Download Chapter 35 Nervous System PowerPoin

Unit 7: Human
Physiology
Chapter 35- The
Nervous System
Directions
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35-1 Human
Body Systems
(Dragonfly Textbook Pages 890-896)
1) How are living things organized?
2) Why do living things need to be organized?
The organ systems of the human body need to work
together to maintain HOMEOSTASIS.
• For Example:
The Circulatory System
transports Oxygen (taken in by
the Respiratory System) and Food
digested by the Digestive System
to the body cells to be used for
Cellular Respiration
3) What is the basic unit of structure and
function in an organism?
4) How are cells organized?
5) What are organs made up of?
• Organs are made up of different types of tissue working
together to perform a function
• For example: The Heart is made up of:
Cardiac Cells (Muscle Tissue)
• Pacemaker Cells (Nervous Tissue)
• Pericardium (Epithelial Tissue)
• Valves (Connective Tissue)
6) Do all organisms need to be organized at an organ
systems level?
Euglena- one cell with organelles
Hydra- cells and tissues
All living organisms must carry
out the life processes, but they
do not have to carry them out
in the same way
Cat- cells, tissues,
organs, organ systems
For Example:
Euglena carry out digestion using
vacuoles and a cell membrane (organelles)
Hydra carry out digestion using a
gastrovascular cavity (cells and tissues)
Cats carry out digestion using a digestive
System (Organ system)
7) How do organism systems work together to
constantly maintain homeostasis?
• Feedback mechanism- occurs when the level of one substance
influences the level of another substance or activity of another organ.
For Example:
1) High Blood Sugar- promotes the release of insulin
(hormone) from the pancreas
2) Insulin stimulates glucose uptake from blood and the
formation of glycogen which decreases blood sugar
3) Low Blood Sugar- promotes the release of
glucagon (hormone) from the pancreas
4) Glucagon stimulates glycogen breakdown which increases
Blood sugar
35-2- The
Nervous System
(Dragonfly Textbook Pages 897-900)
1) What is the nervous system?
The nervous system controls and
coordinates life functions throughout
the body and responds to internal
and external stimuli.
2) Parts of the NERVOUS SYSTEM
Central Nervous System (CNS)
- Brain and Spinal Cord
- The body’s main information
processing center
Peripheral Nervous System (PNS)
- All of the nervous tissue outside
the CNS
- Delivers information to the CNS
and carries the messages from the
CNS to other organs through
communication lines called nerves
3) Nerve Impulse
• Nerve Impulse: the electrical
signal transmitted through
the nervous system
• Nerve – a bundle of neurons.
• Neuron – specialized cell that
transports impulses from one
place to another in the body.
4) Structure of a Neuron
• Dendrites- receive signals and carry
them toward the neuron’s cell body.
• Axon- carries electrical signals away
from the cell body and toward other cells.
• Myelin Sheath- made of fat and
insulates
the axon. Increases the speed that
electrical
signals are transmitted.
• Nodes- uninsulated part of the axon.
Electrical signal jumps from node to node.
• Terminal Branches- end of axon,
transmits signal to the next neuron.
5) How does a nerve impulse work?
• Stimulus - change in internal or external environment
(ex. sound, light, heat, odor)
• Receptor - specialized structures to receive
stimulus (ex. ear, nose, mouth, eyes, and skin)
• Effectors – specialized to produce a response
( a muscle or gland)
• Response - the physical movement made
in response to the stimulus or the secretion
of a hormone from a gland.
6) For Example: What happens when you touch a
hot surface like a metal pot?
Hot Iron (Stimulus)
Pain Receptors in your hand (Receptor)
CNS
PNS
Muscles in your hand (Effector)
Move your hand away (Response)
1) Na+/K+ Pump- pumps out 3 Na+ and
pumps in 2 K+.
2) This leaves a net positive charge on the
outside and a net negative charge on the
inside.
This state is known as Resting
Potential.
This active state is known as
Depolarization!
3) If a neuron is stimulated enough, Na+
Channels open and Na+ will rush in
(diffusion) and cause a temporary positive
charge on the inside of the neuron.
** Keep in mind, that a neuron will only fire if
the stimulus is strong enough to depolarize
the membrane to a certain level called the
Threshold.
This strong depolarization, is the start of the
nerve signal called the Action Potential.
4) This will set off a chain reaction of action
potentials across the neuron.
5) After the signal is
transmitted, K+ Channels
will open and K+ will diffuse
out of the neuron and this
will help restore the Resting
Potential.
8) What type of message is a nerve impulse?
ELECTRICAL!!
What happens at the synapse?
Neurotransmitters:
1) Acetylcholine
2) Norepinepherine
The nerve signal must cross
the synapse. For this to
occur, the electrical signal
is converted to a chemical
signal.
1) The electrical signal
reaches the terminal
branches and causes the
release of a chemical
messenger called a
Neurotransmitter.
What happens at the synapse?
Receptors
Are specific!
2) Receptor molecules on
the receiving neuron’s
membrane accept the
neurotransmitter.
3) A new electrical signal
is transmitted through the
2nd neuron.
4) After the
Neurotransmitter triggers
the new signal, it is broken
down by enzymes thus
preventing the continuous
stimulation of the receiving
neuron.
Types of Neurons


