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Structure And Function Of Living Organisms > Nervous system > Flashcards

Nervous system Flashcards

1
Q

What does the nervous system produce

A

effective responses to a stimulus from the environment

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2
Q

Examples of an external stimulus

A

light, temperature, chemical, touch, vibration

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3
Q

Examples of an internal stimulus

A

chemical – pH, ions, molecules. Blood pressure, temperature

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4
Q

Location of interneurons

A

Located between neurons and form a connection between other neurons

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5
Q

where are interneurons found

A

in both vertebrates and invertebrates

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6
Q

Interneuron distance

A

local or send their axons for long distances within a nervous system (projection interneurons)

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7
Q

Consequence of the presence of interneurons

A

Increase the number of synapses – and therefore the complexity of neuronal circuits

AKA relay neurons, association neurons or connector neurons

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8
Q

How can a neuron vary

A
  1. Cell body (soma) - size and shape
  2. Dendrites – number, branching, length
  3. Axon – length, diameter, branching, myelinated or unmyelinated
  4. Synaptic terminals – number and structure
  5. Synaptic transmission – chemical or electric
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9
Q

What does the structure of the neuron relate to

A

directly relates to its function

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10
Q

What is hydra

A

a freshwater invertebrate

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11
Q

describe the nervous system of a hydra

A

a simple nerve net with no CNS

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12
Q

What movements does the hydras nervous system allow

A

movement of body and tentacles in water

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13
Q

direction of action potentials in hydra

A

conducted in all directions - bidirectional

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14
Q

sea anemone and corals (invertebrates) movements

A
  1. Slow but coordinated movements of polyps
  2. Tentacles (catching prey)
  3. Body movements (defence)
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15
Q

Sensitivity of sea anemone and corals

A

Tentacles/oral disc 4000 x more sensitive than the ‘column’

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16
Q

Complexity of jellyfish nervous system

A

more complex nerve nets

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17
Q

Movements of jellyfish

A

Spontaneous rhythmic activity (slow state and startle). Contractions of the margin of the ‘bell’ produce a propulsive force forward

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18
Q

Star fish’s nervous system

A

a modified nerve net

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19
Q

What coordinates limb movements in a star fish

A

coordinated by neural ring

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20
Q

What controls individual limb movements in a star fish

A

radial nerves

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21
Q

What does the cooperation of radial nerves and neural ring in star fish allow

A

complex movements like movement and feeding

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22
Q

what is bilateral symmetry

A

mirror image on both sides

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23
Q

What did the evolution of bilaterality lead to

A

cephalization - CNS so animal moves forward and has sense organs at the front

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24
Q

What are the consequences of cephalisation

A
  1. Increase in number of nerve cells
  2. Concentration of nerve cells into ganglia; ganglia into brains, nerves into nerve cords
  3. Development of functional speciality: AFFERENT neurons – towards the CNS, EFFERENT NEURONS – away from the CNS
  4. Localization of specific functions in different parts of the nervous system
  5. Development of interneurones and more complex synaptic contacts
  6. Development of head bearing sense organs
  7. Development of ventral nerve cord
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25
Q

What is a segment

A

a unit of anatomical structure that can be repeated along the length of an animal

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26
Q

What are the consequences of segmentation

A
  1. Development of segmental ganglia with sufficiently complex neural circuitry to control locomotion in individual segments
  2. Coordination of movement (and/or limb movement) between adjacent segments. e.g., in annelid worms or earth worms
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27
Q

What are connectives

A

ganglia joined by connecting nerves

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28
Q

What do arthropods

A

connectives, autonomic nervous system (ANS) which innervates the viscera of the body and segmental ganglia

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29
Q

What does the segmental ganglia do

A

Co-ordination of movement in walking/running and flying

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30
Q

How does the segmental ganglia coordinate movements

A
  1. Receiving sensory information from a defined part of a body segment whose activity it regulates directly
  2. Activating dorsal/ventral or left/right limb muscles appropriately in response to stimuli
  3. Using central pattern generators (CPGs) - repeated rhythmic motor output independent of sensory stimulation
  4. Interconnections between segmental ganglia (connectives) cam propagate activity along the length of the ventral nerve cord – and along the length of the animal – coordinated by the ‘brains’
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31
Q

mollusks (invertebrate) nervous system brain ganglia organisation

A

Buccal – feeding
Cerebral – coordination
Pleural – respiration
Pedal – movement

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32
Q

How do octopi exhibit foresight, planning, use of tools

A

Gets food, clears the front of its den and arranges rocks in order to cover the entrance before going to sleep

