A&P 2.6 Withdrawal Reflex/brain functions Flashcards
Stimulus
Pain
Flexor/withdrawal reflex
Response to pain
Reflex occurs SUBCONSCIOUSLY
7 steps
Sensory receptor
Nocicepter
Sensitive to actual or potential tissue damage
Sensory neuron
Conducts impulse from receptors to CNS
Integrating center
Sensory neurons synapse with interneurons to motor neurons = POLYSYNAPTIC
Sone interneurons conduct impulses up/down the cord to other segments = MULTI SEGMENTAL
Motor neurons
To ALL FLEXORS of a limb; ALL EXTENSORS ARE INHIBITED by reciprocal innervation
Effectors
Flexors
Response
Flexors are stimulated; EXTENSORS are inhibited
Flexor/withdrawal reflex
Additional info
- a painful stimulus causes tissue damage
- tissue damage stimulates a nocicepter that causes a sensory neuron to conduct an impulse
Interneurons conduct impulses up/down the cord
Motor neurons (ventral) exit the cord from many segments
All flexors of a limb contract causing withdrawal
All extensors of a limb relax by reciprocal inhibition
Nocicepters detect
Tissue or potential tissue damage rather than pain
Pain
Defined
Pain is the conscious perception of tissue damage
Brain stem
3 parts
Medulla oblongata
Pons
Midbrain
Medulla oblongata
Most inferior part
Continuous with spinal cord
Contains ascending (dorsal) and descending (ventral) tracts
Contains reflex centers
Vital and non-vital
Vital reflex
3
Breathing
Heart rate
Vasomotor
Non-vital reflexes
3
Coughing
Vomiting
Hiccuping
Pons
“Bridge”
Intermediate
Contains ascending and descending tracts
Contains vital reflex centers: breathing
Midbrain
Most superior, just below diencephalon
Contains ascending & descending tracts
Non-vital reflex centers: turning head in response to loud noises or peripheral movement
Parkinson’s disease
Progressive disorder of the CNS
SHAKING TREMOR. Most common symptom
Diencephalon
2 parts
Thalamus
Hypothalamus
Functions of thalamus
6
Main sensory relay to cerebral cortex (SENSATION versus perception)
All sensation except smell passes through the thalamus
Produces conscious recognition of crude pain, temperature and touch
Emotions (pleasantness/unpleasantness)
Arousal and alertness
Complex reflex movements
Functions of the hypothalamus
6
Control of ANS
control of pituitary gland and production of hormones
Regulation of emotional and behavioral patterns
Regulation of eating and drinking
Control of body temperature
Regulation of circadian rhythms and states of consciousness
Cerebral cortex
General
“Bark” is part of the cerebrum
Outer layer of the cerebrum
Cerebral cortex
Largest and most superior division of the brain
Sensory perception - includes all somatic and special senses
Motor - voluntary motor control of skeletal muscles
Integration- all events that take place in the cerebrum between its reception of sensory impulses and its sending out of motor impulses.
CONSCIOUSNESS, LANGUAGE, SPEECH, EMOTIONS, MEMORIES
ALL AFFECTED BY ALCHOL
Cerebellum
Compares motor impulses from the cerebral cortex with proprioceptive from myofascia
Compares intended movements with what is actually happening
Smooths and coordinates complex sequences of skeletal muscle contractions including posture and balance
