Chapter 29: The Senses Flashcards
Sensory Receptor Cells
Detect internal/external stimuli
- located in sense organs
- all nerve impulses are the same, identical
Sensation
Awareness of a sensory stimulus
- results when brain integrates new info
Perception
More meaningful interpretations and understanding of sensory information
- brain integrates new info w/ previous experiences
- combination of different senses
Sensory Transduction
When receptor cells convert stimulus into a nerve impulse
- occurs in plasma membrane of receptor cells
- permeability changes (gated ion channels open)
Receptor Potential
Electrical signal produced by sensory transduction, similar to action potential
- not an all or none effect (stronger stimulus, stronger receptor potential)
- receptor cell synapses w/ sensory neurons –> brain
Sensory Adaptation
Tendency of sensory receptors to become less receptive if there’s too much stimulus
- prevents brain from reacting to normal, useless background info
What are the five sensory receptors?
1) Pain Receptors
2) Thermoreceptors
3) Mechanoreceptors
4) Chemoreceptors
5) Electromagnetic Receptors
Pain Receptors
Aware of injury/disease
- indicate danger to increase survival
- entire body is filled w/ these but brain
Thermoreceptors
Detect heat/cold, monitor temperature of blood
- in vital organs
- hypothalamus is the body’s major thermostat
Mechanoreceptors
Various forms of energy (stretch, motion, sound, pressure, etc)
- inside muscles, ears
Chemoreceptors
Sensitive to chemical stimulation
- nose & tongue
- respond to chemicals dissolved in fluids
- best sense is moths
Electromagnetic Receptors
Sensitive to energy of various wavelengths (magnetism, light)
- photoreceptors are most common and detect light waves from electromagnetic spectrum
What are the three types of photoreceptors?
1) Eye cups
2) Compound Eyes
3) Single Lens Eyes
Eye cups
Found in planar
- detect intensity/direction of light and goes away from light
Compound Eyes
Many tiny light detecting units
- Ommatidia = 1 lens, 1 cornea
- Extremely acute motion detectors, excellent color vision
Single Lens Eyes
Light enters thru small opening in eyes, regulated by structure (camera type eye)
Stretch Receptor
a type of mechanoreceptor sensitive to changes in muscle length; detects the position of body parts
Hair Cells
a type of mechanoreceptor that detects sound waves and other forms of movement in air or water (Cilia or Microvilli)
Sclera
Tough white coating of eye (outermost)
Cornea
Anterior, curved, clear part of sclera
- first structure to focus light
Conjuctiva
Thin mucus membrane on cornea
Choroid Coat
Darkly colored –> absorb light
- right w/ blood vessels
Ciliary muscle
Smooth muscle, where sclera becomes cornea
- attached to lens by suspensionary ligaments to help focus light by contracting
Lens
Elastic, biconvex (curves out on both sides)
- positioned behind pupil, surrounded by iris
Iris
Ring of pigmented tissue, regulates size of pupil
Aqueous Humor
Watery fluid between cornea and lens to provide nutrients
Vitreous Humor
Jelly like fluid in chamber behind lens, helps keep shape
Retina
Contains photoreceptor cells (stimulus transducers)
- rods and cons
Rods (rhodopsin)
Absorb dim light –> black and white image
Cons (photopsin)
Absorb bright light –> colored center
Optic Nerve
Carries impulses to brain, blind spot
Fovea
an eye’s center of focus and the place on the retina where the receptors are highly kind
Blind Spot
the place on the retina of the vertebrate eye where the optic nerve passes through the eyeball and where there are no photoreceptor cells
Accommodation
the automatic changes made by the eye as it focuses on near objects
Visual Acuity
the ability of the eyes to distinguish fine detail
Nearsightedness
an inability to focus on distant objects; occurs when the eyeball is longer than normal and the lens focuses distant objects in front of the retina. Also called myopia.
Farsightedness
an inability to focus on close objects; occurs when the eyeball is shorter than normal and the focal point of the lens is behind the retina. Also called hyperopia
Astigmatism
blurred vision caused by a misshapen lens or cornea
What are the 3 regions of the human ear?
Outer ear, middle ear, inner ear
Outer Ear
one of three main regions of the ear in reptiles, birds, and mammals; made up of the auditory canal, and in many birds and mammals the pinna
Pinna
the flaplike part of the outer ear, projecting from the body surface of many birds and mammals; collects sound waves and channels them to the auditory canal
Auditory Canal
part of the vertebrate outer ear that channels sound waves from the pinna or outer body surface to the eardrum
Eardrum
a sheet of connective tissue separating the outer ear from the middle ear that vibrates when stimulated by sound waves and passes the waves to the middle ear
Middle Ear
one of three regions of the vertebrate ear; a chamber containing three small bones (the hammer, anvil, and stirrup), which convey vibrations from the eardrum to the oval window
Oval Window
in the vertebrate ear, a membrane-covered gap in the skull bone, through which sound waves pass from the middle ear into the inner ear
Eustachian tube
an air passage between the middle ear and throat of vertebrates, that equalizes air pressure on either side of the eardrum
Inner Ear
one of three main regions of the vertebrate ear; includes the cochlea, organ of Corti, and semicircular canals
Cochlea
a coiled tube in the inner ear of birds and mammals that contains the hearing organ, the organ of Corti
Organ of Corti
the hearing organ in birds and mammals, located within the cochlea
Semicircular Canals
fluid filled channels in the inner ear that detect changes in the head’s rate of rotation or angular movement
Utricle
a fluid-filled inner ear chamber containing hair cells that detect the position of the head relative to gravity
Sccule
a fluid filled inner ear chamber containing hair cells that detect the position of the head relative to gravity
