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The Senses. The senses provide us with information about our surroundings, and allows us to respond appropriately. Includes: sight, hearing, touch, taste, smell, equilibrium. Sensory pathway. Receptors : detect stimuli (changes) and generate the impulse .
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The Senses • The senses provide us with information about our surroundings, and allows us to respond appropriately. • Includes: sight, hearing, touch, taste, smell, equilibrium.
Sensory pathway • Receptors: detect stimuli (changes) and generate the impulse. • Neurons: transmit the impulse to the CNS • Sensory Tracts: the spinal cord or brain that transmits the impulses • Sensory Area; most in the cerebral cortex. Feel the sensation.
Cutaneous Senses • The dermis of the skin has receptors that sense touch, pressure, heat, cold and pain
Muscle sense • Also called kinesthetic. Allows brain to detect where muscles are and how positioned.
Sense of taste • Receptors for taste are taste buds. • These are Chemoreceptors. There are 4 main ones • Sweet, sour, salty, and bitter. • Many medications, drugs and smoking interfere with the taste, and may lead to poor nutrition.
Sense of smell • Also from chemoreceptorsthat detect vaporized chemicals. • A lot of what we call taste is actually the smell of food instead.
Hunger and Thirst • Internally triggered by receptors in the hypothalamus. They detect nutrient and chemical levels and the water-salt concentration.
The Eye • Has receptors for vision and focusing light rays • Has 3 layers: • 1. Schlera: thickest layer of fibrous connective tissue and is the visible white part • Cornea: most anterior portion. It is transparent. This is the first part that bends light
2. Choroid layer: contains blood vessels and a blue pigment to absorb light. • Lens: transparent. Shape is changed to allow eye to focus light from varying distances. • Iris: colored part of eye • Pupil: central opening
3. Retina: • Posterior part of eye. Contains all visual receptors, the rods, and cones. • Rods: detect presence of light • Cones: detect colors (absence of cones causes colorblindness) • In order to see, light rays must be focused on the retina and the nerve impulses transmitted to the visual area of the cerebral cortex.
The Ear • The ear consists of 3 areas: • The outer ear • The middle ear • The inner ear • The ear contains receptor for 2 senses • Hearing • Equilibrium