BPK 207 FINAL EXAM QUESTIONS WITH
COMPLETE SOLUTIONS.
What are the major divisions of the CNS
Cerebrum, diencephalon, brainstem, cerebellum & spinal cord
Cerebrum
consists of cerebral cortex, w/continuous layer of grey matter responsible for higher
functions of the CNS.
Also contains subcortical structures such as the hippocampus (memory and navigation),
amygdala (memory, emotion like fear and anxiety) and some of the basal ganglia.
Diencephalon
Consists of thalamus which relays and integrates info b/t cerebral cortex and the
peripheral senses, spinal cord and the brainstem. The thalamus is where sensory info
except olfaction passes thru before the cortex.
Interacts w/basal ganglia to help modify movement.
Subthalamus
includes subthalamic nuclei (part of the basal ganglia
nuclei
refers to clusters of functionally related neurons.
Brainstem
Hindbrain= pons (main connection to cerebellum) and medulla (keeps you alive)
Midbrain= Tectum (superior colliculi relates to eye movement & inferior colliculi relates
to auditory system tegmentum. Tegmentum ( w/ red nucleus which forms descending
tract called the rubrospinal tract and the substantia nigra which is a part of the basal
ganglia.
spinal cord organization
Spinal cord= protected by the vertebral colum consisting of cervical (C1-C8), Thoracic
(T1-T12), sacral (1-5), coccygeal(1)= 31 total nerves.
The nerves end in the upper lumbar region (L1-L2), nerve roots still exit and follow the
canal in the cauda equina or horses tail bundle.
Cervical= upper limb muscles
Thoracic= muscles of trunk and chest (abd muscles)
Lumbar= lower limb and lower back muscles
Sacral= bowel and bladder muscles (S1+S2 involved in controlling leg muscles.
Cervical and lumbar enlargements--> contain neural circuits responsible for
controlling arms and legs allows for communication for interlimb coordination via
propriospinal neurons.
Cross- sections of spinal cord
,Grey matter--> cell bodies of neurons where information gets processed in the brain.
The structures within the grey matter process signals from the sensory organs or from
other areas of the grey matter. Then this info directs sensory stimuli to the neurons in
CNS where synapses induce a response to the stimuli.
White matter--> myelinated & unmyelinated axons form ascending and descending
tracts. Myelin speeds up the signals between the cells which allows the brain to quickly
send and receive messages.
Sensory vs motor neuron organization within the grey matter
4 types of neurons in spinal cord
local interneurons= axons confined to same or adjacent spinal segment
Propriospinal= axons reach far spinal segments
Projection= axons ascend to higher brain centres
Motor= axons exit nervous system to innervate muscles.
Spinal motor neurons (alpha motorneurons)
activate muscles to execute movement w/ special organization within the spinal cord.
Cell bodies of motor neurons which innervate muscles are clustered in motor neuron
pools to form the longitudinal columns extending over 1-4 spinal segments.
Voluntary Movements and Reflex Motor Patterns
What rule does the spatial organization of different motor nuclei follow?
Proximal-distal rule:
Motor nuclei innervating proximal muscles lie more medially and the ones that innervate
distally lie more laterally within the spinal cord.
Motor nuclei more medial allows for quicker rxns and more laterally allows for an easier
path of travel and quicker rxns.
Spinal cord ascending tracts
carry sensory info (bilateral) on R side of body
Spinal cord descending tracts
carry motor info (bilateral) on L side of body
How does somatosensory information enter the spinal cord?
From peripheral receptors via dorsal roots.
How does motor output enter the spinal cord?
Motor output goes through ventral roots.
How do alpha motor neurons work?
Connect to and contract muscles to allow for movement. Typical muscle is controlled by
around 100 large motor neurons.
What is a motor unit?
Motor neuron + the muscle fibre it innervates.
each muscle fibre is innervated by a single motor neuron @ midpoint of muscle. A
single neuron innervates many muscle fibres.
, Are motor units fast or slow twitch?
