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Functional Neuranatomy > Block 3 > Flashcards

Flashcards in Block 3 Deck (105):
1

sclera

-tough, outer layer of the eye
-Gr. skleros, hard

2

cornea

-transparent, focusing apparatus of the eye
-performs 2/3 of the light bending
-is innervated by many nerve endings

3

lens

-performs the final 1/3 of light bending for proper focus
-shape controlled by the ciliary muscles

4

ciliary muscles

-control the shape of the lens
-by contracting they cause the lens to become more convex which sharpens the visual image on the retina

5

accommodation

The change in the shape of the lens is controlled by the ciliary muscles inside the eye. Changes in contraction of the ciliary muscles alter the focal distance of the eye, causing nearer or farther images to come into focus on the retina; this process is known as accommodation.

6

what controls how much light enters the eye by adjusting the size of the pupil?

-the smooth muscles of the iris

7

aqueous humor

-fills in the space in front of the lens and between the iris and the lens

8

vitreous humor

fills in the space between the lens and the retina

9

what muscles control eye position in the socket?

-extraocular skeletal muscles

10

retina

-is part of the CNS and derived from neural tube
-laminated and 250 microns thick
-3 primary cell layers arranged inside out

11

the pigmented epithelium behind the retina

-absorbs light to prevent backscatter
-recycles retinal as part of the transduction process
-possesses tight junctions and forms a blood-retina barrier

12

name the principle cells of the retina

-photoreceptors: rods and cones
-local circuit neurons: bipolar, horizontal, and amacrine
-projection neurons: ganglion cells

13

fovea

-point of the retina with the highest visual acuity
-it lies in the center of the retina (aka the macula )
-there is a higher density of photoreceptors there

14

papilla

aka optic disk
-where axons of ganglion cells are bundled to form optic nerve
-since no photoreceptors are there, there is a blind spot

15

direct vertical pathway

-from photoreceptor to bipolar to ganglion cell

16

indirect lateral pathway

-involves horizontal spread of information through local circuit neurons, the horizontal and amacrine cells

17

what is the overall convergence ratio of rods and cones to ganglion cells

100 to 1

18

what photoreceptor dominates at the fovea?

cones

19

name the ways to increase visual acuity

-absence of intervening cells
-increased density of photoreceptors
-high concentration of cones
-low degree of convergence from photorecetors to ganglion cells

20

visual field

-part of the environment impinging upon the whole retina at any one time

21

binocular field

-subset of the visual field that impinges upon both eyes at the same time

22

monocular field

-parts of the visual field outside of the overlap of the binocular field

23

retinal field

-reversed image of the visual field that is projected onto the retina
-medial part: nasal field
-lateral: temporal field

24

receptive field

-part of the retina that when stimulated by light alters the electrical activity of a neuron

25

what is the photopigment in rods

-rhodopsin

26

what is the photopigment in cones?

-photopsin: either blue, red, or green

27

rhodopsin

-an aldehyde derivative of vitamin A
-is sensitive to electromagnetic radiation from 400-700 nm

28

photoreceptors release transmitter from their ____ onto bipolar cells

-synaptic endings

29

what photoreceptor is responsible for night vision

-rods due to large outer segments, and more photopigment

30

in the dark, rhodopsin is ____, ___ is high, and ion channels are open

-inactive, cGMP is high, ion channels are open

31

in the light, what happens in the outer segment of the photoreceptor

-light bleaches rhodopsin
-opsin decreases cGMP
-Na+ channels close and the cell hyperpolarizes

32

on center ganglion cells

-increase activity when the center of its receptive field is illuminated and decrease activity when its surround is illuminated
-responds best to rapid increases in illumination intensity and to objects brighter than the background

33

ganglion cells show ___ as a result of ____ in the circuit

-center-surround antagonism as a result of lateral inhibition

34

on-center ganglion cell

-increases activity when the center of its receptive field is illuminated and decreases activity when the surround is illuminated

35

off center ganglion cells

-decrease activity when the center of its receptive field is illuminated and increases activity when its surround is illuminated
responds best to: rapid decreases in illumination intenisty and to objects that are darker than the background

36

in the dark, glutamate released from the photoreceptor _____ the off-center bipolar cell and _____ the on-center bipolar cell

-depolarizes the off-center bipolar cell
-hyperpolarizes the on-center bipolar cell

37

how is surround antagonism for cones achieved?

