Nervous System
description
Transcript of Nervous System
![Page 1: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/1.jpg)
Nervous Systemand Senses
![Page 2: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/2.jpg)
Neural Activity
![Page 3: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/3.jpg)
The Neuron
• Which direction does a signal travel down a neuron?
• What do you think a “signal” is?
• How do you think the neuron controls where the signal goes next?
![Page 4: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/4.jpg)
Electrical Events• An action potential
is an “all or nothing” event. A neuron either sends a signal or it doesn’t.
• Relative strength or weakness of a signal come from frequency, not size of the potential.
![Page 5: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/5.jpg)
Resting potential• Using active
transport, the neuron moves N+ ions to the outside of the cell and K+ ions to the inside of the cell.
• Large molecules in the cell maintain a negative charge.
![Page 6: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/6.jpg)
Action potential
• On receiving a stimulus, sodium gates and potassium channels open briefly, allowing these ions to diffuse.
• The gates close, and active transport restores the resting potential.
![Page 7: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/7.jpg)
Traveling Potentials
![Page 8: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/8.jpg)
Traveling Potentials
![Page 9: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/9.jpg)
Synapse
• A gap called a synapse controls the transmission of signals.
• Neurotransmitters cross the synapse and stimulate the next neuron.
![Page 10: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/10.jpg)
Some Neurotransmitters
Neurotransmitter Location Some Functions
Acetylcholine Neuron-to-muscle synapse Activates muscles
Dopamine Mid-brain Control of movement
Epinephrine Sympathetic system Stress response
Serotonin Midbrain, pons, medulla Mood, sleep
Endorphins Brain, spine Mood, pain reduction
Nitric oxide Brain Memory storage
![Page 11: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/11.jpg)
During resting potential, which channels are closed?
1 2 3 4
25% 25%25%25%
1. Potassium2. Sodium3. All4. None
![Page 12: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/12.jpg)
What determines the intensity of a neural signal?
1 2 3 4
25% 25%25%25%1. Speed of action
potential.2. Size of action
potential.3. Duration of action
potential.4. Frequency of
action potentials.
![Page 13: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/13.jpg)
During a resting potential, where are most positively-charged particles
found?
1 2 3
33% 33%33%1. Outside the
neuron.2. Inside the neuron.3. Equal amounts
are found on both sides of the membrane.
![Page 14: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/14.jpg)
• Sketch a neuron and label the four major parts.
• Diagram a synapse and show how action potentials travel from one neuron to the next.
WORK
TOGETHER
![Page 15: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/15.jpg)
Information Processing
![Page 16: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/16.jpg)
Why a CNS?• Neurons control movement. The
brain (or spine) interprets sensory signals and determines the appropriate movements (that is, behavior).
• Appropriate movement is critical to the survival of most animal species.
• Selection has favored a central nervous system to control responses.
![Page 17: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/17.jpg)
Four basic operations
• Determine type of stimulus
• Signal the intensity of a stimulus
• Integrate responses from many sources
• Initiate and direct operations
![Page 18: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/18.jpg)
Type of stimulus
• How does the brain “know” if a sensory signal is visual, auditory, etc.?
• Areas of the brain dedicated to specific sensory signals are connected to nerves that connect to specific sensory organs.
• “Cross-sensory” effects: a poke in the eye produces stimulates the optic nerve, producing visual effects.
![Page 19: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/19.jpg)
Intensity of stimulus
• Intensity = frequency of action potentials
![Page 20: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/20.jpg)
Integration of stimuli
• Convergence = Signals may arrive through many neurons, but may all pass their signal to a single connecting neuron.
• Such cells may be “decision-making” association neurons that may determine an appropriate output.
![Page 21: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/21.jpg)
Directing operations
• Neural pathways consist of:
• Sensory neurons
• Association neurons, which receive signals from many sources
• Motor neurons
• Effectors: muscles, glands
![Page 22: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/22.jpg)
Reflexes
• The simplest neural pathway is the reflex arc.
• This involves one or more sensory neurons, association neurons in the spine, and motor neurons, which carry out the reflex entirely before the brain is aware of the response.
![Page 23: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/23.jpg)
Reflex Arc
![Page 24: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/24.jpg)
What is the effector in the familiar knee jerk reflex?
1 2 3 4 5
20% 20% 20%20%20%1. The knee hammer2. Sensory receptors
in the patellar tendon
3. Sensory neurons running up the leg
4. Motor neurons running down the leg
5. The quadriceps muscles
![Page 25: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/25.jpg)
• You’re probably all familiar with the knee-jerk reflex, which your doctor uses to test your reflexes. Sketch a reflex arc for the knee jerk reflex, beginning with whacking your knee with a hammer. Label the sensor and effector in your diagram.
WORK
TOGETHER
![Page 26: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/26.jpg)
Organization
![Page 27: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/27.jpg)
Neural organization
![Page 28: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/28.jpg)
Central Nervous System
• Consists of brain and spine
• Functions:
• Receives sensory signals and determines appropriate response
• Stores memory
• Carries out thought
![Page 29: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/29.jpg)
Spine: structure• The spinal cord is
protected by the vertebrae.
• Gray matter contains cell bodies; white matter contains myelinated fibers.
• PNS nerves extend outside of the vertebrae.
![Page 30: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/30.jpg)
Brain: Structure• Hindbrain carries
out the most basic functions.
• Midbrain coordinates signals.
• Forebrain processes signals, stores memories, creates thought.
![Page 31: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/31.jpg)
Peripheral nervous system
• Nerves, neurons, and sensory organs outside the central nervous system
• Functions:
• Sends signals to the CNS
• Receives and transmits motor signals from the CNS
• Stimulates effectors
![Page 32: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/32.jpg)
Somatic nervous system• Motor neurons that control
voluntary movements by activating skeletal muscles.
• Also involved in what we perceive as involuntary movements, such as reflexes (though voluntary control of the muscles involved, such as tensing them, can reduce the response).
![Page 33: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/33.jpg)
Autonomic Nervous System
• Motor neurons that control involuntary responses involving the organs, glands, and smooth muscles.
![Page 34: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/34.jpg)
Sympathetic division• Portion of the autonomic
nervous system that produces the “fight or flight” response:
• Dilation of pupils
• Increased heart and breathing rates
• Constriction of blood vessels
• Inhibits digestion
![Page 35: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/35.jpg)
Parasympathetic Division• Portion of the
autonomic nervous system that produces the “rest and ruminate” response:
• Constricts pupils
• Dilates blood vessels
• Reduces heart and breathing rates.
• Stimulates digestion.
![Page 36: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/36.jpg)
The central nervous system includes:
1 2 3 4
25% 25%25%25%
1. Brain only2. Brain and spine3. Brain, spine, and
major nerves4. Spine and major
nerves
![Page 37: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/37.jpg)
Motor neurons carry signals which direction?
1 2 3 4
25% 25%25%25%
1. Sensory organs -> CNS
2. Muscles -> CNS3. CNS -> sensory
organs4. CNS -> muscles
![Page 38: Nervous System](https://reader035.fdocuments.net/reader035/viewer/2022081401/56814097550346895dac2f83/html5/thumbnails/38.jpg)
Which activity is most likely to activate the sympathetic division of
your nervous system?
1 2 3 4
25% 25%25%25%
1. Cuddling kittens2. Watching an
exciting action movie.
3. Meditating4. Lying in the sun