senses

3 ways to classify receptors

Exteroceptors, Interoceptors, and Proprioceptors; each detects stimuli from external environment, internal organs, and body position respectively.

Importance of pain

Pain is a protective mechanism that alerts the body to potential or actual injury.

Tissue without pain receptors

The brain tissue itself lacks pain receptors.

Fast pain

Sharp, immediate, localized pain conducted via myelinated A-delta fibers.

Slow pain

Dull, throbbing, persistent pain conducted via unmyelinated C fibers.

Somatic pain

Pain from skin, muscles, and joints.

Visceral pain

Pain from internal organs, often poorly localized.

Referred pain

Pain perceived in an area different from the source due to shared spinal nerves.

CNS modulation of pain

Includes endorphins, enkephalins, and descending inhibitory pathways that reduce pain perception.

Gustation

The sense of taste.

Olfaction

The sense of smell.

Receptors for taste

Taste buds composed of gustatory cells respond to chemicals in saliva.

5 primary taste sensations

Sweet, sour, salty, bitter, umami.

Factors affecting taste perception

Temperature, texture, smell, age, and health conditions.

Why hot pepper isnt a taste

Capsaicin activates pain receptors, not taste buds.

Stimulation of taste receptors

Occurs when chemicals dissolve in saliva and bind to taste cells.

Olfactory receptor location

Located in the olfactory epithelium in the nasal cavity.

Olfactory cells

Bipolar neurons with cilia that detect odorants.

Olfactory cell lifespan

They regenerate every 30-60 days, unlike most neurons.

Olfactory stimulation mechanism

Odorant molecules bind to receptors on cilia of olfactory neurons.

Synaptic inhibition in olfactory bulbs

Helps fine-tune odor discrimination and prevent overstimulation.

Brain areas for olfaction

Includes olfactory cortex, amygdala, and hippocampus.

Physical responses to odors

Can include salivation, nausea, or emotional memories.

Definition of sound

Audible vibration of molecules transmitted through air or another medium.

Anatomy of the ear

Outer ear collects sound, middle ear amplifies, inner ear transduces to neural signals.

Sound wave travel

Sound waves travel from pinna → auditory canal → eardrum → ossicles → cochlea.

Tensor tympani and stapedius

Protect the cochlea from loud sounds by dampening ossicle movement.

Loudness and pitch coding

Loudness: amplitude of vibration; Pitch: frequency of vibration in cochlea.

Equilibrium

Sense of body position and movement maintained by vestibular system.

Coordination and balance

Managed by integration of visual, proprioceptive, and vestibular input.

Static vs dynamic equilibrium

Static: position of head when still; Dynamic: movement of head.

Saccule and utricle

Detect linear acceleration and head position relative to gravity.

Otoliths and stereocilia

Otoliths shift with head movement, bending stereocilia to send signals.

Crista ampullaris

Sensory structure in semicircular canals detecting rotational movement.

Semicircular ducts

Detect rotational acceleration in three planes.

Eyebrows and eyelashes

Protect the eyes from debris and sunlight.

Conjunctiva

Transparent membrane covering eye and inner eyelids.

Lacrimal apparatus

Produces and drains tears to lubricate and protect the eye.

Extrinsic eye muscles

Six muscles control voluntary eye movement.

Tunics of the eye

Fibrous (sclera, cornea), Vascular (choroid, ciliary body, iris), Neural (retina).

Structures of the optical apparatus

Includes lens, cornea, aqueous humor—focus light on retina.

Optical vs neural apparatus

Optical focuses light; Neural processes the visual signals.

Detached retina effects

Leads to visual impairment or blindness if not reattached quickly.

Ophthalmoscopic examination structures

Optic disc, macula, blood vessels, retina.

Brain and blind spot

Brain fills in the visual field using surrounding cues and both eyes.

Hyperopia vs myopia

Hyperopia: farsightedness, short eye; Myopia: nearsightedness, long eye.

Retinal layers

Photoreceptors → bipolar cells → ganglion cells → optic nerve.

Rod vs cone cells

Rods: low-light, black-and-white vision; Cones: color vision and detail