Sense Organs Flashcards
What are the functions of the tongue?
The tongue’s functions are:
- Swallowing
- Perception (can detect taste, texture, pain, pressure, heat, etc)
- Speech
- Respiration
- jaw development
What are the extrinsic and intrinsic muscles function in the tongue?
The extrinsic muscles in the tongue:
- Move the tongue in and out of the mouth
- Move the tongue from side to side
The intrinsic muscles of the tongue:
- Alter the shape of the tongue
What are taste buds?
- Taste buds are modified epithelial cells that act as taste receptors.
- Most are associated with nipple like projections called papillae
- About 3000 taste buds are on the tongue
- There are 4 primary taste sensations: sweet, sour, salty, and bitter
What are Von Ebner’s glands?
Von Ebner’s glands surround the papillae and secrete salivary lipase, beginning the process of lipid breakdown (hydrolysis) in the mouth
What does the eye analyze?
The eye analyzes form, light intensity, and color
What is the sclera?
The sclera is the white part of the eye
- Tough connective tissue made up of collagen bundles
- It is avascular
- Has sensory receptors for pain
What is the cornea?
The Cornea allows light into the eye
- avascular
- When light hits the cornea, it bends (refracts) the incoming light into the lens of the eye.
What is the choroid?
Highly vascular thin layer that lines most of the internal sclera surface.
- Melanocytes containing pigments are here which can absorb the light that photoreceptors have not and prevents light scattering in the eye
What is the Iris?
The Iris is the colored portion of the eye and is continuous with the choroid.
What is the Pupil?
The pupil is the opening in the center of the iris that controls how much light enters the eye.
- Sympathetic stimulation: dilates pupil
- Parasympathetic stimulation: constricts pupil
What is the Lens?
The lens is located behind the pupil
- It focuses light onto the retina.
- The ciliary muscle will change the shape of the lens
What is the ciliary muscle?
The ciliary muscle is a muscle in the eye that changes the shape of the lens.
- For distant viewing it relaxes and flattens the lens
- For close up viewing it contracts and the lens becomes more spherical
What is the Retina?
The retina is the posterior portion of the eye that contains the photoreceptors.
What are rods?
Rods are a type of photoreceptor
- Dim light
- Black and white vision
What are cones?
Cones are a type of photoreceptor
- Provide color vision
- Respond well to daylight
- provide visual acuity (ability to perceive numbers and letters at a distance)
- concentrated in the center of the retina in a depression called the fovea centralis.
What is the Fovea Centralis?
The Fovea Centralis is a depression in the center of the retina where the largest concentration of cones is.
- This is the area of keenest vision
- There are no rods here
- NB: Common DAT question
How do rods and cones vary from animal to animal?
Animals all have a different breakdown of rods vs cones.
- Nocturnal animals have a larger proportion of rods for night time vision
What is the optic disc?
The optic disc is the area of the eye where the optic nerve leaves.
- There are no photoreceptors here, so it’s a physiological blind spot
- It’s insensitive to light here.
What is the vitreous humor?
Vitreous humor is a jellylike substance that maintains eyeball shape
- makes up 80% of the eye
- Very few cells are found here
- Phagocytes are found here to help clean up cellular debris
What is aqueous humor?
Aqueous humor is a clear, slightly alkaline fluid found in the anterior and posterior eye chambers.
- It resembles blood plasma, but has less protein and glucose.
- It is involved with water removal
- It brings O2 and nutrients to the eye
What is rhodopsin?
Rhodopsin (aka Visual Purple) is a pigment-containing sensory protein that converts light into an electrical signal.
- This pigment is found in Rods
- Very sensitive to light, and allows us to see in dim light
- When rhodopsin absorbs light, it isomerizes its conformation from cis to trans. This conformational change causes an electrical signal to be sent to the brain and a visual image is seen
- Much is still not understood about this mechanism
What organisms can perceive sound?
Many arthropods and most vertebrates can perceive sound.
What is sound?
Sound is a wave of compressed air
What is the external ear?
The external ear consists of the:
- Pinna: The outer ear that you touch
- Auditory Canal: Collects the sound waves that enter the ear
- Tympanic membrane (ear drum): Sound waves are channelled here via the auditory canal. The tympanic membrane vibrates in response to the sound wave.
What is the Pinna?
The Pinna is the outer ear portion that you can touch. It funnels sound into the auditory canal.
What is the auditory canal?
The auditory canal is a part of the external ear that funnels sound inward to the tympanic membrane from the pinna.
What is the tympanic membrane?
The tympanic membrane is the ear drum.
- It is a part of the external ear
- It vibrates in response to sound waves
- It transfers the vibrations to the three bones of the middle ear: Malleus, Incus, Stapes
What are the three bones of the Middle Ear?
The three bones of the middle ear are the Malleus, Incus, and Stapes.
- They receive vibrations from the tympanic membrane and transfer it to the oval window.
- Superficial to Deep the bones are Malleus, Incus, Stapes (More incoming sound)
What is the middle ear?
The middle ear consists of:
- The bridge of bones (Malleus, Incus, Stapes) that transfers vibrations from the tympanic membrane to the oval window.
- The oval window is a membrane that cause vibrations to move to the inner ear.
- The Eustachian tube connects the middle ear to the nasopharynx and ensures that pressure is equalized on either side of the tympanic membrane.
What is the Eustachian tube?
The Eustachian tube connects the middle ear with the nasopharynx, enabling equal pressure on both sides of the tympanic membrane.
What is the oval window?
The oval window is a membrane that receives vibrations from the Malleus, Incus, and Stapes and transfers the vibrations to the inner ear.
What is the inner ear?
The inner ear consists of fluid-filled channels in the bones of the skull
- The Cochlea is one of these channels and is involved with hearing.
- The Utricle is a semicircular canal involved with balance
- The Saccule is another semicircular canal involved with balance
What is the Cochlea?
The Cochlea is a fluid filled channel in the bones of the skull.
- It is a snail like structure
- Contains a sensory response called the Organ of Corti that holds the hair cells, the nerve receptors of hearing. These are the mechanoreceptors of the ear.
What do the Utricle and Saccule do?
The Utricle and Saccule are fluid filled canals that use hairlike structures to detect movement and help with balance.
- Saccule detects movement in the vertical plane
- Utricle detects movement in the horizontal plane
How is sound transferred from the inner ear to nerve impulses to the brain?
- The oval window transmits vibrations to the cochlea.
- The fluid in the cochlea stimulate tiny hair cells
- The signals from these hair cells are changed into nerve impulses.
- The nerve impulses are transferred to the brain via the auditory nerve.
What could cause deafness?
There are several things that can cause deafness:
- Cochlea damage
- Auditory nerve damage
- Vibration transmittance to the inner ear is hindered
- Loud sounds
How do insects detect sound?
Insects use a tympanic membrane which allows sound waves to vibrate and receptor cells convert the sound waves into nerve impulses
How do fish detect sound?
- Fish lack a tympanic membrane and cochlea.
- Many fish conduct sound waves through a series of bones.
- Mechanoreceptors are able to detect sound waves which are converted into neuronal signals.
