Transcript REGULATION nervous system

NERVOUS
and
CHEMICAL
REGULATION
1. Organisms must respond to changes
•
•
Changes outside the organism
Changes inside the organism
REGULATION
2. Organisms must respond in a
coordinated way
•
•
•
Must be controlled and coordinated
Homeostasis must be maintained
Responses must be regulated (in the right
order)
REGULATION
3. Complex organisms control and
regulate responses by
•
•
The nervous system
The endocrine system
VOCAB
• Irritability = the ability of a cell to respond
to its environment
• Regulation = all the activities that help to
maintain an organism’s homeostasis
ORGANISM
PROTISTS
(amoeba and
paramecium)
TYPE OF
SYSTEM
NONE
But can
respond to
stimuli
NERVE NET
HYDRA
EARTHWORM
GRASSHOPPER
No brain or
nerve cord
SIMPLE
SYSTEM
SIMPLE
SYSTEM
but more complex
than the earthworm
ADAPTATIONS
OR
SPECIALIZED
STRUCTURES
Fibers that control
beating cilia
Eyespots sensitive
to certain stimuli
Special receptor
cells connected
to muscle and
gland cells
Central nervous
system (CNS)
SENSE ORGANS
NONE
Coordinated
movement of
the tentacles
Receptors in the
skin
brain and 2 ventral
nerve cords
sensitive to light,
vibrations, chemicals,
heat
Peripheral
nervous system
(PNS)
EYES
ANTENNAE
nerve branches
muscles and glands
(feelers)
taste organs
sound sensors
(tympanium)
Mechanisms of Nervous Regulation
1.
Nerve cells = specialized cells that carry
messages
Impulses = the messages that nerve cells
carry
Receptor = (sense organ) specialized
structures that are sensitive to certain
changes
2.
3.


Physical force
Chemical changes inside or outside the organism
 May respond to heat, cold, light, sound,
pressure, chemicals
 A stimulus to a receptor causes an impulse to
be transmitted (carried)
Mechanisms of Nervous Regulation
4.
Effector = specialized structure that responds to the
commands of the nervous system
a) Gland – will increase or decrease activity
b) Muscle – will contract
5.
Stimulus = anything that causes a receptor to start an
impulse
a) It causes an electrical and chemical change
→Stimulus activates a receptor
→Impulses start across the nerve pathway
→Effector responds to the impulse
Mechanisms of Nervous Regulation
6. Brain = specialized group of nerve cells that
control and coordinate the activities of the
nervous system
•
•
There are many interconnections along the
nerve pathway – it is very complex
The more complex the organism, the more
complex the brain
STRUCTURE OF NEURONS
(bottom of page 6)
Nerve cell = neuron = basic structure in
nervous systems
Neurons can send electrical and chemical
impulses
(electrochemical impulses)
The sending of impulses is the property of
the neuron’s cell membrane
Transmission not through the cytoplasm,
but along the cell membrane
STRUCTURE OF A NEURON
Where cell’s metabolic activity takes place
CELL BODY
Controls the cell’s growth
NUCLEUS
Receives impulses
DENDRITES
NODE OF
RANVIER
AXON
TERMINAL
BRANCHES
Sends out
impulses
SCHWANN CELL
NUCLEUS
SCHWANN CELL
MYELIN SHEETH
Speeds transmission
SYNAPTIC
KNOBS
STRUCTURE OF NEURONS
SYNAPSE
Synapse = microscopic gap at the end of the
terminal branch of the neuron and the
neighboring cell
Each axon can have one or more
synapses with as many as 1,000 other
axons
The many connections make the nervous
system so complex
SYNAPSE
TYPES
OF NEURONS
SENSORY NEURON
MOTOR NEURON
INTERNEURON
SENSORY NEURON
Sensory nerves –
receive impulses and
send them along to
other axons
Carry information
into the central
nervous system
MOTOR
NEURON
Motor neurons –
carry impulses to
effectors (ie: muscles)
Carry information
away from the central
nervous system
INTERNEURON
Interneurons (associative neurons) –
relay impulses neuron to neuron
Found only in the central nervous system
NERVES
Nerves are bundles
of axons and
dendrites bound
together by
connective tissue
cell body
nucleus
dendrites
INTERNEURON
axon
myelin sheath
Schwann cell
cell body
node of
Ranvier
MOTOR NEURON
synaptic
knobs
SENSORY NEURON
THE NERVE IMPULSE
The nerve impulse is the reversal of
polarization
Refractory period = a brief time (~3/1000
sec) when polarization of a neuron is
returning to its normal (resting) state – the
neuron can not be stimulated to carry an
impulse during this period
Turn to page 10 in
your packet
The sodium-potassium pump pumps Na+ out and can’t get back in!
