Download Hormone

AP Biology
Endocrine Systems
• Important concepts from previous units:
• 1) The Signal Transduction Pathway has three
part – 1) Reception, 2) Transduction, 3)
Response
• 2) A ligand is a generic term for a chemical
messenger molecule or a form of stimulus
energy.
• 3) Cells can amplify a signal using the kinase
cascade system.
Signal Transduction Pathway
Kinases “turn on” processes
Phosphotases “turn off” processes
• I. Hormone – This is a chemical produced in
one part of the body and travels to another
part of the body to have an effect.
•
A. Target tissue – This is where the
hormone travels to. (The target cells have the
special proteins receptors “hands”.)
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
Remember the “hands” on cell
membranes? (In GREEN)
• II. Three parts to the hormonal system of
communication:
•
A. Exocrine – The hormone substance is put into
a duct or tube to travel to another body part.
•
B. Endocrine – The hormone substance is put
into the blood to travel to another body part.
•
C. Neurosecretory – Neurons that can also
release hormones - such as the Pituitary gland and
Hypothalamus.
LE 45-7
Hypothalamus
Neurosecretory
cells of the
hypothalamus
Axon
Posterior
pituitary
Anterior
pituitary
HORMONE
TARGET
ADH
Kidney tubules
Oxytocin
Mammary glands,
uterine muscles
III. Local Hormones – These hormones travel in small
localized areas.
A. Growth Factors – These are hormones that cause
cell replication. They are used for “normal” growing
or repair.
B. Nitric Oxide (NO) – If from neuron – Acts as
neurotransmitter to inhibit a process.
- If from WBC – Kills cell or pathogen.
- If from endothelium of blood vessel –
Causes surrounding smooth muscle to dilate (relax).
C. Prostaglandins – These hormones helps with
inflammatory response and muscle contraction.
D. Cytokines – Relay messages between WBC’s about
pathogens. For example, Interleukin 1(IL-1) or
Interleukin 2 (IL-2).
Cytokines
IL 1 – Macrophage to Helper T
IL2 – Helper T to B or Cytotoxic T
IV. Hormone reception by cells:
A. Ligand (hormone) attaching to the membrane
receptor proteins causes a signal-transduction
pathway to begin.
1. If the pathway ends in the cytoplasm – turned
on/off an enzyme.
2. If the pathway ends in the nucleus – turned
on/off transcription.
B. Steroid hormones go through the phospholipid
bilayer portion of the membrane to find its receptor
protein in the cytoplasm. They do not need
secondary messengers. Most are Transcription
activators.
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
V. Hormonal control mechanisms:
A. Negative feedback loops – These stop a
process already occurring and get it going in
the opposite direction.
B. Positive feedback loops – These enhance a
process that is already occurring.
Hypothalamus
Examples of Negative
Feedback Loops
TRH
Anterior
pituitary
TSH
Thyroid
T3
T4
Positive Feedback Loop
VI. Tropic hormones – These are hormones that affect
other endocrine glands causing the release of
secondary hormone.
Major Endocrine Glands Of the Human Body
VII. Hypothalamus gland - This is the master control
gland of homeostasis.
A. It controls the majority of the homeostasitc
mechanisms in our body.
B. Uses releasing hormones or inhibiting hormones
as messengers. These affect the pituitary gland –
second in command
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
VIII. Pituitary Gland - This is the second in charge in
control of homeostasis.
A. This gland is affected by Hypothalamus Hormones.
1. Releasing hormones—Starts a process.
2. Inhibiting hormones —Stops a process that is
occurring.
B. Two Parts of the Pituitary Gland:
1. Anterior - Arises from the Adenohypothesis…
muscle tissue of the mouth.
2. Posterior - Arises from the Neurohypothesis…
neuron tissue of the brain.
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