Senses Part 1

General and Special Senses Types of General Senses: Touch Pain Temperature Vibration Itch Proprioception Types of Special Senses: Smell Taste Sight Hearing Balance

Sensory Receptors Mechanoreceptors: Respond to bending or stretching Sensory Receptors: Are sensory nerve endings or specialized cells capable of responding to stimuli by developing action potentials. Type of Receptors: Mechanoreceptors: Respond to bending or stretching Chemoreceptors: Respond to chemicals Photoreceptors: Respond to light Thermoreceptors: Respond to heat Nociceptors: Respond to pain

Sensory Receptors in the Skin

Olfaction Olfaction: Occurs in response to airborne molecules, called odorants, that enter the nasal cavity. Olfactory neurons are bipolar neurons with in the olfactory epithelium. There are 400+ functional olfactory receptors in humans Olfactory receptors can bind to multiple olfactory receptors. Causing more combination of smells.

Neuronal Pathway for Olfaction Bring odorants into nasal cavity Axons from olfactory neurons form the olfactory nerves (1) Olfactory Nerve These axons pass through the foramen of cribriform plate and enter the olfactory bulb There they synapse with interneurons that send action potentials to the brain through olfactory tracts and travel to the olfactory cortex.

Taste The sensory structures that detect taste are called taste buds. Taste buds are oval structure located on the papillae of the tongue. Each taste bud contains about 40 taste cells Taste HairsTaste Pores

Taste Sensations Taste sensations are divided into 5 basic types: Bitter Salty Sweet Umami Sour Taste is strongly influenced by olfaction

Neuron Pathway for Taste Taste sensations are received by taste buds. Taste sensations are carried by three Cranial Nerves (VII) Facial Nerve (IX) Glossopharyngeal Nerve (X) Vagus Nerve The message is then sent to to the Brain Stem to the thalamus to the parietal lobe of the brain’s (Taste Area)

Vision (Accessory Eye Structures) Accessory Structures of the Eye: Eyebrows: Protect the eyes by preventing perspiration from running down the forehead into the eye, and also provide shade from direct sunlight. Eyelids: Protect the eyes from foreign objects and aid in lubrication. Conjuctiva: Thin mucus layer Lacrimal Apparatus: Produces tears that lubricate and cleanse the eye. Also drain excess fluid into the lacrimal duct.

Anatomy of the Eye Tunics of the eye: Fibrous Tunics Sclera Cornea Vascular Tunics Choroid Iris Ciliary Body Nervous Tunic Retina

Contraction of the Iris

Anatomy of the Eye Eye Structures: Lens: Flexible and Biconcave Pupil: Hole that lets light pass through Optic Nerve: Sends images to the brain Retinal Blood Vessels:

Photoreceptors of the Retina Rod: Detect Light (Dark and Light) Cons: Detect Color Red Blue Green