endocrine glands and hormones Flashcards
where is the pineal gland?
where is the hypothalamus?
where is the pituitary gland?
what is the connection between the hypothalamus and the pituitary gland?
the infundibulum
what is the hypothalamus responsible for?
- thermoregulation
- hormone secretion
- circadian rhythms
- motivation
- emotions
what are the hormone sub groups of the hypothalamus?
- primary hormones
- trophic hormones
what are the hypothalamus motivations?
thirst, feeding, sexual behaviour
thermoregulation sequence after a body temp decrease
- decrease in core body temp
- thermoreceptors in hypothalamus
- compare with ‘set point’
- effectors
- increase heat production and decrease heat loss
how do the releasing hormones of the hypothalamus pass to the anterior pituitary?
via blood vessels- hypothalamic-pituitary portal vessels
what triggers secretion of hormones from the anterior pituitary?
releasing hormones of the hypothalamus passing through blood vessels to the anterior pituitary
how do releasing hormones of the hypothalamus pass to the posterior pituitary?
along nerve axons
what happens after hypothalamus hormones have passed along nerve axons to the posterior pituitary?
released into circulation in posterior pituitary
what are examples of hypothalamic hormones?
Corticotropin releasing hormone (CRH)
Gonadotrophin releasing hormone (GRH)
Thyrotropin releasing hormone (TRH)
Growth hormone releasing hormone (GHRH)
Somatostatin (SS) (GH inhibiting hormone)
Prolactin releasing hormone (PLRH)
Dopamine (DA) (also PLIH)
what are examples of anterior pituitary hormones?
Adrenocorticotropic hormone (ACTH)
Follicle stimulating hormone (FSH)
Luteinising hormone (LH)
Thyroid stimulating hormone (TSH)
Growth hormone (GH)
Prolactin (PL)
describe the sequence of regulation by feedback
- simulus
- hypothalamus inhibition
(hormone 1) - anterior pituitary gland inhibition
(hormone 2) - target organ inhibition
(hormone 3) - actions
what is corticotrophin and what is its function?
releases cortisol in the adrenal cortex
what is gonadotrophin and what is its function?
controls gamete and sex hormone production in ovaries/testes
- LH/FSH production
what is thyrotrophin and what is its function?
releases thyroid hormones in the thyroid gland
what is somatotrophin and what is its function?
release of growth hormone
what is prolactin and what is its function?
breast milk development/ milk production
what are examples of posterior pituitary hormones?
Antidiuretic hormone (ADH)
Oxytocin
which nuclei produces oxytocin?
supraoptic
which nuclei produces ADH?
paraventricular
what is the function of Antidiuretic hormone?
water reabsorption in collecting ducts
what is the function of oxytocin?
contracts uterus
milk ejection
where is the thyroid gland?
in the neck, anterior to the trachea
what hormones does the thyroid gland produce?
thyroid hormone
T3, T4
calcitonin
what does calcitonin do?
regulates calcium levels
where are thyroid hormones produced from?
cells around the follicles of the thyroid gland
where is calcitonin produced from?
para-follicular C-cells in thyroid gland
what are the action of T3 and T4?
Increase metabolic rate of all cells
Determines basal metabolic rate
Essential for normal fetal and childhood growth
Permissive effect on action of adrenaline by upregulating adrenoreceptors
what are disorders associated with undersecretion of thyroid hormone?
Hypothyroidism
Cretinism, Myxoedema
what are disorders associated with oversecretion of thyroid hormone?
Hyperthyroidism
Grave’s disease
what is simple goitre?
Thyroid swelling associated with iodine deficiency
Low levels of thyroxine result in increased secretion of TSH
Iodide added to salt
how many parathyroid glands are there and where are they located?
4-5
on the deep surface of the thyroid gland
what is the function of the parathyroid glands?
produce parathyroid hormone which is involved in regulation of blood calcium levels
what is the EXOcrine function of the pancreas?
produce digestive enzymes
what is the ENDOcrine function of the pancreas?
islets of Langerhans which produce three hormones
what % of pancreatic tissue do islets of langerhans take up?
1-2%
what three hormones do islets of langerhans produce?
- insulin
- glucagon
- somatostatin
what do beta cells produce?
insulin
what do alpha cells produce?
glucagon
what do delta cells produce?
somatostatin
what is the function of insulin?
