The nervous system regulates muscle and gland activity via
electrochemical impulses
Endocrine system stimulates ______ activity, using _____.
Metabolic.
Hormones.
Chemical messengers excreted by cells into extracellular fluid
hormones
What responses last longer?
Endocrine responses or nervous system responses
Endocrine
5 Major processes that are controlled by hormones:
Reproduction.
Growth and development.
Maintenance of electrolytes, water, and blood nutrients.
Regulation of cellular metabolism and energy balance.
Mobilization of body defenses.
Study of hormones is called
endocrinology
Exocrine glands produce ______ and have ______.
nonhormonal substances.
ducts.
Adipose cells release-
leptin
the thymus releases-
thymic hormones
Local chemical messengers that travel short distances-
Autocrine and Paracrine
Autocrines exert their effects on-
the same cell that secreted them
paracrines releases into the same _____, but affect-
tissue.
cells other than paracrine cells.
Somatostatin is release by one form of pancreatic cells, so stop ______ from being made by different pancreatic cells.
insulin
Which 2 endocrine glands are found in the neck?
thyroid and parathyroid
Whats the difference between a hormone and a paracrine?
hormones travel larger distances in the blood while a paracrine affects local cells usually in the same tissue
Nearly all hormones can be chemically classified as either _____ or _____.
amino acid based,
steroids.
most hormones are
amino acid based
peptides are _____ ______ of amino acids
short chains
proteins are _____ _____ of amino acids
long polymers
the amino acid tyrosine and amines construct _____.
thyroxine
synthesized from cholesterol
steroid hormones
only the _____ and _____ produce steroid hormones
gonads and adrenal glands
a possible third class of hormones:
eicosanoids
eicosanoids include _____ and _____
leukotrienes and prostaglandins
signaling chemicals for inflammation and some allergic reactions
leukotrienes
raise blood pressure and increase contractions during birth for blood clotting, pain, and inflammation.
prostaglandins
why are eicosanoids classified as autocrines and paracrines instead of hormones?
Hormones influence distant targets but eicosanoids affect only nearby cells.
True or False.
All major hormones circulate to and influence all tissues.
False.
They circulate to all tissue but only influence tissues with receptors for that particular hormone.
Target cells are ___________.
the cells in the tissues that the hormones are trying to reach.
How do hormones effect the target cells?
It alters the target cell activity, by increasing or decreasing cellular processes.
What happens when epinephrine binds to smooth muscle cells in blood vessel walls?
It stimulates them to contract.
Hormones open or close _____ _____ in the plasma membrane to alter its ______ or _____.
ion channels.
permeability or potential.
Hormones stimulate synthesis of _____ and certain _______ within the cell
Enzymes.
Proteins.
Hormones activate or deactivate ______.
Enzymes.
Hormones induce ______ activity.
secretory.
Hormones stimulate _____ to begin within a cell.
mitosis
What 2 things determine how a hormone communicates with its target cell?
The chemical nature of the hormone
and
The cellular location of the receptors
hormones act at receptors in 2 ways depending on if they are ____ _____ or _____ _____.
water soluble
or
lipid soluble
If hormones are water soluble then they act on receptors ___________
in the plasma membrane.
If hormones are lipid soluble then they act on receptors ___________.
inside the cell.
lipid soluble hormones include:
steroid and thyroid hormones.
water soluble hormones include:
all amino acid based hormones, except thyroid.
If the tissue needs water soluble hormones, its receptors are usually connected to __________ by regulatory molecules called _______.
intracellular second messengers.
G Proteins.
A hormone is also called a ________.
First messenger.
A second messenger used by neurotransmitters and olfactory receptors:
Cyclic AMP
(cAMP)
3 components for cAMP signaling mechanism are
a hormone receptor
a G protein
an effector enzyme (adenylate cyclase)
Step 1 in cAMP mechanism:
Hormone binds receptor.
Step 2 in cAMP mechanism:
Receptor activates G protein.
Step 3 in cAMP mechanism:
G protein activates adenylate cyclase
Step 4 in cAMP mechanism
Adenylate cyclase converts ATP to cyclic AMP.
Step 5 in cAMP mechanism
Cyclic AMP activates protein kinases.
Explain step 1: Hormone binds receptor.
The first messenger, the hormone, binds with the receptor in the plasma membrane.
Explain step 2: Receptor activates G protein.
Hormone binding makes the receptor change shape so it can bind to a G protein. Inactive G proteins are bound to GDP, which is replaced by GTP to activate them.
What is bound to an inactive G protein?
GDP
What does GDP stand for?
Guanosine DiPhosphate
GDP gets replaced by ______ to activate the G protein.
GTP
GTP stands for:
Guanosine TriPhosphate
Explain Step 3: G protein activates adenylate cyclase
The G protein, with attached GTP, then bind to adenylate cyclase to either stimulate it or inhibit it. (Gs= A G protein that stimulates. Gi+ A G protein that inhibits.)
