Chapter 41: Sensory Systems Flashcards
What is echolocation?
bats use this to see in the dark. They send out sound waves and then the waves bounce off objects and the bats can then put together a picture of their surroundings.
gives them secondary vision
What is a stimulus?
a change in the internal or external environment that can be detected by the organism’s body
What detects a stimulus?
sensory receptors
What are the 5 basic types of receptors?
mechanoreceptors, photoreceptors, chemoreceptors, thermoreceptors, nociceptors
What is a mechanoreceptors? ex? found in?
Detect mechanical energy when it deforms membranes, physical movement of receptor
ex) auditory receptors in the ears
found in skin, skeletal muscles, walls of blood vessels, and internal organs
What is a photoreceptors? ex?
detect the energy of light
ex) found in retina of eye
What is a chemoreceptors? ex?
detect specific molecules or chemical conditions (acidity)
ex) taste buds on the tongue
What is a thermoreceptors? ex?
detect the flow of heat energy
ex) temperature receptors in the skin
What is a nociceptors? ex?
detect tissue damage or noxious chemicals, register their activity as pain
ex) pain receptors are located in the skin and in some internal organs
What is a receptive field?
a region in which the receptor responds to a stimulus
What are some of the disadvantages of free nerve endings?
they are not as sensitive b/c stimulus has to hit the free nerve exactly
a nerve “pad” increases the receptor field which increases sensitivity
What is signal transduction?
conversion of a stimulus into a receptor potential
What do photons use for communication?
they use transduction, they are not neurotransmitters
What are the 2 ways intensity of a stimulus are registered?
1) frequency of action potentials
2) number and types of afferent neurons that the stimulus activates to generate action potentials in the pathway
What is sensory adaptation?
the frequency of action potentials generated in afferent neurons is reduced when the intensity of a stimulus remains constant
increases the sensitivity of receptor systems to changes in environmental stimuli, which may be more important to survival than constant factors
How does perceptions differ from reality?
- Lack receptors for some types of energy (e.g., X-rays)
* Sensory input is processed in various ways
How does a mechanical stimulus work?
creates tension in the plasma membrane of a receptor which causes ion channels to open, producing a receptor potential
What are the types of receptors for touch and pressure human skin has?
free nerve endings, Pacinian corpuscles, Ruffini endings, and Meissner’s corpuscles
What do free nerve endings respond to?
light touch
What do pacinian corpuscles respond to?
deep pressure and vibrations—- warning signals
What do ruffini endings respond to?
deep pressure
What do meissner’s corpuscles respond to?
light touch and surface vibrations
What are proprioceptors
a mechanoreceptor that detect stimuli used in the CNS to maintain body balance and equilibrium and to monitor the position of the head and limbs
What are muscle spindles?
bundles of specialized muscle cells wrapped with the dendrites of afferent neurons
cerebellum uses this info
What is the vestibular apparatus?
in the inner ear responsible for perceiving the position and motion of the head
made of three semicircular canals, the utricle, and the saccule – all filled with a fluid called endolymph
What are the semicircular canals?
detect rotational (spinning) motions
What is an ampulla?
each semicircular canal has an ampulla at its base, topped with sensory hair cells that synapse with afferent neurons
What are sterocilia?
Microvilli (stereocilia) extend into a gelatinous cupula which protrudes into the endolymph of the canals
When the head rotates, displacement of the cupula bends the sensory hair cells – depolarization causes release of neurotransmitters, which trigger action potentials—–allows Na+ to rush in
What is the otolitic membrane?
The utricle and saccule contain sensory hair cells covered with a gelatinous otolithic membrane in which small crystals of calcium carbonate (otoliths) are embedded
What is the orientation of the sensory hairs when the animal is upright?
sensory hairs in the utricle are oriented horizontal – those in the saccule are vertical
What is the orientation of the sensory hairs when the animal is tilted?
sensory hairs bend and action potentials are generated
What is the lateral line system?
Fishes and some aquatic amphibians detect vibrations and currents in water through a series of mechanoreceptors in the lateral line system
What are neuromasts?
In fish, the mechanoreceptors (neuromasts) also provide information about orientation with respect to gravity and swimming velocity
What are statocysts?
fluid-filled chambers with walls that contain sensory hair cells enclosing one or more movable stonelike bodies (statoliths)
When the animal moves, statoliths lag behind the movement, bending the sensory hairs and triggering action potentials
Statocysts signal the brain about the body’s position and orientation with respect to gravity
What is sound?
vibrations that travel as waves made by alternating compression and rarefraction of the air
What does the loundness/intensity of a sound depend on?
amplitude of the wave
What does the pitch (how high/low a sound makes) of sound depend on?
frequency of the waves
How do invertebrates detect sound?
through mechanoreceptors in their skin or other surface structures
How do some insects detect sound?
have complex auditory organs on either side of the abdomen or on the first pair of walking legs
These organs consist of a thinned region of the insect’s exoskeleton that forms a tympanum over a hollow chamber
Sounds reaching the tympanum cause it to vibrate – mechanoreceptors connected to the tympanum translate the vibrations into nerve impulses
What is the outer ear?
external structure (pinna) which concentrates and focuses sound waves
Sound waves enter the auditory canal and strike the tympanic membrane (eardrum), which vibrates in response
What is the middle ear?
contains three small, interconnected bones: the malleus (hammer), incus (anvil), and stapes (stirrup)
What is the oval window?
The stapes fits within an elastic membrane (oval window) and is held in place by a ligament
What is the inner ear?
contains the semicircular canals, utricle, saccule, and the cochlea – a spiraled tube
What is the structure of the cochlea?
divided into three longitudinal chambers: the vestibular canal, the cochlear duct, and the tympanic canal