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43 Cards in this Set
- Front
- Back
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In stress, what hormones from the anterior and posterior pituitary are increased?
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Anterior pituitary:
prolactin adrenocorticotropin releasing hormone (ACTH) Posterior pituitary vassopressin *Taken from learning topic 1 |
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Where does the response to psychological stressors being?
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In the CNS, primarily in the hypocamppus and the hypothalamus
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What are the peripheral end-organ changes in anxiety (i.e. what hormones are upregulated in the periphery)?
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Effects are mainly mediated by catecholamines
Adrenal medulla = adrenaline Adrenal Cortex = cortisol SNS activity = adrenaline and release of noradrenaline |
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True or False
Adrenalin and Cortisol both counter act insulin |
True
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What are the similiarties in the actions of Adrenalin and Cortisol?
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1. Opposes insulin
2. Increase glycogenolysis (breakdown of glycogen) 3. Increase gluconeogensis (formation of glucose from a.a.) 4. Increase hepatic output 5. Increase triglyceride breakdown |
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Why does blood volume increase under stress?
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1. Reduced renal blood flow (Adr = vasoconstriction)
2. Increase in renin (due to decrease in renal BF = vasoconstriction) 3. Angiotensin and Aldosterone (due to decrease reanal BF = increase water reabpsortion) 4. Increase in vasopressin (increases water reasorbtion) |
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True or False:
Thryoid hormone potentiates the action of catecholamines? |
True
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Define basic metabolic rate (BMR)
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They energy expended when completely at rest but not asleep, in the absence of muscle movement and without any SNS arousal
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How would you measure resting metabolic rate (RMR)?
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indirect calorimetry. in the fasted stated using a ventilated bood/mask techique or by direct calorimetry in a metabolic chamber
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What is the unit of measurement for BMR and RMR? And what is the percentage difference between the two?
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kilocalories/24hours
RMR is 10-15% higher than BMR |
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What is BMR primarily dependent on?
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Lean body mass
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What is an individual's BMR controlled by?
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Hypothalamic pathways
ANS Genetic factors |
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List 3 ways in which you can increase BMR
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Disease: thyorid overactivity, fever,
Anxiety and agitated states Drugs: amphetamine, caffine, ephedrine |
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What are the two mechanisms that causes a gain of body heat
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Futile Cycle
1. Shivering thermogensis 2. Non-shvering thermogenesis (biochemical reactions) |
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True of false:
The main site of energy production due to futile cycles of non-shivering thermogensis occurs in the adipose tissues of humans |
False
It occus in the skeletal muscles of humans |
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List 3 ways in which BMR is lowered
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Fasting
Caloric restrictions Weight loss hypothryorid state |
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Who is the prime integrator in thermoregulation where there might be weight gain/loss?
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Hypothalamus
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What diseases are usually associated with secondary hypothermia?
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Acute illnesses associated with severe metabolic acidosis
E.g. Congestive heart failure Hypothyroidism |
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What diseases are usually associated with secondary hyperthermia?
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Central nervous system lesions
E.g. Tumors Degenerative disease Encephalitis |
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List the 3 main catecholamine of clincal interest and where they are produced
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1. Adrenaline -Adrenal medulla
2. Noradrenaline -SNS postgangolinic fibres and in CNS 3. Dopamine -in CNS (extrapyramidal mesocortical and mesolimbic pathways) |
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What is the amino acid in which the catecholamines are derived from?
And in what order are they made? |
Tyrosine
Dopamine > Noradr > Adr |
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What is the name of the receptors of catecholamines?
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Adrenoreceptors (alpha and beta)
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How do you tell the difference between alpha and beta adrenoreceptors?
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Beta receptors are activated by dobutamine and selectively blocked by metoprolol
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Where are beta receptor present?
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Heart -increase force of contraction and increase AVN conduction
Kidney -increase renin secretion from jutaglomerular cells Smooth muscle in BVs, bronchi, gut and genitourinary systems -relaxation Adipose tissue -lipolysis |
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What is the beta adrenoceptor's mechanism of action?
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1. Activate G-protein
2. Activate adenylate cyclase 3. ATP -> cAMP |
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What is the alpha adrenoceptor's mechanims of action?
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1. Inhibit adenylate cyclase
2. Decrease cellular cAMP 1. Activation of Phospholipase C 2. Increase IC calcium |
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A patient is hypotensive secondary to shock, but you do not know the cause, what can you give to rectify the hypotension?
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Adrenalin or Noradrenlin
They are potent stimulators of alpha and beta adrenoceptors and can be used to elevate hypotension secondary to shock from any cause |
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Finish the sentance
Many symptoms of thryotoxicosis is mediated by.... |
Catecholamines!
(taken from LT 3) Remember TH potentiates the actions of catecholamines Note: effectively treated by beta blockage |
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How should abnormalities of the thyroid found on examination be confirmed?
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Ultrasound
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Globally, what is the commonest cause of endemic goitre?
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Dietary iodine deficiency
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What are sporodic goitre's due to?
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Heterogenous stimulation of the growth of thyroid epithelial cells by growth hormones such as TSH
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What humoral factors can modulate the effects of TSH?
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insulin
insulin-like growth factor (IGF-1) Human chorionic gonadotriphin (hCH) |
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List the effects of Thyrotoxocosis
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1. weight loss
2. excessive appetite 3. increase heat production 4. excessive sweating 5. heat intolerance 6. vasodilation 7. tachycardia 8. diarrhoea or increase bowel frequency |
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What factors contribute to tachycardia in thyrotoxocosis?
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1. Vasodilation
2. Increase AVN firing 3. Increase in heart contraction 4. Increase in blood pressure |
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List the feactures of hypothyrodism
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1. Increase weight
2. Decrease appetite 3. Intolerance to cold 4. Depresion 5. Sluggish 6. Slow pulse 7. Dry hair and skin (hair loss) 8. Muscles may be painful and have slow reflexes 9. Puffness of the face, hands and supraclavicular fossa 10. Hypercarotenaemia 11. Sleep apnoea (severe hypothyrodism) |
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How do patients with hypothyrodism develop their puffy features?
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Deposition of glycosaminoglycans in the subcutaneous tissue results in the collection of water
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What clinical signs points towards Grave's disease as oppose to other hypothyrodism?
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3 pathopneuomic signs of Grave's disease:
Exopthalmos (sclera are not covered by LOWER lid) pretibital myxodema (rare) Presence of bruit over the thyroid (increase vascularisation) |
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True of False
Eye signs associated with increase SNS activity such as lid retraction and lid lag are clinically suggestive of Grave's disease |
False
They are not necessarily due to Grave's disease |
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Grave's disease is often associated with what type of goitre?
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Diffuse and may have a bruit due to increased vascularity
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How might a hypothyroid goitre look like?
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shrunken
fibrotic goitrous nodular |
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In hashiomoto's thryroiditis, what are the clincal manifestations? and what is the mechanism of action?
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Clincally:
Hypothyrodisim High titre antibodies to thyroid peroxidase Mechanism: Mainly T cells Antibodies are diagnostic but unlikely pathogenic |
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In Grave's Disease, what are the main clinical manifestations?
And what is the mechanism of action? |
Clinical Features:
Thyrotoxicosis Thyroid enlargment exopthalamos |
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Idenitify the type of diease that fits the clinical manifestations and the mechanism below:
Clinically: Hypothyroidism Atrophic thryoiditis Mechanism: Blockage of TSH-R by autoantibodies |
Primary myxodema, hypothyrodism
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