senses

Question 1

what are sensations?

Answer 1

Sensations begin as different forms of energy that are detected by sensory receptors. This energy is converted to action potentials that travel to appropriate regions of the brain.

Sensations are action potentials that reach the brain via sensory neurons.

Question 2

what are the different types of receptors?

Answer 2

-Exteroreceptors detect stimuli originating outside the body.

-Interoreceptors detect stimuli originating inside the body.

-Sensory receptors convey the energy of stimuli into membrane potentials and then transmit signals to the nervous system.

Question 3

what are the steps to an impulse?

Answer 3

1) perception

2) amplification: strengthening of stimulus energy that is otherwise too weak to be detected by the nervous system

3) Transmission: conduction of sensory impulses to the CNS

4) Integration: processing of sensory information.

Question 5

what is sensory adaptation?

Answer 5

sensory adaptation is a decrease in responsiveness to continued stimulation.

Question 6

what are the sensory receptors based on the type of energy they transduce?

Answer 6

-Mechanoreceptors
-thermoreceptors

-general/specific/internal chemoreceptor

-photoreceptor
-pain receptors

Question 7

what are mechanoreceptors?

Answer 7

respond to mechanical energy. Muscle spindles are an interoreceptor that respond to the stretching of skeletal muscle. Hair cells in the inner ear detect motion.

Question 8

what are pain receptors?

Answer 8

receptors = nociceptors. Different types of pain receptors respond to different types of pain.
Prostaglandins increase pain by decreasing a pain receptor’s threshold.
Anti-inflammatories work by inhibiting prostaglandin synthesis.

Question 9

what are thermoreceptors?

Answer 9

respond to heat or cold.

Question 10

what are general chemoreceptors?

Answer 10

transmit information about total solute concentration ( chem stimuli).

Question 11

what are the types of chemoreceptors?

Answer 11

General chemoreceptors transmit information about total solute concentration ( chem stimuli).
Specific chemoreceptors respond to specific types of molecules.
Internal chemoreceptors respond to glucose, O2, CO2, amino acids, etc.
External chemoreceptors are gustatory receptors and olfactory receptors.

Question 12

what are photoreceptors?

Answer 12

Photoreceptors respond to the radiation we know as visible light.

Question 13

what type of eyes do vertebrates have?

Answer 13

single-lens

Question 14

where are 70 percent of sensory receptors?

Answer 14

70% of body’s sensory receptors are in eye
Half of cerebral cortex is involved in visual processing

Question 15

what is sclera? what is the functions?

Answer 15

a tough white layer of connective tissue that covers all of the eyeball except the cornea.
- protects and shapes eyeball
- anchors extrinsic eye muscles
- posteriorly, where optic nerve exits, sclera is continuous with dura mater of brain

Question 16

whats the conjunctiva?

Answer 16

external cover of the sclera
- transparent mucous membrane that produces a lubricating mucous secretion

Question 17

what is cornea?

Answer 17

transparent covering of the front of the eye, allows for the passage of light into the eye and functions as a fixed lens.

Question 18

what is the choroid?

Answer 18

thin, pigmented layer lining the interior surface of the sclera, prevents light rays from scattering and distorting the image.
- anteriorly it forms the iris.

Question 19

what is the iris?

Answer 19

regulates the size of the pupil.

Question 20

whats the retina?

Answer 20

lines the interior surface of the choroid.

• contains photoreceptors, except at the optic disk (where the optic nerve attaches). This is also called the blind spot.

Question 21

whats the ciliary body?

Answer 21

• Anteriorly, choroid becomes ciliary body
• Thickened ring of tissue surrounding lens
• Consists of smooth muscle bundles, ciliary muscles, that control shape of lens

Question 22

whats in the anterior cavity of the eye?

Answer 22

Anterior cavity is filled with aqueous humor produced by the ciliary body.

Question 23

how does a glaucoma happen?

Answer 23

Glaucoma results when the duct that drains aqueous humor is blocked.

Question 24

what is the posterior cavity filled with?

Answer 24

Posterior cavity is filled with vitreous humor.

Question 25

what does the iris do?

Answer 25

colored part of eye that lies between cornea and lens, continuous with ciliary body

Question 26

what does the pupil do?

Answer 26

central opening that regulates amount of light entering eye

Question 27

what plays a role in focusing light onto the retina?

Answer 27

The lens, the aqueous humor, and the vitreous humor all play a role in focusing light onto the retina.

Question 28

what is accommodation?

Answer 28

Accommodation is the focusing of light in the retina, accomplished by changing the shape of the lens.

Question 29

when is the lens flattened?

Answer 29

The lens is flattened for focusing on distant objects

Question 30

when is the lends rounded?

Answer 30

The lens is rounded for focusing on near objects.

Question 31

what type of receptors are on the retina?

Answer 31

photoreceptors

Question 32

what are the types of photoreceptors on the retina? what do they do?

Answer 32

1) About 125 million rod cells. Rod cells are light sensitive but do not distinguish colors. These enable us to see at night but only in black and white. 2) About 6 million cone cells. Not as light sensitive as rods but provide color vision. These are most highly concentrated on the fovea – an area of the retina that lacks rods.

Question 33

what is rhodopsin?

Answer 33

The light-absorbing pigment rhodopsin triggers a signal-transduction pathway. it is the visual pigment of rods

Question 34

what is the visual pathway?

Answer 34

1) light causes the conversion of cis-retinal to trans-retinal, activating rhodopsin 2) the activated rhodopsin activates a G protein called transducin 3) transducin activates a phosphodiesterase 4) the activated phosphodiesterase detaches the cGMP from the Na+ channels in the membrane by hydrolyzing cGMP to GMP 5) this causes the Na+ channels to close. The permeability of the membrane to sodium decreases and the rod hyperpolarizes 

Question 35

what does the rhodopsin mechanism detect? (rod system)

Answer 35

light

Question 36

what are the three subclasses of cone cells?

