Lecture 7 - White Blood Cells And Platelets

Question 1

Leukocytes

Answer 1

WBCS

only formed elements that are complete cells

critical to our defense against disease.

Question 2

Diapedia

Answer 2

Process in which leukocytes leave blood and enter the tissues

Question 3

Leukocytosis

Answer 3

Elevated WBC count

Question 4

Leukopenia

Answer 4

Decreased WBC count

Question 5

Granulocytes

Answer 5

major group of leukocytes characterized as large cells with lobed nuclei and visibly staining granules

all are phagocytic

also known as polymorphonuclear cells (PMNs).

( neutrophils, eosinophils and basophils)

Question 6

Agranulocytes

Answer 6

lymphocytes and monocytes that lack visibly staining granules.

They are also known as peripheral blood mononuclear cells (PBMCs).

(Lymphocytes and monocytes)

Question 7

Neutrophils

Answer 7

55-70% of all leukocytes

chemically attracted to sites of inflammation and are active phagocytes.

An increased neutrophil count commonly indicates bacterial infection.

Question 8

Eosinophils

Answer 8

1-4% of leukocytes.

attack parasites in loose connective tissues, and have role in asthma and allergies.

effective against multicellular endoparasites such as worms.

They are also associated with some viral infections.

commonly linked to allergic reaction

Question 9

Basophils

Answer 9

least numerous type of leukocyte, 0.5-1% of all white blood cells

release histamine to promote inflammation.
associated with multicellular exoparasites such as ticks

commonly linked to allergic reactions.

Question 10

Lymphocytes ( 3 types)

Answer 10

20-40% of white blood cells

the basis for the adaptive immune response.

T lymphocytes- directly attack virus infected cells and tumour cells.

B lymphocytes- bind antigens and produce antibodies as plasma cells.

Natural killer (NK) cells- similar function to T cells but are part of the innate immune response. W

Question 11

Monocytes

Answer 11

2–8% of white blood cells

actively phagocytotic macrophages as they enter tissues, and can activate lymphocytes.

common in chronic infections and inflammatory autoimmune diseases.

Question 12

Leukopoiesis

Answer 12

Formation of WBCS

Regulated by production of interleukins and colony stimulating factors (CSF)

Question 13

Band cells

Answer 13

Immature granulocytes

Question 14

Leukemia

Answer 14

Cancer of WBC

clones of single WBC remains unspecialized and divide uncontrollably

Question 15

How is infectious mononucleosis (MONO) caused?

Answer 15

Epstein Barr virus characterized by excessive numbers of agranulocytes

Question 16

Platelets

Answer 16

Not complete cells- fragments of bone marrow called megakaryocytes

Lifespan approx. 10 days

Question 17

What is the function of platelets?

Answer 17

Form temporary seal when blood vessel breaks

Question 18

Thrombopoietin

Answer 18

Hormone that regulates formation of platelets

Question 19

Hemostasis

Answer 19

Process of preventing blood loss

Three steps:
1. Vascular spasm
2. Platelet plug formation
3. Coagulation (clotting)

Question 20

Vascular spasms

Answer 20

immediate vasoconstriction response to blood vessel injury

become more efficient with increased tissue damage.

a temporary mechanism to reduce blood flow until other mechanisms can begin.

Question 21

Platelet plug formation

Answer 21

Platelets stick to exposed collagen fibres or to each other if collagen not exposed, to form platelet plug

Question 22

Coagulation (clotting)

Answer 22

Multi step process where blood transformed from liquid to gel

Platelet plugs reinforced with fibrin threads

1. formation of prothrombin activator through the intrinsic pathway or extrinsic pathway.
2. Prothrombin activator catalyzes prothrombin into active enzyme thrombin
3. Thrombin converts soluble fibrinogen into insoluble fibrin which causes plasma to become a gel-like trap to catch formed elements. Thrombin also activates fibrin stabilizing factor to cross-link fibrin into a strong mesh to stabilize the clot.

Question 23

Intrinsic pathway

Answer 23

all factors necessary are present within the blood

slower clotting pathway that can clot blood but does not seem to play a major role during injuries

Question 24

Extrinsic pathway

Answer 24

triggered through an endothelium-derived glycoprotein tissue factor (TF)

can occur rapidly by bypassing some steps of the intrinsic pathway.

much more important for clotting blood.

Question 25

What creates fibrin mesh?

Answer 25

When thrombin catalyzes the reactions that convert fibrinogen to fibrin

Question 26

Clot retraction

Answer 26

process in which the contractile proteins (myosin and actin) within platelets contract and pull on neighboring fibrin strands, squeezing plasma from the clot and pulling damaged tissue edges together.

typically occurs within 30-60 minutes.

Question 27

What is repair stimulated by?

Answer 27

platelet-derived growth factor to stimulate endothelial cell division.

Question 28

Fibrinolysis

Answer 28

removes unneeded clots through the action of the fibrin-digesting enzyme, plasmin.

Question 29

What are the two factors that limit size of clots as they form?

Answer 29

1. Rapidly moving blood disseminates clotting factors before they can initiate a clotting cascade.
2. Activated clotting factors are inhibited by other compounds in the blood. For clotting to occur, the concentration of activated clotting factors must overcome a minimum concentration.

As long as the vascular endothelium is smooth and intact, platelets are prevented from clotting.