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33
Q

How do octopi exhibit persistence and thinking

A

Opens childproof caps on pill bottles

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34
Q

How do octopi play

A

Blowing jets of water from the funnel to send a pill bottle to the other end of the tank where the water flow sends it back - repeatedly

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35
Q

How do octopi show memory and affection

A

Recognise their human ‘caretakers’ by moving towards them and squirting water at them

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36
Q

How do octopi show thinking

A

Solving difficult problems using objects of differing colours and shapes

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37
Q

What did the CNS develop from

A

the neural tube

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38
Q

What do walls of the neural tube contain

A

neuroblasts

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39
Q

Structure of the neural tube

A

hollow tube, has a lumen

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40
Q

What are the 3 primary brain vesicles

A
  1. prosencephalon (forebrain),
  2. mesencephalon (midbrain)
  3. rhombencephalon (hindbrain)
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41
Q

What secondary brain vesicles does the forebrain form

A

telencephalon and diencephalon,

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42
Q

What secondary brain vesicles does the midbrain form

A

mesencephalon

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43
Q

What secondary brain vesicles does the hindbrain form

A

metencephalon and myelencephalon

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44
Q

“lower” vertebrate brain features

A
  1. Large area devoted to olfaction (smell)
  2. Importance of the optic lobes in fish and amphibians
  3. Increasing size of cerebrum. Cerebral cortex = 3 layers
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45
Q

What are the key features of the mammalian brain

A
  1. Folding of the cortex (gyri and sulci – cerebral cortex only found in higher vertebrates)
  2. Development of 6 layered neocortex
  3. Enlargement of the cerebellum
  4. Reduction of the olfactory system (especially in primates)
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46
Q

How has the human brain developed

A

the frontal cortex has developed and there is enlargement of cortical areas involved with unique human features: manual dexterity, speech, facial expressions

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47
Q

How is vertebrate CNS tissue organised

A

into white and grey matter

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48
Q

What is white matter

A

myelinated axons

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49
Q

What is grey matter

A

collections of cell bodies

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50
Q

What does the corticospinal tract consist of

A

neuronal pathway - descending and ascending tracts

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51
Q

What matter are tracts

A

white matter

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52
Q

What matter are nuclei

A

grey matter

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53
Q

What is a nucleus

A

a cluster of cell bodies and their dendrites where synapses are made and information is processed

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54
Q

What do bundles of myelinated axons form

A

tracts connecting nuclei

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55
Q

How are the layers of the cortex characterized

A

by the types of neurons they contain and by their connections (afferent, efferent and intracortical)

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56
Q

How do lampreys swim

A

by undulatory movements of the body forwards and backwards using central pattern generators (CPGs) on both sides of the spinal cord

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57
Q

What are CPGs

A

network of neurons which produce rhythmic behaviors

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58
Q

Where are CPGs in lampreys

A

on each side of each spinal cord segment in lamprey

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59
Q

How is the basic rhythmic drive for locomotion in lampreys generates

A

each half of spinal cord generates movement and connactions between left and right ensure coordination

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60
Q

What controls CPGs in lampreys

A

locomoter’s command centers in the brainstem which is controlled by the basal ganglia (nuclei) in the cerebral hemisphere

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61
Q

What do Mauthner (M) neurons mediate

A

All bony fish have a “fast escape” or “startle response”

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62
Q

Which fish has the fastest acceleration from a ‘standing start’

A

the barracuda

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63
Q

Where are M - neurons located

A

on either side of the brainstem. Large neurons (cell soma 100 um diameter)

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64
Q

What do M-neurons detect

A

vibration and sensory input

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65
Q

Axon of M-neurons

A

on either side of the brainstem. Large neurons (cell soma 100 um diameter)

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66
Q

How do M-neurons cause unilateral muscle contraction in fish

A

Collaterals contact interneurones and motor neurones at all spinal levels

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67
Q

First animals to walk on land

A

First by amphibians such as salamanders … then by reptiles

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68
Q

In order for animals to walk on land what is the friction of water replaced by

A

pull if gravity on land

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69
Q

Anatomical concepts of walking on land

A
  1. Antagonistic muscle groups: flexors (bending) and extensors (straightening)
  2. Hip and shoulder joints
  3. Multi-joint movements
  4. Major involvement of the spinal cord
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70
Q

How has the cerebellum evolved during the transition onto land

A
  1. Vestibulocerebellum – balance
  2. Spinocerebellum – body raised off the ground
  3. Neocerebellum – connected to the cerebral cortex for motor coordination
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71
Q

