Endocrinology Intro Flashcards
How does endocrine signalling work
A hormone is released by a cell and circulated in the blood to target specific receptors on target organs
Name the endocrine glands in the body which release hormones from specialised cells
Hypothalamus + pituitary glands
Thyroid glands and parathyroid
Adrenal glands
Pancreas
Ovaries / testes
What is another word for ovaries and testes
The gonads
It was found that not only endocrine glands release hormones: what else (specialised tissues)
Kidney, platelets , WBC’s , heart muscle
Name the 4 ways hormones can interact and explain them
1- SYNERGISTIC : 2 hormones will increase the cellular response instead of 1
2- PERMISSIVE : a presence of 1 hormone will allow the other to work
3- ANTAGONISTIC : 2 hormones which oppose effect
4- COMPETITIVE : 2 hormones similar in structure compete to bind to receptor
Give an example of antagonistic hormones
Insulin and glucagon
Give an example of competitive hormones
Epinephrine and norepinephrine
Name the 3 classes of hormone and what synthesises them
Steroid - produce by modified cholesterol
Peptide - produced by amino acids
Amino acid - produced by modification of tyrosine amino acid
Which type of hormone acts on intracellular receptors (hydrophobic)
Steroid - cholesterol is hydrophobic so can pass membrane
Which type of hormone is fully hydrophilic so can act on cell surface receptors
Peptide hormones
Is amino acid hormones hydrophobic or hydrophilic
Can be both depending on type
What modifies cholesterol into steroid hormones
Enzymes
Why is steroid hormones bound to proteins when produced
Because they are hydrophobic
When are steroid hormones produced
When a hormone is in demand - they ARE NOT STORED
How can steroids produce both gonad hormones such as testosterone and also adrenal gland hormones like cortisol for stress?
Because they will have different enzymes in the different glands to modify cholesterol into different hormones
Name the types of receptor a steroid hormone can activate / bind to (intracellular)
Ligand receptor complex inducing transcription (TF receptor)
What are the 3 domains of a ligand binding TF receptor
Dna binding
Ligand / hormone binding
Transcription inducing domain
Explain what happens to a receptor in the cell when steroid hormones bind
There is a conformational change when it binds to the domain
Hinge region changes and opens up the receptor to expose the dna binding site and transcription inducer
Enters nucleus and allows transcription
What stops steroid hormones binding to intracellular receptors when transcription isn’t needed
Hsp70 protein inhibitor (blocks the hormone binding domain)
Which hormone is stored prior to release
Peptide hormones
What is the inactive form of a peptide hormone called
Prepro hormone
Where are prepro hormones stored before release
In vesicles
What type of receptors do peptide hormones usually bind to which then activates what…
Cell surface G protein coupled receptors
Activating usual cascade then secondary messengers which then allow phosphorylation
And cellular response
Are amino acids released immediately like the steroid hormones?
Yes. They release as soon as made from tyrosine
Name an example of an amino acid hormone which acts intracellular
And another that’s cell surface
Thyroid hormone = intracellular
Epinephrine (also thyroid gland) = cell surface
What would be a short term response example by cells when hormones bind
Change in metabolism eg change in glucose conc when insulin binds
What would be a long term response example by a cell
Gene expression eg when steroid hormones bind
Name the 4 ways hormones can be released and explain
1- continuous release
2- pulsatile : in short bursts
3- circadian : according to cycles eg day and night
4- released by stimulus : when stimulus is detected cause release eg glucose levels
Give an example of circadian hormones
Melatonin release only at night
Which hormone is released in short bursts (PULSATILE)
Gonadoptrophin releasing hormone
Which hormone is released continuously
Thyroid hormone
How are hormones activated and give an example
Post release modifications such as oestrogen modified from androgens
How are peptide hormones activated
Cleaving of amino acids
Name 5 ways to control hormones
1- modification : increase eg by cleaving peptides and decrease activity too
2- degradation/ excretion
3- receptor desensitisation
4- termination of intracellular responses
5- negative feedback
Give an example of a hormone receptor which gets desensitised to control the effect of hormone
Androgenic receptors stop effect of adrenaline
Give an example of how intracellular responses can be terminated to control hormone effect
Phosphatase / de phosphorylation of proteins
Name 3 ways negative feedback works
1- metabolites : eg glucose level detected and = insulin release
2- by hormone level itself
3- by a tropic hormone which is released by pituitary/hypothalamus
Where are androgens like testosterone produced
Gonads and also adrenal glands (they are steroid hormones)