Answer 36

three subclasses of cone cells each with its own type of photopsin.

Question 37

what is the color perception based on?

Answer 37

- Color perception is based on the brain’s analysis of the relative responses of each type of cone

Question 38

what is colourblindness due to?

Answer 38

colorblindness is due to a deficiency, or absence, of one or more photopsins- Inherited as an X-linked trait

Question 39

what makes the optic tract?

Answer 39

- Ganglion cell axons make up the optic tract.

Question 40

how does visual information get conveyed to the primary visual cortex?

Answer 40

- Ganglion cell axons make up the optic tract. - most synapse in the lateral geniculate nuclei of the thalamus - neurons then convey information to the primary visual cortex of the optic lobe.

Question 41

where is the mammalian hearing organ?

Answer 41

within the ear

Question 42

what does the outer ear include?

Answer 42

The outer ear includes the external pinna and the auditory canal

Question 43

what does the outer ear do?

Answer 43

Collects sound waves and channels them to the tympanic membrane

Question 44

what happens after the tympanic membrane?

Answer 44

transmitted through the middle ear: Malleus to incus to stapes

Question 45

what happens after the stapes?

Answer 45

From the stapes the sound wave is transmitted to the oval window and on to the inner ear.

Question 46

what is the Eustachian tube?

Answer 46

Eustachian tube connects the middle ear with the pharynx.

Question 47

what does the inner ear consist of?

Answer 47

The inner ear consists of a labyrinth of channels housed within the temporal bone. The cochlea is the part of the inner ear concerned with hearing. Structurally it consists of the upper vestibular canal and the lower tympanic canal, which are separated by the cochlear duct. The vestibular and tympanic canals are filled with perilymph.

Question 48

what are the vestibular and tympanic canals filled with?

Answer 48

perilymph

Question 49

what is the chochlear duct filled with?

Answer 49

endolymph

Question 50

what does the organ of corti rest on?

Answer 50

The organ of Corti rests on the basilar membrane.

Question 51

where is the tectorial membrane?

Answer 51

The tectorial membrane rests atop the hair cells of the organ of Corti

Question 52

whats the function of the round window?

Answer 52

The round window functions to dissipate the vibrations

Question 53

what happens when there's a vibration in the cochlear fluid?

Answer 53

Vibrations in the cochlear fluid  basilar membrane vibrates  hair cells brush against the tectorial membrane  generation of an action potential in a sensory neuron.

Question 54

how do hair cells in the ear release action potentials?

Answer 54

Energy in the sound waves causes the basilar membrane to vibrate, stimulating hair cells. There are changes in the stiffness of the basilar membrane along its length, and so each point on the membrane vibrates maximally in response to waves of a particular frequency. The hair cells release an excitatory neurotransmitter at a synaplse with a sensory neuron. This conducts and action potential to the CNS. Bending in one direction will depolarize the hair cell, releasing more neurotransmitter and increasing the frequency of action potentials. Bending in the other direction will have the opposite effect.

Question 55

what is the pitch based on?

Answer 55

Pitch is based on the location of the hair cells that depolarize.

Question 56

what is volume based on?

Answer 56

Volume is determined by the amplitude of the sound wave.

Question 57

true or false, perception of taste and smell are interrelated?

Answer 57

true

Question 58

where are taste receptors located?

Answer 58

In mammals, taste receptors are located in taste buds most of which are on the surface of the tongue.

Question 59

what determines somethings perceived flavour?

Answer 59

It is the pattern of taste receptor response that determines something’s perceived flavor.

Question 60

what are the five basic taste sensations?

Answer 60

1) Sweet: sugars, saccharin, alcohol, some amino acids, some lead salts 2) Sour: hydrogen ions in solution 3) Salty: metal ions (inorganic salts); sodium chloride tastes saltiest 4) Bitter: alkaloids such as quinine and nicotine, caffeine, and nonalkaloids such as aspirin 5) Umami: amino acids glutamate and aspartate; example: beef (meat) or cheese taste, and monosodium glutamate 6) Possible sixth taste: Growing evidence humans can taste long-chain fatty acids from lipids

Question 61

how is taste linked the homeostatic value?

Answer 61

Guide intake of beneficial and potentially harmful substances Dislike for sourness and bitterness is a protective way of warning us if something is spoiled or poisonous

Question 62

how do taste receptors get activated?

Answer 62

- Binding of food chemical (tastant) depolarizes cell membrane of gustatory epithelial cell membrane, causing release of neurotransmitter - Neurotransmitter binds to dendrite of sensory neuron and initiates a generator potential that lead to action potentials - Different gustatory cells have different thresholds for activation - Bitter receptors are most sensitive - All adapt in 3–5 seconds, with complete adaptation in 1–5 minutes

Question 63

what are the important roles of taste?

Answer 63

Triggering reflexes involved in digestion, such as: Increased secretion of saliva into mouth Increased secretion of gastric juice into stomach May initiate protective reactions, such as: Gagging Reflexive vomiting

Question 64

where are olfactory receptors?

Answer 64

In mammals, olfactory receptors line the upper portion of the nasal cavity

Question 65

what does the binding of odour molecules do?

Answer 65

The binding of odor molecules to olfactory receptors initiate signal transduction pathways involving a G-protein-signaling pathway and, often, adenylyl cyclase and cyclic AMP

Question 66

what do odorant molecules do?

Answer 66

Odorant molecules bind to specific chemoreceptors in the plasma membrane of the olfactory receptor cells, causing an action potential. Each olfactory receptor has just one type of chemoreceptor. Cells with different chemoreceptors detect different odorants.