Introduction to endocrinology Flashcards
Endocrinology
A study of hormones.
Hormones
Chemical substances secreted directly into the bloodstream by specialised endocrine cells. Hormones bind to specific receptors on target cells, effecting a response.
3 main groups of hormones
- protein/peptide hormones eg. insulin
- steroid hormones eg. cortisol
- amine hormones eg. thyroxine, adrenaline
Basics of hormone action
Lipophilic (steroid) hormones can pass directly through the hydrophobic phospholipid bilayer. Water soluble (peptide) hormones require a mediator, such as a membrane receptor, to effect a response inside a cell.
Hormone regulation
- biosynthesis
- secretion
- circulation/distribution
- peripheral modification
- receptor interaction
- metabolism/excretion
Measuring hormones
1) Bioassays
2) Mass spectrometry
The endocrine system
A system of ductless glands and cells that secrete hormones directly into the bloodstream.
Endocrine glands
- hypothalamus
- pituitary gland
- pineal gland
- thyroid gland
- parathyroid glands
- thymus
- heart
- adrenal glands
- kidney
- digestive tract
- pancreas
- gonads
- adipose tissue
Anterior pituitary hormones
- ACTH; regulation of adrenal cortex
- TSH; thyroid hormone regulation
- GH; growth and metabolism
- LH/FSH; reproductive control
- PRL; breast milk production
Posterior pituitary hormones
- ADH; water regulation
- Oxytocin; breast milk expression
Feedback principle
A stimulus promotes hormone secretion to effect a response. When conditions return to homeostatic levels, the absence/reverse of the stimulus stops hormone secretion to inhibit the response.
Management of endocrine diseases
Hormone excess= BLOCK
Hormone deficiency= REPLACE
