Quiz 1 Endocrine Flashcards
Physiological signals
-Electrical and Chemical
Electrical signals
changes in the membrane potential of a cell
Chemical signals
-secreted by cells into ECF
-responsible for most communication within the body
- chemical signals can be classified by their sources and targets
Cell to cell communicaton
Target cells or targets, respond to signals.
Cell to cell communication molecules
-chemical signals
-secreted by a cell or group of cells
-transported by blood
-distant target tissue receptors
-activates physiological response at low concentrations
Cellular mechanism of action
-depends on binding to target cell receptors
-initiates biochemical responses
Lipid soluble hormones
-steroids, T3 and T4
-bind intracellular receptors
-receptor is often a transcription factor
-directly affect gene expression
Lipid insoluble hormone
-must bind surface receptors
-variety of types and functions
-generally, require signal transduction
-second messenger systems
G-protein couple receptors
-membrane-spanning proteins
-cytoplasmic tail linked to G protein, a three-part transducer molecule
When G proteins are activated
-open ion channels in the membrane
-alter enzyme activity on the cytoplasmic side of the membrane
Control over hormone levels
-HPA (hypothalamic pituitary axis)
-Humoral
-Neural
Hypothalamus
- master control center of endocrine system
-communicates with the rest of the endocrine system via the anterior-pituitary
-directs the activity of the anterior pituitary via releasing and inhibiting hormones
-releasing hormones simulate AP to release tropins
Anterior pituitary
true endocrine gland
-responds to releasing hormones from hypothalamus
-secretes tropins or tropic hormones
posterior pituitary
-extension of hypothalamus
-contains axons of neurons whose cell bodies are in hypothalamus
-secretes neuroendocrines
humoral control
some glands are able to directly control levels of their own hormones.
-monitor body fluids and alter hormone levels as needed