What causes alternating steps

A

flexors and extensors inhibiting each other reciprocally

72
Q

4 phases of walking

A
  1. Flexion (F)
  2. First extension (E1)
  3. Second extension (E2)
  4. Third extension (E3)
73
Q

Spinal reflexes in walking

A

spinal circuits work without control of the brain

74
Q

muscle groups in walking

A

Inhibition/stimulation of antagonistic muscle groups: flexors v extensors

75
Q

coordination in walking

A

Co-ordination of movement of more than one joint

76
Q

Sensory feedback in walking

A

Sensory feedback controls rate of stepping (cutting dorsal spinal roots interrupts pathway)

77
Q

supra-spinal control in walking

A

Supra-spinal control (above spinal cord). Ascending sensory pathways run from spinal cord to sensory cortex in cerebral hemisphere. Neighboring motor cortex (and other motor areas stimulated). Descending motor pathways exert control of motor neurones in the spinal cord

78
Q

Why do birds singing

A

Birdsong is composed of syllables which are characteristic of particular species. Bird song is a learnt behavior

79
Q

Neuroanatomy of birdsong

A

There is a complex interconnection of nuclei and tracts in the bird brain which control the syrinx to produce the song

80
Q

What does the central nervous system include

A

brain and spinal cord

81
Q

What does peripheral nervous system include

A

cranial and spinal nerves

82
Q

what do sensory neurons do

A

brings sensory information to the CNS from peripheral tissues and organs

83
Q

What do motor neurons do

A

sends motor commands from the CNS to target organs (muscles, glands)

84
Q

What does the peripheral nervous system split into

A
  1. Somatic nervous system - controls skin and skeletal muscle
  2. Autonomic nervous system - control viscera e.g., smooth and cardiac muscle
85
Q

what does the autonomic nervous system split into

A
  1. sympathetic - fight or flight
  2. parasympathetic - rest and digest
86
Q

what is the dorsal column ascending pathway split into

A

gracile fasciculus and cuneate fasciculus

87
Q

What is the spinocerebellular tract responsible for

A

sending sensory information that helps coordinate the muscles in the trunk and the limbs

88
Q

What does the spinocerebellular tracts split into

A

the posterior and anterior spinocerebellular tract

89
Q

What does the anterolateral system split into

A

the lateral spinothalamic tract and the anterior spinothalamic tract

90
Q

What are the 3 ascending (afferent) pathways

A

dorsal column medial lemnisucs sysyem, spinocerebellar tract and anterolateral (spinothalamic) system

91
Q

What are the 2 descending (efferent) pathways

A

pyramidal tracts (corticospinal) and extrapyramidal tracts

92
Q

What does the pyramidal (corticospinal) tract split into

A

lateral and anterior corticospinal tract

93
Q

What does the extrapyramidal tracts split into

A

rubrospinal tract, reticulospinal tracts, olivospinal tract and vestibulospinal tract

94
Q

location of the dorsal column

A

at the back of the spinal cord

95
Q

What processes the sensory information in the dorsal column

A

Sensory information (vibration, discriminative fine touch and proprioception) processed by primary sensory neurons with cell bodies in the dorsal root ganglia

96
Q

Type of communication in the dorsal column

A

initially ipsilateral (same side of the body) the neurons then cross over at the medulla oblongata so it is now contralateral (to the other side)

97
Q

Where does the spinothalamic tract carry information

A

from the spine, up the thalamus

98
Q

Spinothalamic tract - where is sensory information processed

A

Sensory information (pain, temperature, touch and pressure) processed by primary sensory neurons with cell bodies in the dorsal root ganglia

99
Q

Where do neurons decussate (cross over) in the spinothalamic tract

A

at the point of entry (L5)

100
Q

Communication within the spinothalamic tract

A

forms synapses with another neuron to create a contralateral pathway

101
Q

What do interneurons connect

A

functionally related lower motor neurons

102
Q

Are descending pathways efferent or afferent to lower motor neurons

A

afferent

103
Q

What is the general somatic efferent

A

motor to skeletal muscle from large ventral horn

104
Q

What is the general visceral efferent

A

motor to visceral frim ventral horn

105
Q

General visceral afferent

A

sensation from the visceral

106
Q

General sensory afferent

A

discriminative touch, proprioception, pain and temperature from skin, joints, muscles

107
Q

Location of the corticospinal tract

A

passes through the pyramidal structures of the medulla and decussates (crosses over)

