Intro Flashcards
define the endocrine system
integration and control of organ function via the secretion of chemical (HORMONES) from CELLS, TISSUES OR GLANDS which are the carried in the BLOOD to DISTAL target organs where they influence the activity of the organ.
define a paracrine chemical
a chemical that acts local to the site of synthesis. e.g. histamine
what is an autocrine chemical?
something which acts on/in the same cell that synthesises the hormone. e.g. cytokines
what is an exocrine chemical?
it is a chemical released from the exocrine gland via ducts to the external environment including the GI tract
e.g. salvia, sweat, bile
how do hormones travel to their target organs/tissues?
through the blood
how do tissues detect hormones?
through specific receptors for the chemical on/in the cell
why are neurotransmitters not hormones?
they act locally within the synaptic cleft (not distally)
what is provided by the endocrine and nervous system acting together?
further control, particularly for long term phenomena such as growth.
what releases neuroendocrine hormones?
nerve cells
true or false:
the same hormone will have the same effect no matter what target cell it is acting upon?
False
the same hormone can have different effects in different target cells.
give some examples of physiological systems that have an embedded endocrine function
> reproductive
renal
gastrointestinal
name some endocrine glands
> thyroid gland
adrenal gland
pituitary gland
hypothalamus
is the endocrine system an anatomical system or functional system?
functional
at what concentration do endocrine hormones exert their effects?
in the range: 10^-9 to 10^-12 M (pico molar range)
name 3 classification of the endocrine hormone
> peptides (proteins)
steroids
amine
from what are peptide hormones composed of?
chains of amino acids
what hormones are derived from cholesterol?
steroids
from what are amine hormones derived from?
one of two amino acids: either tryptophan or tyrosine
name the hormone derived from tryptophan
melatonin
true or false:
peptide hormones are synthesised in advance and stored in vesicles until required
true
what is the name of the initial protein produced by ribosomes in peptide hormone synthesis?
preprohormone
what do preprohormones contain?
one or more copies of the active hormone in their amino acid sequence
how are preprohormones changed into prohormones?
they are cleaved into smaller units in the rough endoplasmic reticulum
