Question 161#

Which one of the following statements is not correct regarding hypertension in pregnancy?

A. An increase above booking readings of > 30 mmHg systolic or > 15 mmHg diastolic suggests hypertension

Correct Answer C: Proteinuria suggests pre-eclampsia.

Hypertension in pregnancy:
The classification of hypertension in pregnancy is complicated and varies. Remember, in normal pregnancy:

• Blood pressure usually falls in the first trimester (particularly the diastolic), and continues to fall until 20-24 weeks
• After this time the blood pressure usually increases to pre-pregnancy levels by term

Hypertension in pregnancy in usually defined as:

• Systolic > 140 mmHg or diastolic > 90 mmHg
• Or an increase above booking readings of > 30 mmHg systolic or > 15 mmHg diastolic

After establishing that the patient is hypertensive they should be categorized  into one of the following groups:

Question 162#

Which one of the following cardiac tissue types has the highest conduction velocity?

A. Atrial myocardial tissue

Correct Answer C: 

Electrical activity of the heart:
Myocardial action potential:
 

Phase	Description	Mechanism
0	Rapid depolarisation	Rapid sodium influx These channels automatically deactivate after a few ms
1	Early repolarisation	Efflux of potassium
2	Plateau	Slow influx of calcium
3	Final repolarisation	Efflux of potassium
4	Restoration of ionic concentrations	Resting potential is restored by Na+/K+ ATPase There is slow entry of Na+ into the cell decreasing the potential difference until the threshold potential is reached, triggering a new action potential

 

 

 

 

 

 

 

NB cardiac muscle remains contracted 10-15 times longer than skeletal muscle

Conduction velocity:

Question 163#

The commonest chromosomal defect in Down's syndrome is: 

A. Trinucleotide repeat disorder

Correct Answer E: 

Down's syndrome: epidemiology and genetics:

Risk of Down's syndrome with increasing maternal age:

• Risk at 30 years = 1/1000
• 35 years = 1/350
• 40 years = 1/100
• 45 years = 1/30

One way of remembering this is by starting at 1/1,000 at 30 years and then dividing the denominator by 3 (i.e. 3 times more common) for every extra 5 years of age.

Cytogenetics:

The chance of a further child with Down's syndrome is approximately 1 in 100 if the mother is less than 35 years ld. If the trisomy 21 is a result of a translocation the risk is much higher.

Question 164#

What is the site of action of antidiuretic hormone?

A. Descending loop of Henle

Correct Answer E: Antidiuretic hormone (ADH) - site of action = collecting ducts.

Antidiuretic hormone:
Antidiuretic hormone (ADH) is secreted from the posterior pituitary gland. It promotes water reabsorption in the collecting ducts of the kidneys by the insertion of aquaporin-2 channels. 

Question 165#

Which one of the following diseases is most strongly associated with HLA antigen DR2?

A. Behcet's disease

Correct Answer E: 

HLA associations:
HLA antigens are encoded for by genes on chromosome 6. HLA A, B and C are class I antigens whilst DP, DQ, DR are class II antigens. Questions are often based around which diseases have strong HLA associations.

The most important associations are listed below:

HLA-A3

• Haemochromatosis

HLA-B5

• Behcet's disease

HLA-B27

• Ankylosing spondylitis
• Reiter's syndrome
• Acute anterior uveitis

HLA-DQ2/DQ8

• Coeliac disease

HLA-DR2

• Narcolepsy
• Goodpasture's

HLA-DR3

• Dermatitis herpetiformis
• Sjogren's syndrome
• Primary biliary cirrhosis

HLA-DR4

• Type 1 diabetes mellitus*
• Rheumatoid arthritis

*Type 1 diabetes mellitus is associated with HLA-DR3 but is more strongly associated with HLA-DR4.