Transcript Nervous System - Cloudfront.net

Human Body Systems
I.
Organization of the Body (Review)
Cells
 Basic unit of structure and function
B. Tissues
 Group of cells that perform a single function
(e.g. epithelial, connective, nervous, muscle)
C. Organs
 Different types of tissues that work together to
perform a closely related function (e.g. eye, liver, lungs)
D. Organ Systems
 Group of organs that perform closely related functions
(e.g. circulatory, respiratory, digestive)
A.
II. Homeostasis
A. Definition: the process by which organisms keep
internal conditions relatively constant despite
changes in their external environments
B. Requires the integration of all organ systems at the
same time
C. Nervous system in conjunction with the endocrine
system (hormones) is responsible for this integration
Examples of Feedback Inhibition
Section
35-1
III.
Maintaining
Homeostasis
A. Negative feedback – your body’s response
results in decreasing the effect of the stimulus
(e.g. body temperature)
Room Temperature
Drops
Room temp. rises
Sensed by
Thermostat
Heater to turn on
Signals
B. Positive feedback – your body’s response
results in an increase in the effect of the
stimulus, (e.g. the flight-fight response)
Nervous System

Recognizes and coordinates the body’s response
to changes in its internal and external
environments.
I.
General Functions of the Nervous System
A. Sensory input – vision, hearing, balance, smell,
taste, and touch
B. Motor output – muscle contraction and movement
C. Memory and integration of information
II. Organization of the NS
A. Central N.S.
1. Brain
2. Spinal Cord
B. Peripheral N.S.
1. Somatic N.S.
2. Autonomic N.S.
a. Sympathetic
b. Parasympathetic
Nervous System
III. Division of Labor
A. Central Nervous System (CNS)
 Control center of the body that relays messages, and processes
and analyzes information
1. Brain
a. Cerebrum – largest region; right and left
hemispheres that are connected by corpus
callosum; voluntary activities and higher brain
functions
b. Cerebellum – located at the lower back part of
brain; coordination and balance
Nervous System
Brain stem – connects the brain and spinal chord;
two regions: pons and medulla oblongata, control
breathing, heart rate and swallowing
d. Thalamus and hypothalamus - between brain stem
and cerebrum
Thalamus: relay station for sensory info
Hypothalamus: most important homeostatic site;
hormones, body’s thermostat, fight or flight, thirst,
hunger, reproduction
c.
Draw Fig. 35-9: The Brain
Cerebrum
Thalamus
Pineal
gland
Hypothalamus
Pituitary gland
Cerebellum
Pons
Medulla oblongata
Spinal cord
Nervous System
2. Spinal Cord
 Two main fxns:
1. Processing of simple responses to
certain stimuli (reflexes)
2. Carries info to and from brain to body
Nervous System
B. Peripheral Nervous System (PNS)
 Receives information from the environment and relays
to and from CNS and sensory, motor and gland cells
Nervous System

