endocrine pt 1 Flashcards
example of autocrine communication substance
prostaglandins
example of paracrine communication substance
somatostatin on insulin secretion
what does autocrine mean
cell secretes substance into interstitial fluid, substance then effects that same cell
what does paracrine mean
substance is released into interstitial fluid and then effects neighbouring cell
where are hormones secreted from in neuroendocrine messages
nerve cells
where do neurones store hormones
in granules in the axon terminal
2 examples of hormones secreted by neurones
oxytocin and arginine vasopressin
what is another name for arginine vasopressin
ADH - antidiuretic hormone
4 different types of endocrine hormones
peptide, steroid, hormones derived from tyrosine and eicosanoids (prostaglandins)
peptide hormones
strings of amino acids, includes those from hypothalamus, anterior and posterior pituitary glands, pancreas and GIT
steroid hormones
derived from cholesterol, includes cortisol, aldosterone and sex hormones
hormones derived from tyrosine
thyroid hormones and catecholamines
where are the catecholamines secreted from
adrenal medulla
examples of catecholamines
adrenaline and noradrenaline
where are cortisol and aldosterone produced
adrenal cortex
what effect does the chemical make up of a hormone have on it
effects the way they are synthesised, stored, transported and how they act
peptide hormone synthesis
they are secreted out the cell, synthesised in same way that proteins are when they are exported
steps of peptide hormone synthesis
- transcription of gene into mRNA
- translation in ribosome (RER)
- pre signal is cleaved
- now a prohormone -> goes to the golgi complex
- hormone is packaged into secretory granules
- exocytosis
what is preprohormone
first molecule made in peptide hormone synthesis, has a “pre” segment which is a hydrophobic signal peptide. Tells the cell there needs to be more processing and packaging
Steroid hormone synthesis
cholesterol converted by enzymatic conversions into a hormone
steroid hormone transportation
must be bound to plasma carrier proteins to travel in aqueous blood plasma as they are lipophilic
peptide vs steroid and thyroid: solubility
peptide are hydrophilic and the others are lipophilic
peptide vs steroid and thyroid: binding to plasma proteins
peptide are free hormones so don’t bind but thyroid and steroid do with weak, reversible bonds
peptide vs steroid and thyroid: half life
peptides have a half life of minutes whereas the others have hours steroid /days thyroid
what does binding to plasma proteins do, other than transport, for hormones
delays metabolism, provides circulating reservoir of hormones, biologically inactive
peptide hormone action
interact w plasma membrane receptors
2 types of plasma membrane receptors that peptide hormones interact w
G protein receptors, tyrosine kinase linked receptor
what physiological response is a result of the signal transduction triggered by peptide hormones
altered enzyme activities, ion channel activity change, altered expression of specific proteins
steroid and thyroid hormone action
interact with intracellular receptors which are regarded as hormone-regulated transcription factors
examples of receptors that steroid and thyroid hormones interact with
cytosolic and nuclear receptors
what happens when the steroid hormone/ thyroid hormone binds to the receptor
the complex then goes and binds to the promotor of specific genes and effect gene expression
what is the endocrine axis
interactions between the hypothalamus, pituitary and peripheral endocrine glands which show feedback regulation
what effects what in the endocrine axis (general model)
hypothalamus releases releasing hormone which stimulates or inhibits the anterior pituitary which releases tropic hormone which stimulates peripheral endocrine gland which releases peripheral hormone which leads to a target cell response
what happens if the peripheral hormone level is too high
activation of the negative feedback loops which decrease effects of the hypothalamus and the anterior pituitary
what does the short feedback loop from the tropic hormone effect
hypothalamus
what does some feedback from the target cell effect
hypothalamus
what are neuroendocrine reflexes
when there is input from higher centres in the brain e.g. stress increasing hypothalamus activity which leads to cortisol release
what is the diurnal rhythm
day-night hormone levels
what is the circadian rhythm
cycle of hormone levels in a day
what does hypersecretion mean
hormone excess
what does hyposecretion mean
lack of hormone
why would someone have decreased target-cell responsiveness
due to differing receptor levels and downstream enzyme levels
what is a primary endocrine disorder cause
when it is associated with gland that makes the hormone
what is a secondary endocrine disorder cause
due to another condition or abnormal hypothalamic -pituitary secretion of tropic hormone
what is cushings syndrome
excess cortisol
treatment for hormone deficiency
hormone replacement
treatment for hormone excess
block production w drugs
treatment for decreased cell responsiveness
drugs to enhance cellular response
treatment for tumour effecting hormone levels
radiotherapy or surgery
