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 Nose 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 Eye sight

 Picks up light rays from light sources or reflected off objects

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

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

StructureDescription 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 StructureDescription 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 lens Vitreous 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

Lab 64- dissect and eye if Nancy has them

Optional lab 65- Adjusting the eye to light

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

hammer anvil stirrup vestibule Semi-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

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