Chapter 24 RegulationSec. 3-5

Question?

• Look around you.• What do you see?• What sounds can you hear?• Do you smell any odors?– Information about your environment is detected

1st by your sense organs.

The 5 Sense organs

1. Eyes2. Ears3. Skin4. Tongue5. Nose

How do sense organs work?

• Each sense organ has special cells called receptor cells that detect information.

• The receptor cells send nerve impulses to sensory neurons, which carry impulses to the brain.

• The brain interprets the impulse (Ex: taste or vision).

Vision• Eyes are very sensitive to light• How light travels through the eye?– Light Cornea Iris/Pupil Lens Retina (rods &

cones) Optic Nerve Brain

• Cornea = curved part of the eye• Iris = smooth muscle behind the cornea (color

part of the eye)• Pupil = controls the amount of light that enters

the eye• Lens = focuses the incoming light

Vision cont.• Retina = thin tissue @ the back of the eye

contains rods and cones• Rod = detect black and white colors• Cones = detect color

Hearing• Ear has 3 main parts:1.Auricle (ear flap) = outer ear2.Eardrum, incus, stapes, malleus = middle ear3.Cochlea, auditory nerve = inner ear

Have you ever felt dizzy after spinning around in a circle?

• Your ear also helps maintain balance.• Dizziness is a sensation produced by 3 looped

tubes (semicircular canals) in your inner ear.• These are fluid filled tubes that have hairlike

receptors.• Every time you move your head, the fluid

inside these tube move.• The hairlike receptors also move based on

orientation.

Touch• Your skin is the largest sense organ in your body.• Skin can detect touch, pressure, pain, heat, and

cold.• Touch receptors are found near the surface of

the skin• Pressure and pain receptors are found deep

within the skin.• Receptors on the skin are not evenly distributed

over your body.

Taste & Smell• The organs of taste and smell are stimulated by

chemicals.• Receptors for taste are located on taste buds

found on your tongue.• Taste buds can only detect 4 tastes: sweet, sour,

salty, and bitter.

Taste & Smell cont.

• The flavor of food is also detected by odor receptor of the nose.

• When your nose is blocked, your odor receptors don’t function as well.

• This is why food often taste bland when you have a cold.

• Odor receptors = olfactory cells respond to gas molecules

Why do people grow rapidly during adolescence? Have you ever heard of

someone having “superhuman” strength during an emergency?

• These responses result from the action of the endocrine system

The Endocrine System• This system is made up

of glands that secrete hormones into the bloodstream.

• Hormones are chemical messages that regulate many of your bodily functions.

Endocrine GlandsEndocrine Gland Hormone FunctionPituitary Growth hormone /

other hormonesControls growth; regulates other glands

Thyroid Thyroxine Regulates growth and metabolism

Parathyroid Parathyroid hormone Regulates calcium useAdrenals Cortisone

Adrenaline

Maintains salt/water balanceRegulates body response to stress

Pancreas Insulin Regulates blood-sugar levels

Ovaries Estrogen Female characteristicsTestes Testosterone Male characteristics

What regulates the endocrine glands?

• Most endocrine glands are regulated by a feedback mechanism.– Ex: Thermostat of an heater or AC unit

Behavior

• 2 main types of behavior:– Innate: unlearned that you are born with• Ex: coughing, swallowing, sneezing, blinking

– Learned behavior• Things that you practice and get better at over time.