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1/3/2013
BSC 2086L
Anatomy & Physiology
Lab II
Chap 22: Human Reflex Physiology
Chap 23: General Sensation
Chap 22: Reflex Physiology
Reflex Arc: mediated by neural paths (connections of neurons) to yield rapid involuntary muscle response to stimuli
Two main groups of reflexes:
1) Autonomic: mediated thru autonomic nervous sys
(smooth muscles in digestion, glands in sweating)
2) Somatic: involve sensory stimulation that causes skeletal muscles to react (withdrawal reflex from pain) 1
1/3/2013
Components of Reflex Arc
1. Receptor: site of stimulus
2. Sensory neuron: transmits afferent impulse to central nervous system (CNS)
3. Integration center: one or more synapses in CNS
4. Motor neuron: conducts efferent impulse to effector
5. Effector: muscle/glands respond to impulses
Monosynaptic & Polysynaptic Spinal Reflex
Arcs
Spinal reflexes: initiated & completed at spinal cord level without involvement of higher brain centers.
Remember, these are somatic reflexes.
Knee-jerk reflex: utilizes a 2 neuron (sensory and motor neurons)
Flexor reflex: utilizes sensory and motor neurons connected by interneurons arc. 2
1/3/2013
Somatic Reflexes (cont)
Spinal reflex:
1. Stretch reflex: maintains posture/balance & locomotion; tendon stretch causes agonist muscle contraction and antagonistic relaxation.
e.g. Patellar (knee jerk) reflex
2. Crossed extensor reflex: flexion of one limb followed by extension of opposite limb.
3. Superficial cord reflex: result from pain and temperature changes. e.g. Plantar reflex
Somatic Reflexes (cont)
Cranial Nerve Reflex
1. Corneal reflex: a function of cranial nerve V
(trigeminal). Touching of the cornea causes blinking to occur.
2. Gag reflex: a function of cranial nerves IX
(glossopharyngeal) & X (vagus). Touching of the uvula causes gag reflex.
3
1/3/2013
Autonomic Reflexes
Pupillary reflexes: reflex caused by light stimulation of cranial nerve II
BSC 2086L
Anatomy & Physiology
Lab II
Chap 22: Human Reflex Physiology
Chap 23: General Sensation
Chap 22: Reflex Physiology
Reflex Arc: mediated by neural paths (connections of neurons) to yield rapid involuntary muscle response to stimuli
Two main groups of reflexes:
1) Autonomic: mediated thru autonomic nervous sys
(smooth muscles in digestion, glands in sweating)
2) Somatic: involve sensory stimulation that causes skeletal muscles to react (withdrawal reflex from pain) 1
1/3/2013
Components of Reflex Arc
1. Receptor: site of stimulus
2. Sensory neuron: transmits afferent impulse to central nervous system (CNS)
3. Integration center: one or more synapses in CNS
4. Motor neuron: conducts efferent impulse to effector
5. Effector: muscle/glands respond to impulses
Monosynaptic & Polysynaptic Spinal Reflex
Arcs
Spinal reflexes: initiated & completed at spinal cord level without involvement of higher brain centers.
Remember, these are somatic reflexes.
Knee-jerk reflex: utilizes a 2 neuron (sensory and motor neurons)
Flexor reflex: utilizes sensory and motor neurons connected by interneurons arc. 2
1/3/2013
Somatic Reflexes (cont)
Spinal reflex:
1. Stretch reflex: maintains posture/balance & locomotion; tendon stretch causes agonist muscle contraction and antagonistic relaxation.
e.g. Patellar (knee jerk) reflex
2. Crossed extensor reflex: flexion of one limb followed by extension of opposite limb.
3. Superficial cord reflex: result from pain and temperature changes. e.g. Plantar reflex
Somatic Reflexes (cont)
Cranial Nerve Reflex
1. Corneal reflex: a function of cranial nerve V
(trigeminal). Touching of the cornea causes blinking to occur.
2. Gag reflex: a function of cranial nerves IX
(glossopharyngeal) & X (vagus). Touching of the uvula causes gag reflex.
3
1/3/2013
Autonomic Reflexes
Pupillary reflexes: reflex caused by light stimulation of cranial nerve II