The nervous system is made up of:

The spinal cord

The senses

The nerves

The brain

The Nervous System

Complex system in the body made up of many parts

Divided into two main systems the central nervous system (CNS) the peripheral nervous system (PNS)

CNS consists of the brain and spinal cord Gets info. from the body and sends out

instructions PNS consists of all the nerves and wiring

Sends messages from the brain to the rest of the body

Peripheral Nervous System

A communication system 3 kinds of neurons connect the CNS to the

body Sensory Motor Interneurons

Sensory- sensory receptors to CNS Motor- CNS to muscles Interneurons- Connections within CNS

Peripheral Nervous System

Unlike other system we have been studying, neurons have a limited ability to repair themselves

nerve cells also have a limited ability for repair if damaged due to injury or disease

Ex.) Spinal injuries

Neurons

Cell Body: functional part Dendrites: short extensions that

receive signals Axon: long extension that transmits

impulses away

Nerve Impulses

Messages carried throughout the body by nerves

Your funny bone is the only nerve on your arm that is not protected!!! FUNNY HUH?

The Action Potential

Threshold potential will trigger an action potential or nerve impulse

The action potential is an all-or-none response

Myelinated Neurons

Myelin sheathing allows neurons to conduct nerve impulses faster than non-myelinated neurons

Myelin insulating sheath around the axon is formed by Schwann cells

Myelin sheathing has bare patches of axon called nodes of Ranvier

Signals move from neuron to neuron

A synapse divides 2 neurons The action potential will not move

across the synapse At the end of an axon, the arrival of an

action potential results in the transfer of info. to another neuron

Communication between neurons occurs in one direction only across a synapse Presynaptic neuron postsynaptic neuron

Signals move from neuron to neuron cont.

Communication between neurons occurs in one direction only across a synapse Presynaptic neuron postsynaptic

neuron Synaptic cleft must be crossed for

the presynaptic neuron to cross and bind to the postsynaptic neuron

Neurotransmitters

This is done through the release of chemicals called neurotransmitters

Move by diffusion across the synaptic cleft

There are many different neurotransmitters

Neurotransmitters

Common Neurotransmitters (brain & Autonomic NS): Acetylcholine (ACh) (muscular junctions,

glands, brain & spinal cord) Norepinephrine (NE) (brain regions- emotions,

dreaming) Excitatory

CNS neurotransmitters: Dopamine Serotonin Inhibitors

Nerve signals jumping synaptic cleft

The axon of one neuron doesn't touch the dendrites of the next. Nerve signals have to jump across a tiny gap (synaptic cleft). To get across the gap they have to change from electrical signals into chemical signals (neurotransmitters) then back into electrical signals.

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Peripheral Nervous System

Skeletal(Somatic)

Sympathetic Parasympathetic

Autonomic

Peripheral Nervous System

Basic Tasks of the Nervous System

Sensory Input: Monitor both external and internal environments.

Integration: Process the information and often integrate it with stored information.

Motor output: If necessary, signal effector organs to make an appropriate response.

Sensory and Motor Pathways

SENSORY PATHWAY Signals from external environment,

skin, muscles, internal organs etc a sensation arrives in the form of an

action potential carries fine touch and pressure

sensations Sensations travel to the thalamus and

are sorted accordingly

Sensory and Motor Pathways

MOTOR PATHWAY: Provides voluntary skeletal muscle

control A rapid, direct mechanism In response to the sensory pathway,

the CNS issues motor commands distributed by the somatic and autonomic nervous systems

Somatic Nervous System

Nerves to and from spinal cord Both voluntary and reflex

movements Skeletal reflexes Directs contractions of skeletal

muscles

Autonomic Nervous System

Issued outside our conscious awareness Activities you don’t think about! Controls involuntary functions

Heartbeat Blood pressure Respiration digestion

Can be influenced by thought and emotion

Autonomic Nervous System

Two divisions:Sympathetic Parasympathetic

Sympathetic

“Fight or Flight” response

Released adrenaline and noradrenaline

Increased heart rate and bp

Increased 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

Parasympathetic

“Rest and digest” system

Calms body to conserve and maintain energy

Lowers heartbeat, breathing rate and bp

Central Nervous System

Spinal Cord Sends messages to the brain Part of the nervous system that connects

the brain to the rest of the body Thickest nerve is 1 inch thick and the

thinnest is thinner than a human hair

Spinal Cord

The spinal cord runs down a tunnel of holes in your backbone or spine

The vertebrae are the many bones that protect the nerves in the spinal cord from damage

Central Nervous System Brain helps to control all of the body systems

and organs allows us to think, feel, remember and

imagine communicates with the body through

the spinal cord and the nerves Tells the body what to do and when to

do it

Major divisions of the brain

The cerebrum The diencephalon The pons----------------- The midbrain------------ The medulla oblongata-- The cerebellum

Cerebrum

Divided into large, paired cerebral hemispheres

hemispheres are covered by a thick blanket of neural cortex called the cerebral cortex Thinking sensations intellectual functions memory (storage and retrieval) complex motor pattern speaking

Diencephalon

A hollow division of the brain that includes the thalamus and hypothalamus

Connected to cerebrum Its sides form the thalamus Its floor forms the hypothalamus where

a narrow stalk connects it to the pituitary gland

Diencephalon cont.

Thalamus – contains relay and processing centers for sensory info.

