Autonomic Nervous System (ANS) Study Guide
• List another name for the ANS and describe how that name exemplifies its function
- Also called visceral motor system – regulates what happens inside body, are automatic and
are involuntary
• List the organs that are controlled by the ANS
- Glands – sweat glands, sebaceous glands, endocrine glands, salivary glands
- Cardiac muscle
- Smooth muscle that lines digestive tract, blood vessels, urinary bladder
• Describe the functions of the ANS
- Regulates unconscious processes that maintain homeostasis – BP, body temp, respiratory
airflow
- Receptors detect internal stimuli – stretch etc
• Regulates unconscious processes that maintain homeostasis
• Define biofeedback and visceral reflexes
- Conscious control of ANS
- Visceral reflexes – unconscious automatic responses to stimulation of glands, cardiac, or
smooth muscle
• Explain the pathway of ANS stimulation and response
- Receptors
o Detect internal stimuli – stretch, blood chemicals, etc.
- 2. Afferent neurons
o Transmit sensory signals to interneurons in the CNS
- 3. Efferent neurons
o Carry motor signals to effects
o ANS is the efferent neurons of these reflex arcs
- 4. Effectors
o Glands, smooth, or cardiac muscle
o ANS modifies effector activity, rather than causing
• List the effectors of the ANS
- Glands, smooth or cardiac muscle
• ANS modifies effector activity, rather than causing it
• List the ANS component of a visceral reflex arc and the number of neurons involved
- 2 neurons span the distance from CNS to effectors
o Presynaptic neuron cell body located in CNS
▪ Brain or spinal cord
o Postsynaptic neuron cell body in peripheral ganglion
• 2 neurons span the distance from CNS to effectors
, • Contrast somatic and autonomic pathways
- Somatic pathways only one neuron located in CNS, axon goes to effector (skeletal muscle)
- Autonomic pathways – 2 neurons, one located in CNS and will synapse with post synaptic
neuron will transmit signal to effector
• List the divisions of ANS and their alternate names – how are the alternate names descriptive of
these divisions?
- Two divisions innervate same target organs – can be cooperative or contrasting effects
- 1. Sympathetic division (thorocolumbar division) thoroco – thoracic lumbar – lower back
o Fight or flight
o Prepares body for physical activity
▪ Increases HR, BP, airflow, blood glucose levels
- 2. Parasympathetic division (craniosacral division) cranio – head sacraum – sacral division – nerves
are cranial or spinal nerves from sacral region
o Rest and digest
o Calms many body functions, assists in bodily maintenance
o Digestion and waste elimination
- Neither has universally or excitatory or calming effects
o IE sympathetic division excites the heart but inhibits digestive and urinary functions
- Effects of each depend on neurotransmitters
• Describe what is meant by autonomic tone and give an example
- Normal rate of activity that represents the balance of the two systems
- This balance shifts depending on the needs of the body
- Sympathetic tone – keeps most blood vessels partially constricted
o Maintains BP
o Loss of sympathetic tone can cause a rapid drop in BP causing a person to go into
shock
• Describe the anatomy of the sympathetic ns
- Origin of presynaptic neurons
o Lateral horns of gray matter of thoracic to lumbar cord
o Fibers exit via spinal nerves T1-L2 leading to
- Sympathetic chain ganglia
o Paravertebral ganglia
o On average 3 cervical, 11 thoracic, 4 lumbar, 4 sacral and 1 coccygeal
o 2 branches called white and gray communicating rami suspend ganglia from spinal
nerve
• Illustrate paravertebral ganglia and how many associated with each spinal cord region
• Characterize the pathways of SNS preganglionic fibers
- Small myelinated preganglionic fibers travel from the spinal nerve to the white
communicating ramus, then enter ganglia
o Some synapse immediately with postganglionic fiber
o Some travel to higher or lower ganglia & synapse
• List another name for the ANS and describe how that name exemplifies its function
- Also called visceral motor system – regulates what happens inside body, are automatic and
are involuntary
• List the organs that are controlled by the ANS
- Glands – sweat glands, sebaceous glands, endocrine glands, salivary glands
- Cardiac muscle
- Smooth muscle that lines digestive tract, blood vessels, urinary bladder
• Describe the functions of the ANS
- Regulates unconscious processes that maintain homeostasis – BP, body temp, respiratory
airflow
- Receptors detect internal stimuli – stretch etc
• Regulates unconscious processes that maintain homeostasis
• Define biofeedback and visceral reflexes
- Conscious control of ANS
- Visceral reflexes – unconscious automatic responses to stimulation of glands, cardiac, or
smooth muscle
• Explain the pathway of ANS stimulation and response
- Receptors
o Detect internal stimuli – stretch, blood chemicals, etc.
- 2. Afferent neurons
o Transmit sensory signals to interneurons in the CNS
- 3. Efferent neurons
o Carry motor signals to effects
o ANS is the efferent neurons of these reflex arcs
- 4. Effectors
o Glands, smooth, or cardiac muscle
o ANS modifies effector activity, rather than causing
• List the effectors of the ANS
- Glands, smooth or cardiac muscle
• ANS modifies effector activity, rather than causing it
• List the ANS component of a visceral reflex arc and the number of neurons involved
- 2 neurons span the distance from CNS to effectors
o Presynaptic neuron cell body located in CNS
▪ Brain or spinal cord
o Postsynaptic neuron cell body in peripheral ganglion
• 2 neurons span the distance from CNS to effectors
, • Contrast somatic and autonomic pathways
- Somatic pathways only one neuron located in CNS, axon goes to effector (skeletal muscle)
- Autonomic pathways – 2 neurons, one located in CNS and will synapse with post synaptic
neuron will transmit signal to effector
• List the divisions of ANS and their alternate names – how are the alternate names descriptive of
these divisions?
- Two divisions innervate same target organs – can be cooperative or contrasting effects
- 1. Sympathetic division (thorocolumbar division) thoroco – thoracic lumbar – lower back
o Fight or flight
o Prepares body for physical activity
▪ Increases HR, BP, airflow, blood glucose levels
- 2. Parasympathetic division (craniosacral division) cranio – head sacraum – sacral division – nerves
are cranial or spinal nerves from sacral region
o Rest and digest
o Calms many body functions, assists in bodily maintenance
o Digestion and waste elimination
- Neither has universally or excitatory or calming effects
o IE sympathetic division excites the heart but inhibits digestive and urinary functions
- Effects of each depend on neurotransmitters
• Describe what is meant by autonomic tone and give an example
- Normal rate of activity that represents the balance of the two systems
- This balance shifts depending on the needs of the body
- Sympathetic tone – keeps most blood vessels partially constricted
o Maintains BP
o Loss of sympathetic tone can cause a rapid drop in BP causing a person to go into
shock
• Describe the anatomy of the sympathetic ns
- Origin of presynaptic neurons
o Lateral horns of gray matter of thoracic to lumbar cord
o Fibers exit via spinal nerves T1-L2 leading to
- Sympathetic chain ganglia
o Paravertebral ganglia
o On average 3 cervical, 11 thoracic, 4 lumbar, 4 sacral and 1 coccygeal
o 2 branches called white and gray communicating rami suspend ganglia from spinal
nerve
• Illustrate paravertebral ganglia and how many associated with each spinal cord region
• Characterize the pathways of SNS preganglionic fibers
- Small myelinated preganglionic fibers travel from the spinal nerve to the white
communicating ramus, then enter ganglia
o Some synapse immediately with postganglionic fiber
o Some travel to higher or lower ganglia & synapse
