The Nervous System

Warm-up:

•Tell me about your favorite memory. When in your life did it happen? What things do you remember about it? Why is it so meaningful to you?

Nervous System—the human body book

• “In some ways, the human brain resembles a computer. But in addition to logical processing, it is capable of complex development, learning, self-awareness, emotion, and creativity. Every second, millions of chemical and electrical signals pass around the brain and the body’s intricate nerve network. But nervous tissue is delicate and needs physical protection and a reliable blood supply. If damaged, repair is often painstakingly slow, and nerve degeneration is one of the least understood medical problems.”

Processes that involve your nervous system

• Memories, thoughts, and emotions

• Touch, taste, and smell

• Ears, hearing, and balance

• Eyes and vision

The Nervous System

• The nervous system is the body system that carries messages to and from the brain and spinal cord and all other parts of the body.

• The nervous system is composed of three divisions: • The central nervous system (CNS)The central nervous system (CNS)• Brain and spinal cord.

• The peripheral nervous system (PNS)The peripheral nervous system (PNS)• Made up of nerves that branch out from the central nervous system to

muscles, skin, internal organs, and glands. • The autonomic nervous system (ANS)The autonomic nervous system (ANS)• It’s work is primarily “automatic”• Deals with activities such as blood pressure control and heart rate

adjustment.

The Central Nervous System

• Brain

• The brain is a mass of nerve tissue that regulates non-conscious processes and coordinates most voluntary movement.

• Accounts for 2% of a person’s body weight but requires 20% of the body’s blood.

• The brain has three major parts: • The cerebrum controls the ability to memorize, think, and learn.• The cerebellum controls and coordinates muscle activity. • The brain stem controls the functions of the internal organs.

The Central Nervous System

• Spinal CordSpinal Cord– The spinal cord is the column

of nerve cells that extends downward from the brain.

– Your spinal cord carries messages to and from your brain and all parts of your body.

– It is the link from your brain to your torso, arms, and legs.

The Peripheral Nervous System

• Nerve CellsNerve Cells– The nervous system is

composed of cells called neurons.

– A neuron is a nerve cell that is the structural and functional unit of the nervous system.

– Each neuron consists of:• A cell body is the main body of the

neuron. • An axon is an elongated fiber that

carries impulses away from the cell body to the dendrites of another neuron.

• Dendrites are branching fibers that receive impulses and carry them to the cell body.

Peripheral Nervous System

• Sensory and motor neurons work together to help you respond to your environment. • Sensory neurons carry impulses

from the sense organs to the spinal cord and brain.

• Motor neurons carry responding impulses to muscles and glands from the brain and spinal cord.

• http://www.youtube.com/watch?v=4eZRkOIj63A

Autonomic Nervous System

• Has the task of maintaining constant conditions of the body, or homeostasishomeostasis.

• It has two divisions that produce contrasting responses:• Sympathetic divisionSympathetic division: prepares the body for action and

stress. • Pupil dilate

• Increases heart rate

• Parasympathetic divisionParasympathetic division: restores normal function to conserve energy. • Pupils contract

• Decrease heart rate

Caring for Your Nervous System

• Eat a well-balanced diet

• Exercise regularly

• Get enough sleep

• Wear protective gear

• Wear a safety belt

• Check depth of water before diving.

• Drugs and alcohol can permanently damage nerve cells, so avoid using them.

• Headaches/MigrainesHeadaches/Migraines

• Head injuries—such as concussionsHead injuries—such as concussions

• Spinal injuriesSpinal injuries

• StrokeStroke

• Dementia or Alzheimer’s diseaseDementia or Alzheimer’s disease

• MeningitisMeningitis• An inflammation of the spinal and cranial meninges caused

by bacterial or viral infection.

• http://youtu.be/_AsvnNrGvOc

• http://abcnews.go.com/GMA/OnCall/video/teens-struggle-bacterial-meningitis-11542169

Problems of the Nervous System

Integumentary System —the human body book

• “Few body parts renew as rapidly as the skin. Every month the outer layer of epidermis is completely replaced, at a rate of 30,000 flake-like dead cells every minute. The hair and nails are likewise self-reinstating and self-repairing. Skin reflects aspects of general health, especially diet and lifestyle. Its exposed and dynamic nature can bring problems such as rashes, lesions, sores and eczema. Skin growths may follow exposure to harmful chemicals or cancer-triggering ultraviolet and other hazardous radiation.”

Integumentary System

• The integumentary system is the body system that covers and protects the body and consists of skin, glands associated with the skin, hair, and nails.

• The skin is the largest organ in the body and contains nerve cells that help you detect pain, pressure, touch, heat, and cold.

• Skin serves as a protective layer that helps prevent injury, keeps microorganisms from entering the body, and helps maintain a healthful body temperature.

• It also helps protect you from ultraviolet radiation because of the presence of melanin, which is a pigment that gives the skin its color.

Skin

– Skin is made up of two layers, the epidermis and the dermis. • The epidermis is the outer layer of

skin cells.

• New skin cells are produced in the deepest layer of the epidermis.

• The dermis is a thick layer of cells below the epidermis that contains sweat glands, hair follicles, sebaceous (oil) glands, blood vessels, and nerves

Glands

– A sweat gland is a gland that aids the body in getting rid of wastes, such as salt, and also helps cool the body.

– A sebaceous gland is a small oil-producing gland that helps protect the skin. Sebum is the oil produced by sebaceous glands.

– The subcutaneous layer is a layer of fatty tissue located below the dermis.

– Warts/Moles/CystsWarts/Moles/Cysts

– Acne Acne – is a skin disorder in which hair follicles or pores in the skin

become plugged with sebum.

– Ring wormRing worm

– PsoriasisPsoriasis

– EczemaEczema

– SunburnsSunburns

Skin Conditions

Hair and Nails

• NailsNails are made up of dead cells and keratin, which is a tough protein.

• HairHair is a threadlike structure consisting of dead cells filled with keratin.

• Each hair grows from a follicle, which is a depression on the surface of the dermis that contains nutrients a hair needs to grow.

Keeping the Integumentary System Healthy• Wear sunscreen!!

• SPF of at least 3030 • UV-AUV-A and UV-BUV-B protection• Apply 30 minutes before sun exposure• ReapplyReapply every 2 hours• Do not rely on just sunscreen

• Examine skin monthly for any changes in moles, warts, or freckles.

• Follow directions when using makeup.• Shower or bathe each day.• Eat foods containing vitamin A.• Seek proper medical care for skin rashes.• Wash hair and body regularly.