108
Q

What does the corticospinal tract control

A

lower motor neurons (LMNs) that innervate skeletal muscles. Non-stereotyped movements (purposeful movements)

109
Q

What is somatotopy

A

the orderly arrangement of the nervous system in relation to the parts of the body

110
Q

What do the consequences of the interruption of the descending pathway depend on

A

level of injury and where and if the tract decussates

111
Q

What does a greater number of neurons mean

A

more intergration can occur

112
Q

what is neurogenesis

A

creation of new neurons - is confined to specific areas

113
Q

where is the association cortex located

A

cerebral cortex outside the primary areas

114
Q

what is the association cortex involved in

A

communication, memory, planning future behaviour, and thought I.e., complex processes

115
Q

Inter-hemispheric commissures (junctions)

A

corpus callosum, anterior commissure

116
Q

Function of motor neurons

A

planning, execution and co-ordination

117
Q

Function of the extrapyramidal system

A

for stereotyped (repetitive) movements e.g., rocking or headbanging

118
Q

What system is the cerebellum part of

A

the extrapyramidal system

119
Q

Cerebellum functions

A

initiating, timing and terminating movements. Cerebellum co-ordinates motor output

120
Q

Examples of grey matter areas within the hemisphere

A

basal ganglia, thalamus and hypothalamus

121
Q

What is the basal ganglia

A

A collection of nuceli which produce regulated movements

122
Q

What system controls the basal ganglia

A

extrapyramidal motor control

123
Q

Major inputs of the basal ganglia

A

cerebral cortex, thalamus, brainstem

124
Q

Where do the major outputs of the basal ganglia go to

A

thalamic nuclei, cortex (via thalamus), brain stem

125
Q

Where does the thalamus relay sensory information to

A

the cerebral cortex (ascending tracts)

126
Q

Function of the thalamus

A

Activating the cerebral cortex – sleep and consciousness. Emotional effects generating autonomic activity. Co-ordination of visual and motor activity

127
Q

What does the hypothalamus respond to

A

physiological, environmental and emotional changes that affect the autonomic nervous system

128
Q

What system is the hypothalamus under

A

limbic system

129
Q

Hypothalamus functions

A

involvement in thirst, hunger, appetite. Reproduction and associated behavior. Maintenace of homeostasis (e.g., body temperature and water/electrolyte balance). Neuroendocrine control - pituitary gland

130
Q

What does the brainstem connect

A

brain to spinal cord

131
Q

What is the brainstem involved in

A
  1. The functional composition of cranial nerves III – XII
  2. Conveying sensory information go the cortex
  3. Conveying motor control from the cortex to motor neurons
  4. Cerebellar connections
  5. Regulation of the autonomic nervous system
  6. Visual and auditory reflexes
  7. Alertness and consciousness
  8. Life and death (breathing = controlled by medulla oblongata
132
Q

What does the basal ganglia do

A

enhances desires movement and inhibits unwanted movement- regulation i.e., kick foot and do not wave arms

133
Q

What does the thalamus control

A

relays sensory info to the cortex i.e., wind direction

133
Q

What does the thalamus control

A

relays sensory info to the cortex i.e., wind direction

134
Q

What does the cerebral cortex do

A

planning of voluntary movement o.e., kick the ball between posts

135
Q

What does the cerebellum do

A

co-ordinates motor output and force of muscle contraction i.e., bring leg forward and hit ball contraction of abdomen to brace

136
Q

What does the brainstem do

A

conveys sensory info to the cortex and motor info to lower motor neurons

137
Q

What info does the ascending dorsal column pathway send

A

vibration, proprioception, fine touch

138
Q

What info does the ascending spinothalamic pathway send

A

pain, temperature, touch and pressurew

139
Q

What info does the descending corticospinal pathway send

A

voluntary movement of musculature

140
Q

What info does the descending extrapyramidal pathway send

A

carry motor fibres to spinal cord

141
Q

Key components if a somatic reflex arc

A
  1. sense organ - generator potential
  2. Action potential
  3. Afferent neuron
  4. Synapse - EPSPSs (and IPSPs)
  5. Efferent neuron - action potential
  6. neuromuscular junction - endoplate potentials
  7. muscle
142
Q

Release of neurotransmitter to skeletal muscle is …

A

excitatory - acetylcholine

143
Q

Inhibition of skeletal muscle …

A

occurs prior at the level of the spinal cord - reciprocal inhibition

144
Q

What does the knee jerk check for

A

checks that lower motor neurons are functional

145
Q

Knee jerk reflex sequence of events

A
  1. Stimulate patella tendon
  2. Activates stretch receptors or muscle spindles within the extensor muscle
  3. Activates sensory nerve, synapse to motor neuron (monosynpatic reflex)
  4. Extensor muscle (quadriceps) contracts
  5. Flexor muscle (hamstring) relaxes
146
Q

