BIPN 100 Lecture Notes - Lecture 8: Golgi Tendon Organ, Alpha Motor Neuron, Gamma Motor Neuron
13 Jun 2018
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BIPN 100 Lecture 8
4/18/2018
• Anatomy of the spinal cord
o Dorsal and lateral columns carry fine touch, pressure, and proprioception to the
brain
o Anterolateral (spinothalamic) carries sensory information, mainly of pain, but
also some pressure
o Ventromedial and dorsolateral tracts carry motor information to the brain
(CNS→body)
• Functions of the spinal cord
o White matter of the spinal cord
▪ Tracts either bringing info in or taking out
o Gray matter of the spinal cord: integrating information (has the cell bodies)
through reflexes
▪ Reflexes: fast, involuntary sequences of actions in response to a stimulus
(spinal and cranial reflexes)
• Perception of what happened happens in the cortex of the brain
later
• Integrated in the spinal cord=spinal reflex
• Integrated in the brain= cranial reflex
▪ Reflex arc: pathway followed by nerve impulses that produce a reflex
(e.g. patellar reflex)
• Components of a reflex
o Sensory receptor: responds to a stimulus by generating a nerve impulse
▪ At the distal end of a sensory neuron or a receptor cell
o Sensory neurons: conducts the AP, the axon terminal is located in the CNS gray
matter
o Dorsal root ganglia→spinal cord interneurons→
o Integrating center: regions of gray matter in the CNS
o Motor neuron: sends efferent signal to the effector
o Effector: responds to the motor nerve impulse (muscle or gland)
▪ Somatic reflexes: effector is skeletal muscle
▪ Autonomic reflexes: effector is smooth muscle, cardiac muscle, or a gland
o Stimulus→conveys sensory information via dorsal root ganglia to →integrating
center in the spinal cord→ventral root→command sent to muscle or
glands→receptors
o Monosynaptic and polysynaptic reflexes exist
• Skeletal muscle reflexes
o Proprioceptors: located in skeletal muscle, joint capsules and ligaments
▪ Input from these go to the CNS through sensory neurons conveying info
on joint movement, muscle tension, and length
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