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Flashcards in Exam 2 Deck (97):
1

Stimulus

A change in the internal or external environment that triggers a respons

2

Sensation

  • a conscious awareness of sensory information and the resulting NS activity
  • ex. Ouch! Pain! (after capsacin binds to the tongue)

3

perception

  • awareness of a sensation, a higher level of understanding
  • understanding the meaning, location and conswequences of a sensation. 
  • Stimuli activate receptors, trigger AP, eventually the signal reaches the brain and is perceived. 
  • ex. pain on tongue, kind of spicy, maybe i should stop eating these jalepenos, or drink some milk (After capsacin binds to tongue
  • Ex. I'm cold, should I put on a sweater? Should I go inside? etc

4

receptors

structures that detect stimuli, on a neuron or associated with a neuron. Receptors are transducers

5

transducers

change one form of energy (a stimulus) into electrical ATP

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reception

  • stimulus reaches the receptor
  • ex. capsacin binds to the tongue

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Sensory transduction

  • Receptor is stimulated
  • Receptod triggers an AP
  • Impulse sent to the brain for interpretation

8

Types of receptors

  • Mechanoreceptors
  • Thermoreceptors
  • Nociceptors
  • Chemoreceptors
  • Photoreceptors
  • Baroreceptors

9

mechanoreceptors

include propriorecpetors, detect changes in teh membrane

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nociceptors

detect pain (both somatic and visceral

11

What does magnitude of sensory graded potentials influence?

the frequency of action potentials

 

12

How is intesity perceived by the brain?

by how many AP are fired

13

Adaptation

  • a decrease in receptor sensitivity despte constant strength of a stimulus
  • ex. sitting on a seat-- touch receptors on butt adapt so that you don't constantly feel it there
  • Degrees of adaptation can vary:
    • Rapid adaptation: sensory receptors in the skin, on, then off until a change
    • Slow adaptation: sensory receptors that need constant monitoring such as muscle tenseness

14

What info does the brain need to understand what is occuring?

  1. Stimulus type: heat, cold, sound, pressure, etc
  2. Stimulus intensity: determined by frequency of AP
  3. Stimulus location: determined by brain location of the ed of the afferent pathway, aka it is based on what portion of the brain is stimulated

15

sensory unit

a single sensory neuron with all its receptor endings OR a sensory neuron and its receptor cell

16

recpetive field

Typically a sesory neuron has many receptor endings, the entire area they encompass is called the receptive field

17

Small receptive field

precise and very sensitive, ex. the lips

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large receptive field

hard to tell exactly where the touch occured, not very sensitive

19

Acuity

the degree of accurate perception. 

ex. discerning touch in one location from another, or discerning two related images

20

Lateral inhibition

  • Ex. if 3 sensory neurons all receive stimuli, the one with the strongest stimulus wins
  •  

21

Afferent sensory pathways

  • Get the signal to the brain.
  • Chains of 3+ neurons
  • Sensory neurons--> intereurons-->more interneurons
  • Chain is specific
  • The location is the brain is also specific

22

Factors that affect perception

  • Adaptation
  • Emotion, personality, stress, social background. 
  • CNS has mechanisms to turn down sensityive reception by the PNS--thalamus can amplify, diminish or edit what you are perceiving
  • Lack receptors for some stimuli--radio waves, infrared light
  • Have receptors but no  mechanism forconscious perception-- blood vessel stretch receptors
  • Drugs-- hallucinations
  • Mental illness-- schizophrenia can produce untrue perceptions of sensory stimuli
  • Damaged neural pathways

23

Phantom limb

sensation associated with a body part that has been amputated. The intact portion of the sensory pathway continues to send signals to the CNS

24

Referred pain

pain impulses from viscera are perceived as originating from the skin. This often occurs with heart attack patients. Percieve arm pain, but actually it is something deeper

25

Reflexes

Neural circuits that operate without conscious control-- involuntary. They usually work to maintain homeostasis. You can't stop it, and can't always perceive it

26

Monosynaptic reflexes

  • One synapse
  • Simple relfex where the afferent neurons synapse onto the effferent axon
  • No interneuron
  • There is a very minor delay between the stimulus and response
  • ex. knee jerk reaction

27

polysynaptic reflexes

  • Many synapses
  • involve a large numvber of synapses and interneurons
  • there is a longer delay between stimulus and response
  • ex. shifting weight to pull legg away from stimulus

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Ipsilateral reflexes

same side reflexes

ex. pummling your arm away from a hot object

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contralateral reflex

opposite side reflex

ex. stepping on something sharp an pulling one leg away while shifting weight to the other leg

30

A reflex arc that includes hand and brain will be:

Polysynaptic

31

Does an area with a large receptor field have a high, or low acuity?

