Endocrine 1 Flashcards
what glands/organs make up the endocrine system?
- hypothalamus
- pituitary gland
- pineal gland
- thyroid gland
- parathyroid gland
- adrenal gland (on top of the kidneys)
- testes (male)
- ovaries (female)
- pancreas
- thymus
- stomach
- kidneys
- liver
what endocrine gland is the control centre for the release of many other hormones (central coordintating hub for the endocrine system)
- hypothalamus
explain how hypothalamus pituitary axis (negative feedback loop) works using low levels of thyroid hormone as an example
- the hypothalamus detects low levels of the thyroid hormone in the blood stream , it secretes TRH (thyrotropin releasing hormone)
- TRH stimulates the anterior pituitary gland to secrete thyroid stimulating hormone (TSH)
- TSH then binds to receptors on the thyroid gland, stimulating the increase secretion of T3 and T4
- when levels return to normal, this signals to the hypothalamus and the anterior pituitary gland to stop production of TRH and TSH
Endocrine dysfunction can be divided into primary and secondary dysfunction: what is primary?
Dysfunction in the secreting gland
(hypothalamus and anterior pituitary functioning normally)
resulting in either:
- over production (autoimmune disease, exocrine gland tumours)
- underproduction (autoimmune disease, drug SE)
Endocrine dysfunction can be divided into primary and secondary dysfunction: what is secondary?
secondary dysfunction is failure of the HP control (either the hypothalamus or the anterior pituitary), target endocrine gland is functionally normally
examples
- pituitary tumours (excessive stimulating hormone production)
- hypothalamic dysfunction (brain tumours, previous brain surgery, radiotherapy, traumatic brain injuries, congenital disorder)
what are the 2 types of pituitary hormones?
functional - tumour promotes secretion of an active hormone
non-functional - consists of tissue that has no hormone secreting ability, but if they groow large enough they can create a pressure effect on the pituitary gland or tissue, which can prevent production of stimulating hormones
what is an adenoma?
a tumour of epithelial tissue with glandular origin
what surgery approach is taken to remove tumours from the pituitary gland?
trans-sphenoidal approach
- access through nasal passage to sphenoid sinus
What regulates the release of growth hormone (GH)
the hypothalamus releases GHRH which stimulates the pituitary gland to release GH
what is the difference between insufficient GH in children vs adults?
children = growth failure
adults = metabolic changes (increased fat)
What is the result of excess GH in adults and children?
children = giantism
adults = acromegaly
What blood tests are used to diagnose excess GH?
IGF-1 (insulin like growth factor 1) is measured
persistently high levels of IGF-1 after puberty suggest acromegaly
what is acromegaly?
abnormal growth of certain tissues (hands, feet, and face) caused by overproduction of growth hormone by the pituitary gland.
slow onset
usually in adults 30-50 years old
what is the most common cause of acromegaly?
benign pituitary tumour
what are the physical effects of acromegaly?
- enlarging of the superior orbital ridges
- mandibular prognathism
- broad nose, thickened lips, macroglossia and soft tissues
- enlarged feet and hands
- deepening of voice
