The Sensory Receptors

• Write the black• Read the blue

What do you know about sensory receptors?

A bit of review

sensory receptors = cells that capture information

Ear

Hearing

Eye

sight

Skin

touch

Tongue

taste

Nos

e

smell

Path

Sensory receptor captures information (stimulus)

A “transformer “ changes info into a nervous impulse

Sensory neurons send info. to the brain for analysis

The Eyesight

Picks up light rays from light sources or reflected off objects

Use pg. 213 of textbook to fill in pg. 129 of workbook

Parts of the eye

sclera

choroid

retina

iris

Aqueous humor

lens

Vitreous humor

Optic nerve

cornea

Use pg. 213 of textbook to fill in the handout on the eye

Structure Description

Sclera the white of the eye, protects eye from shock and gives it shape

Choroid layer of blood vessels that nourish the eye

Retina layer at the back covered with millions of photoreceptors that transform incoming data to nerve impulses

Cornea clear and rigid membrane at the front of the eye

Lens

Aqueous Humour

Vitreous Humour

Structure Description

Sclera

Choriod

Retina

Structure Description Iris pigmented membrane with an

opening (pupil)= regulate amount of light entering the eye

Lens flattened sphere that focuses light onto the retina

Aqueous Humour transparent liquid that fills space between cornea and lens

Vitreous Humour transparent liquid that fills spaces between lens and retina

a

cornea

Aqueous humor

lensVitreous humor

How we see• Light waves pass through the CORNEA and the

AQUEOUS HUMOUR and are controlled by the PUPIL.

• The light is then focused by the LENS and continues through the VITREOUS HUMOUR to the part of the RETINA called the MACULA.

• Photoreceptors change the light waves to nerve impluses.

The Retina specialized nerve cells called photoreceptors

sensitive to light = 2 types of photoreceptors

1. Cones Very few = concentrated in center of retina

called the macula.

Responsible for seeing colour

The retina

The macula

2. Rods

Rods detect contrast (not colour)= important for night vision

Rods cover the retina except in the macula and the “blind spot”.

The blind spot = where optic nerve leaves eye

The “blind spot” where optic nerve leaves the eye

Optional lab65- Adjusting the eye to light

This is weird, but interesting! fi yuo cna raed tihs, yuo hvae a sgtrane mnid too Cna yuo raed tihs? Olny 55 plepoe out of 100 can. i cdnuolt blveiee taht I cluod aulaclty uesdnatnrd waht I was rdanieg. The phaonmneal pweor of the hmuan mnid, aoccdrnig to a rscheearch at Cmabrigde Uinervtisy, it dseno't mtaetr in waht oerdr the ltteres in a wrod are, the olny iproamtnt tihng is taht the frsit and lsat ltteer be in the rghit pclae. The rset can be a taotl mses and you can sitll raed it whotuit a pboerlm. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe. Azanmig huh? yaeh and I awlyas tghuhot slpeling was ipmorantt!

Lets play find the lioness

The Ear

hearing

Ear has sensory receptors:

• For hearing in the cochlea

• For balance in the semicircular canals and the vestibule.

Use pg. 215 of the textbook to fill in pg. 129 of the workbook

Check your answers

ear drum

ossicles

eustachian tube

cochlea

vestibule

Semicircular canals

pinna

Auditory canal

Use pg. 215 of the textbook to fill in the handout on the ear

Structure Description

Pinna funnels sound vibrations into ear

Auditory Canal carries vibrations to eardrum

Tympanic Membrane (ear drum)

thin membrane that moves with sound vibrations

Ossicles (bones)

miniature bones that move with sound vibrations

Eustachian tube

links ear to throat to equalize pressure around ear drum

Semi-circular canals

regulate balance when body = in motion

Vestibule regulate balance when body = in static position

Cochlea walls covered in auditory receptors linked to the auditory nerve

hammer

anvil

stirrup

vestibuleSemi-circular canals

cochlea

How we hear• Sound vibrations enter the PINNA and travel down

the AUDITORY CANAL. • The waves start the EAR DRUM vibrating. As the

OSSICLES are connected at one end to the ear drum, they move at the same speed.

