Leukocytes, Platelets, and Hemostasis Study Guide

Question 1

amount of leukocytes in a microliter (ul) of blood

Answer 1

4,800 to 10,800 (less than erythrocytes)

Question 2

diapedesis

Answer 2

how leukocytes cross blood vessel walls to travel to areas of need

Question 3

Positive Chemotaxis

Answer 3

phenomenon in which damaged/infected cells provide a chemical trail for leukocytes to follow

Question 4

Leukocytosis

Answer 4

elevated number of leukocytes (> 11,000/µl)

Question 5

Leukopenia

Answer 5

decreased number of leukocytes

Question 6

5 types of leukocytes in order of abundance

Answer 6

Neutrophils (Most Abundant)
Lymphocytes.
Monocytes.
Eosinophils.
Basophils (Least Abundant)

Question 7

Agranulocytes

Answer 7

Lymphocytes
Monocytes

Question 8

Granulocytes

Answer 8

Neutrophils
Eosinophils
Basophils

Question 9

Lymphocytes

Answer 9

• Account for 25% of all leukocytes
• Often classified by diameter – small, medium, and large
• Largely live in lymphoid tissues – lymph nodes and spleen – versus the bloodstream
• T Lymphocytes (T-Cells): directly fight against virus-infected and tumor cells
• B Lymphocytes (B-Cells): give rise to antibody-producing plasma cells

Question 10

Monocytes

Answer 10

• Account of 3-8% of all leukocytes
• Are the largest of all leukocytes
• Differentiate into highly mobile macrophages with enormous appetites
• Able to activate lymphocytes to mount an immune response

Question 11

Neutrophils

Answer 11

• The most numerous type of leukocyte (50-70% of all leukocytes)
• Function as “bacteria-slayers” - very active phagocytes
• Are chemically attracted to inflammation

Question 12

Eosinophils

Answer 12

• Account for 2-4% of all leukocytes
• Lead the counter-attack against parasitic worms and other things too large to be phagocytized
• Play a role in responding to allergens and modulating the overall immune system response

Question 13

Basophils

Answer 13

• Rarest leukocytes (0.5-1%)
• Granules contain Histamine – an inflammatory chemical that vasodilates vessels and attracts other leukocytes - and Heparin - an anticoagulant that assists the mobility of other leukocytes

Question 14

What stimulates the creation of leukocytes?

Answer 14

Chemical messengers called interleukins or colony-stimulating factors (CSFs)

Question 15

blood cells that differentiate from the myeloid line

Answer 15

monocytes (following monoblast and promonocyte)

Question 16

blood cells that differentiate from the lymphoid line

Answer 16

Lymphocytes
- T Lymphocyte Precursors give rise to immature T-Cells which mature in the thymus
- B Lymphocyte Precursors give rise to immature B-Cells which mature in the bone marrow

Question 17

leukemia

Answer 17

verproduction of abnormal leukocyteso

Question 18

leukemia cause

Answer 18

• Typically, excessive leukocytes are descendants of a single cell undergoing un-regulated proliferation
• Excessive leukocytes impair normal function of red bone marrow

Question 19

leukemia symptoms

Answer 19

severe anemia, bleeding, fever, weight loss, and bone pain

Question 20

general premise of chemotherapy

Answer 20

Kills both normal and abnormal leukocytes → can help cancer, but also cause undesirable side effects

Question 21

3 steps of hemostasis

Answer 21

Vascular Spasm
Platelet Plug Formation
Coagulation

Question 22

platelet typical lifespan

Answer 22

They age quickly and degenerate within 10 days

Question 22

Where do platelets come from

Answer 22

Fragments of very large cells called megakaryoctyes:
- A hormone called thrombopoietin regulates the formation of platelets
- A megakaryocyte undergoes repeated mitosis without cytokinesis yielding a very large cell
- Cytoplasmic extensions of the megakaryocyte rupture and release platelets into the bloodstream

Question 23

platelet function

Answer 23

stopping blood loss / promoting blood clots

Question 24

What happens after blood successfully clots (hemostasis)?

Answer 24

the blood clot will retract and dissolve. The clot is replaced with fibrous tissue, which more permanently prevents blood loss

Question 25

two things that have anti-coagulant properties

Answer 25

Prostacyclin and nitric oxide have anticoagulant properties (prostaglandins that keeps platelets from sticking to each other or to the endothelial layer of vessel walls)

Question 26

natural anticoagulant found in endothelial cells

Answer 26

Heparin

Question 27

two aggregating agents

Answer 27

Adenosine Diphosphate (ADP): a potent aggregating agent and Serotonin and thromboxane A: messengers that enhance both vascular spasm and platelet aggregation

Question 28

What works to stabilize a forming platelet plug (bound platelets)?

Answer 28

Von willebrand factor

Question 29

What works to reinforce a formed platelet plug?

Answer 29

fibrin threads

Question 30

mineral is essential to the formation of a blood clot

Answer 30

calcium

Question 31

Phase I of III of coagulation

Answer 31

- Intrinsic vs Extrinsic Pathway; either triggered by tissue damaging events - Both involve a series of clotting factors and end with the activation of Factor X - Factor X complexes with Ca2+, Platelet Factor 3, and Factor V to make Prothrombin Activator

Question 31

Phase II of III of coagulation

Answer 31

Prothrombin activator catalyzes the transformation of prothrombin to the active enzyme thrombin

Question 31

Phase III of III of coagulation

Answer 31

- Thrombin converts soluble fibrinogen to fibrin - Fibrin strands form the structural basis of a blood clot and cause plasma to become a gel-like trap catching formed elements

Question 31

two growth factors are involved in blood vessel repair

Answer 31

- Platelet-derived growth factor (PDGF) stimulates smooth muscle cells and fibroblasts to form a connective tissue patch - Vascular endothelial growth factor stimulates endothelial cells to multiply and restore the endothelial lining

Question 31

enzyme that works to dissolve clots

Answer 31

Plasmin: the natural “clot-buster” – a fibrin digesting enzyme. The presence of a clot, triggers endothelial cells to secrete tissue plasminogen activator (tPA).

Question 31

How is this plasmin/tpa used medically?

Answer 31

tPA can be given through IV to stroke patients to restore blood flow by activating plasmin

Question 31

Thrombus

Answer 31

- a clot that forms in an unbroken vessel - A thrombus can cause death of the tissue beyond the blockage - Example: Myocardial Infarction

Question 31

Embolus

Answer 31

- a clot that breaks away from the vessel wall and floats in the bloodstream - An embolus wedged in a small vessel = an obstructing embolism - Example: Pulmonary Emboli or Cerebrovascular Accident

Question 31

two things that increase risk of blood clots

Answer 31

vessel arthrosclerosis or inflammation, slow blood flow (reduced mobility)

Question 32

Thrombocytopenia

Answer 32

low volume of circulating platelets - Severe cases cause to spontaneous bleeds with routine movement - Symptom: petechiae - Cause: suppression or destruction of red bone marrow - Treatment: platelet transfusion

Question 32

Hemophilia

Answer 32

a group of hereditary bleeding disorders; deficiencies of various clotting factors - 2:3 types of hemophilia are X-linked - occur predominantly in males - Symptoms: prolonged bleeding with minor tissue injury, repeated bleeds into joint spaces - Treatment: fresh plasma transfusions; injections of clotting factors