Endocrinology Flashcards

1
Q

What are the main endocrine glands

A
Hypothalamus
Pituitary
Thyroid
Parathyroid
Pancreas
Adrenal
Ovaries/testicles
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2
Q

What is the pituitary gland and what are its two lobes

A

Controls most glands in the body
Found in the brain just below the hypothalamus
Anterior produces various hormones
Posterior stores various hormones

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3
Q

What hormones are produced by the anterior lobe of the pituitary

A

Growth hormone: for skeletal growth
ACTH: stimulate adrenals to produce steroids
Gonadotophins (FSH and LH): stimulate the testicles and ovaries to produce sex hormones
Thyroid stimulating hormone (TSH): stimulates the thyroid to produce thyroid hormones
Prolactin (PRL): stimulates breast milk production

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4
Q

What hormones are stored in the posterior lobe of the pituitary gland

A
Antidiuretic hormone (ADH): stimulates water reabsorption by the kidneys
Oxytocin: helps uterine contractions during labour
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5
Q

What hormones are released by the hypothalamus

A

Corticotrophin releasing hormone (CRH) which stimulate ACTH secretion
Growth hormone releasing hormone (GHRH) which stimulates GH secretion
Thyrotrophin releasing hormone (TRH) which stimulates TSH secretion
Gonadotrophin releasing hormone (GnRH) stimulates FSH and LH secretion

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6
Q

How is prolactin secretion controlled

A

It is under an inhibitory effect of the hypothalamus

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7
Q

How are pituitary hormones switched off

A

Negative feedback which acts on pituitary and hypothalamus

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8
Q

What glands and hormones are not controlled by the pituitary

A

Adrenal medulla: produce adrenaline and noradrenaline
Parathyroid: controls calcium levels
Pancreas: controls sugar levels
Gut hormones

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9
Q

What is the thyroid composed of

A

Midline isthmus( just below the cricoid cartilage)
Right lobe
Left lobe

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10
Q

What are the characteristics of thyroid hormones and cells

A

Thyroid cells are arranged in follicles and produce thyroid hormones
Thyroid contains C cells which produce calcitonin
Thyroid hormones interact with their receptors in various organs, regulating gene expression and aspects of organ function
T3 is active and T4 is inactive

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11
Q

What organs are involved in calcium metabolism and how

A

Parathyroid: main glands controlling calcium metabolism
Kidneys: calcium excretion and production of active vitamin D
Gut: Absorption of calcium
Bone: storage of calcium
Thyroid: produce calcitonin

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12
Q

What are the two parts of the adrenal gland

A

CONTROLLED BY PITUITARY: Adrenal cortex: Corticosteroids (cortisol), Androgens (male hormones)
Mineralocorticoid (aldosterone) consolle by renin angiotensin system
NOT CONTROLLED BY PITUITARY (related to blood pressure):Adrenal medulla: Catecholamines (adrenaline, noradrenaline and dopamine)

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13
Q

What are the characteristics of the ovaries

A

Situated in the pelvis on either side of the uterus
Contain follicles containing oocyte at different stages of maturation
Stimulated first half of cycle by more FSH, second half of cycle by more LH
Secrete Inhibin (negative feedback), oesradiol (1st half) ,progesteron (2nd half)

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14
Q

What is testicular maldescent

A

When the testicles remain in the pelvis and don’t descend into the scrotum

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15
Q

What are the testicles composed of

A

Interstital/leydig cells: produce testosterone
Seminiferous tubules: made up of germ cells producing sperm
Sertoli cells: help in sperm production and produce inhibin
FSH controls sperm production
LH controls testosterone production

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16
Q

What are types of abnormalities within the glands

A

Hormonal over secretion
Hormonal under-secretion
Primary: problem with gland itself
Secondary problem with gland controlling the gland itself
Tumour/nodules int the gland without affecting hormone secretion

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17
Q

What are static tests

A

One blood test and immediately diagnosis hormonal over or under secretion

18
Q

How is primary hyperthyroidism diagnosed in static test

A

Elevated T3 and/or T4

Suppressed TSH

19
Q

What is a stimulation test

A

For suspected hormonal under-secretion where static test is not enough
Is individual fails to respond to a stimulation test then gland failure is diagnosed

