Download Nervous/Endocrine Notes

The Nervous System
approx Human
brain
length=15cm
approx brain
weight=1400g
approx Baboon brain
length= 8cm
approx brain weight=140g
The nervous system REGULATES
how the organism responds to its
environment.
How does it do this???
Stimulus: Any change or
event or condition in the
environment that causes
an organism to react.
How can it know what is happening in
the external environment?
Response: The resulting
reaction of the organism.
How can it make body changes to
respond?
A frog sees an insect
The frog leaps and captures the insect.
What is the stimulus?
What is the response?
Neurons: Specialized cells which are sensitive to particular stimuli
and can transmit messages or impulses.
Dendrites: act as antennae in
that they pick up stimuli and
transmit it throughout the nerve
cell.
•They are elaborately branched
Axon: Carries the electrical
nerve impulse over a long
distance.
Terminals: Contains sacs of
chemicals called
neurotransmitters. The electrical
impulse ends here and turns
chemical.
Neurotransmitters: Chemicals which
are released into the space between
nerve cells
Synapse: The space between neurons
Myelin Sheath: Protects and insulates
the axon, focusing the impulse.
There are 3 classes of neurons which allow for processing of
information.
1. Sensory neuron: receives or senses information from sense receptors
and transports it in towards the brain.
2. Interneuron: Processes information and “decides” where to send it.
3. Motor neurons: Sends information out to the body and causes a
response. Can either stimulate muscles to move or glands to secrete a
hormone.
The working of these 3 neurons can be seen in the reflex arc.
Reflex: The response to a stimulus that does not require any thought.
Stimulus: hitting the kneecap. Sensory
neurons pick up the stimulus and sent it
into an interneuron.
Interneuron directs it information to a
motor neuron.
The motor neuron goes back to the leg
muscles and stimulates them to move.
Do Now:
Explain what a reflex is and how the 3
types of neurons function in a reflex
arc.
Compare and Contrast Nervous and
Endocrine systems
The Nervous system is divided into 2 parts
Central Nervous System
Brain and Spinal Cord
Peripheral Nervous System
Voluntary and Involuntary nerves
CNS = Brain + Spinal Cord
Spinal Cord:
The spinal
cord acts as
a highway of
information
for the brain
to command
the body's
motions
Spinal Cord:
• The spinal cord is a dorsal
(back) hollow nerve cord
found in all chordates
• It is protected by your
vertebrae
• Has a central canal filled
with cerebrospinal fluid
which circulates into the
brain
– Brings nutrients to the brain
Neurotransmitters
Brain:
•Protected by three layers on
connective tissue called meninges
•Spaces between the membranes is
filled with fluid which functions as
a shock absorber and bathes the
brain in nutrient fluids
•Brain is highly convoluted which
allows for more surface area.
•Is divided into 2 hemispheres
which are connected by a band of
fibers.
•Divided into 4 lobes
Parts of the Brain:
• Cerebrum
• Cerebellum
• Medulla
(pons)
Lobes:
1. Frontal:
Involved in
higher order
thinking
2. Parietal:
Contains the
motor cortex
3. Occipital Lobe:
Processes visual
information
4. Temporal:
Involved in
memory and
speech
Cerebellum: Involved in motor coordination
used in things as riding a bicycle…
Medulla has centers for visceral, respiration,
heartbeat and intestinal motility
Rods: Nerve
cells that
encode light
intensity
information
Cones:
Neurons that
encode
different
wavelengths
of color.
Impulse Transmission
Nerve cells make
contact with many
cells. How does the
neurotransmitter
“know” which cell
to work on????
Receptor sites:
Areas on the
cell membrane
that respond to
a particular
chemical
What happens when
the neurotransmitter is
finished locking into
the receptor and the
next response is
triggered?
Meningitis is an inflammation of the
meninges, the brain lining.
The inflammation may be caused by infection, or may be
caused by a non infectious irritant to the meninges. The two
most common forms of meningitis are Bacterial and
Viral. Meningitis should not be confused with encephalitis
which is inflammation of the brain itself.
Polio
• A virus that attacks the
motor neurons of the
spinal nerves
• Mode of transmission:
untreated sewage and can
also be waterborne
• Most often affects the arms
and legs
• Very contagious and
causes irreversible
crippling nerve damage
• Vaccines are effective
Stroke:
• A stroke occurs when
part of the blood supply
to the brain has been cut
off and as a result tissue
has been destroyed
• Symptoms depend on the
area of the brain affected
but can include paralysis
Both contain a nucleus
with the same DNA.
So…. How come they
look so different?
Vocabulary Words for the Week
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Hormone
Target cell
Endocrine gland
Hypothalamus
Pituitary gland
Diabetes
Ovary
Testes
Thyroid gland
Feedback mechanism
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1) stimuli
2) axon
3) dendrite
4) response
5)reflex
6)neurotransmitter
7)sensoryneuron
8)interneuron
9)synapse
10) motor neuron
The Endocrine System
Regulatory systems: Both the nervous and
endocrine systems are responsible for internal
communication and coordination of responses
within an animal.
•The nervous system uses high speed messages
•The endocrine system is slower &involves the
production of hormones.
•Hormones??? What are they?
Hormones: Chemical signals that communicate within an animal.
The vertebrate endocrine system produces hormones which control
metabolism, growth, development and reproduction.
•Cells of the endocrine system are arranged into specific endocrine
glands.
