Download Regulation November 8, 2012 Mr. Alvarez

Regulation
November 8, 2012
Mr. Alvarez
Homeostasis
Homeostasis- The process by which organisms
keep internal conditions relatively constant
despite changes in external environments
Negative Feedback- The process in which a
stimulus produces a response that opposes
the original stimulus
A Nonliving Example
Temperature
Increases
Temperature
Decrease
In the Body
 When you get cold you shiver
When you get hot you sweat
Regulation
A. REGULATION. Our environment, both inside
and outside our body, is constantly changing.
Regulation is the life process by which cells and
organisms respond to changes within and around
them. The structures and actions of the nervous
and endocrine system control and regulate the
body. These two systems allow us to adjust to
internal as well as external environment changes.
REVIEW QUESTIONS
1. What is regulation?
Regulation is the life process by which cells and organisms
respond to changes within and around them.
Nervous system and _________
Endocrine
2. The _______
system
control and regulate the body
B. NERVE REGULATION. If you were to put your
hand on a hot stove, you would quickly, without
thinking, remove your hand. This is an example of
nerve regulation. There are three parts to nerve
regulation: the stimulus, the response, and the
impulse. A stimulus is a specific change in the
environment that affects the nervous system. The
heat in the previous example is the stimulus. A
response is a reaction to this stimulus. Quickly
removing your hand so that you will not be burned
by a response.
Many organs and glands of the body receive
stimuli that are translated into impulses. An
impulse is an electrical or chemical message
that is carried by nerve cells. The impulses are
then transferred to the central nervous system.
The central nervous system then sorts out and
interprets the incoming impulses. The impulse is
then sent to organs or glands. These organs and
glands provide certain responses to these
impulses.
REVIEW QUESTIONS
1. What is the difference between a stimulus and a
response?
A stimulus is a specific change in the environment that affects the
nervous system and a response is a reaction to that stimulus
2. An electrical or chemical message carried by
Impulse
nerve fibers is called a/an_______
3. When you hear a sudden loud sound, you jump.
Name the stimulus and the response.
Stimulus = Loud Sound
Response = Jump
F. RECEPTORS. Receptors are special structures that are
sensitive to stimuli. Receptors receive messages. External
receptors, called sense organs, include the eyes, ears, nose,
tongue, and skin. Stimuli for these receptors are light, sound,
chemicals, and temperature and pressure changes. Internal
receptors are located in the internal organs. They allow the
brain to detect hunger, thirst, muscle position, and carbon
dioxide levels in the blood.
REVIEW QUESTIONS
receive
1. Receptors ___________________
messages.
2. Name five sense organs.
1. Eyes
4. Tongue
2. Ears
5. Skin
3. Nose
The Nervous System
Nervous System- Controls and coordinates
functions throughout the body and responds
to internal and external stimuli
Uses BOTH Electrical and Chemical Messengers
Neuron
 Neuron- Cell that carries signals through the
nervous system
Impulses- Electrical Signals carried by the nervous
system
Stimulus- any changes in the internal or external
environment of a neuron which initiates an impulse.
Dendrites
Dendrites- Branch extensions of neuron that
carry impulses from the environment or other
neurons TOWARD the cell body
Dendrites
Cell Body
Cell Body- Part of the neuron that contains
the nucleus and much of the cytoplasm
Dendrites
Nucleus
Nucleus- In a neuron, interprets the signal
from the dendrites
Nucleus
Dendrites
Axon
Axon- Long fiber that carries impulses AWAY
from the cell body
Nucleus
Dendrites
Myelin Sheath
Myelin (MY-uh-lin) Sheath- Insulating
membrane surrounding the axon
Nucleus
Dendrites
Terminal Branches
Terminal Branches- Branches at the end of the
axon that releases neurotransmitters to the
dendrites of the next neuron
Nucleus
Dendrites
Terminal Branches
Synapse
 Synapse- Space between the terminal branches
of one neuron and the dendrites of the next
neuron
**TWO NEURONS NEVER TOUCH**
 NeurotransmittersChemicals used by a neuron
to transmit an impulse across
a synapse to another neuron