endocrine systems and receptors Flashcards
how do ligand gated ion channels open?
-hormone binds to ligand gated ion channel causing them to open
how do G protein couples receptors work?
- the ligand agonist (hormone) will bind to the membrane bound G protein coupled receptor causing a conformational change
- this allows the G alpha subunit to bind to the G protein coupled receptor
- The GDP bound to the alpha subunit becomes GTP, activating the alpha subunit, allowing it to bind to an adjacent enzyme causing a cellular response
- the G alpha subunit stop signalling once GTP becomes GDP again
where are a2 adrenoceptors located?
the gut
summary table of G protein coupled receptors!! (not question)
what unique about kinase linked receptors?
-you can get lots of different cellular responses
how long is the cellular response in kinase linked receptors?
the response can be going on for hours e.g. insulin binding to insulin receptor
what is autocrine regulation
when chemicals (i.e. signalling molecules) released from the cells bind to receptors on or in the cell that is releasing them (gives negative feedback)
what is paracrine regulation?
chemicals (i.e. signalling molecules) released from the cells bind to receptors on adjacent cells
what is endocrine regulation?
chemicals (i.e. hormones) released from the secretory cells are usually transported via the circulatory system
what provides the highest level of endocrine control?
hypothalamus
what is the endocrine director?
hypothalamus
how does the hypothalamus integrate activities of nervous and endocrine system ?
by:
- secretion of regulatory hormones
- synthesys of hormones
- direct neural control
True or False
Hormone levels are not influenced by the rate at which they are eliminated from the body?
False
Hormones are influenced by the rate at which they are eliminated from the body
what affect does cortisol have on glucose?
cortisol triggers gluconeogenesis and so increases blood glucose
what are the 3 classes of hormones?
- steroids
- amine dervies
- proteins
whats an example of a steroid hormone?
oestrogen
whats an example of an amine derived hormone?
- adrenaline
- epinephrine
whats an example of a protein hormone?
- oxytocin
- ADH
- growth hormone
- insulin
what are steroid hormones derived from?
steroids are lipids derived from cholesterol
are steroids hydrophobic or hydrophilic?
hydrophobic
how are steroids transported in blood?
-transported in blood plasma by binding to carrier proteins (about 90%)
when are steroids biologically active?
when they are free or unbound
are peptide hormones hydrophilic or hydrophobic?
hydrophilic
how are peptide hormones transported in the blood?
unbound or ‘free’ in blood plasma
where are peptide hormones secreted?
by pituitary, parathyroid, heart, stomach, liver and kidneys
how are peptide hormones synthesised and stored?
they are synthesised as precursor molecules and stored in secretory vesicles
are amine hormones hydrophobic or hydrophilic?
hydrophilic
how are amine hormones transported?
- catecholamine amine hormones are hydrophilic and are transported unbound or ‘free’ in blood plasma
- thyroid amine hormones are bound to carrier proteins
where are amine hormones secreted from?
-thyroid and adrenal medulla
whats an example of an amine hormone?
adrenaline
what are amine hormones derived from?
derived from amino acids (e.g. adrenaline derived from tyrosine)
how are steroid and thyroid hormones transported?
-they are insoluble in plasma and are transported in blood via carrier protein
what does binding of steroid and thyroid hormones to the carrier proteins do for the hormones?
- facilitation of hormone transport
- increased half life of hormones
- a reservoir for the hormone
what does cortisol- binding globulin (CBG) bind to?
-it is a specific carrier proteins and so binds to cortisol in a selective manner (also some aldosterone)
what does thyroxine-binding globulin (TBG) bind to?
it is a specific carrier protein so binds to thyroxine T4 selectively (also some triidothyronine T3)
what does sex steroid binding globulin (SSBG) bind to?
it is a specific carrier protein so mainly binds to testosterone and oestradiol
Hormones secreted by hypothalamus and pituitary gland table (no question)
hormones secreted by endocrine glands table (no question)
hormones secreted by endocrine glands table (no question)
examples of endocrinopathies (no question)
examples of endocrinopathies (no question)