- released in response to raised blood glucose/ vagus nerve
- acts to lower blood glucose
- facilitates glucose entry into muscle cells and adipocytes
- promotes formation of glycogen, triglycerides
- facilitates protein synthesis
what promotes insulin secretion?
increase Blood glucose
increase Blood amino acids
Glucose-dependent, insulinotropic peptide
Vagus nerve activity
what inhibits insulin secretion?
Adrenaline
Sympathetic nerves
somatostatin
what is the function of glucagon?
- Released in response to low blood glucose concentration
- acts to raise blood glucose
- Actions:
Glycogenolysis in liver,
Gluconeogenesis in liver,
Lipolysis and ketone synthesis
what promotes glucagon secretion?
decrease in blood glucose
increase in blood amino acids
cholecystokinin
autonomic nerve activity
what inhibits glucagon secretion?
insulin
somatostatin
what is diabetes mellitus?
elevated blood glucose concentration
decrease in glucose uptake by cells
what are the clinical features of diabetes mellitus?
Polyuria (increase in urine production)
Polydipsia (increase in fluid intake; thirst)
Glycosuria (glucose in urine)
Diabetic neuropathy
Skin and oral diseases, incl. periodontitis, xerostomia
what is Type-1 diabetes?
- Insulin-dependent
- decrease in Insulin secretion
- Destruction of beta-cells
- Autoimmune?
- 10% of cases
- “Early” onset
- Insulin injections and diet
what is Type-2 diabetes?
- Insulin-independent
- Insulin levels “normal”
- decrease in target cell responsiveness to insulin
- Related to overweight
- “Late” onset
- Diet, oral hypoglycaemic agents
where are adrenal glands located?
lie on top of the kidneys
compare insulin levels in type 1 vs type 2 diabetes
- type 1- decreased insulin secretion
- type 2- normal insulin secretion
what is the main issue in type 2 diabetes?
reduced responsiveness of target cell to insulin
give examples of cortex hormones
- aldosterone
- cortisol
- androgens
what % of cases of diabetes are type 1?
10%
what is cortisol produced by?
cells of zona fasciculata of adrenal cortex
what is the treatment for type 1 diabetes?
insulin injections and diet
what is the treatment for type 2 diabetes?
diet and oral hypoglycaemic agents
what produces corticosteriods?
adrenal glands
what does the modified sympathetic ganglion produce?
adrenaline
what are the layers of the adrenal glands?
capsule
cortex
medulla
what is cortisol controlled by?
ACTH from anterior pituitary
what are the actions of cortisol?
Metabolic effects
Permissive effects
Anti-inflammatory, immunosuppressant
what does it mean if a hormone has permissive effect?
one hormone exherts its full effect only in the presence of other hormone
what is aldosterone produced by?
cells of zona gomerulosa
what is aldosterone controlled by?
the renin-angiotensin system
what are the actions of aldosterone?
promotes reabsorption of Na+ and H2O in kidney (DCT)
Increases excretion of H+, K+
where is androgens produced?
zone fasciculata and reticularis of adrenal cortex
what are the actions of androgens?
growth and 2 degree sexual characteristics
what can occur with excess glucocorticoid?
cushing’s syndrome
what can occur with excess androgens?
andreno-genital syndrome
what are symptoms of cushings syndrome?
a fatty hump between your shoulders, a rounded face, and pink or purple stretch marks on your skin
what is the adrenal medulla?
a modified sympathetic ganglion
what is the adrenal medulla controlled by?
pre-ganglionic sympathetic nerves
what do the cells of the adrenal medulla produce?
adrenaline
what can an adrenaline deficiency result in?
addisons disease
What type of hormone is cortisol?
Steroid
What type of hormone is aldosterone?
Steroid
What type of hormones are testosterone, oestrogen and progesterone?
Steroid
What type of hormone is adrenaline?
Non-steroid, amino acid derivative
What type of hormone is ADH?
Non-steroid, short-chain peptide
What type of hormone is growth hormone?
Non-steroid, long chain peptide
Where does the pro-hormone become activated to the hormone?
In the endoplasmic reticulum/ Golgi apparatus
Where is growth hormone produced?
Anterior pituitary gland
Where is ADH produced?
Posterior pituitary gland
What hormones does the hypothalamus produce?
Hormones which stimulate the release of action causing hormones from the pituitary gland
What are the actions of T3 and 4?
- increase metabolic rate of all cells
- fetal and childhood growth
What hormones do the adrenal glands secrete?
Aldosterone
Cortisol
Androgens
