Nervous System in Mammals: Learn about the mammalian nervous system, its two main types—the central and peripheral nervous systems—their structures, subdivisions, and the vital functions they perform in coordinating body activities
Table of Contents
- Introduction
- Meaning of the Nervous System
- The Two Main Types of Nervous System in Mammals
- Central Nervous System (CNS): Structure and Functions
- Peripheral Nervous System (PNS): Structure and Functions
- Subdivisions of the Peripheral Nervous System and Their Functions
- Differences between somatic and autonomic nervous system
- Summary of the Functions of Each Part
- Revision questions and answers
- Conclusion
Introduction
The nervous system in mammals is a complex and highly organized network that allows the body to detect, process, and respond to both internal and external stimuli. It plays a central role in maintaining homeostasis, coordinating movement, regulating internal organ functions, and controlling sensory experiences, emotions, memory, and intelligence.
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Meaning of the Nervous System
The nervous system in mammals is a highly specialized system composed of the brain, spinal cord, and an extensive network of nerves. It is responsible for detecting environmental changes, transmitting signals to and from various parts of the body, and ensuring appropriate and timely responses through coordination and control. It consists of millions of nerve cells called neurons and supportive cells known as glial cells. These components work together to collect sensory information, interpret it in the brain or spinal cord, and produce appropriate responses such as movement or secretion.
The Two Main Types of Nervous System in Mammals
The mammalian nervous system is broadly divided into two main parts:
- The Central Nervous System (CNS)
- The Peripheral Nervous System (PNS)
Each of these components has its own structure and unique functions that support the overall operation of the nervous system in mammals.
Central Nervous System (CNS): Structure and Functions
The central nervous system (CNS) includes the brain and the spinal cord. This is the control center of the body’s nervous system where information is received, processed, stored, and interpreted before appropriate signals are sent out.
- The brain is the major control organ housed in the skull and is responsible for interpreting sensory data, regulating emotional responses, learning, memory, reasoning, and making decisions.
- The spinal cord runs from the brain down the vertebral column and serves as a pathway for nerve impulses traveling to and from the brain. It also coordinates reflex actions that are quick and automatic.
Functions of the CNS include
- Receiving sensory information from the body through receptors.
- Analyzing, processing, and storing information.
- Initiating voluntary and involuntary motor actions.
- Coordinating complex processes like thought, emotion, and learning.
- Ensuring communication between various parts of the body via the spinal cord.
Peripheral Nervous System (PNS): Structure and Functions
The peripheral nervous system (PNS) consists of all the nerves and ganglia that lie outside the brain and spinal cord. These include cranial nerves (arising from the brain) and spinal nerves (arising from the spinal cord).
Functions of the PNS include
- Carrying sensory information from sense organs to the CNS.
- Transmitting motor commands from the CNS to muscles and glands.
- Facilitating voluntary and involuntary control over body functions.
Subdivisions of the Peripheral Nervous System and Their Functions
The PNS is further divided into two major subdivisions:
- The Somatic Nervous System (SNS)
- The Autonomic Nervous System (ANS)
Each subdivision plays a distinct role in regulating specific body functions.
A. Somatic Nervous System (SNS)
The somatic nervous system consists of nerves that connect the CNS to skeletal muscles and sensory organs. It is primarily involved in voluntary activities, such as walking, talking, and other movements controlled by conscious thought.
Functions of the Somatic Nervous System include:
- Controlling voluntary muscle movements.
- Receiving sensory inputs such as touch, pain, temperature, and position.
- Carrying motor impulses from the CNS to skeletal muscles for action.
B. Autonomic Nervous System (ANS)
The autonomic nervous system controls involuntary body functions such as heartbeat, digestion, and breathing. It operates automatically, without conscious control.
The ANS is further divided into two branches:
- Sympathetic Nervous System – Prepares the body for emergency actions or stress (“fight or flight” response).
- Parasympathetic Nervous System – Maintains body functions during normal conditions (“rest and digest” functions).
Functions of the Sympathetic Nervous System include:
- Increasing heart rate and breathing rate.
- Dilating pupils and airways.
- Stimulating glucose release from the liver.
- Inhibiting digestion and urinary functions during stress.
Functions of the Parasympathetic Nervous System include:
- Decreasing heart rate and respiratory rate.
