The Endocrine System - Hormones (w9) Flashcards
What is neurotransmission and what is there chemical messenger ?
Nerve to nerve transmission
- uses noradrenaline , acetylcholine and others
What is neuroendocrine communication and what is its chemical messengers ?
Nerve to target cell transmission
- uses oxytocin and ADH
What is endocrine communication and what chemical messenger does it use ?
Secreting cell —> blood vessel —> target cell
- uses insulin, TSH, thyroxine and cortisol
What is paracrine communication and what hormones does it use ?
Secreting cell —> target cells
- uses glucagon and somatostatins
What is autocrine communication and what’s hormones does it use ?
Secreting cell —> secreting cell (released hormone can act on cell released from)
- uses prostaglandins
What is the definition of a hormone ?
Hormones are chemical substances that act like messenger molecules in the body.
What happens when a gland secretes a hormone ?
A gland secretes a hormone directly into the blood stream (ductless) this hormone is then carried to the target cells/ tissue (away from the endocrine gland)
What is the chemical structure of a peptide hormone and give example of both short and large chains ?
- chemical structure: chain of amino acids
- short chain = TRH contains 3 amino acids
- large chain = LH/FSH contains 80 amino acids
Where are peptide hormones secreted from ?
Hypothalamus, pituitary gland, pancreas and GIT (gastrointestinal tract)
How are peptide hormones released and do they require a stimulus ?
Released via exocytosis
Require stimulus
How are peptide hormones transported, what is a negative of the way they are transported ?
-They are hydrophilic so freely circulate in blood vessels.
-This means no plasma protein binding is required.
- a negative of this is they are easily destroyed due to no binding to proteins this causes them to have a shorter Half life (minutes)
What is the chemical structure of a steroid hormone ?
Give examples and where they are secreted from …
Chemical structure = has a cholesterol base
- cortisol and aldosterone - secreted form adrenal cortex
- sex hormones - secreted from gonads
How are steroidal hormones synthesized ?
- enzymatic conversion occurs of the precursor (cholesterol base) molecules into the hormones.
- these aren’t stored in cells.
How are steroidal hormones transported ?
They are lipophilic so bind with plasma proteins. When they bind to these proteins they become inactive so need to be released to become active again.
- they have a Half lift of hours to days.
What is the chemical structure of tyrosine containing hormones ?
Give an example of this hormone and where it is secreted from …
- chemical structure = contains a tyrosine base
- thyroid hormones and catecholamines —> secreted from the adrenal medulla
How are tyrosine containing hormones released ?
Is a stimulus required ?
A stimulus is required
Released by simple diffusion across a membrane
How are tyrosine containing hormones transported ?
-They are lipophilic
-They bind with the plasma proteins and form weak bonds, this means they are reversible so can easily unbind.
-Have a half life of hours to days
What is the chemical structure of eicosanoid hormones ?
Give some examples of these hormones …
- chemical structure = a polyunsaturated fatty acid derivative
- examples = prostaglandins, leukotrienes, prostacyclin, thromboxane
How are eicosanoid hormones released ?
Is a stimulus required ?
They are released by poorly diffusing through the cell membranes
They require a stimulus
What is negative feedback ?
When the outcome negatively controls a process - maintains the original threshold/ tales levels back to normal or equilibrium.
What is a positive feedback mechanism ?
When an outcome amplifies the process (the outcome is increased in comparison to normal levels)
What is the correct receptor for a cortisol hormone ?
Glucocorticoid receptors
What is the corresponding receptor for the aldosterone hormone ?
Mineralocorticoid receptor
What classification of hormones is released form the pituitary gland ?
Peptide hormones
What is hyper-secretion ? and give and example of an endocrine disorder caused by this ….
Hyper-secretion = hypothalamus/ glands are secreting too much of a hormone, resulting in there being an excess amount of a hormone.
E.g. ACTH or cortisol
Tumour or immunological factor e.g. Graves’ disease
What is hyposecretion ? Give and example of an endocrine disorder caused by this …
Hyposecretion = the glands aren’t secreting enough or sufficient amounts of hormones, not enough hormone produced.
Type 1 diabetes Mellitus , genetic, immunological attack, surgical removal, destruction by disease
What is a primary defect ?
Which hormones will you have more of ?
Any defect related to the peripheral endocrine gland
- low CRH and ACTH
- high cortisol
What is a secondary defect ?
What hormones will be in excess/ have more of ?
-any defect related to the pituitary gland
- more CRH and cortisol
What does ectopic mean ?
The defect is external to the hypothalamus pituitary axis (HPA axis)
- these defects are harder to diagnose