They can be both, but slow twitch fibres are recruited first before fast-twitch b/c first
fibres are more prone to get tired quicker.
What is the size of the motor unit dependent on?
It's related to the need for refined movement, more refined movement= fewer
fibres/motor unit.
What does the number of motor units recruited depend on?
How much power is needed for the given movement.
Nerve-muscle synapse (neuromuscular junction)
Highly specialized synapse between a motor neuron nerve terminal and its muscle fiber.
It's responsible for converting electrical impulses generated by the motor neuron into
electrical activity in the muscle fibers.
What is the end-plate?
Where the axon of a motor neuron innervates the muscle and loses its myelinated
sheath dividing into multiple synaptic boutons.
Where does ACH get released in the NMJ?
at the synaptic bouton to allow the channel to open and let sodium in and potassium out
to depolarize and open the gated channels --> AP
How is an action potential generated?
Once the motor neuron is activated, depolarization is spread along the axon which
causes Ca2+ to spread along the synaptic boutons causing a release of ACh. Then the
muscle membrane at the end-plate depolarizes from ACh binding receptors generating
an end-plate potential. This change activates the voltage gated Na+ channels to convert
the AP that propagates along the muscle fibre.
How does the CNS increase muscle force?
- recruit diff size of motor units
- activate more motor units (more motor neurons)
- Increase frequency of AP in muscle fibre which would increase stimulation of alpha
motor neuron.
What is the relationship b/t contractile force and motor unit size?
Larger motor units contain more muscle fibres which generate more force/tension when
activated.
Tension can also be increased by the recruitment of multiple motor units within a
muscle.
Larger muscles have many motor units.
How does motor unit recruitment relate to the size principle?
Smaller motor units have a lower threshold for activation b/c they have smaller motor
neurons. They're also activated at a lower frequency of stimulation from the CNS.
Total muscle tension reflects sum of motor unit activation in a motor neuron pool.
How does increasing stimulation frequency increase muscle force?
Increase in AP produces sustained muscle contraction (eventually) and this provides
max force generation of that muscle.
Temporal summation
COMPLETE SOLUTIONS.
What are the major divisions of the CNS
Cerebrum, diencephalon, brainstem, cerebellum & spinal cord
Cerebrum
consists of cerebral cortex, w/continuous layer of grey matter responsible for higher
functions of the CNS.
Also contains subcortical structures such as the hippocampus (memory and navigation),
amygdala (memory, emotion like fear and anxiety) and some of the basal ganglia.
Diencephalon
Consists of thalamus which relays and integrates info b/t cerebral cortex and the
peripheral senses, spinal cord and the brainstem. The thalamus is where sensory info
except olfaction passes thru before the cortex.
Interacts w/basal ganglia to help modify movement.
Subthalamus
includes subthalamic nuclei (part of the basal ganglia
nuclei
refers to clusters of functionally related neurons.
Brainstem
Hindbrain= pons (main connection to cerebellum) and medulla (keeps you alive)
Midbrain= Tectum (superior colliculi relates to eye movement & inferior colliculi relates
to auditory system tegmentum. Tegmentum ( w/ red nucleus which forms descending
tract called the rubrospinal tract and the substantia nigra which is a part of the basal
ganglia.
spinal cord organization
Spinal cord= protected by the vertebral colum consisting of cervical (C1-C8), Thoracic
(T1-T12), sacral (1-5), coccygeal(1)= 31 total nerves.
The nerves end in the upper lumbar region (L1-L2), nerve roots still exit and follow the
canal in the cauda equina or horses tail bundle.
Cervical= upper limb muscles
Thoracic= muscles of trunk and chest (abd muscles)
Lumbar= lower limb and lower back muscles
Sacral= bowel and bladder muscles (S1+S2 involved in controlling leg muscles.
Cervical and lumbar enlargements--> contain neural circuits responsible for
controlling arms and legs allows for communication for interlimb coordination via
propriospinal neurons.
Cross- sections of spinal cord
,Grey matter--> cell bodies of neurons where information gets processed in the brain.