Sensory Neurons
Motor Neurons

Interneurons
Stimulus
Effector
Response
Receptor
Sensory Neuron
Motor Neuron
Interneuron
a. Sensory Neurons

Sensory Neuron: receives stimulus from the environment and
carry them to
the brain and spinal cord. Found in Receptors!!
 Ex.
 Eyes
 Ears
 Nose
 Toungue
 Skin
b. Motor Neurons

Motor Neuron: carry information from the brain or spinal cord to
muscles or glands (effectors).

* A motor neuron makes
something move.
c. Interneurons

They are found in the brain or spinal cord
(CNS), “BETWEEN” sensory and motor
neurons.

Most neurons are interneurons.
d. Reflexes

A REFLEX is an automatic response to a
certain stimulus (you have NO control
over it).

Ex: Blinking
Sneezing
Coughing
Breathing
Heartbeat
Knee-jerk
Dilation of Pupil
e. Reflex Arc



Message travel to the spinal cord and back to
muscles.
Movement occurs without the use of the brain.
The brain gets the message a split second after
the response.
35-3- Divisions of
Nervous System
(Dragonfly Textbook Pages 901-905)
BRAIN FACTS
• Your brain has reached its full weight of about 3 pounds by the
time you are 6 years old.
• The left side of your brain controls your right side of your body
and the right side of your brain controls your left side.
• The brain has no pain receptors.
• The brain requires 20% of the oxygen supply but is only 2% of
your weight.
• Albert Einstein’s mathematical portion of his brain was 15% larger
than average.
1) NERVOUS SYSTEM
Peripheral N.S.
Central N.S.
Brain
Spinal Cord
Cerebrum
Cerebellum
Medulla
Somatic
Autonomic
2) What are the functions of the central
nervous system?
The CNS (central nervous system) relays messages,
processes information, and analyzes information.
3) Parts of the Brain
a) Cerebrum
b) Cerebellum
c) Medulla (brainstem)
(medulla)
3a) Cerebrum:
• Largest part of the brain.
• It is responsible for:
 Conscience thought
 Intelligence
 Memory
 Sense interpretation
 Reasoning
 Voluntary Activities
 Controls body
movements
3b) Cerebellum:
• Rear of cranium (head)
• Second largest part of the
brain.
• It is responsible for:
Balance
Coordinates muscle activity
Involuntary muscle actions.
3c) Medulla (Brainstem)
• Found at the base of the brain
(connects the brain and spinal cord)
• It acts as a “neural switchboard”
• Responsible for:
• Automatic Processes
–
–
–
–
Blood Pressure
Heart Beat
Breathing
Swallowing
4) Identify These Parts of the Brain
#1
#3
#2
5) Spinal Cord
• Connects to the brain through the medulla.
• Carries messages from the brain to body nerves.
– (like the nerve superhighway)
• Coordinates Reflexes
6) Peripheral Nervous System
Sensory division of the peripheral nervous system transmits
impulses from sense organs to the central nervous system. The
motor division transmits impulses from the central nervous system
to the muscles or glands.
•
•
Lies OUTSIDE the CNS
Divided into two parts:
– Autonomic N.S. – nerves regulating automatic function (Ex: Glands and
involuntary muscles)
– Somatic N.S.- nerves regulating voluntary actions (Ex: moving your
arms and toes)
35-4- The Senses
(Dragonfly Textbook Pages 906-909)
1) What are sensory receptors?
