Week 2 midterm 2 Flashcards
What is a reflex arc?
neural pathways for reflexes
What is the muscle spindle stretch reflex?
the reflex pathway in which muscle stretch initiates a contraction response
What are the 5 neural pathways of a reflex arc?
1. sensor receptor
2. afferent neuron
3. integration center
4. efferent neuron
5. effector organ
Spinal reflexes require what?
require NO input from the brain
Cranial reflexes require what?
require input from the brain (integrated from within)
Genetically programmed in everyones body
learned reflexes - acquired through experience
Have 2 neurons - afferent and efferent (only somatic motor reflexes)
Somatic motor reflexes
Controls the effector - controls skeletal muscles (efferent)
Controls the effector - control smooth and cardiac muscle, glands and adipose tissue (efferent)
One or more interneurons between afferent and efferent neurons (all autonomic reflexes – have 3 neurons)
What is the stretch reflex (aka knee-jerk reflex)
only known monosynpatic reflex
- receptor is a muscle spindle that detects lengthening of the muscle
- tapping the patellar tendon below the knee cap causes the quadriceps in the upper thigh to stretch which excites the muscle spindles, therefore generating AP’s that travel to the spinal cord
What are muscle spindles
stretch receptors that send info to the spinal cord and brain about muscle length and changes in it
What are proprioceptors?
sensory receptors in the subcutaneous tissues that detect motion and position of the body through a stimulus produced within the body (in muscles and joints)
What do extrafusal muscle fibers do?
receptor for stretch and force – most of the muscle and are the major force-generating structure (larger than intra)
What are intrafusal muscle fibers?
found within each muscle spindles, contain afferent receptors for stretch and contractile elements on the ends (smaller than extra)
- central region lacks myofibrils
What is the central region of an intrafusal muscle fiber composed of?
no myofibrils, wrapped with sensory nerve endings stimulated by stretch
What is muscle tone?
the amount of tension in muscles (even a little bit present at rest)
What do sensory neurons do? (X3)
- get activated by sensory input from the environment
- send AP’s to the spinal cord
- continuously activate motor neurons keeping the muscle at a tone
What happens when spindles/muscles stretch?
- causes sensory fibers to fire more rapidly
- more AP generated
- creates a reflex contraction to prevent damage
What keeps muscle spindles alive?
gamma motor neurons
What keeps muscle spindles alive/tense/give them tone?
gamma motor neurons
What do alpha motor neurons do?
largest neurons in the spinal cord, innervate (provide nerves) extrafusal muscle fibers and are directly responsible for initiating their contraction
What are the 4 key things for a successful completion of a voluntary motor task
- development of an idea to move
- putting together a program of motor commands for the movement
- executing the movement
- constant feedback to ensure it was smooth and successful
What does the spinal cord do?
it integrates spinal reflexes and contains central pattern generators
What do the brainstem / cerebellum do?
control postural reflexes and hand / eye movements
What does the cerebral cortex and basal ganglia do?
they are responsible for voluntary movements
What does the thalamus do?
relays and modifies signals (manager) as they pass from the spinal cord, basal ganglia and cerebellum to the cerebral cortex
What do central pattern generators (CPG’s) do?
maintain spontaneous repetitive activity
- neural circuits
- walking, swimming, breathing or chewing
Voluntary movement requires coordination between what 3 things?
- cerebral cortex
- basal ganglia
Voluntary movement requires coordination between what 3 parts of the body?
- cerebral cortex
- basal ganglia
Voluntary movement requires what 4 things?
- knowledge of the bodys position
- a decision to execute
- a plan for execution
- memory of that plan
Limbic system is related to what step of voluntary movement?
Association areas are related to what step of voluntary movement?
Supplementary motor area is related to what 2 steps of voluntary movement?
idea / program
Premotor area is related to what step of voluntary movement?
Primary motor cortex is related to what step of voluntary movement?
Pyramidal tract is related to what step of voluntary movement?
Extrapyramidal tract is related to what step of voluntary movement?
Motor neuron is related to what step of voluntary movement?
Sensory systems are related to what step of voluntary movement?
Cerebellum is related to what step of voluntary movement?
Thalamus is related to what step of voluntary movement?
Basal nuclei are related to what step of voluntary movement?
Brainstem is related to what step of voluntary movement?
What does the pyramidal tract neuron do?
it controls distal extremities: hands, toes, fingers, etc (distal = further away than proximal)
- takes info from upper motor neurons in the cortex and direct lower motor neurons in the spinal cord (directly connected or indirectly connected with interneurons)
- one pathway
- voluntary movement
Why don’t horses have very developed pyramidal tracts?
cause they don’t have hands or toes
Where is the upper motor neuron and what does it do? How does it respond to signals?
- located in the spinal cord
- always excitatory
- receives signal from the upper motor neuron: fires an AP and muscle contracts
- receives no signal: nothing happens, muscle stays at rest
What do extrapyramidal tract neurons do and what kinda inputs do they have?
pathways outside pyramidal tracts
- support voluntary movement of proximal extremeties (closer to the body than distal)
- controls movement of the trunk, neck and legs
- involuntary movement
- indirect input only
What are the 3 pathways for extrapyramidal tracts and where do they go?
- rubrospinal (red): midbrain to spinal cord
- vestibulospinal: vestibular nuclei to spinal cord
- reticulospinal: medualla oblongata to spinal cord
What does the body use for involuntary control over posture?
receives info from the eyes and ears (vestibular system)
- sensory receptors in the skin
- muscles and joints (proprioceptors)
What is the role of the cerebellum? (x4)
- compares actual to planned movements (regulation of motor coordination)
- stores programs for remembered motor activities
- informs the cortex to make corrections
- contributes to muscle tone
Do herbivores or omnivores/carnivores tend to sleep longer/more?
What is the definition of sleep?
a reversible and normal suspension of consciousness
- active process: requires E
What are the most likely reasons for sleep?
- hypotheses why
- conserve E (best/most likely reason)
- allows the body to repair itself
- process memories
- lets brain rest/restore energies
- helps the immune system function
- clearing waste out of the cerebral spinal fluid (especially proteins)
- helps improve performance on tasks and tests
What is electroencephalography?
the electrical activity of the brain
- uses metal discs
What are the 4 stages of sleep?
W: wake stage
REM: rapid eye movement
N1,N2,N3: slow wave or non REM
What is REM sleep (rapid eye movement) stage R?
- every 90 mins
- beta waves
- associated with dreaming
- most likely to wake up during
- eyes move and brain is active
- starts 90 mins after falling asleep and the phases of it get longer throughout the night
- characterized by waves with low amplitude and high frequency
- paralyzes skeletal muscles
What are stages N1 and N2 of non-REM?
- theta waves
- N1 = lightest stage of non-REM sleep
- N2 deeper than N1
What is N3 stage of non REM?
- slow wave / deep sleep
- delta waves
- most difficult to awaken
- high amp, low frequency (opposite to REM)
- adjust body position without command from the brain
Towards the end of sleeping, what stages do you spend in most?
REM and N1
What stages of sleep are you in at first?
N1 and N3
What controls circadian rhythm?
the hypothalamic biological clock