SENSES PART 1

Types of General Senses: Touch Pain Temperature Vibration Itch Proprioception

Types of Special Senses: Smell Taste Sight Hearing Balance

GENERAL AND SPECIAL SENSES

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

SENSORY RECEPTORS IN THE SKIN

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.

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.

NEURONAL PATHWAY FOR OLFACTION

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 HairsTaste Pores

TASTE

Taste sensations are divided into 5 basic types: 1. Bitter 2. Salty3. Sweet4. Umami5. Sour

Taste is strongly influenced by olfaction

TASTE SENSATIONS

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)

NEURON PATHWAY FOR TASTE

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.

VISION (ACCESSORY EYE STRUCTURES)

Tunics of the eye:Fibrous Tunics

ScleraCornea

Vascular TunicsChoroid IrisCiliary Body

Nervous TunicRetina

ANATOMY OF THE EYE

CONTRACTION OF THE IRIS

Eye Structures: Lens: Flexible and Biconcave

Pupil: Hole that lets light pass through

Optic Nerve: Sends images to the brain

Retinal Blood Vessels:

ANATOMY OF THE EYE

Photoreceptors:Rod: Detect Light

(Dark and Light) Cons: Detect Color

1. Red2. Blue 3. Green

PHOTORECEPTORS OF THE RETINA