Autonomic Nervous System Flashcards
Reflex Arc (16 cards)
Somatic nervous system innervates skeletal muscles
ANS innervates cardiac muscle, smooth muscle, and glands
All reflex arcs begin with sensory input.
Explain the source of information for visceral reflex arcs.
Visceral reflex arcs receive information from visceral sensory neurons.
Define the role of visceral sensory neurons in reflex arcs.
Visceral sensory neurons send information about chemical changes, stretch, temperature, and irritation of viscera.
How are receptors for visceral senses structured?
Receptors for visceral senses are free nerve endings widely scattered throughout the viscera.
Where are the cell bodies of visceral sensory neurons located?
Cell bodies are located in dorsal root ganglia and in sensory ganglia of cranial nerves.
Do axons of visceral sensory neurons travel with any other fibers?
Yes, axons travel in the same nerves as autonomic motor fibers, such as the parasympathetic fibers of the vagus nerve.
Explain the components of visceral reflex arcs.
Visceral reflex arcs have the same components as somatic reflex arcs: Receptor, Sensory neuron, Integration center, Motor neuron, Effector.
What are the three main differences between visceral and somatic reflex arcs?
- Visceral reflex arcs have two consecutive neurons in the motor pathway. 2. Afferent fibers are visceral sensory neurons rather than somatic sensory neurons. 3. Effectors are smooth muscle, cardiac muscle, and glands rather than skeletal muscles.
Describe the complexity of autonomic motor endings compared to somatic junctions.
Autonomic motor endings and visceral effectors are simpler than somatic junctions.
What is meant by ‘synapses en passant’ in the context of visceral reflex arcs?
Branches form synapses en passant with effector cells via varicosities.
How do acetylcholine and norepinephrine function in visceral reflex arcs?
Acetylcholine and norepinephrine act indirectly via second messengers.
Compare the speed of visceral motor responses to somatic responses.
Visceral motor responses are slower than somatic responses.
What type of muscles does the somatic nervous system innervate?
The somatic nervous system innervates skeletal muscles.
Identify the types of muscles and glands innervated by the autonomic nervous system (ANS).
The ANS innervates cardiac muscle, smooth muscle, and glands.
