Chapter 16 - Nervous System: Senses Flashcards Preview

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Flashcards in Chapter 16 - Nervous System: Senses Deck (41):
1

what is each unique type of sensation called?

sensory modality

2

what are the general senses?

Somatic senses
-Tactile - touch, pressure, vibration, itch, tickle
-thermal sensations - warm / cold
-Pain
-proprioception
Visceral senses
-Info about internal organs
**scattered throughout body
**simple structures

3

what are the special senses?

Smell
taste
vision
hearing
equilibrium and balance
**concentrated in specific locations in the head
**anatomically distinct structures
**form complex pathways

4

where does sensation begin?

-sensory receptor = specialized cell OR dendrites of a neuron
**Receptors are selective – only respond to one type of stimulus

5

Exteroceptors

near external surfaces of body respond to eternal stimuli

6

Interoceptors (visceroceptors)

internal environment
(In blood vessels, organs, muscles)

7

proprioceptors

tells you position of limbs and body in space
(Muscles, tendons, joints, inner ear)

8

what are the 3 sensory receptors named by location?

Exteroceptors
Interoceptors (visceroceptors)
proprioceptors

9

what are the 6 sensory receptors named by action?

1) Mechanoreceptors – responds to deformation
2) Thermoreceptors- respond to temperature
3) Nociceptors – respond to pain
4) Photoreceptors – respond to light
5) Chemoreceptors - respond to chemicals (tastes, smells)
6) Baroreceptors - respond to pressure

10

what is unique about tactile receptors?

thermo, mechano- or nociceceptors located in the skin

11

describe nociceptors

- chemoreceptive, free-nerve endings
-Activated by tissue damage from intense thermal, mechanical or chemical stimuli
-Little adaptation – pain tends to linger
-In every tissue in the body except the brain

12

fast pain

(acute, well localized) occurs rapidly – myelinated axons

13

slow pain

-gradually increases in intensity
-Burning, aching, throbbing

14

superficial somatic pain

Receptors in skin

15

deep somatic pain

Muscles, joints, tendons, fascia

16

Visceral pain

-Nociceptors in visceral organs
-Pain is felt in or just deep to the skin that overlies the organ
OR pain felt far from affected organ = referred pain

17

referred pain

pain felt far from affected organ
Ex) heart attack – chest pains and pain felt far from area (arm)

18

sensory pathway: first-order / primary somatosensory neurons

Into brain stem or spinal cord

19

sensory pathway: Second-order / secondary neurons

to thalamus

20

sensory pathway: Third-order neurons

From thalamus to cortex

21

describe the distribution of somatic sensory neutrons in the body

not distributed evenly in the body

22

where does motor activity begin?

in the primary motor areas of the primary motor cortex and other cerebral integrative centers

23

Upper motor neuron (UMN)

-Motor neuron not responsible
for stimulating muscle
contraction
-Connects brain to the upper
level in spinal cord

24

lower motor neurons (LMNs)

descend to innervate skeletal muscle

25

what are the 3 external stimulus's

-light rays - strike the retina of eye

-sound waves - tympanic membrane of ear

-molecules in the air and food smells and tastes detects by nose and tounge

26

VISION: 3 steps for converting electromagnetic radiation into an image in the brain

1)Focus light on the retina
2)Convert photons of light into an action potential
- Use photoreceptors
3)Take APs and generate an image in the brain

27

anatomy of the eye: Fibrous tunic and parts

Fibrous tunic- outter layer
-Sclera -protects internal structures
-Cornea- transparent, continuous with sclera

28

anatomy of the eye:Vascular tunic

Vascular tunic -middle layer
-Choroid highly vascularized – nourishes the retina
-Ciliary body changes shape of lense
-Iris smooth muscle, central opening (pupil)

29

anatomy of the eye: Nervous tunic

Nervous Tunic – inner layer (contains many neurons)
-Retina - light deflected here
-Fovea - small central area of retina, Area of sharpest vision, contains Photoreceptor cells – rods and cons
-Optic disc – where CNII exits the eye

30

Vision - what does normal image formation depend on?

-Refraction of light waves
-Accommodation of the lens
-Construction of pupil
-Convergence of 2 eyes

31

Vision: step A: how does the retina focus light?

-Light entering the eye will be bent by cornea (refraction)
-the lens must change shape to focus light on the retina
-Correction are accomplished using a positive (convex) or a negative (concave) lens

32

What are the two types of photoreceptors and where are they located?

1) Rods – in periphery of Retina
2) Cones – more abundant in central areas and fovea
-retina

33

rod - shaped photoreceptors

-Adapt to low light
-High sensitivity – don’t need a lot of light to produce AP
-Produce low resolution, black and white images

34

cone- shaped photoreceptors

-Function in high-light
-Produce high resolution, color images
-3 varieties of cones:
(pick up different light waves)
-Red
-Green
-Blue

*If your missing one of these – results in color blindness
-high concentration in central fovea (digit in centre of retina)

35

Vision: step B: Convert photons of light into an action potential

*visual transduction
-Light is focused on the retina
-Must be converted by photopigments in photoreceptors into signals the brain can interpret
-Photons AP

-Rods have rhodopsin as the photopigment
-Cones have 3 different photopigments
-Photopigment = pigment that is sensitive to light

36

3 main steps of visual transduction. (in light)

-In light:
1) Isomerization - absrption of a photon of light causes cis-retinal to straighten to trans-retinal
2) Bleaching - trans-retinal separation from opsin
-opsin has no color = bleaching
3) Regeneration an enzyme converts trans-cis retinal, binds back on opsin

37

rhodopsin bleaching causes what?

-Process of bleaching causes Na+ channels to close
-Closes Na+ channels = hyperpolarization of plasma membrane

38

process of visual transduction. (in dark)

-In darkness, retinal has a bent shape called cis-retinal
-Na+ channels are open
-Photoreceptor cell is depolarized
-Inhibitory neurotransmitter is released
-Bipolar cell is inhibited
-No signal is sent on to the ganglion cell or brain

39

process of visual transduction. (in light)

-Na+ channels close
-Photoreceptor cell is hyperpolarized
-Ca+ channels stay closed and inhibitory NT is NOT released
-Bipolar cell depolarized
-Excitatory NT to ganglion cell and brain

40

VISION: Step C: Take APs and generate an image in the brain

-graded potentials generated by the photoreceptors undergo considerable processing at synapses
-The axons of retinal ganglion cells provide output that travels back “towards the light”, exiting the eyeball through optic nerve

41

describe the process of processing of visual

b