The membrane is impermeable to Na+
Na+
Na+ rushes in when the
channels open to Na+
In Resting Cell:
•Positive charge outside of the cell is caused by concentration of Na+
outside the cell (negative charge inside the cell)
•The cell membrane is said to be polarized
In the area of impulse:
•Positive charge inside the cell is caused by the permeability change in the cell
membrane – it becomes permeable to the Na+ - this reverses the polarity
•The cell membrane is said to be depolarized
Impulse Transmission
http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter14/animation__the_nerve_impulse.html
Turn back to page
10 in your packet
Turn back to page 9
in your packet
RATE OF IMPULSE CONDUCTION
Depends upon:
1) Size of nerve fibers
2) Whether a neuron is myelinated or not
a) Small non- myelinated neuron’s speed ~ 2
meters/sec
b) Large myelinated neuron’s speed ~ 100
meters/sec
Myelinated neurons are faster because the
impulse “jumps” from one node of Ranvier to the
next node of Ranvier
This is called SALTATORY CONDUCTION
SALTATORY CONDUCTION
• Where the myelin is, depolarization is
blocked
• Depolarization only occurs at the nodes of
Ranvier
• The impulse “jumps” from node to node
• Saltatory conduction is faster and uses
less energy (less active transport)
THRESHOLDS
• Stimulus must have minimum strength to
start an impulse
• All or nothing response
• On a particular axon, all impulses are the
same “size”
DISTINGUISHING SIZE AND TYPE
OF STIMULUS
The greater the strength of the stimulus,
the more frequently the impulses are sent
(increasing the rate of transmission)
Particular types of stimulus (light, touch,
sound) are only picked up by the specific
receptor and travel to a specific place in
the brain to be interpreted
The reflex arc
Please turn to page
18 in your packets
The Reflex Arc
synapse
sensory neuron
synapse
associative neuron
effector
sense receptor
motor neuron
Mechanism of Nervous Regulation
A Reflex Arc
sensory neuron
sense receptor
direction of impulse
associative
neuron
or
interneuron
stimulus
motor neuron
response
muscle
cell
effector
(skeletal muscle)
TRANSMISSION AT THE
SYNAPSE
(page 11 in your packet)
TRANSMISSION AT THE SYNAPSE
Axon of a neuron ends at the synaptic knob
where the impulse must be carried to the axon
(or dendrite) of the next neuron (across the
synaptic gap)
This occurs by a chemical process using
chemicals known as neurotransmitters
• Acetylcholine and norepinepherine
TRANSMISSION AT THE SYNAPSE
When the impulse reaches the synaptic
knob, neurotransmitters are released
Neurotransmitters diffuse across the
synaptic gap
Neurotransmitters change the permeability
of the neighboring axon’s cell membrane
(making it permeable to Na+)
This initiates an impulse
LOOK AT THE DIAGRAM ON THE RIGHT SIDE OF THE PAGE
A. An impulse arrives at the synaptic knob of the pre-synaptic neuron
B. Neurotransmitters are released from the synaptic vesicles
C. Neurotransmitters diffuse across the synaptic gap
D. The neurotransmitters change the permeability of the cell membrane of the
postsynaptic neuron
E. Depolarization occurs
F. An impulse is initiated along the cell membrane of the post-synaptic axon
…this initiates an impulse
** transmission across the synapse is a
chemical process
** transmission across along the axon is an
electrical process
• chemical transmission is much slower than
electrical transmission
TRANSMISSION AT THE SYNAPSE
The stronger the stimulus – the more
neurotransmitter released – this increases the
rate of impulse transmission in the postsynaptic
neuron
Neurotransmitters are broken down in the
synaptic gap by specific enzymes after the
postsynaptic neuron has responded
• Acetylcholine’s enzyme is acetylcholinesterace and
is one of the fastest reacting enzymes in the body
Transmission Across the Synapse
http://www.youtube.com/watch?NR=1&v=WmTXiLndbsc&feature=endscreen
http://www.youtube.com/watch?v=HXx9qlJetSU&feature=related
TRANSMISSION AT THE SYNAPSE
Impulses flow from synaptic knobs to
dendrites (one direction)
Excitatory transmitters
• acetylcholine, norepinephrine, histamine,
glutamic acid
Inhibitory transmitters
• serotonin, epinephrine, glycine
How Neurons
Talk to Each
Other
http://learn.genetics.utah.edu/content/addiction/crossingdivide/
DRUGS AND SYNAPSE
Poisons and drugs can affect chemical transmitters
 Curare (nerve gas)
 Botulin
cause paralysis
 Stimulants
• amphetamines “uppers” cause excitability followed by
depression
• caffeine causes sleeplessness and nervousness
 Depressants
