Endocrine Glands Flashcards
What are the functions of the hypothalamus
- thermoregulation
- hormone secretion
- circadian rhythms
- motivation
- emotions
What are the two pituitary glands called
The posterior and anterior pituitary gland
What connects the two pituitary glands
The infundibulum
Describe the role of the pituitary glands in thermoregulation
Thermoreceptors in the hypothalamus compare the body temperature to a set point and act accordingly to reach the set point
What is a circadian rhythm
One example is Body temperature follows a circadian rhythm over 24hours
When does temperature peak
After meals
What can affect the circadian rhythm of body temperature
Night shifts
Describe how hormone secretion is triggered from the anterior pituitary gland
- hypothalamus produces releasing hormones, these pass to the anterior pituitary via blood vessels which triggers the secretion of hormones from the anterior pituitary
Describe hormones produced in the posterior pituitary gland
Hormones produced in hypothalamus pass to posterior pituitary along nerve axons, released into circulation in posterior pituitary
What hormones are produced by the hypothalamus
- corticotropin releasing hormone
- gonadotropin releasing hormone
- thyrotropin releasing hormone
- growth hormone releasing hormone
- somatostatin
- prolactin releasing hormone
- dopamine
What are the anterior pituitary hormones
- adrenocorticotropic hormone
- follicle stimulating hormone
- luteinising hormone
- thyroid stimulating hormone
- growth hormone
- prolactin
Describe the regulation by feedback on hormone secretion by the hypothalamus
Hormones are released by the hypothalamus when a stimulus occurs, the target organ will then produce a hormone that can inhibit the hypothalamus and stop the releasing hormone secretion
Describe how thyroid hormones are stimulated
A stimulus causes the hypothalamus to produce thyrotropin RH which in turn stimulates the anterior pituitary gland to produce thyroid stimulating hormone hence acting on the thyroid gland and release in thyroid hormones
Where is the thyroid gland
Situated in the neck anterior to the trachea
What hormones are produced by the thyroid gland
- thyroid hormone
- T3, T4
- calcitonin (regulates calcium levels)
What cells produce calcitonin
Para follicular c cells
What are the functions of hormones T3 and T4
- increases metabolic rate of all cells
- determines basal metabolic rate
- essential for normal fetal and childhood rate
- permissive effect on action of adrenaline by upregulating adrenoreceptors
What can undersecretion of thyroid hormones cause
- hypothyroidism
- cretinism, myoedema
What can oversecretion of thyroid hormone cause
- hyperthyroidism
- Graves’ disease
What is goitre
Thyroid swelling associated with iodine deficiency, low levels of thyroxine result in increased secretion of TSH
Where are the parathyroid hormones situated
The 4-5 parathyroid gland lie on the deep surface of the thyroid gland
They produce parathyroid hormone which is involved in regulation of blood calcium levels
What hormones does the islets of langerhans in the pancreas produce
- insulin
- glucagon
- somatostatin
How much of the pancreas is occupied by the islets of langerhans
Occupy 1-2% of pancreatic tissue
When is insulin produced
Released in response to raised blood glucose, acts to lower blood glucose
Facilitates glucose entry into -
- muscle cells
Promotes formation of -
- glycogen
- triglycerides
- facilitates protein synthesis
What does insulin inhibit
The secretion of adrenaline, sympathetic nerves, somatostatin
When is glucagon produced
In response to low blood glucose concentration, acts to raise blood glucose
What are the actions of glucagon
Glycogenolysis in liver
Glucogenesis in liver
Lipolysis and ketone synthesis
Where are the adrenal glands located
They lie on top of the kidneys
What cortex hormones do adrenal glands produce
- aldosterone
- cortisol
- androgens
What are the actions of cortisol
- metabolic effects
- permissive effects
- anti-inflammatory, immunosuppressant
What are the functions of aldosterone
Promotes re absorption of Na+ and H2O in kidney
Increases excretion of H+ and K+
Describe androgens
The main hormones are androgens which contributes to growth and 2 percent of sexual characteristics in boys and girls
Pubertal growth spurts
Describe the adrenal medulla
This is a modified sympathetic ganglion
Controlled by pre ganglionic sympathetic nerves
The cells mostly produce adrenaline
What can adrenal insufficiency lead to
Addison’s disease, decreased adrenal function and reduced levels of adrenal hormones
