Physiology II: Somatic nervous system

…: supply skeletal muscle, bring about movement

motor neurons

Axons of motor neurons originate in the … and end on …

spinal cord, skeletal muscle

motor-neuron axon terminals release … to stimulate muscle contraction

Acetylcholine

The level of activity of motor neuron depends on balances of … due to presynaptic inputs

Excitatory postsynaptic potentials and inhibitory postsynaptic potentials

Presynaptic inputs: … (5)

spinal reflex pathways, motor cortex, basal ganglia, cerebellum, brainstem

…: originating with peripheral sensory receptors

spinal reflex pathways

…: originating within the brain (motor regions of the cortex, basal ganglia, cerebellum, the brainstem among others)

descending pathways

The somatic system is under …

voluntary control

Most of the skeletal muscle activity involving: … (3) is automated and subconsciously controlled

posture, balance, stereotypical movements

…: cell bodies of motor neurons, paralysis of muscles innervated by the affected neurons

poliovirus

…: most common moor-neuron disease, degeneration → eventual death of motor neurons → gradual loss of motor control, progressive paralysis, and finally death

amyotrophic lateral sclerosis (ALS)

Site of origin of sympathetic ANS: … (2)

lateral horn of thoracic spine, lumbar spinal cord

Site of origin of parasympathetic ANS: … (2)

brain, sacral spinal cord

Site of origin of SNS: … (2)

Ventral horn, brain

ANS number of neurons from CNS to effector organs two-neuron chain …

preganglionic and postganglionic

SNS number of neurons from CNS to effector organs single neuron …

motor neuron

Organs innervated by ANS: … (4)

cardiac, smooth, exocrine, endocrine

Organs innervated by SNS: …

skeletal muscle

Type of innervation of ANS: … by two antagonistic branches

dual innervation

Type of innervation SNS: …

only motor neurons

ANS neurotransmitter of effector organs: … (2)

ACh, NE

SNS neurotransmitter of effector organs: …

ACh

ANS effects on effector organs: either … or …

stimulation, inhibiton

SNS effects on effector organs: … (inhibiton possible only centrally through IPSP on dendriteds and cell body of motor neurons)

stimulation

ANS type of control: …

involuntary

SNS type of control: … (2)

voluntary, subconscious

ANS higher centers invoved in control: … (4)

spinal cord, medulla, hypothalamus, prefrontal association cortex

SNS higher centers involved in control: … (5)

spinal cord, motor cortex, basal nuclei, cerebellum, brain stem