Microbiology

Question 1

What is the name of this cell and how prevalent is it in blood? (2)

Answer 1

Basophil (about 1%)

Question 2

What is the name of these cells and how prevalent are they in blood?

Answer 2

Eosinophils (around 3%)

Question 3

What is the name of this cell and how prevalent is it in blood?

Answer 3

Lymphocyte (around 28%)

Question 4

What is the name of this cell and how prevalent is it in blood?

Answer 4

Monocytes (around 8%)

Question 5

What is the name of this cell and how prevalent is it in blood?

Answer 5

Neutrophils (around 60%)

Question 6

What would cause an increase in the percentage of neutrophils?

Answer 6

• Stress
  
  • physiological or pathological
  • acute infection
  • trauma
  • infarction
  • inflammation
• Steroids can cause demargination

Question 7

What would cause an increase in the percentage of eosinophils?

Answer 7

• Parasitic infections
• hypersensitivity/ allergic reactions

Question 8

What would cause an increase in the percentage of basophils?

Answer 8

• hypersensitivity reactions

Question 9

What do red cells have instead of a nucleus?

Answer 9

Hb

Question 10

What does a lack of iron or B12 do to red cells? (MCV)

Answer 10

It can alter their size

Question 11

What does lower Hb suggest?

Answer 11

Anaemia

an=without

aemia=blood

Question 12

What type of anaemia does a patient have if it presents on a microcytic level?

Answer 12

iron deficiency!

e.g. chronic blood loss

Question 13

What type of anaemia does a patient have if it presents on a macrocytic level?

Answer 13

Vitamic B12/ folate deficiency

(nuclear defects)

Question 14

What type of anaemia does a patient have if it presents on a normocytic level?

Answer 14

• Acute blood loss
• Anaemia of chronic disease (eg inflammation, infection)

Question 15

What other changes may chronic disease anaemia cause in blood results?

Answer 15

Changes in

• iron homeostasis
• the proliferation of erythroid cells
• the production of erythropoeirin
• the life span of red cells

Question 16

What would you worry about if a patient has a high Hb level?

Answer 16

• False result- dehydration
• Secondary cause- hypoxia driven
• Primary- bone marrow disorder

Question 17

What additional abnormalities can blood films indentify (that analysers cannot)?

Answer 17

• target cells in liver disease
• red cell fragmentation
  
  • reflecting mechanical damage

Question 18

What would cause an increase in the percentage of monocytes?

Answer 18

• chronic infections
• malignancy
• autoimmune disorders

Question 19

What would cause an increase in the percentage of Lymphocytes?

Answer 19

• Viral infections
  
  • eg glandular fever, ‘reactive’ or activated lymphocytes

Question 20

What aspects of plasma are you interested in?

Answer 20

• Coagulation proteins
• Plasma viscosity

Question 21

What is haemostasis?

Answer 21

The arrest of bleeding and the maintenance of vascular patency

Question 22

What are the four requirements of haemostasis?

Answer 22

• Permanent state of readiness
• Prompt response
• Localised response
• Protection against unwanted thrombosis

Question 23

What are the four components of a regular haemostatic system?

Answer 23

• Formation of platelet plug
  
  • primary haemostasis
• Formation of fibrin clot
  
  • secondary haemostasis
• Fibrinolysis
• Anticoagulant defences

Question 24

What kind of cells are platelets?

Answer 24

Small anucleate discs

Question 25

What is the mean lifespan of platelets?

Answer 25

7-10 days

Question 26

What to platelets adhere to and where?

Answer 26

They adhere to the collagen at the site of endothelial injury

Question 27

What happens after platelets adhere to the injury site?

Answer 27

* There is *_secretion_* of various chemicals from the platelets * There is then *_aggregation_* of platelets at the site of injury

Question 28

Where do reactions of secondary haemostasis occur?

Answer 28

The surface of platelets

Question 29

What causes a false low platelet count?

Answer 29

The formation of clumps in the collection tube, confusing the analyser

Question 30

What causes a genuine low platelet count?

Answer 30

* inbalance in production * drugs * consumption/trapping * acute blood loss * enlarged spleen

Question 31

Does high platelet count affect haemostasis?

Answer 31

No

Question 32

What are the causes of a high platelet count?

Answer 32

* blood loss * iron deficiency * inflammation * malignancies

Question 33

What is the process of secondary haemostasis?

Answer 33

_Fibrin clot formation_ * _series of reactions_ involving activation of _coagulation factors_ to an active state (pro-enzyme to enzyme), that results in the conversion of **_soluble fibrinogen_** to **_insoluble fibrin_**

Question 34

What does a coagulation screen measure?

Answer 34

* time taken to form a fibrin clot along diffferent coagulation pathways * coagulation activities in vitro

Question 35

What coagulation screens do you know?

Answer 35

* prothrombrin time, PT (**II**, **V**, VII, **X**) * activated partial thrombroplastin time, aPTT (**II**, **V**, VIII, IX, **X**, XI, XII)

Question 36

What are D-dimers?

Answer 36

Degranulation products of fibrin (from fibrinogen) can reflect increased fibrin deposition * post surgery * heart failure * malignancy * abnormal thrombus

Question 37

What causes changes in coagulation times?

Answer 37

Prolongation due to multiple coagulation factor deficiencies * liver disease (production problem) * disseminated intravascular coagulation (DIC, consumption problem)

Question 38

What does plasma viscosity indicate?

Answer 38

It is an index of changes in plasma proteins (fibrinogen and some globulins)

Question 39

What do changes in plasma viscosity relect?

Answer 39

Can reflect 1. systemic inflammtion 2. *less commonly*- haematological malignancies producing an abnormal protein