Overview Flashcards
Definition of endocrinology
The study of hormones and their glands of origin, their receptors, intracellular signalling pathways, and their associated diseases
Definition of hormone
A regulatory substance produced in an organism and transported in tissue fluids (i.e. blood) to stimulate a specific cellular tissue into action
Definition of endocrine
Glands which secrete hormones or other products directly into the blood
Definition of exocrine
Glands which secrete their products through ducts opening on to an epithelium rather than directly into the blood
Name the key organs of the endocrine system
Pituitary, thyroid, parathyroid, adrenal glands, pancreas, ovaries, testes
What is the endocrine hormone action?
Blood borne, acts at distant sites
What is the paracrine hormone action?
Acting on adjacent cells
What is the autocrine hormone action?
Feedback on the same cell that secreted the hormone
Give features of the functional anatomy of water-soluble hormones
- Transported unbound
- Bind to surface receptor on cells
- Have a short half-life
- Are cleared fast
Give examples of types of water-soluble hormones
Peptides and monoamines - both stored in vesicles
Give features of the functional anatomy of fat-soluble hormones
- Transported bound to protein
- Diffuse into cells
- Have a long half-life
- Are cleared slowly
Give examples of types of fat-soluble hormones
Thyroid hormones and steroids (synthesised on demand)
Name the four classes of hormones
- Peptides
- Amines
- Iodothyronines
- Cholesterol derivatives and steroids
Give features of peptide hormones
- Vary in length
- Stored in secretory granules in the cytoplasm
- Hydrophilic and water soluble
- Cleared by the tissue or circulating enzymes
- Synthesised first as preprohormones then processed (by ER and Golgi) to prohormones
Describe how insulin is activated to cause glucose uptake
- Insulin binds to its receptors
- This causes the receptor to be phosphorylated
- The secondary messenger, tyrosine kinase is activated
- There is phosphorylation of the signal molecules
- Cascade of effect
- Glucose uptake
Give features of amine hormones
- Water soluble
- Stored in secretory granules
- Released in pulses
- Have rapid clearance
- Synthesis = Phenylalanine -> L-Tyrosine -> L-Dopa -> Dopamine -> Noradrenaline -> Adrenaline
- Rate limiting step is conversion to L-DOPA
What does cortisol do in relation to noradrenaline?
Converts noradrenaline to adrenaline
Name some physiological reactions that alpha receptors are responsible for
- Vasoconstriction
- Pupil dilatation
- Bowel muscle and anal sphincter contraction
- Sweating
- Anxiety