) to the antigen they do not posses. Thus if type A blood is given to a type B individual an immune reaction will occur and the blood will coagulate. Since individuals with type AB blood have no antibodies they are ‘universal recipients’ as they can receive any blood group, while type O blood is the ‘universal donor’ as it posses neither antigen.

Question 19

What does it mean to have a rhesus group as part of your blood type?

Answer 19

The rhesus blood grouping relies on the presence of 6 antigens; C, D, E, c, d, e. Only C, D, and E cause immune reactions. If an individual posses any of these antigens they are said to be Rh+, otherwise they are Rh-. Most people are Rh+.

Question 20

Why can Rh+ blood be given to someone that is Rh- only once?

Answer 20

The body does not usually contain the antibodies to these rhesus antigens, and they take several months to form. The wrong rhesus group can therefore be administered once (thereafter the antibodies are present).

Question 21

What are properties of granulocytes?

Answer 21

Have granules in their cytoplasm Tend to have lobed nuclei

Question 22

What are some properties of agranulocytes?

Answer 22

No granules in cytoplasm Tend to have regular shaped nuclei

Question 23

What is the function of granulocytes and monocytes collectively (but not lymphocytes)?

Answer 23

Protect the body via phagocytosis

Question 24

What is the primamry function of lymphocytes?

Answer 24

They are involved in the immune response.

Question 25

What are some key properties of neutrophils?

Answer 25

Granular cytoplasm Accounts for 60-70% of all white blood cells/leukocytes They have a diameter of 10-15 µm and a nucleus composed of 2-5 sausage-shaped lobes.

Question 26

How do leukocytes leave the vascular system?

Answer 26

By the process of diapedesis

Question 27

What needs to happen before diapedesis occurs?

Answer 27

Margination- the act of the cell adhereing to the cell wall (in this case the capillary wall).

Question 28

How are objects recognised as foreign?

Answer 28

By roughness Difference in charge Presence of antibodies as flags.

Question 29

What happens in phagocytosis?

Answer 29

When a white blood cell encounters a ‘foreign’ object it grows pseudopodia, enclosing the object in a phagocytic vesicle called a phagosome. A lysosome containing proteolytic enzymes fuses to this phagosome creating a phagolysosome. Proteolytic enzymes released by lysozymes then destroy the object. (Hydrogen peroxide also results in the production of chlorine.) Eventually the neutrophil itself is destroyed and in turn phagocytosed by monocytes.

Question 30

What are the key properties of monocytes?

Answer 30

They are agranular (12-20 µm in diameter). They mature into large macrophages (80 µm) only within extravascular tissue. Powerful phagocytes.

Question 31

What are some key properties of basophils?

Answer 31

Basophils have a diameter of ca 10-15 µm and account for 0.5-2% of all leukocytes. Their nucleus is often Sshaped and their cytoplasm contains large granules They are weak phagocytes that contain histamine, heparin, serotonin, and are therefore important in the inflammatory response & allergic reactions. They may mature into mast cells

Question 32

What are the key properties pf eosinophils?

Answer 32

Eosinophils are granulocytes and make up 1-4% of all white blood cells. They are 9 µm in diameter and have a bilobed nucleus.

Question 33

What is the function of eosinophils?

Answer 33

Their function is to detoxify foreign proteins and they have a possible role in blood clotting and phagocytosis of the antibody-antigen complex.

Question 34

What are the key properties of lymphocytes?

Answer 34

Lymphocytes develop from their own stem cell. T-lymphocytes mature in the thymus, B-lymphocytes mature in the bone marrow

Question 35

What do T-lymphocytes do?

Answer 35

T-lymphocytes mediate cellular immunity in which the whole cell ‘attacks’ the invader.

Question 36

What do B-lymphocytes do?

Answer 36

B-lymphocytes mediate humoural immunity via plasma cells producing antibodies.

Question 37

What are key characteristics of a thrombocyte?

Answer 37

2 µm in diameter 5-14 day life span. no nucleus

Question 38

What produces a thrombocytes?

Answer 38

A megakerocyte (160µm). These disintergrate to form 4000 platelets.

Question 39

What are the three phases of haemostasis?

Answer 39

1. Vascular phase (endothelial cells produce chemicals which cause;) - vascular spasm - division of endothelial cells, smooth muscles etc.. - endothelial cells to become ‘sticky’ 2. Platelet phase - platelets adhere to the damaged endothelium and aggregate to form a platelet plug. (If the damage is not too severe this is enough repair the ‘wound’) 3. Coagulation - this occurs via both an extrinsic route (chemicals released by endothelial cells) and an intrinsic pathway (signals initiated by the blood itself)

Question 40

Describe in more detail the process of coagulation.

Answer 40

Intrinsic and extrinsic pathways involving enzyme cascades result in the production of substance X and prothrombin activator. Promothrombin activator converts a plasma protein (prothrombin) into thrombin, which converts fibrinogen into fibrin threads. Fibrin threads stabilise and form a net that makes up the eventual clot.

Question 41

How long does coagulation/clot formation take?

Answer 41

Depending on the pathway, clot formation occurs in 15 secs - 18 mins. On average it takes 3-6 mins