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AP Biology
Homeostasis and Development
Signal Transduction Pathway
Kinases “turn on” processes
(can amplify)
Phosphotases “turn off” processes
• Ligand
• Hormone
• Target tissue
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
3 parts of hormonal system
•Exocrine
•Endocrine
•Neurosecretory
Remember the “hands” on cell
membranes? (In GREEN)
Local Hormones
• Growth factors
• Nitric Oxide (NO)
• Prostaglandins
• Cytokines
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 – Macrophage to Helper T
IL2 – Helper T to B or Cytotoxic T
SECRETORY
CELL
Polar versus
Non-polar Hormone
Signal Reception
SECRETORY
CELL
Hormone
molecule
VIA
BLOOD
Hormone
molecule
VIA
BLOOD
Signal receptor
TARGET
CELL
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
Hypothalamus
Examples of Negative
Feedback Loops
TRH
Anterior
pituitary
TSH
Thyroid
T3
T4
Positive Feedback Loop
Tropic Hormones of
the PosteriorPituitary
Hypothalamus
Neurosecretory
cells of the
hypothalamus
Axon
Posterior
pituitary
Anterior
pituitary
HORMONE
TARGET
ADH
Kidney tubules
Oxytocin
Mammary glands,
uterine muscles
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
• Most of the cells in the thyroid are called follicular cells, but
there are others called parafollicular cells (or C cells) which
produce another important hormone called calcitonin. The
thyroid also has four teensy glands called
the parathyroid glands, which are embedded in the back of
the thyroid and produce the hormone creatively
called parathyroid hormone. These two hormones, calcitonin
and parathyroid hormone, work in tandem to keep your
body's calcium level in check. We all know how important
calcium is to prevent diseases like osteoporosis, but too much
of a good thing isn't ideal either. That's where calcitonin
comes in; it decreases how much calcium is in your blood,
while parathyroid hormone works to beef those levels up.
• http://www.youtube.com/watch?v=-S_vQZDH9hY
• http://www.innerbody.com/image/endoov.html