nervous system
TRANSCRIPT
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I control everything…
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Functions of the Nervous System
1. Communication and coordination Adapt and respond to changes from both inside and
outside the body
2. Site of reasoning- your brain
3. Two main divisions Central nervous system (CNS): brain and spinal cord Peripheral nervous system- the nerves
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Neuron- basic structural unit of the nervous system
Dendrites- carry impulses towards the cell
Axon-carry impulses away from the cell
Myelin sheath Synaptic terminal
Epinephrine Norepinephrine Acetylcholine
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Nerves
Nerves are made of many nerve cells
Afferent-sensory nerves carry message to brain
Efferent-motor neurons carry message from brain to muscle
Associate- do both
Heads up
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The Nervous System
Major division - Central vs. Peripheral
Central or CNS- brain and spinal cord
Peripheral- nerves connecting CNS to muscles and organs
Central Nervous System
Peripheral Nervous System
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Central Nervous System
Brain and Spinal Cord
SpinalCord
Brain
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Cerebrum Cerebrum-largest
part of brain. Responsible for reasoning, thought, memory, speech, sensation, etc.
Divided into two halves.
Further divided into lobes; occipital, parietal, temporal and frontal
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Parts of the Brain
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Cerebellum and Brain Stem Cerebellum-
responsible for muscle coordination
Brain stem- most basic functions; respiration, swallowing, blood pressure. Lower part (medulla oblongata) is continuous with spinal cord
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Parts of the brain and their functions
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Spinal cord
Spinal cord- begins at foramen magnum and ends at second lumbar vertebrae
Contains both afferent (to the brain) and efferent (motor neurons- away from the brain)
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Both the brain and spinal cord are covered by a membrane system called the meninges
In addition, the brain has four hollow areas called ventricles. Cerebrospinal fluid is produced in the ventricles and bathes the brain and spinal column
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Left & Right sides are separate
Corpus Callosum : major pathway between hemispheres
Some functions are ‘lateralized’ language on left math, music on right
Lateralization is never 100%
Brain has 2 Hemispheres
LeftHemisphere
Corpus CallosumRight
Hemisphere
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Each hemisphere is divided into 4 lobes
Frontal
Parietal
Occipital
Temporal
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Sensory Information sent to opposite hemisphere
Principle is Contralateral Organization
Sensory data crosses over in pathways leading to the cortex
Visual Crossover left visual field to right
hemisphere right field to left
Other senses similar
Left visualfield
Right visualfield
Opticnerves
CorpusCallosum
Left VisualCortex
Right VisualCortex
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Contralateral Motor Control
Movements controled by motor area
Right hemisphere controls left side of body
Left hemisphere controls right side
Motor nerves cross sides in spinal cord
Somatosensory CortexMotor Cortex
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Corpus Callosum
Major ( but not only) pathway between sides
Connects comparable structures on each side
Permits data received on one side to be processed in both hemispheres
Aids motor coordination of left and right side
Corpus Callosum
Medial surface of right hemisphere
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Corpus Callosum
What happens when the corpus callosum is cut?
Sensory inputs are still crossedMotor outputs are still crossedHemispheres can’t exchange data
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Nonverbalrighthemisphere
Verballefthemisphere
??
“What didyou see?”
Picture to left brain can name the object left hand cannot
identify by touch
Picture to right brain can’t name the object
left hand can identify by touch
“Using your left hand,Pick up what you saw.”
The ‘Split Brain’ studies
I saw anapple.
“What didyou see?”
