Introduction to Endocrinology Flashcards
what makes up the endocrine system?
discrete glands/cells that secrete hormones
what do the hormones of the endocrine system do?
regulate chemical reactions in cells - controls functions of other organs, tissues and cells
what are the principle functions of the endocrine system?
Homeostasis of the internal environment of the body (Maintenance of optimum biochemical environment)
Integration and regulation of growth and development
Control of sexual reproduction, including gametogenesis, fertilisation, foetal growth and development and nourishment of the newborn
what are the endocrine organs?
- Pituitary gland
- Pineal gland
- Thyroid gland
- Parathyroid glands
- Adrenal: 2 glands
- Cortex
- Medulla
where are endocrine glands present in other organs?
- Pancreas
- Thymus
- Gonads
- Hypothalamus
what are the endocrine cells in the GI tract?
Diffuse neuroendocrine system (DNES)
what are the endocrine cells in the heart?
atrial natriuretic peptide (ANP)
what is the function of the ANP?
Stimulates kidney to secrete more salt & decreases excess blood volume, high BP and high blood sodium concentration
what is the role of the endocrine cells in the kidneys?
Juxtaglomerular cells secrete renin
– Renin indirectly signals adrenal cortex to secrete aldosterone
Erythropoietin: signals bone marrow to increase RBC production
what are hormones?
Chemical messengers act as molecular triggers
what are the effects of hormones dependent on?
The effects are dependent on the programmed response of the target cells
what are the basic categories of hormones?
modified amino acids polypeptides glycoproteins steroids fatty acid derivatives - eicosanoids
how is hormone secretion controlled?
controlled by receptor-mediated feedback loops
what are the 3 mechanisms of hormone release?
- humoral
- neural
- hormonal
what hormone is released through the humoral mechanism?
PTH
what hormone is released through the neural mechanism?
catecholamines
how does the humoral mechanism of hormone release work?
low concentrations of Ca2+ stimulates secretion go PTH
how does the neural mechanism of hormone release work?
preganglionic SNS fibres stimulates adrenal medulla cells to secrete catecholamines
how does the hormonal mechanism of hormone release work?
the hypothalamus secretes hormones that –> stimulates the anterior pituitary gland to secrete hormones–> that stimulate other endocrine glands to secrete hormones
where is the hypothalamus?
Located at the base of the brain
how does the hypothalamus control the endocrine system?
by controlling the pituitary gland
what does the hypothalamus do?
provides communication between the nervous system & the endocrine system
how does the hypothalamus control the pituitary gland?
- Secretes releasing hormones to cause the pituitary to release hormones
- Secretes inhibiting hormones to turn off secretion of pituitary hormones
what does TRH (thyroid releasing hormone) stimulate?
release of TSH
what does CRH (corticotropin releasing hormone) stimulate?
release of ACTH
what does GnRH (gonadotropin releasing hormone) stimulate?
release of FSH & LH
what does PRF (prolactin releasing hormone) stimulate?
release of PRL
what does GHRH (growth hormone releasing hormone) stimulate?
release of GH
what does PIF (prolactin inhibiting factor) inhibit?
PRL
what does GH inhibiting hormone inhibit?
growth hormone
what hormones does the posterior pituitary release?
ADH (antidiuretic hormone or vasopressin)
oxytocin
what is the function of ADH?
stimulates the kidneys to reclaim more water from the urine, raises blood pressure
what is the function of oxytocin?
prompts contraction of smooth muscle in reproductive tracts, in females initiating labor and ejection of milk from breasts
what does the anterior pituitary gland release>
- Melanocyte stimulating hormone (MSH)
- Adrenal corticotropic Hormone (ACTH)
- Thyroid stimulating hormone (TSH)
- Luteinizing Hormone (LH)
- Follicle stimulating Hormone (FSH)
- Prolactin (PRL)
- Growth Hormone (GH)
what are tropic hormones?
hormones that regulate other hormones