1. ST
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M
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Done By: Mint + Thon
IB Biology HL Y2

2. SENSORY cells: send messages to the part of the brain that controls
emotion and memory
Music or food reminds our childhood times
Sense organ: Mouth, Eye, Tongue, Nose, Skin
Filled with sensory neurons
Send messages to CNS
We see, smell, taste, feel with our BRAIN!
(not sense organ)

4. Mechanoreceptors: respond to mechanical force/pressure
Pressure: Touching (Skin)
Change in blood pressure (Arteries)
Auditory and Equibrioception* (Ears)
(sense of balance)
Proprioreceptors: maintain posture and balance

5. Proprioreceptors: maintain posture and balance

6. Chemoreceptors: respond to chemical substances
Chemical: Taste and Smell (Tongue + Nose)
Monitor pH changes (blood vessels)
Adjust breathing rate according to
change in pH (Ears)
Painreceptors: respond to chemicals from damaged tissues
e.g. reflex protects us from danger

8. Thermoreceptors: respond to change in temperature
Warmthreceptors: respond when temperature rises
Coldreceptors: respond when temperature drops
REGULATING body temperature
(related to HOMEOSTASIS!)

10. Photoreceptors: respond to light energy
Light: Sensitive to light & give us vision (eye)
Rod Cell: Respond to dim light
Give black and white vision
Cone Cell: Respond to bright light
Give us color vision

13. Outer ear catches sound waves
Sound waves: successive vibrations of air molecules
1. EARDRUM
2. BONES of the MIDDLE EAR
3. OVAL WINDOW
4. HAIR CELLS in the COCHLEA

14. Sound waves entered  VIBRATE the eardrum
ROLE: Pick up sound vibrations from the air Transmit
them to the middle ear

15. There’s a risk of breaking the ear drum
(perforation)
Although this is commonly done…it’s
recommend against using cotton tipped
applicators, hair pins, and similar devices to
clean the ear.

16. Series of small bones --- Ossicles
Ossicles: All of them are touched
Touched with eardrum and oval window
A lever to reduce the amplitude of waves

17. Muscles:Attached to ossicles to protect ear from loud
sounds --- by contracting to damp down vibrations in ossicles

18. Membranous structure --- like eardrum
Oval Window: Transmitting sound waves to fluid
Round Window: Allows movement of fluid in cochlea
(by moving away)
Oval window move towards cochlea
|
Round window moves away

19. Fluid in cochlea can vibrate freely -- volume remaining constant

20. Cochlea --- a tube wound to form spiral shape
hair receptors (hair cells) on membrane
Sound waves pass through fluid in cochlea
Each hair bundle resonates with particular frequencies
Hair cells: have hair bundles
send messages across synapse on to brain through
auditory nerve
http://www.youtube.com/watch?v=dCyz8-eAs1I&feature=related

23. . .
.
.
.
On the Outside
• Iris: Regulation
• Pupil: Admittance
• Lens + Cornea: Focus
• Sclera: Protect & Serve
• Conjunctiva: Cover & Moisture

24. From the Inside
• Aqueous Humor:
Transmission & Support
.
• Vitreous Humor:
..
Transmission & Support
In the Back
• Retina: Receptors
• Rods: Black, white, dim
• Cones: Colorful, bright
• Fovea: Dense with
.
.
cones, acute vision
• Choroid: Absorb strays
• Optic Nerve: Transmission
• Blind Spot: No vision
perceived

25. • Light focused on retina’s photoreceptor cells
• Rods
• Cones
• Vision: Light → Photoreceptor cell → Bipolar neurone → Ganglion cells →
Optic Nerve
•D&C
• Rods: Very sensitive to light, better in dim light
• Cones: Less sensitive to light, better in bright light
• Bipolar Neurone: Sends message of rods and cones to ganglion cells
• Ganglion cells: Cell bodies of optic nerve, transmission to brain.

26. • Sensitivity & Function
• Rods: High sensitivity, prefers dim lights
• Cones: Low sensistivity, prefers bright lights
• Types of cells
• Rods: One type
• Cones: 3 types, (Red – Blue – Green)
• Attachment to Bipolar Neurones
• Rods: Group of rod cells
• Cones: Single cone cell

27. • Light stimulates rods and cones
• Impulses sent to Bipolar Neurones & Ganglion cells
• Brain corrects image orientation
• Study of vision
• Optical Illusions
• Effects of brain injuries

28. • Ganglion cells stimulated when light
falls in receptive field
• 2 types of Ganglion cells
• A: Light on receptive field =
Stimulation, Light on periphery =
reduced stimulation
• B: Light on periphery =
Stimulation, Light on receptive
field = reduced stimulation
• Both Most Stimulated = Edge
between contrasts in the receptive
field
• Body has a knack for seeing
edges

30. • Optic Chiasma: Intersection of L & R optic
nerves
• Sharing of information:
• L to R, R to L
•½+½=1
• Brain able to deduce distance, sizes, and
identity.
• R Lesions: Identification problems
• L Lesions: Naming problems