FACT OF THE DAY:

* Messages travel along the nerves as electrical impulses. They travel

at speeds up to 248 miles per hour!

Nervous SystemThe nervous system maintains homeostasis by

controlling and regulating all other parts of the body.

http://faculty.washington.edu/chudler/stm0.html(short-term memory)

REGULATION

Functions of the Nervous System

1. Sensory-uses receptors to gather information from all over the body

2. Interpretation-the brain then processes the information into possible responses

3. Response-sends messages back through the system of nerve cells toA. Control and coordinate functions throughout the

bodyB. Respond to internal and external stimuli

Evolutionary Trends of the Nervous System

Animal Taxon

Aquatic Invertebrates

Flatworms & Roundworms

Segmented Worms &

ArthropodsVertebrates

Type of Nervous Tissue

A simple system with interconnected neurons called nerve nets; contain specialized cells for touch and chemical detection

Ganglia (a group of nerve cells) and nerve cords run along the body; can detect chemicals, touch, and some have eyespots

Cephalization occurs which is the concentration of nerve cells in a head region to form a brain; intense senses in arthropods

A well developed brain evolved from the spinal cord; the size and complexity

increases from fish to mammals

Picture of system

Examples sponges, jellyfish, hydraplanaria, flukes,

tapeworm, hookworm

earthworm, ants, grasshopper, bees

mammals, birds, reptiles, fish, amphibians

Simple Complex

Structures of the Nervous System

Neurons: the functional cell that transmits signals through the body; an individual nerve cell

Parts of a Neuron1. cell body- the largest part of the neuron;

contains the nucleus and organelles2. dendrites- short, branching extensions

spreading out from the cell body; receive and carry impulses to the cell body

3. axon- long, fibrous part of neuron; conducts nerve impulses away from cell body

cellbody

muscle tissue

TYPICAL MOTOR NEURON

Axondendrite

synapse

cell body

Because neurons never touch, chemical signalers called neurotransmitters must travel through the space called synapse between two neurons.

Neurotransmitters

Synapse (gap)

The message is transferred when RECEPTORS receive neurotrans-mitters.

(pinkspheres)

NeuronNerve Impulse- an electrical signal is sent from the dendrite, along the axon, to the terminal. A chemical message, called a neurotransmitter is released from the axon terminals into the synapse, where it travels to the next cell.

Types of Neuronsa. sensory neurons- carry

impulses from sense organs to brain/spinal cord (CNS)

b. motor neurons- carry impulses from brain/ spinal cord (CNS) to muscles/ organs

c. interneurons- carry impulses between sensory and motor neurons (within CNS)

Reflexes• They are involuntary • They happen very quickly• Take place without the brain receiving the message• They protect you by triggering an involuntary

response to stimuli (stepping on a tack)

Reflexes:

Divisions of the Nervous System

• Central Nervous System (CNS)

• Peripheral Nervous System (PNS)

Central Nervous System (CNS)

A. Brain- “control center”- receives and analyzes information; processes and sends back instructions

Parts of the Brain

1. Cerebrum• Controls muscles• Jobs that are

voluntary• It stores

messages• Studying/

thought• Language• judgment

Lobes of the cerebrum

Reasoning, logic, language, etc.

Processes sensory impulses from the body

Visual images

Hearing, smell, memories

SpeechLogic/reasoning

Language and Speech – strokes, tumors, injuries

• Broca’s Area:– Primary motor cortex

in the frontal lobe that controls muscles

– Damage to area means you can understand language but are unable to speak it

• Responsible for speech generation• Ex – stroke patients

http://www.hulu.com/#!watch/378989 (NY Med brocas area) 28:28- d section)

• Wernicke’s Area:– The posterior part

of temporal lobe– Damage to area

means you can speak but unable to comprehend speech

• Responsible for hearing speech

http://www.hulu.com/watch/339577/greys-anatomy-one-step-too-far

Go to 21 min mark

Parts of the Brain

2. Cerebellum: controls involuntary functions of muscles & maintains balance and posture ( hand-eye coordination)

Parts of the Brain3. Hypothalamus: Controls homeostasis in body* body temperature, water balance, hunger, thirst, biological clock, flight or fight response)

Parts of the Brain4. Brain stem

Controls involuntary functions

Medulla Oblongata & Pons : *breathing, heart rate, blood pressure, swallowing, vomiting, digestion

Peripheral Nervous System (PNS)

A. Consists of nerves –ropelike bundles of neurons outside of the CNS

B. Gathers information, delivers it to and from CNS

C. PNS divided into two systems:

Somatic (voluntary)Autonomic (involuntary)

Autonomic Nervous System

· Autonomic Nervous System - The involuntary branch of the nervous system

· Divided into two divisions:

1. Sympathetic division

2. Parasympathetic division

Autonomic Functioning· Sympathetic – “Fight-or-flight”

· Response to unusual stimulus

· Takes over to increase activities· Increases heart rate, blood pressure,

blood glucose levels, dilates the bronchioles of the lungs, and dilates the pupils

· Remember as the “E” division = Exercise, excitement, emergency, and embarrassment

Autonomic Functioning· Sympathetic – “Fight-or-flight”

· The effects of sympathetic nervous system activation continue for several minutes until its hormones are destroyed by the liver.

· Helps explain why we need time to “calm down” after an extremely stressful situation.

Autonomic Functioning· Parasympathetic –

Housekeeping activites· “Resting and digesting” system· Chiefly concerned with promoting normal

digestion and elimination of feces and urine and with conserving body energy

· Heart rate, blood pressure, and respiratory rates are at low normal levels; pupils are constricted; skin is warm; digestive tract is actively digesting food

· Remember as the “D” division - Digestion, defecation, and diuresis (urination)

Levels of Organization

Nerves

Brain, spinal cord

Nervous

Neurons

Interaction with other systems for Regulation

Bones of the skeletal system protect the spinal cord and brain.

The brain controls heart rate, blood pressure, and breathing via the circulatory and respiratory systems.

Glands in the brain control the release of hormones of the endocrine and reproductive systems.

The brain controls muscles both in digestion and movement.

Diseases / Disorders of the Nervous System

1. Polio- a virus that attacks the spinal cord; eventually causes paralysis

2. Multiple Sclerosis (MS)- affects neurons; slows nerve impulses, causing muscle weakness, possibly paralysis.

3. Alzheimer’s- brain tissue deteriorates; severe memory loss

4. Stroke- a blockage in a blood vessel in the brain, causing brain damage

5. Concussion- a bruise to the brain when the brain hits the inside of the skull

Fun Facts

• A human body contains more nerve cells than there are stars in the Milky Way

• Neurons are the largest cell in the body and do NOT undergo mitosis

• Nerve impulses move at 100 meters per second or more

• Longest axon of a neuron is 15 ft! (in the giraffe)

Reticular Formation – neurons in the core of the brainstem (midbrain -arousal, pons & medulla-sleep)

•Sleep & wakefulness produces patterns of electrical activity in the brain

• Recorded as an ElectoEncephaloGram (EEG)

• Most dreaming during REM (rapid eye movement sleep)

Did You Know…

• Bottlenose Dolphins swim while sleeping, rising to the surface to breathe air regularly! – Their forebrain is divided into two

halves. Since they sleep with one eye open and one closed they are able to sleep with one brain hemisphere at a time.

Lobotomy…• Phineas Gage, 1848 – was a loving,

caring father until the accident andthen became detached, impatient & erratic

• Later in the 20th century, surgical procedures were done to remove portions of the frontal lobe in attempt to cure severe behavioral and psychiatric behaviors