20
Q

What are examples of stimulation tests

A

Synacthen test
Glucagon stimulation
Insulin stress test

21
Q

What are suppression tests used for

A

Some hormonal over-secretion

22
Q

What are examples of suppression tests

A

Giving steroids and testing for endogenous steroid production (healthy person this would be switched off)
Giving glucose and testing GH secretion (glucose switches of GH secretion in normal individuals)

23
Q

What tens to cause over and under secretion

A

Over-secretion: benign tumours
Under-secretion:gland destruction due to: inflammation, infarction, other
Both can be caused by tumours/nodules with normal hormone production

24
Q

What is prolactin over-secretion

A

Due to prolactin secreting tumour
Increased breast milk production (galactorrhea)
Amenorrhea (irregular periods)
Sexual dysfunction in men
Headaches and visual field problems in large tumours
Diagnosed by static test

25
What can cause mildly raised prolactin
Sexual intercourse Nipple stimulation Stress Large number of drugs including antipsychotics and antidepressants Non-functioning pituitary tumour, compressing the hypothalamus and interfering with the inhibitory effect on prolactin secretion
26
What is the result of growth hormone over-secretion
In child: excessive growth spurt and increased size of feet and hands; if left untreated leads to gigantism In adult: affects the skin, soft tissue and skeleton; acromegalic face; wide and large hands/ feet; increased sweating
27
What causes Cushing's syndrome
Pituitary secreting ACTH tumour (Cushing's disease) Adrenal tumours secreting cortisol Cancers producing ACTH (such as lung cancers)
28
How does Cushing's present
Growth arrest in children Face: Round, Acne, Hirsuitism Fat redistribution: truncal obesity, thin extremities Skin abnormalities: thin skin, easy bruising, striae on abdomen Complications: hypertension, diabetes, high risk of infection, poor wound healing
29
What are the causes of hyperthyroidism
Graves' disease: Genetic autoimmune condition, 80% Toxic nodule or toxic multi-nodule-goitre, 15% Thyroiditis, 1% Drug induced: amiodarone Rarities
30
How do people with hyperthyroidism present
``` Hyperactivity Irritability Insomnia Heat intolerance and increased sweating Palpitations Weight loss despite overeating Menstrual problems Can have thyroid eye disease (swelling, paralysis, proptosis) if Graves' disease ```
31
How do you examine hyperthyroidism
``` Hand tremor Increased sweating Fast pulse Inspection of thyroid: Enlarged: Smooth: Graves' disease Nodular: toxic nodule Tender: thyroiditis ```
32
What is the treatment for hyperthyroidism
Anti-thyroid drugs: Disease remission in 50% of patients after treatment for 6-18months, can rarely suppress white cell production Radioactive iodine: destroys the thyroid gland Surgery
33
What are the characteristics of growth hormone deficiency
Children: failure to grow Adults: no symptoms, tiredness, depression
34
How is growth hormone treated
Injections of growth hormone replacement, very expensive
35
How do patients with steroid under-secretion present
``` Failure to grow in children Severe tiredness Dizziness due to low blood pressure Abdominal pain Vomiting in diarrhoea ```
36
What are the symptoms of hypothyroidism
``` Weakness and dry skin Sensation of cold and decreased sweating Impaired memory Constipation Weight gain Hair loss ```
37
What causes pituitary failure
Large tumour Infarction Something else
38
How to test for pituitary failure
Test biochemically -> Static tests -> dynamic tests -> image pituitary last
39
How do steroid and thyroid hormones alter the cellular activity
Act within the nucleus to alter gene transcription, switching genes on and off Binding of hormones to proteins and the binding of the receptor-hormone complex (a transcription factor) to specific DNA sequences
40
What is the clinical relevance of nuclear hormone receptors
They are drug targets
41
What do steroid hormones derive from
Cholesterol
42
What do thyroid hormones derive from and where are they synthesised
Tyrosine in the thyroid gland