• The ossicles are connected at the other end to the VESTIBULE, which is filled with liquid. The sound wave continues to the liquid-filled CHOCLEA where AUDITORY RECEPTORS pick up individual frequencies and change them to nerve impulses

How we Balance

• 3 x SEMICIRCULAR CANALS let body know location on the X, Y and Z axis (3D) while the body moves.

• The VESTIBULE helps with posture

Homework: pg. 130 of workbook

The Skin

Touch

• Touch sensory receptors are found in the dermis layer

• Skin= body’s largest organ, but only about 7% of our body mass.

• It is made of 3 layers:– Epidermis– Dermis– Hypodermis

Use pg. 217 of textbook to fill in pg. 131 of workbook (top)

Hypodermis

Use pg. 217 of textbook to fill in the handout on the skin

Structures of the Skin

Layer Structures Description

Epidermis Dead Layer Outer layer of skin. protects against elements

Living layer Constantly dividing cells push up old ones

Dermis Sensory Receptor

Pick up stimuli like temperature, pain, gentle and heavy pressure, and touch

Blood Vessels Nourish cells

Sebaceous Glands

Secrete sebum to waterproof skin

Sweat Glands Secrete sweat to cool the body

Hair Starts in dermis and continue through epidermis. Muscles can contract to raise hairs

Hypodermis Fat cells Energy reserve and thermal insulator

• Melanin =brown pigment that protects us from the sun’s harmful radiation

• The more sun exposure the more melanin is produced, “tanning”

• Over exposure to these harmful rays can cause mutations in the melanocytes causing melanoma (a deadly form of skin cancer) or basal cell carcinoma

Skin Physiology• Free nerve endings detect temperature,

tactile (touch) and pain

• touch receptors =not spread out evenly over the body - more touch receptors in the fingers and face, especially the lips, than in any of the other areas or the body

• why babies put everything into their mouths

• If human body drawn proportionally according to the number of touch receptors = looks like this

How we feel

• Various items may come in contact with the skin• Depending on the number of touch receptors,

you may or may not feel the touch• The pressure, temperature or touch is picked up

by different nerves and changed to a chemical impulse

Lab 66- skin’s receptors

• Bill Nye- skin

The Nose

smell

• The sensory receptor for smell = the olfactory epithelium

Use pg. 219 of textbook to fill in pg. 131 (middle) of workbook

Olfactory nerve

Olfactory bulb

Olfactory epithelium

Nasal Cavity

Nostrils

How we smell • The molecules that have odour travel up the nostril

to the nasal cavity.• The turbinates cause the air to swirl around• The mucus makes the molecules to stick and dissolve

into it. • The molecules come in contact with the olfactory

cilia in the epithelium.• They change the smell into a chemical impulse

• Bill Nye-smell

The Tongue

taste

• The sensory receptors are located in the taste buds

• has receptors to capture flavour molecules• tongue =muscle = covered with epithelial cells

(moist) that form rough bumps called papillae

Use pg. 220 of textbook to fill in pg. 131 (bottom) of workbook

Flavour detection• The tongue can only detect flavourful

molecules of the following 4 basic flavours:• Bitter• Sour• Salty• Sweet

• Taste and smell are interrelated. • Ever tried eating with a blocked nose = food has

very little flavour?• Other receptors on the tongue = temperature,

discomfort, and texture of food

How we taste• The molecules that have flavour cover the tongue.• The papillae increase the surface area in contact

with the flavour molecules• The saliva moistens the food and helps flavour

molecules to stick and dissolve into it. • The molecules come in contact with the taste buds • They change the flavour into a chemical impulse

Lab 67- Relationship taste and smell

Did You Know?

• Gene Simmons from KISS has his tongue insured for 1 million dollars

Homework: pg. 132 of workbook

Discuss pg. 230 q 9-13 in textbook