ppwt 1 Flashcards
what is the classical definition of a hormone
chemical messenger released by one type of cell and carried in the bloodstream to act on distant target cell
what is the general definition of an hormone
chemical messenger released from one cell to act on another cell
what is endocrinology about
it is about communication between cells
communication between cells are required for
- growth of an organism through an increased number of cells (proliferation)
- development from the fertilized egg to large adult organism (differentiation)
- maintenance of the environment in which cells can live (homeostasis)
the 50 trillion cells in a human body is coordinated by what
by less than 24 000 protein encoding genes
what are the 3 layers of signalling network
- within cell
- between group of cells
- between tissues
in homeostasis what happen when you knock out one gene
nothing happens
what is the difference between nervous system and endocrine system
nervous : direct connection between organs
endocrine : sending chemical messages (hormones) into the circulation
where are signals generated
hormone producing cell
autocrine signaling
act upon themselves
juxtacrine signaling
act on another cell but their signal don’t go into the blood
paracrine signaling
signal released in the extracellular espace
endocrines signalling
releases in the circulation
what is the composition of endocrine gland
- parenchyma (mass of cells - they are clustered in one spot)
- blood vessels
- no ducts
what are some permanent endocrine gland
pituary, adrenal, pancreas
what are some transient endocrine glands
ovarian follucle and corpus luteum, placenta
what is the difference between protein and lipids hormones in the microscopic level
protein : rough endoplasmic reticulum, lysosome
lipid: mitochondrion, lipid droplet, smooth ER
what are 2 general characteristic of hormones
- very low in concentration
- very specific receptor
what are some examples of lipid and protein hormones
- lipids
ex : steroid, eicosanoids - proteins
ex : short polypeptide and large proteins
what are the cholesterol derivatives
vitamin D, bile acid, steroid horones
steroid hormone can be from
gonads or adrenals
some examples of the steroid hormones from adrenal
mineralocroticoids
glucocorticoids
some examples of the gonads hormones from adrenal
- estrogens
- progestogens
- androgens
steroid hormones comes from
cholesterol
steroidogenesis hormones shuttle between 2 places
er and mitochondria
cholesterol makes
pregnenelone in the mitochondria
pregnenolone can go in the ER yes or no
yes
pregnenolone will make
progesterone
estrogen cannot be produced without
androgen
testerones needs what enzyme to make estradiol
aromatase (CYP19A1)
LIPID HORMONE eicosanoid
metabolites of arachidonic acid
membrane phospholipid make arachidonic acid by wich enzyme
phospholipase a
arachidonic acid can make by the enzyme cyclooxygenase (COX1) which molecules
prostaglandins, prostacyclins and throboxanes
arachidonic acid can make by the enzyme 5-lipoosygenase which molecules
leukotrienes
