1 Endocrine System Flashcards
what is paracrine communication?
products of secretion affects neighbouring cells
what is exocrine secretion?
products of secretion released into a body cavity
what is the main feature of endocrine glands?
ductless glands
what forms can hormones come in?
proteins, polypeptides or lipids
what examples of hormones are at constant levels?
thyroid hormones
what is an example of a hormone that is at a variable level?
hormones such as epinephrine
what is an example of a cyclic level hormone?
reproductive hormones
what are amine hormones?
derivatives of the amino acid tyrosine
what are examples of amine hormones?
dopamine, T3 or T4
what are peptide hormones?
the majority of hormones, may also serve as neurotransmitters
what are steroid hormones?
produced by the adrenal cortex and the gonads
what are examples of steroid hormones?
cortisol or oestrogen
how can hormones travel in the blood?
water soluble hormones travel dissolved in plasma, there circulate in the blood bound to plasma proteins
how are hormones broken down?
either excreted by kidneys or metabolised in blood or target cells
what is up regulation?
a low concentration of a hormone is compensated for by an increase in number of receptors
what is down regulation?
a high concentration of hormone compensated for by a reduction in number of receptors
what is antagonism?
a hormone reducing the number of receptors available for a second hormone resulting in decreased effectiveness of the second hormone
what is permissiveness?
a hormone increasing receptors available for second hormone making it more effective
what are catechalomines?
hormones made by the adrenal gland
where are receptors for peptide hormones and catecholamines found?
on extracellular surface of plasma membranes
where are receptors for steroid and thyroid hormones found?
mainly on intracellular surface of the membrane or nucleus due to being lipid soluble
what action can a hormone binding to a receptor have?
open ion channels, enzyme activity, activity of kinases, turn on genes for second messengers
what does the anterior pituitary control?
functions of endocrine glands
what are the 5 main cell types of the anterior pituitary?
gonadotroph, lactotroph, somatotropin, corticotroph, thyrotroph
what do gonadotrophs secrete?
LH, FSH
what do somatotropin secrete?
somatostatin and growth hormone
what do corticotrophs secrete?
ACHT
what do thyrotrophs secrete?
thyroid stimulating hormone
what hormones are secreted by anterior in response to hypothalamus?
ACTH, TSH, GH, PRL, FSH and LH
what hormones are stored in the posterior?
MSH, Oxytocin and ADH
what is the difference between the anterior and posterior pituitary?
anterior is under control via hypothalamus, yet posterior carries out direct release of hormones
how does negative feedback occur in hypothalamus control?
the tissue targeted by the pituitary produces a hormone that causes inhibition of the hypothalamus to stop production