There are five general categories of sensory receptors:
pain receptors, thermoreceptors, mechanoreceptors,
chemoreceptors, and photorecepors.
- Very Specific to particular
Stimuli!!!
- Located throughout the body,
But concentrated in sense organs (eyes, ears, nose, mouth, skin)
2) How do we sense light (vision)?
• Cornea- focuses light entering eye
• Iris- colored part of eye
• Pupil- regulates amount of light (larger in dim
light, smaller in bright light)
• Lens- changes shape to focus near/distant
objects
• Retina- photoreceptors convert light into nerve
impulses
– Rods- sensitive to light, but not colors
– Cones- less sensitive to light, respond to
colors
• Fovea- site of sharpest vision
• Optical nerve- transmits impulses to the brain
for interpretation
Fovea
3) How do we hear and maintain balance?
• Hearing
– Sound vibrations enter ear
causing eardrum to vibrate
– Hammer and Anvil vibrate,
and Stirrup transmits
vibration to oval window
– Pressure waves travel
through fluid-filled cochlea
– Hair cells in cochlea move,
producing nerve impulses
that are sent to brain
• Balance
– Semicircular Canals monitor the
position of your body (esp. head)
in relation to gravity to help your
CNS maintain equilibrium
4) How do we smell and taste?
• Chemoreceptors in nasal
passages- detect
chemicals and transmit
information to brain
• Taste buds on tonguedetect salty, bitter, sweet,
and sour tastes and
transmit information to
brain
Try tasting something while holding your nose. Does it work as well?
5) Touch and related senses
• Sensory receptors in skin
respond to temperature,
touch and pain
• More receptors = more
sensitive area
• Most sense receptors
found in fingers, toes, and
face
Chapter 35 Key Ideas Summary
35-1 Human Body Systems
The eleven organ systems
of the human body work
together to maintain
homeostasis
35-2 The Nervous System
the nervous system controls
and coordinates functions
throughout the body and
responds to internal and
external stimuli
A nerve impulse begins when
a neuron is stimulated by
another neuron or by its
environment
Chapter 35 Key Ideas Summary
35-3 Divisions of the Nervous System
The CNS relays messages,
processes information, and
analyzes information
The sensory division of the PNS
transmits impulses from sense
organs to the CNS. The motor
division transmits impulses from the
CNS to the muscles or glands
35-4 The Senses
There are give general
categories of sensory
receptors: pain receptors,
thermoreceptors,
mechanoreceptors,
chemoreceptors, and
photoreceptors
Chapter 35 Key Ideas Summary
35-3 Drugs and the Nervous System
Stimulants increase heart rate,
blood pressure, and breathing rate.
In addition, stimulants increase the
release of neurotransmitters at
some synapses in the brain
Depressants slow down heart rate
and breathing rate, lower blood
pressure, relax muscles, and
relieve tension
Cocaine causes the sudden release
of a neurotransmitter in the brain
called dopamine
Opiates mimic natural
chemicals in the brain known
as endorphins, which normally
help to overcome sensations
of pain
Alcohol is a depressant, and
even small amounts of alcohol
slow down the rate at which
the nervous system functions