Low touch acuity

32

Which reflexes are maintained even after spinal cord injury?

Erection, defecation, stretch/tendon reflexes, urination

33

Somatic senses

pain, temperature, touch, stretch and pressure

all over the body

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special senses

gustation (taste), olfaction (smell), vision, equilibrium and hearing

limited to the head

35

Recepector classification: distribution

  • Where in the body
  • Somatic: receptors in skeletal muscle or skin
  • Visceral- guts

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Receptor classifications: where the stimulus comes from

  • Extteroreceptors
  • Interorecptors
  • Proprioreceptors

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Exteroreceptors

Detect change from the external environmentm touch thermal

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Interoceptors

Detect stimuli in internal organs, like [O2] chemicals from cell damage

39

proprioceptors

detect changes in limb position, located in muscles, tendons and joints. Where our body is relative to the world. 

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Proprioceptors

mechanoreceptors that detect the stretch of muscles and ligaments to determine body position

41

Tactile sensation

touch, heat, cold, pressure, detected though skin. Different types of receptors specialize in types of touch.

42

Pain reception

somatic and visceral nociceptors respond to tissue damage

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Tactile receptors

  • perceive touch
  • are mechanreceptors that react to touch, pressure and vibration
  • Have specialized structure for different functions
  • Have Small receptive fields
  • Pathways of neurons bring touch sensation to the brain

44

Temperature

  • Is sensed by dendritic endings of unmylenated sensory neurons
  • Contain ion channels that open at specific temps
  • Some chemical stimulus can override this, like capsacin and menthol. These don't actually change temperature, but it gives the same sensation

45

Pain

  • Protect us from tissue damage
  • Stimuli- mechanical deformation of tissue, extremes in temp, chemicals
    • Acids and bases can directly trigger nociceptors
    • Chemicals like histamines, cytokines and prostaglandins are all released when cells are damaged
  • Neurons that have ligand dated channels for these stimuli are called nociceptors

46

Nociceptors

Have ligand gated channels for pain stimuli (chmicals, deformation of tissue, extremes of temp)

Mostly unmylenated

Mostly use substance P or glutamate as NT

can be inhibited by other receptors, lateral inhibition and CNS inhibiiton

47

photoreceptors

  • in the eyes, detect light, color and movement
  • Light is filtered, bent and absorbed by other parts of they eye before it reaches the photoreceptors
  • Information from the photoreceptors is sent to the visual region of the brain for interpretation. 

48

Sclera

  • tough outer portion of the eyeball
  • the anterior surface of the sclera is the clear cornea

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cornea

the clear anterior surface of the sclera

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Choroid

the dark middle portion of the eyeball

anterior choroid is iris, lens and ciliary muscle

most of the blood vessels are found here

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retina

reflective inner portion of the eyeball

formed as an extension of the brain

contains photoreceptors clustered in the macula lutea and fovea centralis

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macula lutea and fovea centralis

area where photoreceptors are clustered in the retina

the curved surfave of the cornea bends light onto these spots

macula lutea is a larger area, and fovea centralis is a small part within that area

is an area so the photoreceptors are not covered by blood vessels

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ciliary muscles

shape the lens to bend light waves

in the choroid- ventral part of eye

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accommodation

bend lens to change the path of light. 

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sight acuity

bending light to focus it on the fovea centralis

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presbyopia

lens get tougher- happens when you get old

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nearsighted

eyeball is too long (oval) can't bend light to the right place

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far sighted

eyeball is to short- can't bend light to the righ place

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Müller cells

  • type of glial cells
  • make up 20% of the volume of the retina
  • work like fiber-optic cables
  • channel light to the location of photoreceptors

60

Pigment layer behind retina

absorbs any light photons that are not caught by photoreceptors. This works to protect structures and adds to the clarity of vision

helps with acuity, like reading.

61

Rods

extremely sensitive.

