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Neuroscience > 23-30 > Flashcards

23-30 Flashcards

1
Q

Why is the resonse of a knee jerk seen in the patella reflex

A

Counteracts the stretch in the thigh extender muscles and associated tendons in attempt to maintain body posture

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2
Q

What is reciprocal inhibition

A

The simultaneous inhibition of motor neurons attached to the antagonistic muscle fibres of the muscle being contracted

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3
Q

What are proprioceptors

A

Sense organs that monitor the position and movement of boys parts

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4
Q

What are muscle spindles

A

Proprioceptors found in most striated muscle

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5
Q

Whats the difference between Golgi tendon organ and muscle spindles?

A

Golgi tendon organ detects contraction of muscle unlike muscle spindles that detect stretch

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6
Q

What is activated in the flexor (withdrawal) reflex

A

Nociceptors

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7
Q

Is the flexor reflex a mono or polysynaptic reflex

A

Polysynaptic (but still very fast)

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8
Q

What is a parallel after-discharge circuit

A

different pathways from the same stimulus take different lengths of time to reach the output so the signal is sustained over an extended period of time

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9
Q

Whats the difference between tonic and phasic mechanoreceptors

A

Phasic is rapidly adapting and gives information about changes in the stimulus whereas phasic is slowly adapting and continues to respond as long as stimulus is present.

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10
Q

How are the axons coming from the skin differentiated

A

A=longest/fastest C=smallest/slowest

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11
Q

How are axons coming from muscles differentiated

A

In roman numerals - I=largest IV=smallest

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12
Q

What does does the medial lemniscal tract carry to the thalamus?

A

Mechanoreceptor and proprioceptor signals

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13
Q

What does the spinothalamic tract send to the thalamus

A

Pain and temperature signals

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14
Q

What 3 neutrons are normally passed through by somatic information?

A

1st order - Detect the stimuli and transfer it to the spinal cord
2nd order - relays the signal to the thalamus
3rd order - Relays the signal from the thalamus into the relevant area of the cortex

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15
Q

What is an important characteristic of the 2nd order somatic neurons

A
  • they are commissural (cross the midline)
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16
Q

What is a dermatome

A

A specific region of skin that a specific root ganglion innervates

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17
Q

How can the size of a receptive field be measured

A

Using two points, the area of the field is how far apart the two points are before only one is felt

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18
Q

T/F where receptive fields are large, discrimination is low?

A

True

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19
Q

What are the upper motor neurons of the cortex mostly involved in and how are they projected

A

Voluntary movement - mainly projected con trilaterally via the corticospinal tract, to muscles involved in precise limb movement

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20
Q

How are the upper motor neurone of the cortex involved in speech

A

Project via the corticobulbar tract to the brainstem which controls movements in the tongue.

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21
Q

What are the upper motor neurone of the brainstem most involved in

A

Maintenance of posture and balance

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22
Q

How do upper motor neurons in the brainstem project

A

Mainly ipsilaterally to lower motor neurons connected to muscles involved in posture maintenance

23
Q

What occurs in the basal ganglia when no movement is initiated

A

The globes pallidus inhibits the Vlo, due to its activation from the striatum

24
Q

What occurs in the basal ganglia when input converges on the striatum

A

The globes pallidus is no longer activated as the striatum inhibits the inhibitory action of the GP allowing Vlo to activate area 6 and initiate movement

25
Q

What occurs in hunting tons disease to disrupt the action of the basal ganglia

A

Degeneration in the striatum results in reduced inhibition of Vlo by the globes pallidus causing hyperkinesis

26
Q

How does the degeneration of the substantial nigra lead to parkinsons

A

Increased tonic inhibition of Vlo due to overactivity of the striatum (usually inhibited by the substantia nigra) leads to jerky restrictive movement - hypokinesis

27
Q

What is the primary function of the cerebellum in terms of movement control

A

To detect and correct differences between the wanted movement and the actual movement produced - this is called motor - error control

28
Q

What do lesions in the cerebellum result in

A

Cerebellar ataxia - characterised by poorly integrated movement

29
Q

What is the engram?

