1. The Senses

2. Review! Divisions of the Nervous System

3. Review: Reflex Reflex: quick, automatic response to a stimulus
Allows your body to respond to danger immediately
Reflex Arc: includes a sensory receptor, sensory neuron, motor neuron, and effector

4. Fight or Flight Response
Which portion of the PNS is responsible for the fight or flight response?
What are some ways that your body responds?
What is the evolutionary history to this response? (why did it arise in the first place?)
Fight or Flight Video

5. Sensory Receptors
Sensory Receptors: neurons that react to a specific stimulus
5 types of sensory receptors:
Pain receptors
Thermoreceptors
Mechanoreceptors
Chemoreceptors
Photoreceptors
Sensory Receptors are located throughout the body but they are concentrated in the sensory organs (eyes, inner ears, the nose, the mouth, and the skin)
The body contains millions of neurons that react directly to stimuli from the environment, including light, sound, motion, chemicals, pressure, and changes in temperature
Make link to organ and receptor
Located throughout the body but are concentrated in the sense organs
Sense organs: eyes, inner ears, the nose, the mouth, and the skin
Sensory receptors within each organ enable it to respond to a particular stimulus

6. Sensory Receptors Pain receptors: Thermoreceptors:
Located throughout the body, except in the brain
Respond to chemical released by damaged cells
Thermoreceptors:
Located in the skin, body core, and hypothalamus
Detect variations in temperature

7. Sensory Receptors Mechanoreceptors: Chemoreceptors: Photoreceptors:
Located in the skin, muscles, and inner ears
Respond to touch, pressure, stretching of muscles, sound, and motion
Chemoreceptors:
Located in the nose and taste buds
Sensitive to chemicals in the external environment
Photoreceptors:
Located in the eyes
Sensitive to light
What receptors were we testing at compass station

8. Vision

9. Vision Iris: Color portion of the eye
Pupil: middle of the iris, allows light to enter eye
Lens: Focuses light onto the back of the eye (Retina)
Photoreceptors are arranged in a layer onto the retina
Rods: Black and white
Cones: Respond to different colors
Cones are concentrated on the macula fovea
Pupil trick with light
Tiny muscles in the iris adjust the size of the pupil depending on the amount of light
Two types of photoreceptors

10. Myopia Nearsightedness: Close objects are clear
Distant objects are blurry
Eye is too long

11. Hyperopia Farsightedness Distant objects clear Near objects blurry
Eye is too short

12. Blind Spot Area on the retina without receptors that respond to light
Located where the optic nerve exits the eye

13. Vision
How we see

14. Vision Stations
Copy the highlighted charts into your Notebook and record your data at each of the stations. For each station, copy the highlighted chart into your Notebook and follow the provided directions.
Station 1: Where is your blind spot?
Station 2: Optical Illusions: What is real?
Station 3: How is your depth perception?
Station 4: Reaction Time

15. Hearing and Balance
The ear has two sensory functions: hearing and detecting potential changes associated with movement
Vibrations enter the ear through the ear canal
The vibrations cause the eardrum to vibrate
Vibrations of the oval window create pressure waves in the fluid-filled cochlea
Hair cells in the cochlea produce nerve impulses that are sent to the brain through the cochlear nerve
Ear infection is a bacterial or viral inflammation of the middle ear
Balance is determind by semi-circular canals

16. Hearing and Balance
How we hear

17. Smell and Taste
Smell chemoreceptors in the lining of the nasal passageway respond to specific chemicals and send impulses to the brain through sensory nerves
Much of your taste of food is actually smell
Taste: chemical sense. Taste buds detect taste
5 tastes:
Salty, Bitter, Sweet, and Sour, Umami (meaty)
Humans are capable of detecting more than 10,000 different odors

18. Smell and Taste
How we smell and taste

19. Touch All regions of the skin are sensitive to touch
The skin is actually the largest sense organ
Skin contains sensory receptors that respond to temperature, touch (pressure), and pain
Not all parts of the skin are equally sensitive to touch because not all parts have the same number receptors
Greatest density of touch receptors are found on fingers, toes, and face

20. Touch
How are skin perceives touch

21. Senses Stations Station 1: A penny heard…
Station 2: Are you a super taster?
Station 3: The Link Between Taste and Smell
Station 4: Two Point Touch