Formative Exam

Question 1

What are the functions of the gallbladder?

Answer 1

To store and concentrate bile and to release it when it is needed, i.e. when chime enters the duodenum.

Question 2

What hormone is involved in causing the gallbladder to contract?

Answer 2

Cholecystokinin (CKK). It has other functions including relaxation of the sphincter of Oddi (which makes sense as this allows the bile to enter the duodenum)

Question 3

Liver function tests show raised serum bilirubin, alanine

transaminase (ALT) and alkaline phosphatase. Why are these substances at high concentrations in the blood?

Answer 3

Hepatocellular damage causes intracellular proteins to leak into the extracellular space and thence into the blood stream.

Question 4

Which hormone stimulates transaminase synthesis in the liver?

Answer 4

Cortisol

Question 5

Describe what bilirubin is and how it is derived from Heme?

Answer 5

Bilirubin consists of a stack of porphyrin rings that have broken open and lost their iron. Heme is broken down into biliverdin which in turn is broken down to bilirubin.

Question 6

Name the condition that results from a build-up of

Bilirubin in the blood

Answer 6

Jaundice

Question 7

The FBC results show an increase in white blood cells
count and there are a high number of young, immature white blood cells present.
List two specific types of nucleated cell that will be seen in a normal blood film.

Answer 7

Two of neutrophils, eosinophils, monocytes, lymphocytes, basophils.

Question 8

What term is used to describe the presence of immature white blood cells

Name of type of bacteria most often implicated in this condition?

Answer 8

A "left shift"
Gram negative bacteria:
· Escherichia coli (in 25-50% of cases)
· Klebsiella (15-20% of cases)
· Enterobacter (5-10% of cases)

Question 9

The body must recognise pathogens as they enter the system name two types of receptors responsible for this?

Answer 9

TOLL like receptors and NOD

Question 10

Extracellular bacteria activate the complement system. Name the three complement pathways and what activates them in each case

Answer 10

Classical: Initiated by antigen-antibody complexes and certain negatively charged structures.
 Alternative pathway – activated by several molecules found on microbial surfaces
 Mannan-binding lectin (MBL) pathway – activated by particular carbohydrate structures on microbes

Question 11

What are the three functions of the complement system?

Answer 11

 Opsonisation and phagocytosis. C3b coats microbes and promotes the binding of these microbes to phagocytes, by virtue of receptors for C3b that are expressed on the phagocytes. Thus, microbes that are coated with complement proteins are rapidly ingested and destroyed by phagocytes.

 Inflammation. Some proteolytic fragments of complement proteins, especially C5a and C3a, are chemoattractants for leukocytes (mainly neutrophils and monocytes), so they promote leukocyte recruitment (inflammation) at the site of complement activation.

Cell lysis. Complement activation culminates in the formation of a polymeric protein complex that inserts into the microbial cell membrane, disturbing the permeability barrier and causing either osmotic lysis or apoptosis of the microbe.

Question 12

Which of the following is the general mechanism of action for erythromycin?

a) Inhibition of a metabolic enzyme b) Inhibition of cell wall synthesis
c) Disruption of protein synthesis
d) Inhibition of nucleic acid transcription and replication?

Answer 12

c) Bacterial and animal cells both have a well-defined nucleus.

Question 13

Blood test detect an elevated level of troponin. What is the normal function of troponin in skeletal or cardiac muscle cells?

Answer 13

The three subunits of troponin (troponin- I, troponin- T and troponin-C are involved in regulating excitation contraction coupling. They sit alongside tropomyosin on the actin filament to obscure the binding site for the myosin head. Only when intracellular Ca2+ increases and Ca2+ binds to troponin-C can contraction take place.

Question 14

A 73 year old woman presented at the emergency department with a tight crushing pain which spread down the left arm. She was feeling cold and clammy. She has a BMI of 22 and smokes about 20 cigarettes a day. She was diagnosed with having a heart attack and is now in the acute coronary care unit for monitoring.

She is prescribe rampiril or hypotension. After less than 4 hours she returns back to the emergency department as she is covered in a Maculopapular rash. You suspect an allergic reaction
Which immunoglobulin that can bind to the Fc epsilon receptor on cell surfaces and is most commonly implicated in medical conditions such as allergy, and anaphylactic shock ?

