Endocrine Control Review Flashcards
What is a hormone?
a blood borne chemical mediator released from an endocrine gland that acts on distant target cells
What is a neurocrine signal?
a signal that travels down a neuron axon and is then released into the blood to act on a distant target with the appropriate receptor
What is a paracrine signal?
a signal from one cell type to a differing neighbouring cell type via diffusion
What is an autocrine signal?
a signal from one cell to a neighbouring identical cell or back to itself via diffusion
What is a tropic hormone?
a hormone that controls the secretion of another hormone
What is a trophic hormone?
a hormone that stimulates growth and development
Where is the receptor for hydrophilic hormones?
on the cell membrane
Where is the receptor for hydrophobic hormones?
intracellular
What is an example of a peptide hormone?
insulin
What is the half life of peptide hormones?
short
What is the half life of steroid hormones?
long
What is an example of a steroid hormone?
oestrogen
Are peptide hormones hydrophobic or hydrophilic?
hydrophilic
Are steroid hormones hydrophobic or hydrophilic?
hydrophobic
What are the two types of amine hormones?
catecholamines and thyroid hormones
Are catecholamines hydrophobic or hydrophilic?
hydrophilic
Are thyroid hormones hydrophobic or hydrophilic?
hydrophobic
What is an example of a catecholamine?
adrenaline
What is the mechanism of action of hydrophilic hormones?
activate a second messenger system
What is the mechanism of action of hydrophobic hormones?
alter gene transcription
What factors influence plasma hormone concentration?
rate of secretion, rate of metabolic activation, extent of binding to plasma proteins, rate of inactivation and excretion
How are steroid hormones removed from the body?
conjugation
How are amine hormones removed from the body?
circulating degrading enzymes
How are large peptide hormones removed from the body?
receptor mediated endocytosis
How are small peptide hormones removed from the body?
by the kidney
What is antagonism?
hormones acting together but in opposite directions
What is synergysm?
hormones acting together where the effect is more than additive
What is permissive?
first hormone cannot exert its effect without presence of second hormone
What is a primary endocrine disorder?
where the gland is abnormal
What is a secondary endocrine disorder?
where the gland is normal but secretion is abnormal
What would be the levels of CRH, ACTH and cortisol in a secondary hypersecretion due to hypothalamic pathology?
high CRH, high ACTH, high cortisol
What would be the levels of CRH, ACTH and cortisol in secondary hypersecretion due to anterior pituitary pathology?
low CRH, high ACTH, high cortisol
What would be the levels of CRH, ACTH and cortisol in primary hypersecretion due to adrenal pathology?
low CRH, low ACTH, high cortisol