• Barbiturates “downers” block formation of norepinepherine
 Mind altering drugs
• LSD
• mescaline
interfere with serotonin (inhibitory transmitter)
DRUGS AND SYNAPSE
http://learn.genetics.utah.edu/content/addiction/mouse/
The reflex arc
Please turn to page
18 in your packets
The Reflex Arc
synapse
sensory neuron
synapse
associative neuron
effector
sense receptor
motor neuron
Mechanism of Nervous Regulation
A Reflex Arc
sensory neuron
sense receptor
direction of impulse
associative
neuron
or
interneuron
stimulus
motor neuron
response
muscle
cell
effector
(skeletal muscle)
Please turn to page 15
THE CENTRAL NERVOUS SYSTEM
Made up of the brain
and the spinal
cord
• Also interneurons
and cell bodies of
the motor neurons
Protection of the Central Nervous
System
Cranium
The spinal column
Disks
Meninges
Three tough membranes filled with cerebrospinal fluid
Ventricles
Cranium – protects the brain
The spinal column – protects the
spinal cord
Disks – between the vertebrae
absorb shock
•Meninges – shock absorbers for
the brain
Three tough membranes filled with
cerebrospinal fluid
Ventricles –spaces in the brain
filled with cerebrospinal fluid
The Brain
Blood Flow to the Brain
• 20% blood from the heart goes to the brain
• Greatest metabolizer of glucose
Major parts of the brain
CEREBRUM
THALAMUS
HYPOTHALAMUS
PONS
MEDULLA
OBLONGATA
CEREBELLUM
Complete the right side of
page 15 in your packet
Identify the parts of the brain in the
diagram numbered 1 - 5
PARTS AND FUNCTION
OF THE
BRAIN
CEREBRUM
 2/3 of the entire brain
 deep grooves separates 2 halves into the right and
left hemispheres
• right hemisphere – artistic and musical abilities
• left hemisphere – mathematical abilities
CEREBRUM
Functions:
1. sensory – receives
and interprets
impulses from
sensory receptors
(eyes, ears, taste
buds, nose, touch,
pain, pressure, heat,
cold)
2. motor – all voluntary
motion and position
sense
3. associative – memory,
learning, thought
CEREBRUM
Nerve fibers cross on
route from the brain to
the spinal cord
• the right side of the brain
controls the left side of the
body
• the left side of the brain
controls the right side of
the body
1. Frontal lobe –
personality, planning,
higher level thoughts,
emotional responses
2. Temporal lobe –
speech
3. Occipital lobe – vision
4. Parietal lobe –
language
comprehension, spatial
understanding (ie:
depth perception), and
tactile understanding
CEREBRUM
Lobes
II. CEREBELLUM
 located below the rear
of the cerebrum
 controls all voluntary
and some involuntary
motions
1.
receives input about body
position, and muscle
contractions
2. sends impulses to the
cerebral cortex to correct
and coordinate muscle
movements
3. receives input from the
inner ear to control balance
4. cerebellar damage results
in a “drunken sailor gait”
III. MEDULLA OBLONGATA
Controls breathing, heart beat, blood flow,
coughing
IV SPINAL CORD
 Connects peripheral
nerves with the brain
(interneurons)
 Reflexes (automatic
responses)
V. THALAMUS
 relay center between
brain and spinal cord
 receives and changes
all sensory impulses
(except smell) before
they travel to the
cerebrum
 involved in pain and
consciousness
VI. HYPOTHALAMUS
 involved in controlling
body temperature,
blood pressure,
sleep/wake cycles,
emotions, and the
endocrine system
(hormones)
VII. Pons
relay center
linking the spinal
cord and the
medulla
oblongata,
cerebellum, and
cerebrum
PONS
Structure of the Brain
4. forebrain
1. thalamus
2.cerebrum
3. Hypothalamus
5. Corpus
callosum
6. midbrain
10. hindbrain
7. Cerebellum
8. Pons
9. medulla
11. Spinal cord
Area of the Brain
Primary Function
2. CEREBRUM
Voluntary motions
Sensory input
Motor output
Personality / thoughts
7. CEREBELLUM
Voluntary motions
Coordinates muscle control
Balance / equilibrium
9. MEDULLA OBLONGATA
Involuntary responses
(breathing ,heartbeat, blood flow,
coughing, vomiting, sneezing,
peristalsis)
1. THALAMUS
Feeling pain / consciousness
3. HYPOTHALAMUS
Involuntary responses
(body temperature, blood pressure,
sleep, emotion)
Endocrine system
8. PONS
Relay center
THE PERIPHERAL NERVOUS
SYSTEM
Includes all nerve fibers outside the CNS
(not the spinal cord and brain)
Spinal nerves – nerves that exit the spinal
cord (31 pair)
Cranial nerves – nerves that exit directly
from the brain (12 pair)
THE PERIPHERAL NERVOUS SYSTEM
Includes all nerve fibers
outside the CNS
Cranial nerves exit the brain
Spinal nerves exit the spinal cord
The PNS is divided
as follows
PNS
Motor
Sensory
Review the flow sheet on
page 19 of your packet