Two divisions:
Sensory - Made of sensory neurons that bring info to the
CNS
2. Motor - Made of sensory neurons that convey info from
the CNS; two subdivisions
a. Somatic (voluntary): respond to external stimuli
b. Autonomic (involuntary): respond to internal stimuli
w/the parasympathetic and sympathetic divisions
1.
1)
Sympathetic ↑energy consumption
2)
Parasympathetic ↓energy consumption
Nervous System Flow Chart
Nervous System
Central NS
Brain
Peripheral NS
Spinal chord
Sensory Division
Autonomic NS
(Involuntary)
Sympathetic
(activities that increase
energy consumption)
Motor Division
Somatic NS
(Voluntary)
Parasympathetic
(activities that gain
and conserve energy)
Nervous System
IV. Neurons (Nerve Cells)
 Specialized cells that carry electrical signals
called impulses (Draw Fig. 35-5; pg. 897)
A. 3 Types of Neurons:
1. Sensory – carry impulses from the sense
organs to the spinal cord and brain
2. Motor – carry impulses from brain and spinal
cord to muscles and glands
3. Interneurons – Connect sensory and motor
neurons and carry impulses between them
Nervous System
B. Anatomy of a Neuron
1. Cell Body
 Largest part of the neuron
 Contains the nucleus and most of the cytoplasm
 Metabolic activity takes place in the cell body
Cell
Body
Nervous System
2.
Dendrites
 Carry impulses from the environment or other
neurons to the cell body
Nervous System
3.
Axon
 Long fiber that carries impulses from the cell body
 Ends in axon terminals that contain vesicles for
neurotransmitters
Nervous System
4.
Myelin Sheath
 Insulates the axon
 Gaps in the myelin sheath allow an impulse to jump
from node to node, thus increasing its speed
Which part of the neuron is yellow? Which parts are blue?
V.
A.
The Nerve Impulse
The Resting Neuron
1.
At rest, the outside of the cell has a net positive
charge and the inside has a net negative charge.
This charge difference is called the resting
potential.
(-70mVolts, about 5% of the voltage in AA battery)
A.
2.
3.
The Resting Neuron (cont)
The charge difference is created by active transport of ions
across the cell membrane via the sodium-potassium pump.
Sodium ions (Na+) are pumped outside the cell and
potassium (K+) ions are pumped into the cell.
B.
The Moving Impulse
1.
2.
An impulse begins when a neuron is stimulated
by the axon of another neuron or by the
environment.
Na+ pores open and the flood of Na+ ions
makes the inside positive.
_
+
+
_
B.
The Moving Impulse (cont)
3.
4.
This reversal of charges, from negative to positive is
called a nerve impulse, or an action potential.
As the impulse passes, K+ pores open and K+ flows
out which restores the resting potential (charge
difference)
+
_
+
_
B.
The Moving Impulse (cont)
5. How do things get back to the original condition?
The sodium potassium pump kicks in.
6. The minimum level of a stimulus that is required to
activate a neuron is called the threshold.
Nerve Impulse Summary
C.
1.
2.
3.
Nerve Impulse Pathway Overview
Impulse is received by the dendrites from the
environment or another neuron, then gets rapidly
channeled through the cell body to the axon
Axon branches out into axon terminals, which
contain tiny vesicles filled with neurotransmitters,
which are chemicals used by a neuron to transmit an
impulse to another cell. (e.g. acetylcholine, serotonin,
dopamine and adrenalin).
Vesicles release neurotransmitters into the open
space between neurons called the synapse.
C. Nerve Impulse Pathway (cont)
4.
The neurotransmitters
diffuse across the
synapse and attach
themselves to receptors
on dendrite of
neighboring cell
Direction of Impulse
Dendrite of
adjacent neuron
Axon
Vesicle
Receptor
Axon
terminal
Synaptic cleft
Neurotransmitter
Nervous System
VI. Reflexes
Reflexes are automatic responses to stimuli
 Controlled by 5-part reflex arc:
1. Sensory receptors on finger reacts to stimulus (heat)
2. Impulse is carried to the spinal cord by a sensory
neuron
3. In the spinal cord, the impulse is transferred by an
interneuron to motor neuron
4. Motor neurons conducts the impulse to an effector
(arm muscles)
5. Effector responds to the impulses by contracting (hand
gets pulled away from the heat)

Nervous System
VIII. The Senses
5 General Sensory Receptors: pain, thermo-, mechano-,
chemo- and photoreceptors.

Where do you think these different types of
receptors are found and what is their function?
A. Vision
Hearing and Balance
C. Smell and Taste
D. Touch
B.
Nervous System
IX.
Nervous System Disorders
A. Migraine Headaches – caused by change in serotonin
levels? (affected by caffeine, estrogen, certain foods)
B. Parkinson’s –caused by damage to dopamine
transmitters; causes uncontrollable shaking, no cure
C. Tay-Sachs –lack enzyme to break down fatty deposits
in the brain; neurological deterioration; death by age 4-5
D. Dementia - damaged brain cells caused by injury or disease
(Alzheimer’s); memory loss and personality change.
Nervous System
X.
Drugs and the Nervous System
A. Stimulants
 Accelerate HR, BP, and breathing rate
 Increases the release of neurotransmitters; leads

1.
2.
3.
to release of energy and feeling of well-being
When effect wears off, brain’s supply is depleted
Caffeine
Cocaine
Methamphetamines
Nervous System
B. Depressants
 Slow down HR, lower BP and breathing
rate, relax muscles and relieves anxiety
1. Alcohol
2. Marijuana
3. Sleeping Pills
Commonly Abused Drugs
Commonly Abused Drugs
Section 35-5
Drug Type
Medical Use
Examples
Effects on the body
Stimulants
Used to increase alertness,
relieve fatigue
Amphetamines
Increase heart and respiratory rates;
elevate blood pressure; dilate pupils;
decrease appetite
Depressants
Used to relieve anxiety,
irritability, tension
Barbiturates
Tranquilizers
Slow down the actions of the central
nervous system; small amounts cause
calmness and relaxation; larger
amounts cause slurred speech and
impaired judgement
Opiates
Used to relieve pain
Morphine
Codeine
Act as a depressant; cause
drowsiness, restlessness, nausea