Peripheral and Autonomic Nervous System
Somatic and autonomic divisions, sympathetic and parasympathetic effects. (Biology › Neural Control and Coordination, NEET UG syllabus.)
What is Peripheral and Autonomic Nervous System?
All nerves and ganglia outside the brain and spinal cord, connecting the CNS to the rest of the body.
Key points
- Differentiate between the Somatic and Autonomic Nervous Systems.
- Describe the components and functions of the Somatic Nervous System.
- Explain the roles of the Sympathetic and Parasympathetic Nervous Systems.
- Compare and contrast the effects of sympathetic and parasympathetic stimulation on various organs.
Common exam trap
Confusing sympathetic and parasympathetic effects (e.g., pupil dilation vs. constriction).
Definitions
- Term
Peripheral Nervous System (PNS)
- Meaning
All nerves and ganglia outside the brain and spinal cord, connecting the CNS to the rest of the body.
- Term
Somatic Nervous System (SNS)
- Meaning
The division of the PNS responsible for voluntary control of skeletal muscles and transmitting sensory information from the body to the CNS.
- Term
Autonomic Nervous System (ANS)
- Meaning
The division of the PNS that regulates involuntary functions of internal organs, smooth muscle, and glands to maintain homeostasis.
- Term
Sympathetic Nervous System
- Meaning
A division of the ANS that prepares the body for stressful situations, often termed the 'fight or flight' response.
- Term
Parasympathetic Nervous System
- Meaning
A division of the ANS that conserves energy and promotes normal body functions during periods of rest, often termed the 'rest and digest' system.
- Term
Neurotransmitter
- Meaning
A chemical messenger that transmits signals across a chemical synapse from one neuron to another target cell.
- Term
Acetylcholine (ACh)
- Meaning
The primary neurotransmitter of the parasympathetic nervous system (postganglionic) and at neuromuscular junctions in the somatic nervous system.
- Term
Norepinephrine (NE)
- Meaning
The primary neurotransmitter released by most postganglionic neurons of the sympathetic nervous system.
Learning objectives
Differentiate between the Somatic and Autonomic Nervous Systems.
Describe the components and functions of the Somatic Nervous System.
Explain the roles of the Sympathetic and Parasympathetic Nervous Systems.
Compare and contrast the effects of sympathetic and parasympathetic stimulation on various organs.
Identify the primary neurotransmitters associated with each division of the ANS.
Prerequisites
Basic understanding of neuron structure and function.
Knowledge of the Central Nervous System (brain and spinal cord).
Understanding of nerve impulse transmission.
Common mistakes
Confusing sympathetic and parasympathetic effects (e.g., pupil dilation vs. constriction).
Mixing up the primary neurotransmitters for postganglionic sympathetic (norepinephrine) and parasympathetic (acetylcholine) neurons.
Forgetting that the Somatic NS is voluntary and the Autonomic NS is involuntary.
Not understanding the structural difference between SNS (single neuron) and ANS (two-neuron chain) pathways.
Keywords
PNS
Somatic
Autonomic
Sympathetic
Parasympathetic
Fight or Flight
Rest and Digest
Acetylcholine
Norepinephrine
Voluntary
Involuntary
Cranial Nerves
Spinal Nerves
Homeostasis
Ganglia
Practice preview
During a 'rest and digest' state, which of the following would be observed in the digestive system due to parasympathetic activation?…
medium
The autonomic nervous system is composed of:…
medium
Which of the following statements regarding the autonomic nervous system is INCORRECT?…
hard