-lateral inhibition from horizontal cells

38

in the dark horizontal cells are ____ by ____ which is released by photoreceptors

depolarized by glutamate

39

depolarized horizontal cells release ___ onto the __-synaptic terminals of _____

release GABA onto the presynaptic terminals of photoreceptors

40

retinal ganglion cells: M cells

-magnocellular
-large cell bodies, dendritic trees and axons
-large receptive field sizes and are slowly adapting
-sensitive to: contrast illumination, large objects, and movement

41

retinal ganglion cells: P cells

-parvocellular
-small cell bodies, dendritic trees, and axons
-more numerous with small receptive fields
-rapidly adapting
-specially sensitive to: fine spatial resolution, form, and color for slow events

42

what thalamic subdivision is dedicated to relaying visual information to the cortex?

-lateral geniculate nucleus

43

axons of ganglion cells from nasal parts of the retina cross the midline at the

-optic chiasm
**information from the right visual field is projected to the left thalamus and cortex

44

In the lateral geniculate nucleus, the contralateral eyes innervate

layers 1,4, and 6

45

In the lateral geniculate nucleus, the ipsilateral eyes innervate

2,3, and 5

46

scotoma

hole in the visual field

47

olfactory and gustation involve ____ of chemical to ____ energy

-transduction
- electrical

48

olfactory sensory neurons are located in the ____ at the top of the nasal cavity

olfactory epithelium

49

what makes up the olfactory cranial nerve (I)?

axons from the primary olfactory neurons

50

In the olfactory system, the axons from the ___ project through the __(bone)__ into the ____

-primary olfactory neurons
-cribriform plate of ethmoid bone of skull
-olfactory bulb

51

T or F: individual primary olfactory neuronal axons are myelinated

False: the unmyelinated axons of primary olfactory neurons are ensheathed by Schwann-cell like olfactory ensheathing cells

52

the olfactory bulb consists of series of ___

glomeruli

53

Within the ___, olfactory axons contact the dendrites of ____ cells

glomerulus
-mitral

54

Mitral cells send their axons through the ___ to the brain

olfactory tract

55

name the 3 cells of the olfactory epithelium

-basal cells, supporting cells, and primary olfactory cells

56

olfactory neurons are replaced every __ days, with new neurons proliferating from the ___ cells

-30-60 days
-basal cells

57

describe primary olfactory neurons

-bipolar cells with ciliated processes on their dendrites that contain the specific olfactory receptors

58

molecular receptive range

-the range of odorant molecules that will alter the activity of the cell in the olfactory system

59

describe how olfactory system generates a map that spatially encodes odors

-primary olfactory neurons with the same receptor appear to be randomly localized in the olfacory epithelium, but they converge onto a common glomerulus in the olfactory bulb

60

primary visual cortex

-Brodman's area 17
-striate cortex or V1

61

A map of the ___ field is projected onto the primary visual cortex by ____

-retinal
-lateral geniculate neurons

62

the ____ is represented by the largest proportion of lateral geniculate neurons, optic radiation fibers, and primary visual cortical neurons

-fovea

63

Inputs from LGN terminate mainly on stellate cells in layer __ of __

-layer 4 of V1

64

Do axons of magnocellular and parvolcellular layers of the geniculate terminate in same or separate sublayers of layer 4 of V1?

-separate sublayers

65

stellate cells in layer 4 project to

-pyramidal neurons in superficial or deep layers

66

the receptive fields of simple cortical cells in V1

-consist of elongated centers (on or off characteristics)
-preferred orientations
-antagonistic suuround
-stimulus must have proper orientation, size, and position!!