Reciprocal inhibition - knee jerk reflex

A

occurs in the spial cord - there is no involvment of the brain

147
Q

Motor neuron inhibition - knee jerk reflex

A

sensory neurons travelling from muscle spindle stimulate internueorns that inhibit motor neurons that supply opposing muscle causing quadricep muscle to be unopposed

148
Q

What happens during the crossed extensor reflex

A

Removing foot from stimulus (flexor contracts and extensor relaxes). Other side of the body stabilises (flexor relaxes and extensor contracts)

149
Q

What does the autonomic system involve

A

sleeping, eating, thermoregulation, CV control, crying, stress response, light reflex, breathing and respiration, elimination of waste products

150
Q

When does the autonomic nervous system function

A

without you being aware of it or exerting voluntary control over it - involuntary

151
Q

What does the autonomic system respond to

A

physiological demands, environmental and emotional demands, controls organs of the body

152
Q

Autonomic nervous system reflex arc

A
  1. Afferent neuron with receptive ending
  2. interneurone
  3. autonomic preganglionic neuron
  4. Autonomic postganglionic neuron
  5. Effector
153
Q

What are the 2 subdivisions of the autonomic nervous system

A
  1. Sympathetic nervous system - fight or flight
  2. Parasympathetic nervous system - rest and digest
154
Q

How does the sympathetic nervous system and parasympathetic nervous sytem function

A

antagonistically because they usually have opposing effects on an oragsn

155
Q

When does the parasympathetic nervous system use acetylcholine

A

for transmission of preganglionic and postganglionic neuron

156
Q

When does the sympathetic nervous system use acetylcholine

A

transmission of preganglionic neuron

157
Q

When is nicotonic AchR USED

A

For receptors on postganglionic neuron

158
Q

When is noradrenaline used

A

sympathetic nervous system - transmitter of postganglionic neuron

159
Q

When is alpha/beta adrenergic receptors used

A

sympathetic nervous system - receptors on target tissue

160
Q

When is muscarinic AChR used

A

parasympathetic nervous system - receptors on target tissue

161
Q

What controls all preganglionic autonomic neurons

A

pathways descending from higher regions of the brain, in particular they hypothalamus

162
Q

Why are postganglionic axons not attached to the target organ

A

because they need to move in relation to them

163
Q

Parasympathetic outflow of the CNS (I.e., the location of the preganglionic neuron cell bodies)

A

Cranial: 4 cranial nerve nuclei – controlling secretory glands in the head; two intra-ocular muscles of the eye
Sacral spinal cord S2, 3 and 4 - ‘the emptying nerves’ controlling the large bowel/anus, the bladder and erectile tissue of the ganglia

164
Q

Direction of vagus nerve

A

leaves the head and enters the thoracic anf abdominal cavities

165
Q

Distribution of the sympathetic outflow of the CNS

A

relatively unrestricted throughout the body

166
Q

Distribution of parasympathetic outflow

A

relatively restricted

167
Q

Sympathetic outflow from the CNS

A

Lateral horn of the spinal cord in: Segments T1 – L2(3). Preganglionic axons synapse. Either: in paravertebral ganglia (sympathetic chain) Or: in prevertebral ganglia (e.g., coeliac plexus)

168
Q

How do postganglionic axons reach their target organs

A

either by joining peripheral nerves or by running along arteries that supply the target organs

169
Q

How many possible routes are there for sympathetic preganglionic axons

A

3

170
Q

What is the direct pupillary response

A

when light is shone directly into one eye and its pupil constricts

171
Q

What is the afferent neuron in the light reflex

A

projection of the optic nerve to the oculomotor nucleus

172
Q

What causes the pupils to narrow

A

Short postganglionic fibres travel to the circular muscles of the iris

173
Q

Sympathetic reflexes contributing to thermoregulation

A

Increase in body temperature -> increased activity in central thermoreceptors (via hypothalamus):
1. Reflex increases sympathetic discharge to sweat glands -> sweating
2. Reflex decreases sympathetic discharge to cutaneous blood vessels -> vasodilation in skin
-> decrease in body temperature

174
Q

What is the enteric nervous system

A

the innervation of the GI tract is intrinsically controlled in the intetsinal wall

Structure And Function Of Living Organisms (10 decks)

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