Nervous System - Period 3 - PowerPoint Presentation

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Nervous System - Period 3

BY

kate

, sierra, Kathryn, and Carson

WHAT IS THE NERVOUS SYSTEM AND WHAT ARE ITS FUNCTIONS?

Complex series of nerves and specialized cells (neurons or nerve cells) that transmit electrical signals between parts of the body

Similar to electrical wiring

Takes

in and processes information through the senses and triggers

reactions

Coordinates

muscle activity, monitors organs, constructs and processes data received from senses and initiates

actions

Metabolic

processes also included

ORGANS AND THEIR FUNCTIONS

Brain and spinal chord – analyze and respond to information accordingly; sends signals to rest of the body; controls

simple musculoskeletal

reflexes

Eyes – send information to the brain and convert into vision

Ears – send information to brain and convert it into sounds

Sensory organs of

taste (taste buds, etc.) – send information to the brain and convert into taste

Sensory organs of

smell -

send information to the brain and convert into

smell

Sensory receptors located in the skin, joints, muscles, and other parts of the

body – send information to the brain and convert into feelings and response such as touch or heat

HOW DOES THE NERVOUS SYSTEM WORK?

THE NERVE AND ITS PARTS

A.

CELL BODY

-

contains

the nucleus and much of the

cytoplasm; most

of the metabolic activity of the cell, including the generation of ATP

and

synthesis of protein

.

B. DENDRITES - Short branch extensions spreading out from the cell body. Dendrites receive STIMULUS and carry IMPULSES from the environment or from other neurons towards the cell body C. AXON - Long fiber that carries impulses away from cell body. Each neuron has only ONE axon. The axon ends with AXON TERMINALS

TYPES OF NEURONS

Sensory neuron

Interneuron

Motor Neuron

Length of Fibers

Long dendrites and short axon

Short dendrites and short or long axons

Short dendrites and long axons

Location

Cell body and dendrite are outside of the spinal cord; the cell body is located in a dorsal root ganglion

Entirely within the spinal cord or CNS

Dendrites and the cell body are located in the spinal cord; the axon is outside of the spinal cord

Function

Conduct impulse to the spinal cord

Interconnect the sensory neuron with appropriate motor neuron

Conduct impulse to an effector (muscle or gland)

Axon is covered by lipid layer called

MYELIN SHEATH

that speeds up transmission of messages

Axon terminals may come into contact with dendrites, effectors, or receptors to pass on messages

Receptors are in sense organs; effectors are muscles or glands that coordinate a response

Impulses are passes from one cell to another through

SYNAPSES

(gap between axon of one neuron and dendrite or cell body of another neuron)

Chemicals, or neurotransmitters, bridge this gap to transfer information to each other through electrical signals received from receptors or effectors; neurotransmitters are released when an electrical impulse reaches the end of a neuron

QUICK SUMMARY

Nerve has a cell body with multiple extensions

The shorter extensions (

dentrites

) act like antennae and receive signals

The longer extension (axon) passes along signals to other cells which are relayed to the brain

Synapses and neurotransmitters bridge the gap between cells to relay messages to

the brain

TWO MAIN PARTS OF THE SYSTEM

central

Composed of the brain and spinal chord

Purpose: to

collect information and respond

accordingly

Living

nervous tissue has consistency of jelly and must have special protection from

damage

Interprets messages from the peripheral nervous system

PERIPHERAL

Composed of everything but the brain and spinal chordPurpose: to connect the limbs and organs to the central nervous systemConsists of 12 pairs cranial nerves and 31 pairs of spinal nerves, some are exclusively sensorySensory cells carry messages to the central nervous system and motor cells carry the signal from the CNS to the organs, muscles, etc.

THE NERVOUS SYSTEM AND OTHER SYSTEMS

BODY SYSTEM

Cardiovascular

Endocrine

Lymphatic

Respiratory 

Digestive

INTERACTION

The brain receives information about blood pressure through baroreceptors; regulates heart rate and blood pressure

Hormones provide information to affect neural processing; controls pituitary gland and other glands

Brain stimulates defense mechanisms against infection

Brain monitors respiratory volume, blood-gas levels, and respiratory rateDigestive system provides building blocks for neurotransmitters; sends information relating to thirst or hunger; controls muscles for eating and waste removal

THE NERVOUS SYSTEM AND OTHER SYSTEMS

WHAT ARE RECEPTORS AND WHAT ARE THEIR FUNCTIONS?

Receptor:

an organ or cell

that responds to an external stimulus

and

transmits

a signal to a sensory nerve

Interoceptors

-transmits

pulses to detect stimuli inside of the body

Exteroceptors

- similar to interoceptors but detects stimuli outside of the bodyChemoreceptors-detects the concentration of oxygen in the blood streamPhotoreceptors-respond to the presence of lightMechanoreceptors-responds to mechanical pressure or distortion, touchThermoreceptors- responds to absolute and relative changes in temperature

DISEASES THAT AFFECT THE NERVOUS SYSTEM

MULTIPLE SCLEROSIS

Affects brain and spinal cord

Myelin sheath is damaged (material that surrounds and protects nerve cells)

Slows or blocks messages between brain and body

Symptoms include: weak muscles, difficulty with coordination or balance, difficulty thinking or remembering, feelings of numbness or prickling

Cause is unknown; disease can be mild to severe depending on the affected person

Currently no cure but medicine and physical therapy can manage and lessen

symptoms

PARKINSON’S DISEASE

Malfunction of vital nerve cells, mostly in the

substanita

nigra

portion of the brain

Malfunctioning neurons die and release dopamine (a chemical that messages the part of the brain that controls movement and coordination)

Progressive movement disorder, which means symptoms continue and worsen over time

As the disease worsens, dopamine levels decrease and the person loses control of their movements

Symptoms include: tremor, slowness of movement, rigidity, poor balance or posture

Cause is unknown; no cure currently but medication and surgery can manage

symptoms

HOW DOES THE NERVOUS SYSTEM HELP MAINTAIN HOMEOSTASIS?

The central nervous system is comprised of the brain and the spinal cord, whereas the peripheral nervous system is composed of the nerve extensions beyond those central pathways. Both, when combined, interconnect all of the parts of the body and allow for the processes creating homeostasis to occur.  The autonomic nervous system regulates involuntary bodily

functions. Without interpretation and responses to sensations such as becoming too warm, the body would become imbalanced.

BIBLIOGRAPHY

http

://www.ncbi.nlm.nih.gov/pubmedhealth/PMHT0024762/?figure=1

https://faculty.washington.edu/chudler/nsdivide.html

http

://www.hopkinsmedicine.org/healthlibrary/conditions/nervous_system_disorders/overview_of_nervous_system_disorders_85,P00799/

http

://www.ncbi.nlm.nih.gov/pubmedhealth/PMHT0024762/

http://www.ncbi.nlm.nih.gov/pubmedhealth/PMHT0025454/ http://www.livescience.com/22665-nervous-system.html http://www.ninds.nih.gov/disorders/parkinsons_disease/parkinsons_disease.htmhttps://faculty.washington.edu/chudler/organ.html http://leavingbio.net/the%20nervous%20system_files/the%20nervous%20system.htm