Systems Pathology

Question 1

Explain why respiratory failure is defined as an arterial PO2 below 60mmHg

Answer 1

Due to the sigmoid shape of the O2- haemoglobin dissociation curve, if the arterial PO2 falls below 60mmHg, haemoglobin saturation begins to fall off steeply and thus represents an increased risk of tissue ischaemia.

Question 2

Define FEV1

Answer 2

FEV1 (Forced Expiratory Volume in the 1st second) measures the rate of exhalation and impaired in patients with obstructive diseases.

Question 3

How can COPD be diagnosed by a Reduced FEV1/FVC ration

Answer 3

COPD patients can’t exhale air as quickly due to airway obstruction, causing slower exhalation. Their FEV1 is low (less than 80% of FVC). However, the final FVC volume can be relatively normal in mild or moderate cases - they just take longer to get there hence the FEV1 to FVC ratio is decreased.

Question 4

Name two autoimmune thyroid disorders and describe their pathophysiology.

Answer 4

1. Grave’s Disease: Caused by thyroid stimulating hormone (TSH) receptor antibodies. These are activating antibodies which act like TSH activating the receptor and stimulating the persistent release of T4 (thyroxine) causing a hyperthyroidism.

Lab tests show high T4 and low TSH due to negative feedback inhibition.

2. Hashimoto’s Thyroiditis: is an autoimmune condition caused by antibodies that don’t activate but instead attack thyroid peroxidase. Leading to the immune system mistakenly destroying the thyroid gland, causing hypothyroidism.

Lab tests will reveal low T4 and high TSH as the pituitary tries to stimulate thyroid hormone production.

Question 5

What is Type 1 diabetes

Answer 5

Autoimmune disease that causes destruction of beta cells, leading to the inability to synthesise insulin. People are usually healthy before diagnosis symptoms are weight loss and hyperglycaemia.

Question 6

How is Type 1 diabetes treated

Answer 6

1. Ultra-short acting -
   Monomer insulin readily absorbed.
   Taken: 5 mins before meal
2. Short acting -
   Insulin with zinc buffer
   Taken: 15-30mins before meal
3. Intermediate Acting -
   Two options:
   a) Insulin + Zn acetate buffer for relative rapid onset
   b) Isophane (NPH) insulin with protamine.

Long-acting analogue:
Glycine replaces asparagine at A21 in the insulin molecule.
Acidic isoelectric point precipitates after injection for slow release.

Question 7

Briefly describe the three most common causes of a stroke

Answer 7

a) Cerebral Infarction:
Blockage of the cerebral artery
80% of most strokes

b) Intracerebral Haemorrhage
Vessel rupture into brain tissue

c) Subarachnoid Haemorrhage
vessel rupture into subarachnoid space

Question 8

What are the 6 metabolic changes in chronic renal failure

Answer 8

High urea and creatine
Hyperkalaemia
Hypocalcaemia
Increased PTH
Increased uric acid
Metabolic acidosis

Question 9

Describe the most likely causative factors of essential hypertension

Answer 9

Salt sensitivity
Psychological stress
Hypersensitive to plasma catecholamine
Renin-angiotensin-aldosterone dysfunction

Question 10

What is meant by secondary hypertension with examples

Answer 10

Secondary hypertension has a known underlying cause.

Examples include: Renal disease, endocrine disorders (corticosteroids, contraception pill, NSAIDS), adrenaline secreting tumour.

Question 11

Four main groups of immune disorders

Answer 11

Primary immunodeficiencies
secondary immunodeficiencies
autoimmune diseases
allergy and hypersensitivity

Question 12

What causes Myasthenia Gravis

Answer 12

Muscle weakness due to antibodies blocking acetylcholine receptors at the postsynaptic neuromuscular junction

Question 13

How does obesity link to T2D

Answer 13

Link: most people with T2D are obese

How: Through insulin resistance

Result: Beta cells release insufficient insulin

Effect: Blood glucose levels rise

First signs: Fatigue and dizziness

Next stage: Kidney damage, eye problems, nerve damage

Question 14

PKU is defined as [ ] levels above 1000 μmol/l at which residual [ ] activity is absent or nearly absent, and the risk of [] damage without treatment approaches 100%. Too much phenylalanine up in the blood can lead to [ ] [ ] but, once detected, this can be avoided by treatment with a special restricted [ ].

Answer 14

phenylalanine
enzyme
neurological
mental
retardation
diet

Question 15

This is screened for in newborns, along with a variety of disorders. , can be screened for using a biochemical test on a heel prick sample instead of looking for the gene mutations in the [ ] [ ] condition. The presence of [ ] phenylalanine is characteristic of this disease.

Answer 15

Phenylketonuria
autosomal
recessive
extra

Question 16

Alzheimer’s disease (AD) is a [ ] disease and the most common cause of [ ] in the Western world. AD results in the loss of [ ] neurones within specific regions of the brain involved in memory processing (in the [ ] and cognitive functions (in the cerebral cortex).

Answer 16

neurodegenerative
dementia
cholinergic
hippocampus

Question 17

Name five short-term effects of ethanol consumption?

Answer 17

Hangover
Headache
Diarrhoea
Anorexia
Tremor
Fatigue
Nausea
Dehydration
Low blood sugar

Question 18

Name 5 risks factors of cardiovascular disease

Answer 18

Hypertension
Serum cholesterol
Obesity
Diabetes Mellitus
Physical inactivity
cigarette smoking
Alcohol intake

Question 19

Name two main types of arthritis

Answer 19

Rheumatoid Arthritis
Osteoporosis-arthris

Question 20

Describe the pathophysiological feature of Crohn’s disease

Answer 20

weight loss
lethargy, malaise
Inflammation of the tongue
affects all wall and with oedema and thickened
deep ulcers form linear fissures
can initiate abscesses or fistulae between adjacent bowel loops patchy changes causing skip lesions

Question 21

What are the components of the blood urinary barrier in the glomerulus?

Answer 21

The blood-urinary barrier in the glomerulus of the kidney is a crucial structure that prevents the passage of larger molecules, such as proteins, from the blood into the urine. The main components of the blood-urinary barrier in the glomerulus include:

Endothelial Cells

Basement Membrane:

Podocytes:

Question 22

Describe why the liver can be characterised as both an exocrine and endocrine organ?

Answer 22

Exocrine =
Bile production - the liver produces bile a crucial digestive fluid that also aid in digestion.

Biliary system: Bile is transported through the ducts to the duodenum

Endocrine

Hormone production: The liver produces insulin-like growth factor 1 (IGF-1)

Growth and development: IGF-1 influences growth and development

Blood glucose Regulation: The liver manages blood glucose levels by storing glucose as glycogen

In essence, the liver wears two hats: exocrine for digestion (bile secretion) and endocrine for hormonal regulation (IGF-1 and blood glucose). Understanding these dual roles is key to grasping the liver’s versatility in maintaining overall bodily function.