Chapter 15 Flashcards
Sensory receptors
- sense organs
- receptors that make it possible for the body to response to changed in the external and internal environment
Sensation
- a physical feeling or perception resulting from changes in or the contact with the body
- occurs when receptor potential is reached
- graded response, to the strength of a stimulus
Define special sense
- smell, taste, vision, hearing and equilibrium
- locally distributes in the body (tightly grouped)
Define general sense
- touch, pain, pressure, temperature
- widely distributed throughout the body
Receptors can be classified according to?
Location
Stimulus detection
Structure
Exteroceptors
Located on or very near the surface of the body
- respond to external changes
Visceroceptors (interceptors)
- located internally, within the bodily organs
- respond to internal environments (heat, stretch, chemicals)
Proprioceptors
- specialized visceroceptor
- located in skeletal muscle
Classifications of receptors
Mechanoreceptors - “deform” or change position of the receptor
Chemoreceptors - amount of the changed concentration of certain chemicals
Thermoreceptors - change in temperature
Nociceptors - any stimulus that rebuts in pain or tissue damage
Photoreceptors - light stimuli
The somatic sensations that arise form receptors
- detect touch, pressure, vibration, pain and body position and movements
- send impulses to the primary somatosensory area of parietal lobe of cerebral cortex
- somatosensory area processes the information and send it to the primary motor areas in the frontal lobe.
The 5 sensory receptors in the skin
Unencapsulated dendrites: detect pain, light, pressure, changes in temperature
Merkel disks: detect light, touch, and pressure
Meissner’s corpuscles: detect beginning and end of light touch and pressure
Ruffini endings: respond to ongoing pressure
Pacinian corpuscles: detect deep pressure and high-frequency vibration
Mechanoreceptors
1) in joints: detect joint position
2) in skeletal muscles: muscle spindles, specialized Mechanoreceptors for monitoring muscle length, which relay information about limb position
3) in tendons: detect tension
Proprioception
- the unconscious perception of movement and spatial orientation arising from stimuli within the body itself
- specialized Mechanoreceptors- “muscle sense”
- tells us the level of contraction and stretch in each skeletal muscles
The two types of proprioception stretch receptors
- muscle spindles
- Golgi tendon receptors
Themoreceptors detecting temperature
- themoreceptors near skin surface provide information about external environment
- surface themoreceptors adapt quickly
- themoreceptors in thoracic and abdominal organs monitor core temperature.
- core temperature receptors do not adapt quickly
Pain receptors signal?
- unencapsulated nerve endings respond to injury from excessive pressure, heat, light, or chemicals
- fast paint (acute, sharp)
- occurs very quickly
- informs us of stimuli to be avoided
- slow pain
- occurs more slowly
- originates in muscles or internal organs
- referred pain may be perceive as originating in a different area of the body
Olfaction
Sense of smell
- olfactory epithelium consists of yellow-colored epithelial support cells, basal cells, and bipolar type of olfactory sensory neurons
- chemoreceptors
Taste buds
- sense organs that respond to
- taste stimuli - most taste buds are associated with papillae
- small, elevated projection on the tongue
Types of tongue papillae
Fungiform: large mushroom-shaped bumps found int he anterior two thirds of the tongue surface
Circumvallate: huge, dome-shaped bumps that for a transverse row near the back of the tongue
Foliate: red, leaf-like ridge of mucosa on the lateral edges of the posterior tongue surface
Filiform: bumps with tiny, thread-like projections, scattered among the fungiform papillae
Gustatory cells
- chemoreceptors found in taste buds that are responsible for taste
- stimulated by chemicals called tastants that dissolve in saliva
The five primary taste sensations
Bitter
Salty
Sweet
Savory
Sour
The sense of hearing and balance
- The ear serves as a duel sensory organ
- hearing and equilibrium (balance)
- stimulation for both is the activation of Mechanoreceptors called hair cells
- which are triggered by the displacement of fluid
Middle ear
- also called the tympanic cavity
- a tiny epithelial-line cavity hollowed out of the temporal bone
Contains:
- tympanic membrane (eardrum)
- auditory ossicles:
Malleus (hammer)
Incus (anvil)
Stapes (stirrups)
Inner ear
Called the labyrinth
Bony labyrinth:
Vestibule
Cochlea
Semicircular canals
Membranous labyrinth:
Utricle
Saccule
Main structure of the eye
Sclera
Iris
Pupil
Lens
Iris
Cornea
Accessory structure of the eye
Eyebrows
Eyelashes
Eyelids
Lacrimal apparatus
The layers of the eye
Fibrous layer: sclera, cornea
Vascular layer: choroid, ciliary body, iris
Inner layer: retina, optic nerve, retinal blood vessels
Muscles of the eye
Extrinsic:
- skeletal muscle, that voluntarily moves the eyeball
Includes: superior, inferior, medial, and lateral rectus muscles. Superior an inferior oblique muscles
Intrinsic:
- smooth muscles, located within the eye itself
- iris; ciliary muscles
Regulating the amount of light
- the iris (smooth muscle) causes pupils to constrict or dilate to control the amount of light entering the eye
Focusing the image
- involves bending of light by cornea and lens
- accommodation
- adjustment of lens curvature to enable focusing on near and far objects
- made possible by ciliary muscles
- ability to accommodate deteriorates with age
Retina
- allows us to see in color, adapt to varying light intensities, and perceive images
The four layers of the retina
1) outermost: pigmented cells, absorb excess light
2) photoreceptors: rods and cones
3) bipolar cells: synapse with rods and cones
4) innermost: ganglion cells, axons become the optic nerve
Photoreceptors
- rods and cones
- response to light: photopigment (protein) changes shape
- Rods: approximately 120 million
- cones: approximately 6 million - one million ganglion cells
- significant amount of convergence and summation
Rhodopsin
Rhodopsin: photopigment within the rods
- more sensitive to light than photopigment in cones
- in dim light, vision primarily depends on rods
- rods do note enable color vision
- rods and cones are not evenly distributed on the retina
- regions of the retina farthest from the fovea have the highest ratio of rods to cones
The cones providing color vision and accurate images
- three types of cones enable color vision: red, green, and blue
- brain interprets ratios of impulses combined from ganglion cells connected to the three kinds of cones
- cones require stronger light to be activates
- in dim light, we primarily use rods and don’t see color
- cones responsible for visual acuity
Visual receptors adjust how
Depends on:
- adjustment of pupil size by iris
- adaptation by the rods
Adaptation takes longer when going from light to dim light
- bright light “uses up” the rhodopsin temporarily
- takes several minutes to resynthesize rhodopsin
