Chapter 15: The Endocrine System
The endocrine system works with which system?
Does the endocrine system use chemical or electrical messages?
The endocrine system includes
ductless glands, organs, and hormones
produce hormones in the body
have other functions but also produce hormones
Endocrine glands in the brain
hypothalamus, pituitary gland, pineal gland
Endocrine glands elsewhere in the body
adrenal gland, thyroid gland, parathyroid gland
What is a hormone?
a molecule made in a cell or a group of cells that is transported through the blood to a target cell
What must hormones have at their target cells?
Hormone-receptor binding triggers what?
biochemical changes in target cells by either second messenger systems or transcription factors
second messenger systems
hormone binds to a receptor outside of the cell and trigger activity inside of the cell
hormone enters the cell, binds to its receptor, then triggers transcription of dna, which is later transcribed to form new proteins
What turns on glands and stimulates hormone production?
3 types of stimuli in hormones
humoral, neural, hormonal
hormones are released in response to changes in blood chemistry
NT release at gland stimulates hormone release
hormones from one endocrine gland stimulate the release of hormones from another gland
For the hormone to turn off there must be what?
mechanism to stop signal activity
Hormones can be degraded in the blood by?
Are hormones released in low or high concentrations?
Hormone concentrations have to be regulated because target cells are ____________
What regulates hormone concentrations?
negative feedback loops
Hormones are classified based on?
Most hormones like insulin and growth hormones are made up of?
Hormones such ad testosterone and cortisol are made up of?
Few hormones like NE, epinephrine, and thyroid hormone are made up of?
Examples of nonpolar hormones
steroids, thyroid hormone
How are nonpolar hormones released into the bloodstream?
diffuse across the cell membrane
How do nonpolar hormones travel through the bloodstream?
use carrier proteins to deliver them to target cells
What is the lifespan of a nonpolar hormone in the bloodstream?
What is the site of action in a nonpolar hormone?
the cytoplasm and/or nucleus of the target cell
Where are the receptors of nonpolar hormones found?
inside the cell cytoplasm (steroids) or nucleus (thyroid)
What type of response is initiated by nonpolar hormones?
Examples of polar hormones
all amino acid based hormones and all amines (except thyroid)
How are polar hormones released into the bloodstream?
exocytosis (bulk discharge from vesicle)
How do polar hormones travel in the bloodstream?
dissolve in the bloodstream and arrive at the target cell unaided
What is the life span of a polar hormone?
What is the site of action of polar hormones?
outside of the cell membrane
Receptors of polar hormones are found where?
receptors are founf outside of the membrane
What response is initiated by polar hormones?
The hypothalamus produces hormones that are released to control the?
Hormones released by the pituitary gland travel to?
other endocrines glands to stimulate them to release their own hormones
Overproduction of growth hormone leads to
gigantism in children, acromeagly in adults
underproduction of growth hormone leads to
dwarfism in children
The hypothalamus produces GHRH or GHIH which does what to the pituitary gland?
inhibits or promotes the release of GH
The hypothalamus produces thyroid releasing hormone (TRH)which does what to the pituitary gland?
stimulates the release of TRH
The thyroid hormone stimulates all body cells to increase what?
Overproduction of TH can lead to
Underproduction of TH can lead to
goiter or cretinism