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Sensory systems

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... impulse or action potential All or nothing response Response depends on part of brain that receives the info Sensory information ... system Spin around become ... – PowerPoint PPT presentation

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Title: Sensory systems


1
Sensory systems
  • Chapter 50

2
Five senses
  • Touch
  • Taste
  • Smell
  • Sound
  • Vision

3
Sensory systems
  • Sensory info is received
  • Nerve impulse or action potential
  • All or nothing response
  • Response depends on part of brain that receives
    the info

4
Sensory information
  • Sensory info to CNS
  • 1. Sensory reception
  • 2. Transduction
  • Graded potential
  • Ion channels open or close
  • Receptor potential
  • Change in membrane potential
  • Depolarization

5
Sensory information
  • 3. Transmission
  • Goes to CNS via afferent pathway
  • 4. Interpretation
  • Perception by the brain

6
Sensory receptors
  • Nerve endings
  • Specialized neurons or epithelial cells
  • Associated with sensory organs -eyes
  • All stimuli is a form of energy

7
Sensory receptors
  • Stimuli-outside body
  • Heat, light, pressure chemicals
  • Stimuli-inside body
  • BP, body position, body temperature

8
Types of sensory receptors
  • Mechanoreceptors
  • Pressure, stretch, touch
  • Chemoreceptors
  • chemicals
  • Electromagnetic receptors (photoreceptors)
  • Nociceptors (pain)
  • Thermoreceptors

9
Receptors
  • Cutaneous receptors
  • Skin
  • Heat, cold, pressure, pain touch
  • Thermoreceptors
  • Heat/Cold
  • Hypothalamus
  • Regulates temp of blood (core temp)

10
Receptors
  • Mechanoreceptors
  • Touch
  • Close to surface of skin
  • Hair follicle receptors
  • Pressure
  • Deeper

11
skin
Cold
Hair
Heat
Gentletouch
Pain
Epidermis
Dermis
Hypodermis
Hairmovement
Connectivetissue
Strongpressure
Nerve
12
Receptors
  • Nociceptors
  • Pain
  • Severe temperature change
  • Tissue damage
  • Free nerve endings (naked dendrites)
  • Located in the epidermis

13
PAIN
14
Receptors
  • Proprioceptors
  • Give info on animals body parts
  • Position
  • Movement
  • Stretch receptors on muscle
  • Prevent over stretch

15
Receptors
  • Baroreceptors
  • Detect tension or stretch in blood vessel walls
  • Internal carotids
  • Aortic arch
  • Drop in BP
  • Stimulation to increase HR vasoconstriction

16
Receptors
  • Chemoreceptor
  • Aorta carotid
  • Medulla oblongata
  • pH (blood CSF)
  • Slow breathing
  • Increased CO2
  • Lowers pH
  • Causes an increased respiration rate

17
Taste
  • Taste buds
  • Collections of receptor cells
  • Epithelial cells
  • Papillae
  • Raised areas on tongue
  • Taste buds located

18
Taste
  • Taste buds contain 50-100 taste cells
  • Food dissolves in saliva
  • Contact taste cells
  • Taste salty, sweet, sour, bitter

19
Taste
  • Chemoreceptors
  • Salt Na1
  • Sour H1
  • Directly through ion-channel
  • Sweet receptor proteins for sugar
  • Bitter Kchannels are closed by receptor proteins

20
Papilla
Papillae
Tastebuds
Tongue
(a) The tongue
Sweet
Taste bud
Salty
Sour
Bitter
Umami
Tastepore
Foodmolecules
Sensoryreceptorcells
Sensoryneuron
(b) A taste bud
21
Sweet
Sugar molecule
G protein
Sweetreceptor
Tongue
Phospholipase C
SENSORYRECEPTORCELL
Sugarmolecule
Taste pore
PIP2
Sensoryreceptorcells
Tastebud
IP3(secondmessenger)
Sodiumchannel
Sensoryneuron
IP3-gatedcalciumchannel
Nucleus
ER
Ca2(secondmessenger)
Na
22
Smell
  • Olfactory receptors
  • Chemoreceptors
  • Located upper portions of nasal passages
  • Dendrites are in cilia
  • Axon goes directly to cerebral cortex
  • Odorant or odorous substance binds proteins
  • Second messenger response in receptor cell

23
Smell
  • Opens membrane to Ca Na
  • Causes impulse (action potential)
  • Distinguish thousands of odors
  • Very accurate
  • Single odorant molecule

