Nervous/Sensory System

Central Nervous System

• To carry information from sensory organs and internal organs to CNS • To carry information between CNS and other parts of the body, excluding the brain and spinal cord

• Controls voluntary movement via skeletal muscles

• Regulates involuntary movement of muscles of internal organs and glands (automatic functions) • Heart rate, blood pressure, respiration, arousal, digestion • Reflexes

• Eyes: sense of sight • Nose: sense of smell • Tongue: sense of taste • Ears: sense of hearing and balance • Skin: sense of touch

• Epidermis • Dermis • Hypodermis

Subcutaneous tissue

• Outer/top layer • Thinnest layer of skin • Composed of a stratified layer of flattened cells • Lacks blood cells • Can be found in plants • Provides water proof barrier • Makes skin tone with melanin

• Middle layer • Thickest layer of skin • Composed of dense irregular connective tissue • Is vascular (has blood vessels) • Is not found in plants • Supports elasticity, sweat glands and oil • Supplies nutrients to epidermis

• Insulates body • Contains energy • Links to muscles

• Sclera • Pupil • Iris • Cornea • Lens • Retina • Optic nerve

• White part • Fibrous tissue • Protects eyeball • Maintains shape of eyeball

• Black centre of the eye • Changes size to let light into the eye

• Coloured tissue that makes eye colour • Muscles in the iris control the opening size of the pupil

• Transparent cover over the pupil and iris • Focuses entry of light into the eye

• Behind the pupil • Focuses light onto the retina at the back of the eye to obtain clear images of objects at various distances

• A layer of photoreceptor cells and glial cells • Cone cells - Helpful for seeing vivid colours in brightness • Rod cells - Helpful for seeing in dark conditions • Converts light that enters the eye into electrical signals that the optic nerve sent to the brain to create the images you see

• Outer ear • Middle ear • Inner ear

• Transfers all information obtained by the eye to the brain

• Collects sound waves and channels them into the external auditory meatus (ear canal) where sound will be amplified • Pinna/auricle - external part of the ear • External auditory canal - tube that connects the outer ear to middle and inner ear

• Ossicles - small bones that transmit sound waves to the inner ear: Malleus, Incus, Stapes • Eustachian tube - connected to nose, stabilises middle ear pressure which is important for sound wave transmission

• Cochlea - detects sound low in frequency • Vestibule - contains receptors to maintain balance during rotational movements • Semicircular canals - 3 fluid-filled tubes that help you maintain balance during rotational movements

• Sound waves enter the outer ear (pinna/auricle) • Sound waves hit eardrum after travelling through the ear canal causing vibrations • Sound moves through the middle ear and sound waves are amplified • Sounds moves though the inner ear (cochlea) where vibrations are transformed into electrical signals by hair cells • Signal/sound is interpreted by brain

• Taste is detected with receptor cells known as taste buds • Different taste buds detect different taste sensations • Taste buds are evenly distributed across the tongue