Download Ch. 21.1 Nervous Lecture

The Nervous System
21.1
MINI MASUESSE DEMO
I. Functions
A. Detect Stimuli
1. Stimulus- A change in the
environment that causes a
response
a. Temperature, light, taste,
touch, vision, sound, etc
I. Functions
B. Maintain Homeostasis
1. Keeps internal conditions
steady by detecting and
responding appropriately to
stimuli
II. Nerve Cell Structure
A. Neurons- Basic functioning
unit (“Nerve Cell”)
B. 3 Parts of a Neuron
1. Dendrites- Receive impulses
from other neurons and send
them to the cell body
II. Nerve Cell Structure
2. Cell body (“Soma”)
interprets the impulse, and
sends it to the Axon.
3. Axon carries impulses away
from cell body and to the next
neuron or cell.
III. Types of Neurons
A. Sensory Neurons collect
information about suroundings
and send it to the brain and/or
spinal cord.
1. Senses temperature,
pressure, pain, taste, etc.
III. Types of Neurons
B. Interneurons send impulses
from sensory neurons to motor
neurons
1. Act as connectors
2. Located in the brain and
spinal cord
III. Types of Neurons
C. Motor neurons receive
impulses from the interneurons
and cause the tissues of the
body to respond.
1. Ex: Muscles contract, glands
release hormones, etc
Sensory Neuron
Interneuron
Motor Neuron
III. Types of Neurons
D. Synaptic Gap- The gap in
between neurons that the impulse
must cross to relay the message.
1. Chemicals called
neurotransmitters are released
across the gap and picked up by
the next neuron
2. Spray bottle demo
IV. Central Nervous System
A. Consists of brain and spinal
cord
B. The Brain
1. Cerebrum
2. Cerebellum
3. Brain Stem
IV. Central Nervous System
C. The Cerebrum
1. The “thinker”
a. The more pathways the
quicker information is
processed—Thank you school!
2. Memory storage
3. Interpreting senses
IV. Central Nervous System
D. Cerebellum
1. Coordinates muscle
movement & balance
2. Injury to cerebellum causes
paralysis or jerky movements
IV. Central Nervous System
E. Brain Stem
1. Acts as a bridge between the
brain and spinal cord
2. Coordinates involuntary
activities such as heart rate,
breathing, blood pressure,
sneezing and vomitting
IV. Central Nervous System
F. Spinal Cord
1. Bundles of neurons that
carries impulses to and from all
parts of the body.
2. Routine tasks are handled by
the spinal cord.
IV. Central Nervous System
3. Reflex- An involuntary,
automatic response to a
stimulus
a.Controlled by the spinal
cord, not the brain.
b. Speedy response protects
the body
V. Peripheral Nervous System
1. Consists of all the other
neurons outside the brain and
spinal cord
2. Two Major Divisions
a. Somatic
b. Autonomic
V. Peripheral Nervous System
3. Somatic System
a. Controls voluntary actions
b. Ex: writing your name
4. Autonomic
a. Controls involuntary actions
b. Ex: heart rate, digestion, etc
VI. Affect of Drugs
A. Many drugs directly affect the
nervous system
1. Alcohol is absorbed into the
blood quickly and causes
neurons to operate slower. It is
classified as a depressant.
VI. Affect of Drugs
2. Heavy alcohol use destroys
non-repairable brain cells and
liver cells
VI. Affect of Drugs
3. Caffeine is a stimulant that
causes neurons to fire more
rapidly. This increases heart
rate, causes restlessness and
insomnia. Also increases urine
production.
VI. Affect of Drugs
4. All drugs make it more difficult
for the body to maintain
homeostasis!