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