•A gland: A secretory organ. Ex. Pancreas, Pituitary gland, Adrenal
gland
•The specific hormones are released into the blood and transported
to the specific organ called the TARGET ORGAN.
•The target organ contains target cells which contain specific
receptor sites which bind with the hormone and allow it into the
cell to do its job.
Most hormones circulate in blood, coming into contact with
essentially all cells. However, a given hormone usually
affects only a limited number of cells, which are called
target cells. A target cell responds to a hormone because it
bears receptors for the hormone
•Endocrine action: the hormone is distributed in blood
and binds to distant target cells.
Endocrine Glands:
1. Hypothalamus: Integrates information from
both the nervous & endocrine systems.
Controls the secretions of the pituitary
gland.
2. Pituitary Gland: Master gland: Controls the
release of most of the endocrine hormomes.
Composed of 2 sections:
1. Posterior Pituitary: Secretes 2 hormones:
A. Oxytocin: Causes contractions of the
uterus and ejection of milk from the
mammary glands. Released during labor to
push the baby out.
B. ADH: Affects water balance. Controls
how much water is released by the kidneys.
Pituitary: Master Gland
Affects all other glands in
the body by releasing
stimulating hormones into
the blood
2. Anterior Pituitary: Secretes 6 major
hormones.
A. Growth Hormone: (GH) Increases growth
of bones and muscles. Defective GH can
lead to
Gigantism: Excessive secretions of GH.
Individual grows tall but in proportion.
Dwarfism: Hyposecretion (too little) of GH.
Individual is small but well proportioned and
has normal intelligence.
.
Picture 4. These girls are sisters. The girl on the left
lacked growth hormone. In this picture she was 18cm
shorter than her sister, despite being one and a half
Dwarfism is autosomal dominant: If you have one defective
gene, you have the syndrome.
B. Thyroid Stimulating Hormone: TSH
Targets the thyroid gland and stimulates it to
release thyroxin which regulates cell
metabolism
Thyroid Gland: Located on the front of the
neck. Uses Iodine from the diet to manufacture
thyroxin.
Essential for normal growth:
Goiter: A dramatic enlargement of the thyroid
gland resulting from a deficiency of iodine in
the diet.
.
C. ACTH: Stimulates the Adrenal gland to release adrenaline
Adrenaline: a hormone which is released during stress to prepare
the body for fight or flight responses
On top of the kidney
Adrenaline is sometimes
called the'emergency
hormone'. Adrenaline is
produced when we are
frightened or excited. It
prepares the body for
"fight or flight".
These preparations include:
increasing the heart rate,narrowing the arteries that supply the gut.
The effect of these 2 changes is to allow more oxygenated blood to
flow to the muscles.
Adrenaline makes the airways in the lungs dilate and stimulates the
bowels and bladder to empty themselves
D. FSH: Follicle Stimulating
Hormone: Stimulates the
ovaries to release an egg.
E. LH: Lutenizing hormone:
Stimulates the egg release and
preparation of the uterus to
receive the egg
Ovaries: Located in the
abdomen of the female.
Produces estrogen : Stimulates
the development of breasts,
external genitalia and
secondary sex characteristics.
Progesterone: Helps prepare
the uterus for implantation of
the embryo.
Do Now:
Why is the Pituitary Gland called the Master
gland?
How does it affect other glands in the body?
Give an example.
Gonads in the males: Testes:
Produce testosterone: Causes
development of the secondary
sex characteristics in males.
Cause increased aggressiveness
When released during pregnancy,
it causes the fetus to become
male.
Pancreas: Secretes digestive enzymes as
well as hormones. Cells are arranged
in little island-like formations.
Islets of Langerhans: Secretes 2 opposing
hormones:
1. Insulin: Secreted in response to
elevated blood glucose levels,as
occurs after a meal. Set point for adult
is 90mg/100ml.
When blood glucose in above this point
insulin is released which causes
glucose to be taken out of the blood
and converted to glycogen which is
stored in the cells of the liver and
muscles.
If blood glucose is too lowGlucagon is released to put back
the stored glucose into the blood.
Diabetes Mellitus: Glucose
cannot be reabsorbed and is
secreted into the urine.
Loss of glucose is accompanied
by loss of water causing thirst
and dehydration.
Causes:
Autoimmune disorder: Your
own body attacks cells in the
pancreas that produce insulin.
Reduced responsiveness in
insulin receptors. Usually occurs
after 40. Can manage with diet.
Elevated concentrations of
glucose in blood stimulate release
of insulin, and insulin acts on cells
throughout the body to stimulate
uptake, utilization and storage of
glucose
•Insulin stimulates the
liver to store glucose in
the form of glycogen
Glucagon has a major
role in maintaining
normal concentrations
of glucose in blood,
and is often described
as having the opposite
effect of insulin.
That is, glucagon has
the effect of increasing
blood glucose levels.
•Feedback loops are used extensively
to regulate secretion of hormones
•Neurons in the hypothalamus secrete thyroid
releasing hormone (TRH), which stimulates
cells in the anterior pituitary to secrete thyroidstimulating hormone (TSH).
•TSH binds to receptors on epithelial cells in
the thyroid gland, stimulating synthesis and
secretion of thyroid hormones, which affect
probably all cells in the body.
•When blood concentrations of thyroid
hormones increase above a certain threshold,
TRH-secreting neurons in the hypothalamus
are inhibited and stop secreting TRH. This is
an example of "negative feedback".
DON’T SMOKE!!!!!!!