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Endocrinology Flashcards

1
Q

Endocrinology is the study of

A

hormones, their receptors, the intracellular signalling pathways and their associated diseases.

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2
Q

Endocrine glands are…

A

ductless and release hormones directly into the blood.

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3
Q

Endocrine glands allow

A

rapid adaptive changes, integration of whole body physiology, chronic maintenance of metabolic environment

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4
Q

Examples of endocrine glands

A

Thyroid, adrenal and beta cells of the pancreas

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5
Q

Exocrine glands secrete

A

through a duct to site of action

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6
Q

Examples of exocrine glands

A

submandibular, parotid, pancreas- amylase and lipase

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7
Q

3 types of hormone action

A

endocrine - blood-borne acting at distant sites
paracrine - acting on adjacent cells
autocrine - acts on itself

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8
Q

2 types of hormones

A

Water soluble

Fat soluble

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9
Q

Water soluble hormones

A

Transported unbound
Bind to surface receptor on cells
Short half-life
Cleared fast

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10
Q

Examples of water soluble hormones

A

Peptides and monoamines (both stored in vesicles before secretion)

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11
Q

Fat soluble hormones

A

Transported bound to protein
Diffuse into cells
Long half-life
Cleared slowly

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12
Q

Examples of fat soluble hormones

A

Thyroid hormone and steroids (synthesised on demand)

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13
Q

Hormone classes

A

Peptides e.g insulin
Amines e.g. dopamine, adrenaline and noradrenaline
Iodothyronines
Cholesterol derivatives and steroids

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14
Q

Hormone classes - peptides

A 
E.g Insulin
Stored in secretory granules
Hydrophilic and water soluble
Released in pulses or bursts
Clearing by tissue
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15
Q

Synthesis of peptide hormone

A

Synthesis:
Preprohormone –> prohormone

Packaging:
Prohormone –> hormone

Storage and secretion:
hormone

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16
Q

Insulin activation

A
  1. Binds to insulin receptors
  2. Results in phosphorylation of the receptor and the activation of secondary messenger - Tyrosine kinase
  3. Phosphorylation of signal molecules
  4. Cascade effect
  5. Glucose uptake
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17
Q

Amine synthesis from Phenylalanine

A

Phenylalanine –> L-Tyrosine –> L-Dopa –> Dopamine –> noradrenaline –> adrenaline

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18
Q

Noradrenaline and adrenaline are broken down by

A

COMT (Catechol-O-methyl transferase)

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19
Q

Noradrenaline and adrenaline are broken down into

A

Normetanephrine and metanephrine.

Serum levels of these acts as indicators for the activity of noradrenaline and adrenaline.

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20
Q

NAd and Ad binding to alpha receptors causes

A

VasoConstriction
Bowel muscle contraction
Sweating
Anxiety

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21
Q

NAd and Ad binding to beta receptors causes

A

VasoDilation
Increase heart rate
Increases force of contractility
Relaxation of bronchial smooth muscles

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22
Q

Iodothyronines are not

A

water soluble so are bound to protein (Thyroid-binding globulin TBG)