The structures within the grey matter process signals from the sensory organs or from
other areas of the grey matter. Then this info directs sensory stimuli to the neurons in
CNS where synapses induce a response to the stimuli.
White matter--> myelinated & unmyelinated axons form ascending and descending
tracts. Myelin speeds up the signals between the cells which allows the brain to quickly
send and receive messages.
Sensory vs motor neuron organization within the grey matter
4 types of neurons in spinal cord
local interneurons= axons confined to same or adjacent spinal segment
Propriospinal= axons reach far spinal segments
Projection= axons ascend to higher brain centres
Motor= axons exit nervous system to innervate muscles.
Spinal motor neurons (alpha motorneurons)
activate muscles to execute movement w/ special organization within the spinal cord.
Cell bodies of motor neurons which innervate muscles are clustered in motor neuron
pools to form the longitudinal columns extending over 1-4 spinal segments.
Voluntary Movements and Reflex Motor Patterns
What rule does the spatial organization of different motor nuclei follow?
Proximal-distal rule:
Motor nuclei innervating proximal muscles lie more medially and the ones that innervate
distally lie more laterally within the spinal cord.
Motor nuclei more medial allows for quicker rxns and more laterally allows for an easier
path of travel and quicker rxns.
Spinal cord ascending tracts
carry sensory info (bilateral) on R side of body
Spinal cord descending tracts
carry motor info (bilateral) on L side of body
How does somatosensory information enter the spinal cord?
From peripheral receptors via dorsal roots.
How does motor output enter the spinal cord?
Motor output goes through ventral roots.
How do alpha motor neurons work?
Connect to and contract muscles to allow for movement. Typical muscle is controlled by
around 100 large motor neurons.
What is a motor unit?
Motor neuron + the muscle fibre it innervates.
each muscle fibre is innervated by a single motor neuron @ midpoint of muscle. A
single neuron innervates many muscle fibres.
, Are motor units fast or slow twitch?
They can be both, but slow twitch fibres are recruited first before fast-twitch b/c first
fibres are more prone to get tired quicker.
What is the size of the motor unit dependent on?
It's related to the need for refined movement, more refined movement= fewer
fibres/motor unit.
What does the number of motor units recruited depend on?
How much power is needed for the given movement.
Nerve-muscle synapse (neuromuscular junction)
Highly specialized synapse between a motor neuron nerve terminal and its muscle fiber.
It's responsible for converting electrical impulses generated by the motor neuron into
electrical activity in the muscle fibers.
What is the end-plate?
Where the axon of a motor neuron innervates the muscle and loses its myelinated
sheath dividing into multiple synaptic boutons.
Where does ACH get released in the NMJ?
at the synaptic bouton to allow the channel to open and let sodium in and potassium out
to depolarize and open the gated channels --> AP
How is an action potential generated?
Once the motor neuron is activated, depolarization is spread along the axon which
causes Ca2+ to spread along the synaptic boutons causing a release of ACh. Then the
muscle membrane at the end-plate depolarizes from ACh binding receptors generating
an end-plate potential. This change activates the voltage gated Na+ channels to convert
the AP that propagates along the muscle fibre.
How does the CNS increase muscle force?
- recruit diff size of motor units
- activate more motor units (more motor neurons)
- Increase frequency of AP in muscle fibre which would increase stimulation of alpha
motor neuron.
What is the relationship b/t contractile force and motor unit size?
Larger motor units contain more muscle fibres which generate more force/tension when
activated.
Tension can also be increased by the recruitment of multiple motor units within a
muscle.
Larger muscles have many motor units.
How does motor unit recruitment relate to the size principle?
Smaller motor units have a lower threshold for activation b/c they have smaller motor
neurons. They're also activated at a lower frequency of stimulation from the CNS.
Total muscle tension reflects sum of motor unit activation in a motor neuron pool.
How does increasing stimulation frequency increase muscle force?
Increase in AP produces sustained muscle contraction (eventually) and this provides
max force generation of that muscle.
Temporal summation