Good for dark, good for perceiving motion

photopigment=Rhodpsin + retinal

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Cones

only respond to bright light, responsible for color vision

photopigment=opsins +retinal

63

pigments

are in photoreceptors, they absorb different wavelengths of light (those that are notabsrobed are reflected) 

64

retinal

derived from vit A

65

opsins

differ based on different types of cones, each absorb a different spectrum

66

photoreceptor depolarization

photreceptors are constantly depolarized, and always have their channels open

Stimulation closes these channels and polarizes the cell

67

What type of receptors are nociceptors

Chemoreceptors

68

Color vision

Retina has 3 types of cones: 

Long wavelengths (red cones)

Medium wavelengths (green cones)

Short wavelengths (blue cones)

there is some overlap

Perception of shade is determined by relative outputs of the 3 types

69

Color blindness

when one or more cone pigments are not made properly

Red-green colorblindness is most common (1:12 males, 1:200 females)

Genes for red and green are on X chromosome, blue is on chrom 7

70

Volume (hearing)

as molecules radiate outward, the difference between the waves of compessed molecules, and the compression of molecules between them determines volume. This is why 

71

Pitch (hearing)

the frequency of vibration determines pitch

faster vibration=higher pitch

72

Auricle

is the external ear

funnels sound in toward the midle ear

sound passes through a bony tube

73

tympanic membrane

an epithelial sheet found inside the ear canal that vibrates when the sound wabes hit it 

aka war drum

74

Middle ear

  • is internal to the tympanic membrane
  • is an air filled space containing 3 bones
  • maintains a connection to the atmosphere by way of the eustacian tube--connects middle ear to throat
  • the 3 bones magnify the vibrations from the tympanic membrane and transmit them to the inner ear by pounding on the oval window

75

eustacian tube

a connection between the middle ear and the throat

is what get clogged with changes to altitude etc. 

76

Inner ear

  • fluid filled
  • Sectioned into 3 regions
  1. Vestibule-detects tilt of head
  2. Semicircular canals
  3. cochlea-hearing

77

Vestibule

in inner ear, detects the tilted position of the head. Especially due to acceleration or decelleration

78

semicircular canals

in inner ear- detect the rotation of the head

79

Cochlea

in inner ear-- hearing

80

Basilar membrane

suspended within the cochlea, bounces with the vibrations (that are passed from the 3bones to the oval window) 

81

Hair cells

in cochlea, are sandwiched between the basilar membrane and a stationart membrane located above it. As the basilar membrane bounces, the cilia hit the tectorial membrane, cilia bending depolarizes the hair cells. 

82

Hearing sensory reception

All 3 regions of the inner ear use the same sensory receptors for three different things. 

  1. Hair cell
  2. Bend cilia in one direction=depolarization
  3. Bend cilia in other direction=repolarization

83

Vestibulochlear nerce

carries action potentials in toward the brain

84

IN terms of action potentials, what is volume (hearing)

The frequency of action potential=volume

85

Sense of balance

Hair cells with their cilia

2 locations

  1. rotational equilibrium in the semicircular canals
  2. gravitational equilibrium in the vestibule

86

Equilibrium and alcohol

alcohol changes the viscosity of the endolymph, leading to misperception of balance, vertigo and movement. 

Frequent and persistent use of alcohol can make the inner ear vulnerable to permanent changes in endolymph viscosity-- leading to long lasting vertigo

87

Vertigo

dizziness and sense of rotation

-inflammation in brain or inner ear

unusual fluid movement/viscocity

88

Motion sickness

innerear senses a movement, but the visual stimuli doesnt match

89

Taste

aka gustation or chemoreception

90

taste buds

structures on the tongue, mouth and throat that hose taste cells

They are found within papillae, ~100 taste cells/papillae

Contain taste cells, supporting cells and basal cells

Basal cells replace gustatory cells every 7-10 days

# is determined by genetics

toleration of spicy foods=fewer taste buds

91

The 5 different tastes

Salty, sweet, sour, bitter, umami

92

Salty taste sensation

Salt on tongue dissociates, Na enters and depolarizes the receptor-->opens ion channels

93

sour taste sensation

H+ in the acidic food blocks K+ channels. Loss of hyperpolarizing K+ allows the cells to come to threshold

 

94

Sweet, bitter, umami taste sensation

all signal through G-coupled protein receptors

95

Olfaction

  • uses chemoreceptors
  • 80% of flavor of food comes from smell
  • olefactory neurons are replaced by stem cells every 2 months
  • female sex hormones increase olfactory eurogenesis

96

olfactory epithelium 

in nasal cavity, is location of cell bodies and dendrites of olfactory receptor cells. 

97

 Olfactory bulb

the acons of receptor cells extend through the base of the skill in into the olfactory bulb. 

In the olfactory bulb, they synapse with neurons of the olfactory nerve