67

the axons of mitral/tufted cells project through the ___- to target cells in the _____

-olfactory tract
-rhinencephalon

68

the ____ provides interhemispheric communication between the two olfactory bulbs via the ___ commissure

-anterior olfactory nucleus
-anterior commissure

69

the olfactory tubercle projects to the ___ nucleus of the thalamus, which relays information to the orbitofrontal cortex

-mediodorsal nucleus of the thalamus

70

What cortex was thought to be the main olfactory processing cortex, but now appears to be involved in processing exploratory olfactory info from active sniffing

piriform cortex

71

Name important regions for the emotional conditioning and memory formation

-temporal lobe structures, amygdala, and entorhinal cortex

72

reflexes

-rapid, stereotyped, and involuntary

73

rhythmic motor patterns

-voluntarily initiated and terminated, but maintained through reflexes

74

voluntary movements

are purposeful and learned

75

agonist

-the prime movers

76

synergistic muscles

cooperate to produce movement in the same direction as agonsist

77

antagonists

-muscles that decelerate agonist movement and move limbs in opposing directions

78

Axial muscles

-move the trunk and maintain posture

79

proximal muscles

-move the shoulder, elbow, pelvis, and knee
-posture, locomotion, and strong arm force

80

distal muscles

move the hands and feet, fingers and toes, and eyes and face
-facial expression, maintain binococular vision, and fine manipulation of objects

81

describe the hierarchy of the motor system

-cortex: general commands
-brainstem: regulates spinal motor neuron activity
-spinal cord: integrates local and descending drive to motor neurons

82

basal ganglia

plan appropriate movements

83

cerebellum

-correct errors and are involved in motor learning

84

Motor neurons are ____ organized

-somatotopically
-those supplying proximal/trunk/axial muscles are located more medially than those supplying distal muscles

85

Where are flexor muscle motor neurons located compared to extensor?

flexors tend to be more dorsal

86

muscle paresis

-muscle weakness
-can result when a single spinal nerve is damaged

87

insecticides and nerve gases

-block AChEase
-The inhibition of the enzyme leads to accumulation of ACh in the synaptic cleft resulting in over-stimulation of nicotinic and muscarinic ACh receptors and impeded neurotransmission. The typical symptoms of acute poisoning are agitation, muscle weakness, muscle fasciculations, miosis, hypersalivation, sweating.

88

botulinum toxin

-blocks release of ACh

89

Black widow spider venom

-overstimulates the release of ACh

90

Curare

-blocks ACh receptors

91

AChEase inhibitors are used to treat

myasthenia gravis:
a disorder characterized by muscle weakness and autoimmunity for ACh receptor

92

twitch

-the contraction created by a single action potential in a muscle fiber

93

Renshaw cell

-an inhibitory spinal interneuron which is activated by a motor neuron inhibitng its own activity

94

tetanospasmin

-a neurotoxin released by clostridium tetani that destroys Renshaw cell synapses with motor neurons
-this results in unrelieved motor neuron firing and muscle tetanus

95

the orientation selectivity of cortical cells has what kinds of organization

-columnar organization

96

orientation columns have what kind of organization

-pinwheel

97

dorsal stream

-"where" pathway
-originates primarily from retinal M ganglion cells
-processes spatial features and movement
-carried out via projections to posterior parietal cortex

98

the ventral stream

-what pathway
-primarily from retinal p ganglion cells
-object recognition and involves projections to the inferior temporal cortex

99

agnosia

-inability to recognize objects
-results from damage to inferior temporal cortex or other parts of ventral stream

100

akinetopsia

-deficits in detecting motion
-results from damage to posterior parietal cortex

101

prosopagnosia

-inability to recognize people from their face
-results from damage to ventral stream pathway

102

Tectospinal pathway

Origin: superior colliculus
Main input: visual, auditory, somatosensory
Muscle Group: eye/neck
Function: orienting reflexes, saccadic eye movements

103

Lateral Vestibulospinal Pathway

Origin: lateral vestibular nucleus
Main input: otolith organs
Muscle groups: trunk and proximal extensors
Function: feedback postural controls and adjustments of spinal reflexes

104

Medial vestibulospinal pathway

Origin: medial vestibular nucleus
Main input: otolith organs and Semicircular canals
Muscle groups: neck
Function: coordinate neck and head movements with body

105

Reticulospinal tract

Origin: reticular formation
Main input: visual, auditory, somatosensory, vestibular, cortical, cerebellar
Muscle groups: trunk/proximal extensors
Function: feedforward postural adjustment of spinal reflexes, orienting reflexes, crude voluntary movement