Download Endocrine System PPT

AP Biology
Endocrine System and Hormones –
Overall Function and Feedback
Mechanisms
Signal Transduction Pathway
Kinases “turn on” processes
Phosphotases “turn off” processes
Basic Hormone Pattern
Example
Pathway
Low blood
glucose
Stimulus
Receptor
protein
Endocrine
cell
Pancreas
secretes
glucagon ( )
Blood
vessel
Target
effectors
Response
Liver
Glycogen
breakdown,
glucose release
into blood
Simple endocrine pathway
Hormone – a chemical
produced in one part of the
body that travels to another
part of the body (target
tissue) and elicits a response.
The basic mechanism of the
endocrine system can be
seen in the diagram to the
left:
1. A stimulus is recognized
by the body.
2. Endocrine cells release a
hormone into the blood
stream.
3. The hormone travels
throughout the body to the
target tissue.
4. The appropriate response
is triggered.
Remember the “hands” on cell
membranes? (In GREEN)
Just as we discussed
with the nervous
system and the
immune system, the
endocrine system
works through
interactions between
chemicals and
protein receptors
found on the surface
of all cells throughout
the body.
Hormonal System of
Communication
• There are three majors parts to the hormonal
system of communication:
1. Exocrine: a hormone is secreted by a gland, and the target is
the outside of the body.
– Ex. Sweat and pheromones
2. Endocrine: a hormone is secreted by a gland, enters the blood
stream and targets tissues in the body.
– Ex. Insulin, glycogen, ADH, Oxytocin, etc.
3. Neurosecretory: these are specialized neurons that can also
secrete hormones.
– Ex. Hypothalamus, pituitary
LE 45-7
Hypothalamus
Neurosecretory
cells of the
hypothalamus
Axon
Posterior
pituitary
Anterior
pituitary
HORMONE
TARGET
ADH
Kidney tubules
Oxytocin
Mammary glands,
uterine muscles
Cytokines
IL 1 – Helper T to Cytotoxic T Cell
IL2 – Helper T to B Cell
Different Types of Hormones
• The two major types of hormones found in living organisms
are steroid hormones and peptide hormones. These work
differently when targeting cells.
1. Steroid (lipid-based) hormones – steroid hormones are lipidbased, so they can easily pass through the phospholipid bilayer.
Once in the cell, they target receptors deep in the cytoplasm or
the nucleus. Ex. Testosterone, estrogen, aldosterone
2. Peptide (protein-based) hormones – peptide hormones are
protein-based, so they can not pass directly through the
phospholipid bilayer. These hormones must bind to a cellsurface receptor and then transmit their message into the cell.
This follows the stereotypical signal transduction pathway.
Ex. Prolactin, HGH, oxytocin, insulin, glucagon
SECRETORY
CELL
SECRETORY
CELL
Hormone
molecule
VIA
BLOOD
Hormone
molecule
VIA
BLOOD
Signal receptor
Peptide and
Monoamine
Hormone Binding
TARGET
CELL
Steroid
Hormone
Bonding
TARGET
CELL
Signal
transduction
pathway
OR
Signal
receptor
Cytoplasmic
response
DNA
Signal
transduction
and response
mRNA
DNA
NUCLEUS
Nuclear
response
NUCLEUS
Receptor in plasma membrane
Synthesis of
specific proteins
Receptor in cell nucleus
Many hormones are involved in negative feedback loops. The most easily
understood examples are insulin and glucagon. When changes in blood
sugar are sensed by the body, these hormones are secreted to reverse the
change. The secretion of the hormone stops the situation.
TRH
TSH
Positive feedback loops are also very important in living organisms. These are
the opposite of negative feedback. The production of a hormone causes
continued production of a hormone, or the continuation of a behavior. Oxytocin
and prolactin are examples of hormones that function through positive
feedback.
Human Endocrine Glands
Important Human Endocrine Glands:
1. Hypothalamus – produces
hormones that regulate the pituitary
2. Pituitary Gland – major gland that
produces hormones that travel
throughout the body
3. Thyroid Gland – produces
hormones that regulate metabolism
4. Pancreas – produces hormones
that regulate blood sugar
5. Thymus Gland – produces
hormones that stimulate production
of T-Cells
6. Adrenal Glands – produces
hormones that stimulate “fight or
flight” and kidney function
7. Ovaries – female sex hormones
8. Testes – male sex hormones
Tropic Hormones of
the Anterior Pituitary
Tropic Effects Only
FSH, follicle-stimulating hormone
LH, luteinizing hormone
TSH, thyroid-stimulating hormone
ACTH, adrenocorticotropic hormone
Neurosecretory cells
of the hypothalamus
Nontropic Effects Only
Prolactin
MSH, melanocyte-stimulating hormone
Endorphin
Portal vessels
Nontropic and Tropic Effects
Growth hormone
Hypothalamic
releasing
hormones
(red dots)
Endocrine cells of the
anterior pituitary
Pituitary hormones
(blue dots)
HORMONE
FSH and LH
TSH
ACTH
Prolactin
MSH
Endorphin
TARGET
Testes or
ovaries
Thyroid
Adrenal
cortex
Mammary
glands
Melanocytes
Pain receptors
in the brain
Growth hormone
Liver
Bones