24
NOSE
25
Nose
Brain
Action potentials
Olfactorybulb
Odorants
Nasal cavity
Bone
Epithelialcell
Odorantreceptors
Chemo-receptor
Plasmamembrane
Cilia
Odorants
Mucus
26
Hearing
  • Outer ear
  • Pinna, canal
  • Middle ear
  • Tympanic membrane (ear drum)
  • Eustachian tube
  • Small bones (malleus, incus, stapes)
  • Inner ear
  • Cochlea, auditory nerve

27
Figure 50.10a
Middle ear
Outer ear
Inner ear
Skull bone
Stapes
Semicircularcanals
Incus
Malleus
Auditorynerve to brain
Cochlea
Ovalwindow
Auditorycanal
Eustachiantube
Pinna
Tympanicmembrane
Roundwindow
28
Ear
29
Hearing
  • Vibrations move in canal
  • Cause eardrum to move
  • Vibrations pass through the bones
  • Stapes pass vibration to inner ear
  • Causes pressure waves in fluid in cochlea
  • Basilar membrane of the cochlea vibrates

30
Hearing
  • Hair cells on membrane vibrate
  • Leads to change in membrane potentials in sensory
    neurons
  • Sound interpreted
  • Humans hear 20-20,000 hertz
  • Age decreases higher frequencies
  • Dogs hear sounds at 40,000 hertz

31
Ears
  • Inner ear
  • Body position balance
  • Two chambers near the cochlea
  • Utricle saccule
  • Filled with fluid
  • Hair cells in chambers respond to changes in head
    positions

32
Ears
  • Utricle horizontal motion
  • Saccule vertical motion
  • Different movement causes different sensory
    neurons to be stimulate
  • Labyrinth system
  • Spin around become dizzy

33
Equilibrium
Semicircular canals
Flow of fluid
Vestibular nerve
Cupula
Hairs
Haircells
Axons
Vestibule
Utricle
Body movement
Saccule
34
Eye
  • Sclera
  • White outer layer of connective tissue
  • Conjunctiva
  • Epithelial layer
  • Covers outer surface of sclera
  • Under surface of the eyelid
  • Cornea
  • Clear part of sclera, light passes through

35
Eye
  • Choroid
  • Pigmented layer under the sclera
  • Iris
  • Color part of eye formed by the choroid
  • Pupil
  • Opening at the center of the iris
  • Controlled by iris
  • Lens
  • Behind the pupil, held in place by ligaments

36
Eye
  • Retina
  • Back of eye where image is focused
  • Optic nerve
  • Sensory neurons
  • Vitreous humor
  • Jellylike substance behind the lens
  • Aqueous humor
  • Thinner fluid
  • Fills smaller chamber in front of the lens

37
EYE
38
Choroid
Sclera
Retina
Suspensoryligament
Fovea
Cornea
Iris
Optic nerve
Pupil
Aqueoushumor
Lens
Centralartery andvein ofthe retina
Optic disk
Vitreoushumor
39
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40
Eye
  • Light enters eye through cornea
  • Passes through pupil to lens
  • Lens focuses images on retina
  • Photoreceptor cells of retina transduce light
    energy
  • Action potentials pass via sensory neurons in the
    optic nerve

41
Eye
  • Rods cones
  • Photoreceptors of eyes
  • Rods black and white vision in dim light
  • Cones high visual acuity color vision
  • Located in center of retina

42
EYE
43
Rods/cones
Retina
Choroid
Photoreceptors
Neurons
Retina
Cone
Rod
Light
Tobrain
Optic nerve
Light
Ganglioncell
Amacrinecell
Horizontalcell
Opticnerveaxons
Bipolarcell
Pigmentedepithelium
44
Figure 50.17ba
Rod
Disks
Synapticterminal
Outersegment
Cellbody
Cone
Rod
Cone
45
Eyes
  • Binocular vision
  • Axons of ganglion cells form optic nerves
  • Optic nerves meet at the optic chiasm (base of
    the cerebral cortex)
  • Visions from the right visual field go to the
    left side of the brain and vise versa
  • Thalamus
  • Cortex

46
Vision
Rightvisualfield
Opticchiasm
Righteye
Lefteye
Leftvisualfield
Optic nerve
Primaryvisual cortex
Lateralgeniculatenucleus
47
Near and Distance Vision
48
Eyes
  • Nearsightedness longer eyeball
  • Farsightedness shorter eyeball
  • Asitgmatism problems with lens or cornea
  • Light rays converge unevenly
  • Colorblindness inherited lack of one or more
    types of cones
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