QB

Question 1

Why give iodine pills in case of a nuclear accident?

Answer 1

In case of a nuclear accident iodine pills are given to saturate the thyroid gland with stable iodine hence prevent the thyroid gland from taking up radioactive iodine thus Reducing the risks of thyroid cancer

Question 2

What does HbA1c measure? What range of values is associated with pre-Diabetes?

Answer 2

blood test - measures % of haemoglobin molecules that have glucose attached. levels of 5.7% - 6.4% considered to be in pre-diabetes range. 6.5% > considered to be a diagnosis of diabetes.

Question 3

Thyroid hormones are conceptually very similar to steroid hormones. What does this tell you about the mechanism of action in altering metabolism?

Question 4

Give a description of how hormone-sensitive lipase is controlled and its mechanism?

Question 5

The energy expended for walking is 1 calorie per second per kilogram of body mass (1 cal=4.184J). The energy content of fat is 9kcal/g. Assume that the patient weighs 70 kg and that it takes her 30 minutes to walk to work. How much body fat does she burn in the journey?

Answer 5

Doubt
16.3 kj by calculation but not in the list

Question 6

Dopamine question MEM

Question 7

Compare and contrast sympathetic and parasympathetic nervous excitation. Use specific examples of tissues or organs. (8)

What would be the consequences for blood pressure of cutting the vagus nerve?

Answer 7

A
Using the heart as a specific example, sympathetic excitation is via the cardiac accelerator nerves and vasomotor nerves (spinal nerves via cervical and upper thoracic T1-T4). Fibres reach the pacemaker and most of the myocardium

Sympathetic excitation leads to realease of stimulatory neurotransmitter norepiephrine. Binds to beta adrenergic receptors, increases influx of Ca2+, increasing heart rate + contraction force, increasing blood flow to tissue, getting body ready for action / fight or flight response

Parasympathetic excitation is via the vagus nerve
Fibres reach the pacemaker and some of the myocardium
Activation releases ACh, binds and activates cholinergic muscarinic receptros, closes Ca2+ channels, decreases rate and force of contraction, decreasing blood flow to tissue, rest and digest

Parasympathetic excitation is via the vagus nerve. Electrical impulses are sent via rthe vagus nerve from the CV centre to the heart to decrease contractility and therefore heart rate,

IF VAGUS NERVE CUT, NO PARASYMPATHETIC EFFERENTS /ELECTRICAL IMPULSES SENT VIA VAGUS NERVE FROM CV CENTRE TO HEART DO DERCREASE HEART RATE

therefore, we cannot reduce heart rate, leading to pesistent high heart rate, persistant high BP, persistant hypertension -> many other complications

Question 8

The liver breaks down glycogen and release glucose to the blood. The key regulatory enzyme for glycogen degradation is ——– which exists in two forms. A less active ——– form and a more active ——– form. The two forms different in that a ———residue is ————- (5)

Answer 8

The liver breaks down glycogen and release glucose to the blood. The key regulatory enzyme for glycogen degradation is GLYCOGEN PHOSPHORYLASE which exists in two forms. A less active B form and a more active A form. The two forms different in that a SERINE residue is PHOSPHORYLATED

Question 9

Breifly describe the cori cycle (3)

Answer 9

During intense exercise, muscles respire anaerobically, producing lactate.

Lactate transported back to liver where it is converted back into glucose by gluconeogenesis

Allows muscles to keep gaining ATP even when they run out of oxygen

Question 10

Parkinson’s disease is a neurogenative disease, describe the consequences of loss of neuronal function, referring to the underlying pathophysiology (6)

Answer 10

Mutation to parkin leads to dopaminergic cell death

death of dopaminergic cells in substantia nigra, less dopamine produced, increased output from basal nuclei to thalamus and cerebral cortex, leading to reduced output of cerebral cortex and thalamus, leads to less muscle coordination and therefore, hypokinetic disorder

Question 11

Glucose 6 phosphatase transports —- into the ER and ——– and ———-out of the ER

Answer 11

Glucose-6-phosphate
Glucose
Pi

Question 12

Hypothyroidism leads to an increase production of glucose. Which two enzymes are required to form phosphoenolpyruvate from pyruvate?

Answer 12

Pyruvate carboxylase
Phosphoenolpyruvate carboxylase

Question 13

Describe the cellular actions of insulin in different tissues. Include the cell type (6)

Answer 13

A
Insulin is secreted by beta cells of islets of langerhans to 3 different tissues:

Muscle / skeletal tissue
Liver tissue
Adipose tissue

MUSCLE: Increases gluocse uptake from blood - converts glucose to glygen - glycogenesis
Increase amino acid uptake from blood - to form protein (protein synthesis)
Decreased glycogen + protein breakdown

LIVER:

Increased glucose uptake from blood to produce glycogen - glycogenesis
Decreased rate of glycogenolysis - glycogen to glucose
Increased TAG synthesis
Decreased ketone formation
Decreased protein + TAG breakdown

ADIPOSE TISSUE

Increased uptake of glucose from blood, leading to fat production (increased TAG synthesis, decreased TAG breakdown)

Question 14

Name three ketone bodies and three organs which can utilise ketone bodies (3)

Answer 14

A
Acetoacetate
Acetone
3-hydroxyburate
3 organs which can utilise ketone bodies:

Liver
Heart
Kidney
Brain

Question 15

Cells enter futile substrate cycling during which increased intracellular glucose overwhelmes the TCA cycle. As a result, non oxidative glucose metabolism ——- producing ————

Question 16

In conversion of oxaloacetate to phosphoenolpyruvate, the phosphoryl donor is ——-

Answer 16

GTP

Question 17

Briefly describe a few different hypothesis of the underlying cause of Alzheimer’s disease (8)

Answer 17

A
Tau hypothesis:

Taupathis, abnormal phosphorylation of Tau - hyperphosphrylation, tau phosphorylates into helical paried filaments forming NFTs (neurofibrillary tangles) - toxic to surrounding neurones

Cholinergic hypothesis - ACh loss

Amyloid Hypothesis - Proteolysis of APP (amyloid precursor protein, in synapses) leads to formation of beta amyloid deposits
Beta amyloid deposits accumulate as extra cellular plaques
This is neurotoxic

Noradrenergic hypothesis - loss of noradrenergic neurones in locus coerulus, therefore, loss of noradrenaline

Question 18

What disorders might be associated with altered norepinephrine activity? (6)

Answer 18

Alzheimer’s disease. Noradrenergic hypothesis of AD: loss of noradrenergic neurones in locus coerulus, therefore, loss of noradrenaline

Parkinson’s disease - same as AD

Epilepsy - loss of hippocampal neurons, could result in alteration of noradrenergic innervation in hippocampus

Question 19

Justify the following statement by providing concise explanation. The mechanism of action potential generation in autoryhtmic cells is independent of the nervous system (3)

Answer 19

Exhibit unstable membrane potential of -60mV

This slowly depolarises up to theshold which causes action potential to fire

The unstable membrane potential is due to funny current channels, which ae permeable to both, Na+ and K+ ions

Unstable membrane potential, no resting potential, because, as they are repolarised, the membrane potential reaches -60mV, funny current channels open again, process of depolarisation starts again