- Constricting pupils and promoting digestion.
- Stimulating glandular secretions and urinary functions.
- Promoting energy storage and conservation.
Differences between the Somatic and Autonomic Nervous Systems
| Feature | Somatic Nervous System (SNS) | Autonomic Nervous System (ANS) |
|---|---|---|
| Control | Voluntary (under conscious control) | Involuntary (not under conscious control) |
| Effectors | Skeletal muscles | Smooth muscles, cardiac muscles, and glands |
| Function | Controls body movements and receives external stimuli | Regulates internal body processes like heartbeat and digestion |
| Type of Response | Usually involves conscious movement | Involves automatic and reflexive responses |
| Nerve Pathways | Single motor neuron connects CNS to muscles | Usually involves two neurons (preganglionic and postganglionic) |
| Neurotransmitter | Acetylcholine | Acetylcholine and norepinephrine |
| Examples of Activity | Walking, writing, speaking | Breathing, heart rate, pupil dilation, digestion |
Summary of the Functions of Each Part
| Nervous System Part | Components | Function |
|---|---|---|
| Central Nervous System (CNS) | Brain and spinal cord | Interprets sensory input, initiates responses, and coordinates body functions. |
| Peripheral Nervous System (PNS) | Cranial and spinal nerves | Transmits messages to and from the CNS. |
| Somatic Nervous System (SNS) | Nerves to skeletal muscles and sense organs | Controls voluntary movements and receives external stimuli. |
| Autonomic Nervous System (ANS) | Sympathetic and parasympathetic nerves | Regulates involuntary functions like heartbeat and digestion. |
| Sympathetic Nervous System | Autonomic nerves | Prepares body for stress (fight or flight). |
| Parasympathetic Nervous System | Autonomic nerves | Conserves energy, maintains resting state. |
Coordination and Communication in the Nervous System
The mammalian nervous system works through rapid electrochemical signals transmitted along neurons. It provides fast communication throughout the body, controls immediate responses to environmental changes, and maintains internal balance through a delicate coordination between the CNS and PNS.
The neurons are functionally specialized into sensory neurons (which detect stimuli), motor neurons (which initiate actions), and interneurons (which connect neurons within the CNS). These components allow for quick reflexes, controlled actions, memory formation, and learning processes in mammals.
Revision Questions and Answers
- Question: What is the primary function of the somatic nervous system?
Answer: The somatic nervous system primarily controls voluntary movements of skeletal muscles and conveys sensory information from the sense organs to the central nervous system. - Question: How does the autonomic nervous system differ from the somatic nervous system in terms of control?
Answer: The autonomic nervous system functions involuntarily, while the somatic nervous system operates under voluntary control. - Question: Name the two major divisions of the autonomic nervous system.
Answer: The two major divisions are the sympathetic nervous system and the parasympathetic nervous system. - Question: What type of muscles does the autonomic nervous system control?
Answer: The autonomic nervous system controls smooth muscles, cardiac muscles, and glands. - Question: Which neurotransmitter is commonly used by the somatic nervous system?
Answer: Acetylcholine. - Question: Give one example of an activity controlled by the somatic nervous system.
Answer: An example is writing with a pen. - Question: What is the function of the sympathetic nervous system?
Answer: The sympathetic nervous system prepares the body for “fight or flight” responses, such as increasing heart rate and dilating pupils. - Question: What is the role of the parasympathetic nervous system?
Answer: The parasympathetic nervous system promotes “rest and digest” functions by slowing down the heart rate and stimulating digestion. - Question: How many neurons are involved in the autonomic nervous system pathway from the CNS to the effector organ?
Answer: Two neurons – a preganglionic neuron and a postganglionic neuron. - Question: Why is the autonomic nervous system important for survival?
Answer: It maintains vital bodily functions like heartbeat, respiration, and digestion without conscious effort, ensuring the body’s internal environment remains stable.
Conclusion
The nervous system in mammals is a sophisticated and highly organized network made up of the central nervous system and the peripheral nervous system, which includes the somatic and autonomic branches. Each part plays a unique and critical role in ensuring the mammal’s survival, adaptation, awareness, and proper functioning. Its design allows for the integration of sensory input, motor output, and internal regulation, making it one of the most vital systems in the mammalian body.