Download Name - G9Biology

Name:
Class:
Date:
#23 Notes – Endocrine System
Homeostasis = maintaining a stable (constant) internal environment

maintained by the endocrine system and the nervous system, both working together

What does the endocrine system do? It produces chemical signalers (a.k.a. hormones) that go to another place
by traveling through the bloodstream.
How do the nervous system and the endocrine system interact?
Part of nervous system only
neuron - a nerve cell; has three parts:
cell body, axon, dendrites
Part of both systems
hypothalamus - receives messages
from brain and internal organs
- stimulates --------------------------------->
(tells it what to do)
Part of endocrine system only
Pituitary gland - main organ of the
endocrine system
- located at the base of the
hypothalamus
- controls other glands
In general, how does the endocrine system work?
produces a
that travels via
to reach a
A gland ------------------> hormone ---------------------> bloodstream -----------------> target cell
and attaches to a
found on either
--------------------> receptor (a.k.a. binding site) ----------------------> cell membrane or nucleus.
Example of endocrine control:
Hypothalamus monitors
blood sugar levels
too low?
tells pituitary gland
to make hGH (human growth hormone)
normal or too high?
tells pituitary gland
to stop making hGH
hGH binds to receptor on target cells (liver cells)
liver releases more glucose
*This is also an example of negative feedback – the amount of one substance decreases the amount of another
substance
Negative feedback:
 Example 1: hGH (see above)
 Example 2 (generic): Gland A produces Hormone X. When the body has enough of Hormone X, Gland A gets a
message to stop producing Hormone X
 results in stable levels of chemicals/molecules in our body (stabilization); a.k.a. equilibrium; a.k.a. homeostasis
 Example 3: blood water levels
o if blood water levels are low, the hypothalamus tells the pituitary gland to release antidiuretic hormone
(ADH)
o ADH binds to receptors on kidney cells so that water is reabsorbed and you urinate less (less water in
urine)
o If you drink water to replenish blood water levels, the hypothalamus tells the pituitary gland to stop
releasing (secreting) ADH, so you go to the bathroom more often (more water in urine)

Example 4: regulation of blood glucose levels – Your explanation below can be a summary, bullet points,
diagram, etc.
Read Problem-Solving Lab 35.3 on page 932 of your text.
1. Examine the graph and explain how exercise affects the concentrations of insulin and glucagons in the blood.
The more you exercise, glucagon increases and insulin decreases.
2. Relate the changes shown on the graph to what is occurring in muscle cells as well as to blood glucose levels.
As muscle cells take in glucose (cellular respiration), more glucagon is produced (by the pancreas), which tells the liver
to release more glucose. (Because you don’t want to store glucose, so the amount of insulin should decrease.)
3. Design a flowchart that shows the steps involved in maintaining homeostasis of blood glucose during exercise.
Begin your flowchart with muscle cells.
Types of Hormones:
Steroid hormone
Peptide hormone
Is composed of
Lipids
Amino acids
Can it enter the
cell?
Yes
No
Why/Why not?
Because the cell membrane is made out of the
same material, the hormone is soluble in it. (like
dissolves in like)
Cell membrane is impermeable to the amino
acid. Too big?
Action
Binds to a hormone receptor inside the cell to
form a hormone-receptor complex
Binds to a hormone receptor on the _cell
membrane of the _target cell_
Travels to the _nucleus_ to stimulate mRNA
synthesis (a.k.a. ___transcription_)
Opens _ion__
channels in the target
cell’s _(cell)
membrane_
Activates an enzyme
inside the cell
Ions can _go in__ or
___go out of_ the cell
Enzyme acts as a
stimulus for other
molecules in the cell
(How? By lowering
activation energy –
the energy needed to
start a reaction (rxn)
Immediate result
Then
_protein synthesis occurs – the protein made is
what the cell specifically needs (based on the
mRNA template made earlier)
Label the figure below with the principal human endocrine glands.
Glands:
Name of gland
Location
Name of hormones
secreted
Type
Hormones affect/result in
Regulate
Steroid
Inc glucose
Increase blood pressure
Stress levels
Peptide
Inc blood pressure
Inc heart rate
Inc respiration rate
Inc efficiency of muscles
Inc blood sugar levels
(adrenaline rush)
Fight-or-flight response
Thyroxine
Peptide
Rate at w/c the body uses
energy
Determines food intake
requirements
Growth, development, metabolism
Calcitonin
Peptide
Inc Ca excretion in kidneys
Inc Ca absorption of bone
Growth, development, metabolism
- Ca levels in the blood
Peptide
Inc Ca, P, Mg absorbed by
the intestines
Releases Ca, P from
bones
Inc Ca, Mg removed from
urine (kidneys)
Growth, development, metabolism
- also regulates minerals (CA, P,
Mg)
Glucocorticoids
and
Aldosterone
Adrenal glands
(why plural?)
Superior to
kidneys
Epinephrine (a.k.a.
adrenaline)
and
Norepinephrine
Thyroid gland
Parathyroid glands
Ovary or Testes
neck
Neck (attached
to thyroid
glands)
Ovary or Testes
Parathyroid hormone
Estrogen
Progesterone
Testosterone
Menstrual cycle, pregnancy
Steroid
puberty
Sperm cell production