1
Name a gland or organ in the endocrine system
pineal gland, hypothalamus, pituitary, thyroid, parathyroid, thymus, adrenal, pancreas, ovary, testis
what is a hormone?
long-distance chemical signals
What class of hormone cannot enter target cells?
amino acid based hormone
Steroids/Thyroid hormones are synthesized from what?
cholesterol
Do Steroids/Thyroid hormones act directly or indirectly to activate genes
directly
What does the liver help do to hormones
remove from the blood
How do hormones travel through the body
through blood or lymph
What is a half life?
the time required for a hormone’s blood level to decrease by half
What do degrading enzymes do?
help remove hormones from the blood
blood levels of hormone are controlled by what kind of feedback system?
negative feedback
Humoral stimulus involves changes in hormone levels in the ______
blood
What is up regulation?
target cells form more receptors in response to the hormone
This kind of hormone directly triggers DNA transcription and protein synthesis
steroid
Insulin is released in response to increased blood glucose. This is an example of a _____ stimulus
Humoral Stimuli
What is the term for target cells lose receptors in response to the hormone
down regulation
This class of hormone act on plasma membrane receptors
amino acid based hormones
Release of norepinephrine and epinephrine from the adrenal glands (activation of the fight or flight) is what kind of stimulus?
neural
What are the 3 stimuli indicating hormone synthesis?
humoral, neural, hormonal
What are two of the three factors that target cell activation depend on?
Blood levels of the hormone
Relative number of receptors on or in the target cell
Affinity of binding between receptor and hormone
Type II diabetes (cells become resistant to insulin) is an example of what kind of regulation?
Down regulation
What are all 5 steps of protein synthesis from Steroid hormones and thyroid hormone gene activation
Diffuse into their target cells and bind with intracellular receptors
Receptor-hormone complex enters the nucleus
Receptor-hormone complex binds to a specific region of DNA
This prompts DNA transcription to produce mRNA
The mRNA directs protein synthesis
What are 4 of the 5 hormone actions on target cells
Alter plasma membrane permeability of membrane potential by opening or closing ion channels
Stimulate synthesis of proteins or regulatory molecules
Activate or deactivate enzyme systems
Induce secretory activity
Stimulate mitosis
Releasing and inhibiting hormones produced in the hypothalamus regulate the secretion of most anterior pituitary hormones. These anterior pituitary hormones in turn stimulate other endocrine organs to release their hormones. This is an example of a ______ stimulus.
hormonal stimulus
When a hormone is released in direct response to changing blood levels of certain critical ions and nutrients is called a _______ stimulus
humoral
What kind of stimulus would this be? a drop in blood temperature triggers the release of thyroid hormone to increase metabolic activity
humoral