Central Nervous System III

Question 1

What are the different classes of reflexes?

Answer 1

Neural processing, Efferent division controlling effector, Developmental pattern, Number of synapses in a pathway

Question 2

Describe neural processing

Answer 2

Spinal (muscle spindle stretch reflex - Knee jerk)

Cranial (pupil reflex)

Question 3

Describe efferent division controlling effector

Answer 3

Somatic (muscle spindle)

Autonomic (baroreceptor reflex controls bp)

Question 4

Describe developmental pattern

Answer 4

Innate (muscle spindle)

Conditioned (salivation Pavlov)

Question 5

Describe the number of synapses in a pathway

Answer 5

Monosynaptic (muscle spindle)

Polysynaptic (all other reflexes)

Question 6

Describe the stretch reflex process (knee jerk) - Monosynaptic

Answer 6

Stimulus hammer hits patellar tendon, activates muscle spindle triggers AP via afferent neuron (SN) to dorsal horn in integrating centre. Synapses to efferent neuron are excited, triggers AP causes quadriceps to contact

Question 7

Describe how the antagonist pair allow the efficient contraction to occur

Answer 7

To avoid resistance of quadriceps contraction by hamstrings.
Afferent synapses to brain and another synapse in integrating centre via exciting interneuron which releases inhibitory NT GABA so inhibits excitation of efferent neuron to hamstring so remains relaxed

Question 8

What are the 2 types of ascending pathways to the somatosensory area of the cerebral cortex

Answer 8

Lateral spinothalamic tract (pain pathway)

Decussation of medial lemniscus (sensory pathway)

Question 9

Describe the pathway of the lateral spinothalamic tract

Answer 9

Sensory afferent neuron to dorsal horn, crosses over and synapses ascending lateral tract to thalamus which synapses to somatosensory area

Question 10

Describe the decussation of medial lemniscus

Answer 10

Sensory info from mechanoreceptors via sensory afferent neuron to dorsal horn ascend to brainstem medulla oblongata, synpases and cross over decussation of medial leminscus and ascending to dorsal column nuclei to thalamus to synapse to somatosensory

Question 11

Describe the pupillary light reflex

Answer 11

Its a cranial, autonomic, innate and polysynaptic reflex

Question 12

Describe the reflex arc of the pupillary light reflex

Answer 12

Photoreceptors at back of eye detects light stimulus via sensory afferent neurons to midbrain nuclei (IC) to efferent neurons to smooth muscle around pupils

Question 13

Describe the different voluntary motor control areas

Answer 13

1) prefrontal and limbic association
2) Premotor neuron cortex
3) Primary motor cortex
4) Subcortical areas - Basal ganglia, thalamus, sensory feedback systems

Question 14

Describe the pyramidal descending tract

Answer 14

Primary motor cortex in the cerebral cortex to thalamus, descends via brainstem to spinal cord through tract to skeletal muscles synpased at spinal cord

Question 15

Describe the motor unit of the spinal cord

Answer 15

3 lower motor neurons exit via ventral horn each innovate single muscle fibre within a muscle. Only these control skeletal muscle contraction (always excitatory)

Question 16

Describe what it means if the muscle is relaxed and the effect of a single motor neuron on muscle fibres

Answer 16

If muscle is relaxed, motor neuron is not active.
Single motor neuron can innovate many muscle fibres but only one muscle fibre can be innovated by one motor neuron (divergence no convergence)

Question 17

Describe language in the brain in terms of Broca and Wernicke’s area

Answer 17

Broca - Speech formation, found at base of motor cortec in frontal lobe
Wernicke - Language comprehension, found in temporal lobe
Both cause aphasia eg via stroke

Question 18

Describe the electrical patterns found during the different stages of sleep using an electroencephalogram (EEG)

Answer 18

Awake (alert) - Beta waves
Stage 1 Awake (resting) - Alpha/Theta waves
Stage 2 sleep - K-complex forms
Stage 3 sleep - Delta waves
Stage 4 sleep - Higher amplitude delta waves
REM sleep - No delta waves, similar waves to being awake

Question 19

Define sleep

Answer 19

A state of decreased arousal, controlled by hypo, thalamus and brainstem.
Active process so requires energy, cyclic, decreased motor/perception

Question 20

Describe the characteristics of slow-wave sleep

Answer 20

EEG: Slow, med-high amplitude
Movement: Muscle tone, movement, shift position (Can sleepwalk, snore)
Heart/Resp rates: Decreased
Dreams: Rare, logical
REM: Rare
CNS site of induction: Forebrain

Question 21

Describe the characteristics of REM sleep

Answer 21

EEG: Fast, low amplitude
Movement: Paralysis of postural muscles, twitches of distal muscles
Heart/Resp rate: Increased
Dreams: Common, Vivid
REM: Frequent
CNS site of induction: Pons

Question 22

Describe NTs in the sleep and awake state

Answer 22

Sleep: Caffeine blocks the affect of the NT adenosine
Awake: ACh, Norepinephrine, dopamine

Question 23

Describe emotions and motivations in the CNS

Answer 23

Involved within the cerebral cortex and limbic system
Hippo: Emotions triggered by sensory input of memories
Amygdala: Fear, anxiety response
Hypo: Hormonal response
Prefrontal cortex: Motivation (physiological, psychological)

Question 24

Define learning

Answer 24

Acquisition of new info

Question 25

Define memory

Answer 25

Retention of info, skills or thoughts

Question 26

Describe the difference between procedural and declarative memory

Answer 26

Procedural - Automatic, unconscious effort of motor skills via cerebellum
Declarative via hippo for recalling learned facts with conscious effort

Question 27

Describe plasticity of memory

Answer 27

Brain’s tendency to adapt due to development of new learning and synapses, LT use of synapses firing strengthen and keep the neural pathways. Infrequent use causes the pathway to weaken/eventually die