Exam Questions Flashcards
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?
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
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)
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
Breifly describe the cori cycle (3)
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
Parkinson’s disease is a neurogenative disease, describe the consequences of loss of neuronal function, referring to the underlying pathophysiology (6)
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
Glucose 6 phosphatase transports —- into the ER and ——– and ———-out of the ER
- Glucose-6-phosphate
- Glucose
- Pi
Hypothyroidism leads to an increase production of glucose. Which two enzymes are required to form phosphoenolpyruvate from pyruvate?
- Pyruvate carboxylase
- Phosphoenolpyruvate carboxylase
Describe the cellular actions of insulin in different tissues. Include the cell type (6)
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)
Name three ketone bodies and three organs which can utilise ketone bodies (3)
- Acetoacetate
- Acetone
- 3-hydroxyburate
3 organs which can utilise ketone bodies:
- Liver
- Heart
- Kidney
- Brain
Cells enter futile substrate cycling during which increased intracellular glucose overwhelmes the TCA cycle. As a result, non oxidative glucose metabolism ——- producing ————
- Activated
- Lactate
In conversion of oxaloacetate to phosphoenolpyruvate, the phosphoryl donor is ——-
GTP
Briefly describe a few different hypothesis of the underlying cause of Alzheimer’s disease (8)
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
What disorders might be associated with altered norepinephrine activity? (6)
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
Justify the following statement by providing concise explanation. The mechanism of action potential generation in autoryhtmic cells is independent of the nervous system (3)
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