The GTP is then broken back down to GDP and the G protein becomes inactive again.
Explain Step 4: Adenylate cyclase converts ATP to cyclic AMP.
Before the activated Gs is broken down, the adenylate cyclase uses ATP to generate the second messenger, cAMP.
Explain Step 5: Cyclic AMP activates protein kinases.
cAMP moves freely within the cells and triggers many chemical reactions using protein kinases, which are enzymes that add a phosphorus group to various proteins. creating millions of product molecules.
The sequence of reactions from cAMP depend on what 3 things?
the type of target cells.
the protein kinases it contains.
the substance available for phosphorylation.
In thyroid cells, binding TSH promotes synthesis of the thyroid hormone ______.
thyrosine.
TSH stands for
thyroid stimulating hormone
In liver cells, binding glucagon activates enzymes that break down ______, that release ______ into the blood.
glycogen.
Glucose
The action of cAMP lasts only _____, because the molecules are degraded by the enzyme _______.
briefly,
phosphodiesterase.
_______ makes sure that no extracellular controls are needed to stop the activity caused by the hormones.
phosphodiesterase.
_____ and _____ work without second messengers
insulin
growth hormones
__________ act as the second messenger in the PIP2-calcium mechanism
intracellular calcium ions
In the PIP2- Calcium mechanism, what is the membrane bound effector?
Phospholipase C
Phospholipase C splits a plasma membrane phospholipid called _____
PIP2
PIP2 splits into ______ and ______
DAG
and
IP3
What does DAG do?
activates protein kinase enzyme to trigger response.
What does IP3 do?
Released CA^2+ from storage.
How does releasing CA^2+ amplify cellular response?
CA^2+ works as a second messenger
to either directly alter activity
or
by binding to calmodulin to activate enzymes that amplify
ACTH receptors are normally only found on
the adrenal cortex
thyroxine receptors are normally found on
almost all body cells
What is the main hormone to stimulate cellular metabolism?
Thyroxine
3 factors of target cell activation
1. Hormone blood levels
2. # of receptors
3. Binding strength
When you have too little of a hormone, eventually the target cells will create additional receptors, this is called_____.
Up-regulation
Decreasing the amount of receptors for a hormone because there is too much of the hormone being produced is called _____.
Down-regulation
Progesterone down-regulates ______ receptors in the uterus
estrogen
Estrogen up-regulates _______ receptors in the uterus.
Progesterone
Hormones are regulated by __________, where a stimulus triggers hormone secretion.
negative feedback mechanisms
3 types of stimuli that trigger endocrine glands to make and release their hormones:
Humoral
Neural
Hormonal Stimuli
The type of stimuli that occurs from a change in blood level of critical ions and nutrients
Humoral
Cells of the ______ gland monitor CA^2+ levels
parathyroid
The simplest endocrine controls are the ________
Humoral stimuli
Hormones released from Humoral stimuli:
1.
2.
3.
1. PTH - Parathyroid
2. Insulin - Pancrease
3. Aldosterone - Adrenal Cortex
Nerve fibers stimulus that releases hormones:
Neural stimuli
Example of neural stimuli:
stress
How the body handles stress:
The nervous system stimulates the adrenal medulla to release _______ and _______.
norepinephrine
and
epinephrine
Hormones are produced because of other hormones that were produced somewhere else:
Hormonal stimulus
True or False:
All endocrine organs use only 1 type of the stimuli for producing hormones.
False.
Some of them respond to multiple stimuli
The _________ functions as the hormonal safeguard, turning production on and off when it is needed.
nervous system
Using blood glucose while under stress, explain why the nervous system over-ride is important.
When under severe stress, you need more glucose in the blood in case of vigorous activity. So the nervous system is responsible for increasing blood glucose levels.
Hormones circulate in the blood either _____ or __________.
Freely
or
Bound to a protein carrier.
Lipid-soluble hormones travel
bound to a protein
The concentration of a circulating hormone reflects:
1.
2.
1. The rate of release
2. The speed it is activated and removed from the body
True or False:
Water soluble hormones have shorter half-lives.
True.
3 types of hormone interactions
Permissive
Synergism
Antagonism
One hormone needs cannot be fully effective without another hormone in this interaction:
Permissive
Reproductive hormones and ______ hormones are needed for normal and timely development of reproductive structures
Thyroid
True of False:
Without Thyroid hormone, reproductive structures and development will not take place.
False.
They will still take place, it will just be delayed.
When one or more hormones produce the same effect and are used at the same time to amplify the effect, this is a _______ reaction
Synergism
Glucagon and epinephrine cause the liver to release _______ into the blood
Glucose
Hormones oppose actions of other hormones in ________ interactions
antagonism
______ antagonizes insulin to raise glucose levels.
Glucagon