Answer 14

IgE has the capacity to bind to Fc epsilon receptor on the surface of mast cells. This property is responsible for the cross-linking of the Fc receptor on the mast cell leading to degranulation and release of vasoactive substances. IgA is the antibody subtype that is secreted into nasal, oral, gastrointestinal, and urinary tract. IgM is the first antibody to be produced in an immune response, and IgG is produced during the secondary response. The role of IgD is not yet as defined as the other immunoglobulins

Question 15

Name the three stages of a type I hypersensitivity

Answer 15

Sensitisation, activation and effector phase

Question 16

The hospital order a Coombs test. What is this test and how does it work?

Answer 16

Coombs test is also known as antiglobulin test. The Coombs test tests for antibodies that may stick to the red blood cells and cause red blood cells to die too early.
The direct Coombs test is used to detect antibodies (IgG or C3) that are stuck to the surface of red blood cells. Many diseases and drugs can cause this. These antibodies sometimes destroy red blood cells and cause anemia.
The indirect Coombs test looks for free-flowing antibodies against certain red blood cells. It is most often done to determine if you may have a reaction to a blood transfusion.

Question 17

Reema, aged 17, lives in Oadby. Her family came to this country from Kenya more than twenty years ago, but they still have relatives in Gujerat, India, whom Reema visited in March last year for six weeks. She has recently noticed a soft, painful lump on the side of her neck which has increased in size over the past three weeks. She has not felt as well as usual recently and on occasions she has thought that she had a mild fever. She has a dry, non- productive cough.
You suspect TB, you decide that she needs a chest x-ray.

Her chest x ray shows paratracheal adenopathy. What is this? Why has this probably occurred?

Answer 17

Enlargement of the lymph nodes on either side of the trachea. Could be due to primary tuberculous infection of hilar lymph nodes.

Question 18

TB. Sample analysis would provide what Gram stain result?

Answer 18

Gram stain does not work so results would be inconclusive you would need an acid fast test

Question 19

What properties does the infectious organism causing TB have that allows it to avoid death by phagocytosis

Answer 19

Mycolic acid think cell wall

Question 20

Elimination of the tuberculosis causative agent relies more on the Cell mediated immune system, why will humoral systems not be effective

Answer 20

The infectious agent is internalised in the host cells. The bacterium will live in phagocytic vesicles but will be protected from the humoral system only by killing the infected phagocytic cell will you kill the organism

Question 21

Describe the 4 stages of T cell mediated immune reactions

Answer 21

Naive T cells are stimulated by microbial antigens in the peripheral
lymphoid organs which generates effector T cells. The 2. Differentiated effector T cells travel to the sight of infection.
3. Phagocytic cells have ingested the microbes and are presenting them on MHCI molecules for recognition by CD8+ effector cells and MHCII molecules for recognition by CD4+ effector cells.
4. The effector T cell is activated once it recognises and bind the antigen.

Question 22

CD4+ T helper cells (Th) can be activated into a number of

effector cells name two of them ?

Answer 22

There are three main types: T helper cells type 1 (TH1), type 2 (TH2) and type 17 (TH17).
A further subtype of T cells are called regulatory T cells (Treg).

Question 23

Reema, aged 17, lives in Oadby. Her family came to this country from Kenya more than twenty years ago, but they still have relatives in Gujerat, India, whom Reema visited in March last year for six weeks. She has recently noticed a soft, painful lump on the side of her neck which has increased in size over the past three weeks. She has not felt as well as usual recently and on occasions she has thought that she had a mild fever. She has a dry, non- productive cough.
You suspect TB, you decide that she needs a chest x-ray.

Which T cell effector cell would you expect to be involved in this patient and why?

Answer 23

Acting through CD40-ligand and IFN-γ Th1 cells activate macrophages that have phagocytosed bacteria that manage to survive within the macrophage.

Question 24

The Mantoux test is a DTH response to tubercullin, why?

Answer 24

Both Th1 and Th17 are involved in DTH reactions to antigens. This is the basis of the Mantoux test in response to tuberculin. DTH results because of the induction of Thelper cells and effector functions of enhanced cytokine production and recruitment of other inflammatory cells such as neutrophils, but not antibody production