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23
Q

T3

A

More active

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24
Q

T4

A

Less active but more is produced

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25
Cholesterol derivative - Vitamin D
Fat soluble Enters cell directly to bind to nucleus and stimulate mRNA production Transported by vitamin D binding protein
26
Adrenocortical and gonadal steroid examples
cortisol, aldosterone, testosterone, oestrogen, progesterone. 95% protein bond
27
Hormone receptor locations and examples
Cell membrane - peptide e.g. insulin Cytoplasm - steroids: - Cortisol - aldosterone - Androgens e.g. testosterone - Progesterone Nucleus - thyroid hormones: - Thyroid hormones - Oestrogen - Vitamin
28
Hormone secretion patterns
Continuous release e.g prolactin Pulsatile e.g. insulin Circadian rhythm e.g. ACTH, prolactin, GH, TSH, cortisol
29
GH is inhibited by
Somatostatin and GHRH (negative feedback)
30
5 ways to control hormone action
1. Hormone metabolism 2. Hormone receptor induction 3. Hormone receptor down regulation - hormone secreted in large quantities 4. Synergism - 2 hormones amplify effect e.g. glucagon with adrenaline both increase sugar levels 5. Antagonism - glucagon antagonises insulin
31
Cavernous sinus structures
``` Abducens nerve (VI) and carotid artery. Can be affected in pituitary pathology. ```
32
Anterior pituitary is sometimes referred to as
adenophysis
33
Posterior pituitary is sometimes referred to as
neurohypophysis
34
Hypophysiotrophic hormones (6) released by the hypothalamus
1. Corticotropin-releasing hormone (CRH) 2. GHRH 3. Somatostatin 4. Thyrotropin-releasing hormone (TRH) 5. GnRH 6. Dopamine
35
Blood supply of anterior pituitary gland
No arterial blood supply. | Receives blood through portal venous circulation.
36
Hormones of the anterior pituitary
6 Peptide hormones: 1. FSH 2. LH 3. Adrenocorticotrophic hormone (ACTH) 4. TSH 5. Prolactin 6. GH
37
Functions of FSH and LH
Target the gonads Stimulate germ cell development FSH stimulates oestrogen release Positive feedback is the release of oestrogen and stimulates LH. LH stimulates the release of the egg which in turn stimulates progesterone release --> thickening of the uterine wall. In men, LH stimulates Leydig cells --> testosterone release
38
Functions of GH
Stimulates growth and protein synthesis Effect on whole body Stimulates glucogenesis and inhibits insulin Works on adipose tissue to breakdown fat Acts on Liver to increase protein synthesis and stimulate IGF-1 --> acts on skeleton to increase cartilage proliferation
39
What is measured to reflect GH levels
IGF-1
40
Functions of ACTH
Stimulates adrenal cortex to secrete Cortisol from zona fasiculata Androgen release from zona reticularis Ad release from adrenal medulla Cortisol - breakdown proteins, fats, carbs, anti-inflammatory effects, overcome stress.
41
TSH functions
Stimulates thyroid hormone release: - controls rate of metabolic reactions - accelerate food metabolism - increases protein synthesis - stimulation of carbohydrate metabolism - enhances fat metabolism - increase ventilation rate - increase CO and HR
42
T3 half life
1 day
43
T4 half life
5-7 days
44
Prolactin functions
Stimulates breasts to produce milk and breast development. | Inhibited by dopamine
45
Posterior pituitary hormones are produced in
the hypothalamus. Stored in the posterior pituitary
46
Posterior pituitary originates
neuronal tissue with large quantities of glial type cells
47
Vasopressin/ADH is synthesised in
supraoptic nucleus
48
Oxytocin is synthesised in
paraventricular nucleus
49
Vasopressin/ADH functions
- Decrease H20 secretion in urine - Vasoconstriction --> increase BP - Stimulates ACTH release to increase aldosterone release to further increase fluid retention
50
Vasopressin is released in response to
- decreased blood volume - trauma - stress - increase blood CO2 - decreased blood O2 - increased osmotic pressure of blood
51
Oxytocin functions
-Ejection of milk during breast feeding Pregnancy: -contraction of uterine smooth muscles until baby is born -promotes onset of labour
52
All pituitary and hypothalamic hormones act on
G-protein coupled receptors
53
Diseases of the pituitary
- Benign pituitary adenoma - Craniopharyngioma - Trauma - Sheehans - pituitary infarction after labour - Sarcoid/TB
54
Vital presentations of pituitary tumour
1. Pressure on local structures - Optic chiasm --> bitemporal hemianopia - Can cause hydrocephalus - Can get CSF leak 2. Pressure on normal pituitary - hypopituitarism 3. Functioning tumour - hyperpituitarism - Prolactinoma (treated using Cabergoline - dopamine agonist) - Acromegaly - Cushing's Disease
55
Diabetes mellitus definition
Syndrome of chronic hyperglycaemia due to relative insulin deficiency, resistance or both. Hyperglycaemia results in serious microvascular (retinopathy, neuropathy, nephropathy) or macrovascular problems (strokes, renovascular disease) problems.
56
Normal blood glucose levels
3.5 - 8 mmol/L
57
Principal organ of glucose homeostasis
Liver
58
How much glucose is produced and utilised each day
200g
59
Where is glucose derived from?
90% from liver glycogen and hepatic gluconeogenesis. | Remainder from renal gluconeogenesis.
60
Major consumer of glucose
Brain | Cannot utilise fatty acids are they cannot cross BBB.
61
Glucose taken up by muscle is stored as
Glycogen or metabolised to lactate or CO2 and H2O
62
Fat uses glucose for
Triglyceride synthesis
63
Lipolysis of triglyceride releases
fatty acids + glycerol. | Glycerol used as a substrate for hepatic gluconeogenesis.
64
Insulin functions
- Suppress hepatic glucose output - decreases glycogenolysis and gluconeogenesis - Increases glucose uptake into muscle and fat tissue
65
Biphasic insulin release
- B-cells sense increase in glucose levels. - First phase response is rapid release of stored insulin. - If glucose levels remain high, second phase is initiated. This takes longer as more insulin must be synthesised.
66
Glucagon functions
- Increases hepatic glucose output - increases glycogenolysis and gluconeogenesis - Reduces peripheral uptake of glucose - Stimulates peripheral release of gluconeogenic precursors e.g. glycerol & AA - Stimulates lipolysis , muscle glycogenolysis and breakdown.
67
Counter regulatory hormones which increase glucose production
Adrenaline, cortisol and GH
68
Insulin produced by
beta cells of the Islets of Langerhans
69
Precursor of insulin
proinsulin
70
Proinsulin contains
Alpha and beta chain joined by C-peptide. | C-peptide is cleaved when insulin is formed
71
Synthetic insulin does not have
C-peptide
72
GLUT 1
Enables basal non-insulin stimulated glucose uptake
73
GLUT 2
Found in Beta cells of pancreas, renal tubules and hepatocytes Transport glucose into beta cells - enable them to sense glucose levels only lets glucose in when there is a high concentration
74
GLUT 3
Enables non-inulin stimulated glucose uptake into brain neurones and placenta.
75
GLUT 4
Mediates peripheral action of insulin. | Channel through which glucose is taken up into muscle and adipose tissue after insulin binds to it.
76
Insulin receptor activation
1. Insulin binds 2. Activates tyrosine kinase. Cascade response 3. Migration of GLUT-4 transporter to the cell surface and increased transport of glucose into the cell
77
Primary diabetes
Type 1 and Type 2
78
Secondary diabetes due to
- Pancreatic pathology e.g pancreatectomy, chronic pancreatitis, haemochromatosis - Endocrine induced disease e.g. Acromegaly or Cushing's - Drug induced (thiazide) - Maturity onset diabetes of youth (MODY) - -> autosomal dominant form of type 2 diabetes altering beta cell function

Phase 2A (1 decks)

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