Hypothalamus – involved with emotions, autonomic function and hormone production

Pituitary gland – 1° link between the nervous system and endocrine system

Brain Stem

Consists of Midbrain Pons Medulla

Contains important processing centers and relay stations for info. headed to/from cerebrum or cerebellum

Midbrain

Middle Visual and auditory information Generates involuntary motor

responses Maintenance of consciousness

Pons

Bridge Connects the cerebellum to the

brain stem Tracts and relay centers Contains nuclei involved with

somatic and visceral motor control Connect to the medulla oblongata

Medulla Oblongata

Attaches to the spinal cord Relays sensory info. to the thalamus

and other brain stem centers Regulation of autonomic functions

Heart rate Blood pressure Respiration Digestive activities

Cerebellum

Lg. and sm. hemispheres cover most of the brain stem

Adjust voluntary and involuntary motor activities

based on sensory info. and stored memories of previous movements

Controls balance and posture

Brain

Has 2 hemispheres Left & Right sides are separate Corpus Callosum: major pathway

between the two hemispheres Permits data received on one side to

processed in both hemispheres Language on left, Math, music on right

Note* this is never 100%

Brain

Each hemisphere is divided into 4 lobes Frontal Parietal Occipital Temporal

The Brain

Motor Cortex

WorkingMemory

Frontal Lobe Contains 1°

working cortex Working memory-

prefrontal No direct sensory

input Important planning

and sequencing areas

Area for speech

Phineas Gage

Railroad worker Iron rod straight through

his skull SURVIVED! Entered cheek bone and

excited top of skull Went through frontal

lobe Led to important

discoveries in neurology b/c his behavior could be studied

Changes in personality, work ethic, speech, planning etc.

Parietal Lobe

Inputs from multiple senses

Borders visual & auditory cortex

Outputs to frontal lobe Hand-eye

coordination Eye movements attention

ParietalLobe

TemporalLobe

Auditory Cortex

Temporal Lobe

1° auditory cortex Auditory & Visual patterns

Speech recognition Face recognition Word recognition Memory formation

Occipital Lobe

Input from optic nerve

Contains 1° visual cortex

Outputs to parietal and temporal lobes

Occipital Lobe

VisualLobe

The Senses

Sight Taste Touch Hearing Smell

Carry messages about the environment to the central nervous system

Examples of Sense Organs

Eyes, ears, nose, tongue, and skin

Sense organs gather information from the environment Light Sound Heat pressure

Seeing - Vision

Your ability to see

Involves the eye and the brain

The blind spot for the eye is caused by the optic nerve

Sight Receptors

Photoreceptors – rods and cones of the retina- detect photons basic unit of light

Rods provide the CNS with info. on the presence or absence of photons

No colors of light, very sensitive, enables us to see in dim rooms

Hearing

Hearing begins when some of the sound waves go into the ear

When a sound is made, the air around the sound vibrates

Hearing

Ear captures and transmits info. about movement, gravity and sound

Sound converted into action potentials in the cochlea

Hair cells are deflected as sound waves move through the cochlea

Action potentials are sent to the brain via the auditory nerve

Hearing

Loud sounds can damage hair cells leading to cell death and deafness

Once hair cells have died, they do regenerate

External (pinna)- collects/directs sound Middle- collect/amplify sound waves Inner- sensory organs responsible for

equilibrium

Touch

Sense of touch is located on the skin Nerves in the skin allow us to feel

texture, pressure, heat, cold and pain Thermoreceptors- temperature

receptors Tactile receptors- touch, pressure

and vibration Baroreceptors- monitor changes

in pressure

Smell

The nose controls your sense of smell Olfactory receptors aid with smelling *the nose can smell 80 different

kinds of smells* Doesn’t come close to

comparing with that of other animals

Taste Sense of taste comes from the taste

buds on your tongue Taste Buds (taste receptors) are the

parts on the tongue that allow us to taste

there are 4 kinds of taste buds: Sweet Sour Bitter salty

12 Cranial Nerves

I - Olfactory II - Optic

III - Oculomotor IV - Trochlear V - Trigeminal VI - Abducens

VII - Facial VIII - Auditory

IX - Glossopharyngeal X - Vagus

XI - Accessory XII - Hypoglossal

Cranial Nerves

Olfactory nerves(I)– Sensory, smell

Optic nerves(II) – Sensory, vision

Oculomotor nerves(III) – muscles that move the eyeball

Trochlear nerves(IV) – smallest cranial nerves innervate the superior oblique muscles

of the eyes

Cranial Nerves Cont.

Trigeminal nerves(V) – largest cranial nerves, ophthalmic, maxillary and mandibular branches

Abducens nerves(VI) – innervate the intrinsic eye muscle (lateral rectus)

Facial nerves(VII) – mixed nerves control muscles of scalp & face provide pressure sensations over face receive taste information from tongue

Vestibulocochlear nerves(VIII) – vestibular nerves (monitor balance, position &

movement) cochlear nerves (monitor hearing)

Cranial Nerves Cont.

Glossopharyngeal nerves(IX) - mixed nerves that innervate tongue & pharynx Control swallowing

Vagus nerves (X)– mixed nerves, vital to autonomic control of visceral

fxn have a variety of motor components

Accessory nerves(XI) – Medullary Branch- innervates swallowing muscles of

soft palate & pharynx Spinal Branch- controls muscles in pectoral girdle

Hypoglossal nerves(XII) – voluntary control over tongue movements