ENDOCRINE HOMEOSTASIS AND INTERVENTIONS

Question 1

what is endocrinology?

Answer 1

the study of glands and hormones they produce

Question 2

what’s the difference between exocrine and endocrine?

Answer 2

Exocrine: hormones secreted externally or into a lumen e.g sweat gland
Endocrine: hormones secreted internally e.g islets of pancreas

Question 3

what are hormones?

Answer 3

chemical messengers produced by endocrine glands which have a specific effect on target tissues.

Question 4

describe the 2 types of hormones?

Answer 4

lipid soluble (need transport proteins and receptors are inside the cell) and water soluble (no need for transport proteins, receptors in cell membrane)

Question 5

outline the hypothalamic-pituitary adrenal axis?

Answer 5

stress stimulates the hypothalamus to release corticotropin releasing hormone which stimulates the anterior pituitary to release adrenocorticotropin releasing hormone. this then stimulates the adrenal cortex to release cortisol which can act on various tissues

Question 6

what’s the mechanism for when cortisol levels are too high?

Answer 6

it will inhibit the hypothalamus so that CRH can’t be released

Question 7

what is adrenal insufficiency?

Answer 7

when the adrenal glands don’t produce enough cortisol

Question 8

what are the 3 types of adrenal insufficiency?

Answer 8

primary adrenal insufficiency (pathology in the adrenal gland)
secondary adrenal insufficiency (pathology in anterior pituitary)
tertiary adrenal insufficiency (pathology in the hypothalamus)

Question 9

what is Addison’s disease?

Answer 9

primary adrenal insufficnecy

Question 10

describe the pathophysiology of Addison’s disease?

Answer 10

autoimmune destruction of the adrenal cortex so it produces less cortisol. we get higher levels of CRH and ACTH because they are trying to stimulate the adrenal cortex to produce cortisol

Question 11

why does Addison’s disease cause hyperpigmentation?

Answer 11

as high ACTH levels stimulatesmelanocytes to produce more melanin

Question 12

describe the pathophysiology of secondary adrenal insufficiency?

Answer 12

destruction of pituitary gland so less ACTH produced which means the adrenal cortex produces less cortisol but we lose the negative feedback loop so CRH levels are high

Question 13

describe the pathophysiology of tertiary adrenal insufficiency?

Answer 13

damage to the hypothalamus means less CRH is produced so ACTH and cortisol levels are low

Question 14

what test do you do if you suspect Addison’s disease

Answer 14

synacthen stimulation test

Question 15

what is synacthen?

Answer 15

synthetic adrenocorticotropin releasing hormone

Question 16

how do you carry out a synacthen test?

Answer 16

Take the baseline cortisol then give intramuscular synacthen. Check the blood after 30 minutes to measure cortisol. If there’s a suboptimal rise in cortisol then we suspect adrenal insufficiency.

Question 17

what test do you use to diagnose secondary adrenal insufficiency?

Answer 17

the insulin stress test

Question 18

how do you carry out the insulin stress test?

Answer 18

Take baseline cortisol. Give them insulin and this will cause hypoglycemia which stimulates stress. This stress causes CRH, ACTH, and cortisol to be released. If there’s a suboptimal rise in cortisol, then we suspect secondary adrenal insufficiency.

Question 19

what’s the other name for Cushing syndrome/disease?

Answer 19

hypercortisolemia

Question 20

what are the symptoms of Cushing’s syndrome?

Answer 20

protein depletion= poor wound healing
hyperglycaemia
hyperlipidaemia
osteoporosis
round face
weight gain
hypertension
more prone to metabolic diseases

Question 21

what’s the difference between Cushing’s disease and Cushing’s syndrome?

Answer 21

Cushing’s syndrome is a disorder caused by the body’s exposure to an excess of the hormone cortisol
Cushing disease is when a pituitary tumor causes the body to make too much cortisol.

Question 22

what is the pathophysiology of Cushing’s syndrome?

Answer 22

Due to adrenal cortex producing excess cortisol we see negative feedback to the hypothalamus and pituitary causing low CRH and ACTH levels.

Question 23

what test is used to diagnose whether it’s Cushing’s disease or Cushing’s syndrome?

Answer 23

the dexamethasone suppression test

Question 24

what is the body’s normal response to dexamethasone?

Answer 24

suppression of endogenous cortisol due to inhibition of ACTH release from pituitary gland

Question 25

what does the thyroid gland secrete? and for what function?

Answer 25

T3 and T4- growth, development, and metabolism

Question 26

what is hyperthyroidism?

Answer 26

excess T3 and T4 secretion which causes negative feedback inhibition of the hypothalamus so less thyrotropin-releasing hormone and less thyroid stimulating hormone from the anterior pituitary is secreted

Question 27

what are the symptoms of hyperthyroidism?

Answer 27

``` weight loss increased appetite heat intolerance irritability tremor ```

Question 28

what are the signs of hyperthyroidism?

Answer 28

tremor tachycardia exophthalmos goitre (enlarger thymus that moves up and down with deglutition)

Question 29

what is hypothyroidism?

Answer 29

low T3 and T4 so no inhibition on the hypthalamus= TRH and TSH levels high

Question 30

what are the signs and symptoms of hypothyroidism?

Answer 30

``` dry hair weight gain reduced appetite thin eyebrows peri-oribital oedema puffy face dry skin intolerance to cold ```

Question 31

describe the hyothalamo-pituitary gonadal axis?

Answer 31

Hypothalamus produces gonadotrophin releasing hormone with stimulates the pituitary gland to produce LH and FSH. These act on the testis to produce testosterone and the ovaries to produce oestrogen

Question 32

what is primary hypogonadism?

Answer 32

not enoygh sex hormones caused by a problem with the gonads | this means there's no inhibition on the hypothalamus and pituitary gland so we have ahigh levels of GnRH, LH and FSH

Question 33

what is secondary hypognadism?

Answer 33

problems in the anterior pituitary which causes low levels of LH and FSH and this means low levels of oestrogen and testosterone but the hypothalamus isn't inhibited so we get high levels of GnRH

Question 34

describe the positive feedback mechanism of prolactin?

Answer 34

When the baby begins to suck, nerve cells in the mother's breast send a message to the hypothalamus. On receiving the message, the hypothalamus stimulates the pituitary to produce prolactin. The prolactin secreted by the pituitary gland stimulates the milk glands in the mother's breast. The more the baby sucks, the more prolactin is secreted, and the more milk is produced.

Question 35

what is sopamines effect on prolactin?

Answer 35

it inhibits it so sopamine antagonists can cause hyperprolactinemia

Question 36

how do you treat hyperprolactinemia?

Answer 36

with dopamine agonists

Question 37

describe the negative feedback loop involved in producing insulin-like growth hormone 1?

Answer 37

GnRH from the hypothalamus stimulates the pituitary gland to produce growth hormone which then acts on the liver to produce insulin-like growth hormone 1 (stimulates cells for growth and development). when levels get too high then it inhibits the hypothalamus and pituitary gland

Question 38

what is gigantism?

Answer 38

excess growth hormone from the pituitary gland

Question 39

which molecule inhibits growth hormone release?

Answer 39

somatostatin

Question 40

what does the posterior pituitary secrete?

Answer 40

vasopressin and oxytocin

Question 41

what is the function of vasopressin?

Answer 41

maintain bp and produces diaresis

Question 42

What is the function of oxytocin?

Answer 42

contracting uterine muscles and lactation