A

The physical embodiment of memory

30
Q

What is declarative memory

A

The memory of facts or events

31
Q

What is procedural memory

A

A form of nondecarative memory that forms the memory of skills, habits and behaviours

32
Q

What is working memory

A

A form of short term memory that serve immediate behavioural needs

33
Q

What part of the brain is associated with our working memory

A

The prefrontal cortex

34
Q

What role does the hippocampus have in memory

A

Essential for converting short term memories into long ones - damage to the hippocampus cause memory loss

35
Q

What role does the amygdala have in memory formation

A

Multiple sensory inputs so memory of smell etc, also involved in emotional memory - things like learnt fear

36
Q

What is unusual about the cortex of the hippocampus

A

It is made up of only three layers - usually six

37
Q

What is the name of the nerves of bundles that synapse on neurones of the dentate gyrus

A

The perforate path

38
Q

What is the name of the axons that the dentate gyrus neurons give rise to

A

Mossy fibres

39
Q

What do mossy fibres synapse onto

A

Cells in the CA3 that either branch off and leave the hippocampus via the fornix or synapse with neutrons of CA1

40
Q

What effects the sleep cycle

A

In the day serotonin is secreted more, whereas at night melatonin is secreted from the pineal gland and promotes sleep

41
Q

What are the steps of the direct pathway

A
  1. Motor cortex excites the striatum (Glu)
  2. Increased inhibition of the globes Pallidus internal by the striatum (GABA)
  3. Reduces inhibition of the thalamus which excites the motor cortex further
  4. Dopamine from the substantial nigra acts on D1 receptors in the striatum to further inhibit the globes pallidus internal
42
Q

What are the steps of the indirect pathway

A

1: Motor cortex excites the striatum
2: Increased inhibition of the globes pallidus external
3: Decreased inhibition of the sub thalamic nucleus
4: Increased excitation of the globes pallidus internal
5: Increased inhibition of the thalamus so less excitation of the motor cortex
6: Also substantia nigra sends dopamine to D2 receptors on the striatum - inhibits the striatum reducing movement inhibition (lost in parkinsons)

43
Q

Where does the protein leptin act and what does this cause?

A

Leptin acts on the arcuate nucleus of the hypothalamus and prevents the feeling of hunger - in obese individuals its effectiveness is lost so even when energy stores are adequate the individual continues to feel hungry

44
Q

What is the term for the building up of macromolecules for storage

A

anabolism

45
Q

What is the term for the breaking down of macromolecules for energy usage?

A

Catabolism

46
Q

What do the neurons of the arcuate nucleus project to

A

1.The periventricular nucleus of the hypothalamus
2.The lower brain stem and the spinal cord
3.The lateral hippocampus
These three produce a co-ordinated response to high levels of leptin

47
Q

What does the activation of the periventricular nucleus cause

A

Causes TSH and ACTH to be released from the anterior pituitary gland - These act on the thyroid and adrenal gland to increase base metabolic rate

48
Q

What does stimulation of the upper brain stem and spinal cord cause

A

Increases sympathetic activity causing a rise in body temperature and BMR

49
Q

What does stimulation of the lateral hypothalamus cause

A

Feeding behaviour is inhibited by somatic motor activity

50
Q

How is the parasympathetic nervous system sometimes referred

A

The rest and digest system - decreases heart rate and increases intestinal and gland activity

51
Q

What does falling levels of leptin stimulate

A

Activates another set of neurones in the arcuate nucleus that include NPY and AgRP

52
Q

What do NPY and AgRP cause

A

Decreased TSH and ACTH secretion, activate the parasympathetic nervous system and stimulate feeding behaviours

53
Q

What is meant by polyandry

A

One female mates with many males but the male will not mate with another female - uncommon in mammals

54
Q

What is meant by polygyny

A

One male mates with many females and the female will not mate again after - very common in mammals

Neuroscience (4 decks)

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