Option A.3 Perception of Stimuli IB BIOLOGY HL Option A.3 Perception of Stimuli

Sensory Receptors Diversity of Stimuli Detect changes in environment Mechanoreceptors: Stimulated by mechanical force or pressure Touch BP detectors in arteries Stretch receptors in lungs Proprioceptors in muscles, tendons joints, ligaments Inner ear- balance

Sensory Receptors, cont. Chemoreceptors: Respond to chemical substances Taste and smell Monitor pH of blood Respond to damaged tissues as pain receptor Located at the top of the nasal passage Genes recognize smells, no gene for a substance, you can’t smell it. https://www.youtube.com/watch?v=mFm3yA1nslE

Sensory Receptors, cont. Thermoreceptors Respond to change in temperature Located in skin in humans Photoreceptors Respond to light energy Found in eyes Rods- black and white Dim light Cones-color vision Bright light

Structure of the Human Eye

Retinal Arrangement

Retinal Arrangement, cont.

The Retina Lightrods and conesoptic nerve brain Rods and cones synapse with own bipolar cells Bipolar cells synapse with ganglion cell Axons of ganglion cell make up optic nerve Rod cells- dim light Synapse in groups onto bipolar neurons Cone cells- bright light Have 1 to 1 relationship with bipolar neurons Bipolar neurons- carry impulse from rods and cones to ganglion cell Ganglion cells- synapse with bipolar neurons, send impulse to brain via optic nerve

Red- Green Color Blindness Three classes of cones in normal color vision: red, green, blue Some people have red-green color vision defects Sex-linked trait Rare in females

Field of Vision Right field from both eyes sent to left visual cortex, vice versa Contra-lateral processing

Structure of the Ear

Structure of the Ear, cont. The Middle Ear Transmits and amplifies sound Air filled chamber Eardrum separates outer ear from middle ear Ossicles: Malleus, incus and stapes articulate to transmit vibrations

Structure of the Ear, cont. The cochlea Sensory hairs detect wavelengths of sound Tubular, coiled, fluid-filled Has layers of tissue with sensory cells (hair cells) attached Round window-separates middle and inner ear

Structure of the Ear, cont. The auditory nerve Impulses caused by sound perception transmitted to brain via auditory nerve Action potential sound Cranial nerve to brain https://www.youtube.com/watch?v=ssKoVTWV99s

Semi-Circular Canals Three semi-circular canals Contain fluid and hair cells Movement of fluid detects orientation of the head Hair cells vestibular nerve brain

Cochlear Implants Convert sound into electrical signals brain Pg. 258 https://www.youtube.com/watch?v=-GA9gEh1fLs