what is a hormone ?
a chemical messeger secreted into the blood by cells
what is the difference between exocrine vs endocrine glands
exocrine gland has a duct and it secreted on to the epithilium surface
endocrine has no duct and secretes via blood
what the 4 functions of a hormone
- growth
- metabolism
- regulates internal enviroment
- reproduction
what happens when you remove the testes from a chicken ?
it reduced masculine behaviour and phenotype
what are 4 things about the classical hormone ?
- secreted from epithilian tissue that make glands
- secreted into blood
- targets are far
- acts at low concentration
what are 3 things about non classical hormones?
- secreted by neurons, immune or endocrine cells
- acts locally
- can be a neurotransmitter
what are the target cells for a hormone ?
must have receptors for that specific hormones and they can increase and decrease sensitivity of a hormone by increasing/ decreasing receptor expression
what are 3 ways to remove hormones from receptors
- inactivtation of hormone through kidney
- proteases break them down
- endocytosis by target cells
what are 4 key facts about peptide/protein hormones
- dont live long ,short half life
- largest group of hormones
- hydrophilic- bind to membrane receptors
- fast signal transduction
where are peptide/protein hormones made ?
in the secretory pathway
how are amine hormones made ?
it is made from trytophan or tyrosine
what hormone is tryptophan and where is it from ?
melatonin hormone an from pineal gland(brain)
what hormones do tyrosine make
- catechol amine which are neurohoromones etc dopamine epinehprine
- thyroid hormones
what are thyroid hormones and where is it made ?
an intercellular hormone t4 and t3 that are made via epithelial cell in the thyroid gland
what differentiates thyroid hormones and catechol amine
based on iodine molecules as thyroid hormones have them
what are 4 facts about steroid hormones?
- made in only a few organs etc adrenal cortex , gonands and placenta bc they must have cleaving functionality
- they are small
- need to be cleaved
- long half lives
how are steriods made
they are imported or made within the cells they are made on demand by increased enzyme activity and are usually bound to protein and have lots of smooth ER
what type of steriods does the adrenal gland produce from cholesterol?
cortisol and aldosterone
what type of steriods does the ovaries produce from cholesteral
estradial and progesterone
what type of steriods does the gonads produce ?
testerone (DHT)
what is the steriod pathway ?
- intracelluar ligand
- bind to receptors
- activates transcription factors
- makes new protein
etc aldestrerone
what is an example of the endocrine reflex pathway?
- hyper kalemia ( high K+)
- adrenal cortex
- aldersterone. (travels blood)
- kidenys
- save na + loose k +
6 decrease potassium
where are key neurohormone made ?
adrenal medulla -epinphrine
hypotalamus - vasopressin
what is made in the posterios pitutary gland ( neuro hypophysis)
vasopressin through neurons then released into blood
