Lecture 22 Flashcards
Compare the endocrine system to the exocrine system:
The endocrine system is ductless and secretes into the surrounding interstitial fluid/blood. The exocrine system involves products secreted on the epithelial surfaces of the skin via ducts.
Name the three different types of hormones and briefly describe them:
- Classical hormones that are secreted by endocrine organs that then enter the blood
- Neurohormones- released from the end of the neurons and travel to the target cell
- Local hormones- immediate facility, paracrine- neighbouring cells,
What are the three main classifications of hormones based on their structure?
- Amide hormones- single amino acid
- Protein hormones- synthesised as much larger non active hormones
- Steroid hormones- lipid molecules derived from the cholesterol, example is glucocorticoids (cortisol)
What are the main methods of communication for hormones with target cells?
- surface receptors, hormone doesn’t enter the cell
- binds to the surface receptor activating a second messenger
What are the two lobes of the pituitary gland?
- anterior pituitary
- posterior pituitary
What is the function of hypo-physiotropic hormones?
Tropic hormones can be inhibitory or stimulatory in acting on the anterior pituitary gland.
What is the main function of the hypothalamus and anterior pituitary gland?
This system regulates the release of a wide variety of other hormones
What is the main function of the hypothalamic/pituitary portal system?
connects the hypothalamus and the anterior pituitary system together
What is the function of thyrotropes?
Stimulates the release of thyroid stimulating hormone from the anterior pituitary, this then activates the thyroid gland to release a wide variety of thyroid hormones
What is the function of gonadotropes?
Releases luteinising hormone (LH) and follicle stimulating hormone (FSH) that will then produce male androgens and female (oestrogen and progesterone)
What is the function of lactotropes?
Release prolactin from the breast
What is the function of corticotropes?
Adrenocorticotropic hormone (ACTH) which then acts on the adrenal cortex to release cortisol.
What is the function of somatotropes?
Release growth hormone that then acts on the liver and other cells throughout the body
Where is oxytocin synthesised?
supraoptic and paraventricular nuclei of the hypothalamus
Where is oxytocin stored?
posterior pituitary
What are the signals for the release of oxytocin?
massage of the udder, stretching of the cervix, sound of young
What is the function of oxytoxin?
Parturition-increasing the strength and frequency of uterine contractions
Where is antidiuretic hormone synthesised?
supraoptic and paraventricular nuclei of the hypothalamus
Where is antidiuretic hormone stored?
pituitary gland
What are the signals for release of anti-diuretic hormone?
Osmoreceptors - increase in extracellular fluid osmolality
Baroreceptors - low blood volume and/or pressure
What is the function of ADH?
- acts as a second messenger to increase water re-absorption
What are the two different feedback mechanisms that occur for the release of the pituitary gland hormones?
Short feedback loops- inhibition from the anterior pituitary hormones to the hypothalamus
Long feedback loops- inhibition from the target cell.
What are the two main types of diabetes insipidus that occur and what usually causes them?
Diabetes is a form of diabetes associated with insulin. Central DI failure of ADH secretion/synthesis. Nephrogenic DI inappropriate renal response to normal levels of ADH
How can you tell the difference between the two different types of diabetes insipidus?
If administering ADH results in urine production then the problem will be central.
