Hormone signalling and structure Flashcards
what are the 3 basic components that make up the endocrine system
-endocrine gland/cell (secretes hormone)
-hormone (chemical product, release upon stimulation)
-target organ (express hormone-specific receptors, show biological responces)
different types of glands and their differences
-endocrine glands (ductless + releases substances directly into circulation, can be water-soluble via exocytosis or lipid soluble via diffusion)
-exocrine glands (release secretions via a duct into an epithelial surface (e.g. sweat glands)
definition of a hormone
physiological organic substance produced by specialized cells and released into circulating system (bloor or lymph) for transport to target tissues in distant organs to exert different actions
classical hormones are signal molecules that:
-are synthesized by endocrine cells
-are secreted into the circulation
-interact with proteins called receptors
-have specific effects on target cells
how are hormones classified
-type of signalling
-chemical structure
-solubility
types of cell signalling with hormones
-endocrine
-paracrine
-autocrine
-neuroendocrine/neurocrine
-intracrine
endocrine signalling characteristics
-when hormones enter the bloodstream/lymph and bind to hormone receptors in target cells in distance organs
-eg: beta cells in the pancreas produce and release insulin into the blood, where it travels to many tissues, including the liver, signalling it to store glucose in the form of glycogen
paracrine signalling characteristics
-when hormones bind to cells near the cell that released them (same organ or tissue)
-often degrade quickly or taken up rapidly
-eg: testosterone secreted from the leydig cells in testes act as a paracrine agent to stimulate spermatogenesis in the adjacent seminiferous tubules
autocrine signalling characteristics
-when a hormone produces a biological effect on the same cell that has released it
-eg: the lining of mammalian endometrium responds to oxytocin in an autocrine/paracrine manner to cause the production of prostaglandins (causes uterine contraction)
intracrine signalling charicteristics
-when a hormone is synthesized and acts intracellularly (in the same cell)
-does not actually leave the cell
-eg. precursor sex steroid hormones are synthesized and then converted by enzymes to active androgens/estrogens which bind to receptors within the same cell
neuroendocrine signalling characteristic
-a chemical is produced by a neuron or nervous tissue and is released into the blood stream to act on another cell type
-neurohormone
what are some major differences between a hormone and a neurotransmitter
-hormones are long lasting vs neurotrans is broken down quickly
-transmitted through blood vs transmitted through synapses
-large diversity in size vs typically just small
-continuous release of and due to a response vs typically released upon stimulation
-slow or fast response vs extremely fast action
what are some hormones that also act as neurotransmitters
-VODS
-oxytocin
-dopamine
-vasodepresent
-saratonin
what kind of endocrine action are pheromones an example of
exocrine cell signalling
what do pheromones do
-released internally to initiate response and/or communicate with another organism
-with in species for identification
-repro attractants
-repel predators
-eg: fish use to assist social behaviours, such as schooing, id of conspecifics and potential mates etc
types if pharmones
-primer
-signaler
-modulator
-releaser
primer pharmone
-causes a shift in the endocrine system of the receiving animal
-menstrual cycles matching up when is common environment
signaler pharmones
-relays information
-olfactory recognition of newborn babies by its mother (humans and non-human animals)
modulator pheromones
-influences mood or emotion, odor of a body changes with emotional state
-androstadienone and estratetraenol (steroid chemicals, simular to est and test)
releaser pheromones
-changes behaviour
-aggression, maternal behaviour, sucking from infants, sexual attraction
hormone chemistry
hormones are catigorized into four structral groups, with members of each group having some properties in common what are they
-peptides and proteins (AA based hormone)insulin
-amino acid derivatives (amines)(AA based hormones)thyroid hormones
-steroids (derived from cholesterol)sex and stress hormones ie testosterone and cortosol
-eicosanoids (fatty acid derivatives)prostoglandins
peptide + protein hormones
-constitute majority of hormones
-ranges from 3 to 200 AAs
-synthesized as preprohormones and undergo post-translational processing
-enzymes typically cleve these
examples of post-translational processing
-prehormones-> large, inactive precursors
-prohormones->smaller, inactive
-protolytic, post-translational modification
-peptide/protein hormones (bind surface membrane receptors, cellular response through signalling systems)
processing of insulin
1) prehormone of insulin is translated in the ER and peptidase cleaves the signal peptide
2) folding of the prohormone and formation of disulphide bonds. the C-peptide plays an essential role in orienting the two chains of insulin during this step
3) prohormone is then secreted into the Golgi
4) then packaged into secretory vesicles
5) prohormone convertase creates separate and distinct insulin and C-peptide molecules
6) insulin and C-peptide remain in the secretory vesicles of the beta-cell release
