Introduction (1) Flashcards
What is a hormone?
Chemical messenger released from one tissue carried in the blood circulation
→ producing a specific receptor mediated change in another tissue
What do hormones regulate?
Development
→ proliferation, growth, differentiation, organogenesis
Metabolism
→ energy storage, metabolic rate, temperature
Reduction
→ sexual maturity, behaviour, pregnancy, lactation
Fluid homeostasis
→ water balance, salt levels, blood volume and pressure
What are some endocrine glands?
Tissues with endocrine functions:
Brain
Pituitary
Thyroid
Thymus
Adrenal
Pancreas
Kidney
Testes
Ovary
Uterus
What hormones does the pituitary gland release?
Anterior pituitary → growth hormone, thyroid-stimulating hormone. adrenocorticotropic hormone, follicle-stimulating hormone, luteinising hormone, prolactin
Intermediate pituitary → melanocyte-stimulating hormone
Posterior pituitary → oxytocin, vasopressin, oxytocin (stored), anti-diuretic hormone (stored)
What hormones does the hypothalamus release?
Thyrotropin-releasing hormone, dopamine, growth hormone-releasing hormone, somatostatin, gonadotropin-releasing hormone, corticotropin-releasing hormone, oxytocin, vasopressin
What hormones does the thyroid release?
Triiodothyronine
Thyroxine
What hormones does the liver release?
Insulin-like growth factor (somatomedin)
Angiotensinogen
Angiotensin
ThrombopietinW
What hormones does the stomach release?
Gastrin, gherkin, neuropeptide Y, somatostatin, histamine, endothelin
What hormones does the pancreas release?
Insulin
Glucagon
Somatostatin
Pancreatic polypeptide
What hormones does the ovary release?
Progesterone
Androstenedione
Oestrogens
Inhibit
What are the endocrine organs of the brain?
Hypothalamus
Pineal gland
Pituitary gland
What are the 4 types of signalling?
Autocrine → self signalling
Paracine → signalling over short distance
Endocrine → signalling over longer distance via blood stream,
Neurocrine → via blood stream, involving neurone
What are the 2 derivations of hormones?
Derived from amino acids
Derived from lipid precursors
What are the characteristics of peptide and catecholamine hormone systems?
Changes in [plasma] → rapid
Plasma half life → short
Type of receptor → cell membrane
Mechanism → activate preformed enzymes secretory granules, constitutive + bursts
Speed of effect → rapid
What are the characteristics of steroids and thyroid hormones?
Changes in [plasma] → slow fluctuations
Plasma half-life → long (mins to days)
Type of receptors → intracellular
Mechanism → stimulate protein synthesis, direct rapid passage, related to secretion rate
Speed of effect → slow (hours to days)
How are hormones synthesised?
1 → Proteins are formed on the ribosomes attached to the ER.
2 → These nascent protein are then transferred into the ER.
3 → From here they go to the Golgi complex.
4 → In the Golgi complex the proteins are concentrated and transformed into zymogen granules.
5 → The zymogen granules released from the Gogli complex migrate to the surface of the cell.
Name 3 hormones formed from tyrosine?
Dihydroxyphenylalanie
Dopamine
Norepinephrine
What does a pre-pro-PTH consist of?
Pre-pro-peptide/protein hormone
N- signal sequence - pro sequence - biologically active sequence - c-terminal fragment sequence -C
How are steroid hormones synthesised?
More complicated than peptide
→ comes from cholesterol
→ occurs in discrete sub-cellular environments
- hydrolysis of esters and release of cholesterol
- cholesterol to pregnenolone
- processing
- diffusion
What are feedback mechanisms?
Systems in place to stop hormones working
→ positive/negative
What are tropic hormones?
Act on another endocrine gland to drive hormone secretion
What are trophic (non-tropic) hormones?
Stimulate growth of a target tissue
→ growth, metabolism or other functions
Can hormones have both tropic and trophic roles?
Yes
Why are hormones receptors important?
Hormones levels in circulation are low
→ hormone effects are mediated by specific, high affinity receptors
→ receptors are presents inside the cell or on the cell membrane
→ one molecule can effect through amplification
What are some endocrine disorders?
Excess secretion of a hormone
Deficient secretion of a hormone
Failure to response to a hormone
(due to a malfunction/defect of a receptor, or down-stream signalling)
What are some endocrine diseases?
Diabetes mellitus → insulin deficiency or insensitivity
Thyroid disease → too little or too much
Infertility → hypothalamic, pituitary, gonadal
Obesity → leptin