Nonverbalrighthemisphere
Verballefthemisphere
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Localization of function
Frontal
Parietal
Occipital
Temporal
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Peripheral Nervous System
3 kinds of neurons connect CNS to the body sensory motor interneurons
Motor - CNS to muscles and organs
Sensory - sensory receptors to CNS
Interneurons: Connections Within CNS
SpinalCord
Brain
Nerves
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Peripheral Nervous System
Skeletal(Somatic)
Sympathetic Parasympathetic
Autonomic
Peripheral Nervous System
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Somatic System
Nerves to/from spinal cord control muscle
movements somatosensory
inputs Both Voluntary and
reflex movements Skeletal Reflexes
simplest is spinal reflex arc
Muscle
MotorNeuron
Interneuron
Skin receptors
SensoryNeuron
Brain
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Autonomic System
Two divisions: sympathetic Parasympatheitic
Control involuntary functions heartbeat blood pressure respiration perspiration digestion
Can be influenced by thought and emotion
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Sympathetic
“ Fight or flight” response Release adrenaline and
noradrenaline Increases heart rate and
blood pressure Increases blood flow to
skeletal muscles Inhibits digestive functions
CENTRAL NERVOUS SYSTEMBrain
Spinalcord
SYMPATHETIC
Dilates pupil
Stimulates salivation
Relaxes bronchi
Accelerates heartbeat
Inhibits activity
Stimulates glucose
Secretion of adrenaline,nonadrenaline
Relaxes bladder
Stimulates ejaculationin male
Sympatheticganglia
Salivaryglands
Lungs
Heart
Stomach
Pancreas
Liver
Adrenalgland
Kidney
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Parasympathetic
“ Rest and digest ” system
Calms body to conserve and maintain energy
Lowers heartbeat, breathing rate, blood pressure
CENTRAL NERVOUS SYSTEMBrain
PARASYMPATHETIC
Spinalcord
Stimulates salivation
Constricts bronchi
Slows heartbeat
Stimulates activity
Contracts bladder
Stimulates erectionof sex organs
Stimulates gallbladder
Gallbladder
Contracts pupil
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Summary of autonomic differences
Autonomic nervous system controls physiological arousal
Sympatheticdivision (arousing)
Parasympatheticdivision (calming)
Pupils dilate EYES Pupils contract
Decreases SALVATION Increases
Perspires SKIN Dries
Increases RESPERATION Decreases
Accelerates HEART Slows
Inhibits DIGESTION Activates
Secrete stresshormones
ADRENALGLANDS
Decrease secretionof stress hormones
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Disorders of the nervous system
Meningitis- inflammation of the linings of the brain and spinal cord
Encephalitis- inflammation of the brain Epilepsy-seizure disorder. Excessive discharge
from neurons. 1 in 200 suffer. Grand mal or petit mal seizures
Cerebral palsy- disturbance in voluntary muscular action
Parkinson’s –decreased neurotransmitter MS multiple sclerosis- autoimmune
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The Nervous System: Summary
Major structures of the nervous CNS, Somatic, Autonomic Two hemispheres & 4 lobes
Organization contralateral input & output primary sensory areas motor areas Commissure
Localization of functions
Central Nervous System
Peripheral Nervous System
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Sense organs carry messages about the environment to the
central nervous system.
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The eyes, ears, nose, tongue, and skin are examples of sense organs.
The sense organs gather information (light, sound, heat, and pressure) from the environment.
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The environment is everything outside the body.
The sense organs gather information from outside the body, then send the messages to the brain.
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Vision is your ability to see.
Vision involves the eye and the brain.
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The eye is one of your sense organs.
The eye is made of the iris and the pupil.
The eye gathers pictures and sends them to the brain.
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The colored part of the eye is the iris.
The black part of the eye is the pupil.
The pupil becomes larger and smaller as it controls the light
coming into the eye.
IrisPupil
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When a sound is made, the air around the sound vibrates.
Hearing starts when some of the sound waves go into the ear.
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There are nine main parts of the ear.
1. Pinna
2. Ear canal
3. Ear drum
5. Anvil
6. Stirrup
7. Cochlea
4. Hammer 8. Eustachian tube
9. Auditory nerve
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The ear canal is the tube between the outside of the ear and the ear drum.
The ear drum is in the middle ear. It vibrates when sound waves hit it.
The pinna is the part of the ear that you can see.
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The three smallest bones in the body, the hammer, the anvil, and the stirrup, are in the middle ear.
The hammer gets the vibrations from the eardrum, then sends them to the anvil.
The anvil passes the vibrations to the stirrup.
The stirrup passes the vibrations to the inner ear.
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The inner ear is made of the cochlea and liquid.
The cochlea is in the inner ear. The cochlea looks like a shell.
The Eustachian tube controls the amount of pressure in the ear.
The auditory nerve carries the hearing information to the brain and the brain tells
us what we heard.
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The ear works with the brain to control your balance.
All of your movements are controlled by balance and muscles.
The liquid in your inner ear is responsible for your balance.
The liquid in your ear moves when we move. The liquid movement sends information to the
brain to tell it how we are moving.
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The sense of touch is located in the skin.
The nerves in the skin allow us to feel texture, pressure, heat, cold, and pain.
Texture is how something feels.
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The nose controls your sense of smell.
The nose is able to smell 80 different kinds of smells.
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Your sense of taste comes from the taste buds in the tongue.
Taste buds are the parts on the tongue that allow us to taste.
The four kinds of taste buds are sweet, sour, bitter, and salty.
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Tastes and smells work together to make flavors.
Flavors are the tastes of food and drinks.