A complex nervous system is found in Animals. It is an important system that plays a vital role in every aspect of our life and is responsible for all voluntary and involuntary actions of our body. Logical thinking, reading, remembering feeling emotions, and all other complex activities are guided by the nervous system. The nervous system constitutes the nerve network, spinal cord, and brain. All these organs work together and perform complex activities of the nervous system.
It is a communication network that carries messages to and from the brain and spinal cord to all the parts of the body with the help complex network of nerves. Animal nervous systems are classified into three divisions which are described below−
Central nervous system (CNS)
CNS constitutes the brain and spinal cord
The brain is covered with three membranes namely dura mater, arachnoid, and pia mater.
The parts of humans are the forebrain, the midbrain, and the hindbrain
The cerebrum and diencephalon constitute the forebrain. The forebrain is further divided into the dorsal thalamus and ventral hypothalamus
Our intelligence, thinking, consciousness, memory, imagination, reasoning, and willpower are all controlled by the cerebrum.
Four rounded bodies which are known as corpora quadrigemina and cerebral aqueduct constitute the mid−brain.
The cerebrum, medulla oblongata, and cerebellum formed the hindbrain.
The cerebellum is responsible for body balance and all voluntary movements while the pons controls respiration and sleep cycle.
The cylindrical structure lying in the neural canal of the vertebral column is known as the spinal cord.
Central canal is present in the spinal cord.
Autonomic nervous system (ANS)
ANS has been segregated into the sympathetic and parasympathetic systems
It controls the involuntary function of the internal organ of our body.
Peripheral Nervous System (PNS)
Nerves arising from the spinal cord and the brain together formed the PNS.
Nerves that are emerging from the brain are known as cranial nerves.
Nerves that are emerges from the spinal cord known as spinal nerves
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The functional and structural units of the nervous system are known as neurons. Generally, neurons are known as nerve cells. It is the longest cell in the human body and transmits information in the form of electrical impulses. The neuron is further subdivided into three parts
Cyton − It is the main part of the neuron and is also known as the cell body. Nucleus cytoplasm and cell organelles are present in the cyton.
Dendrites − It is numerous highly branched cytoplasmic extensions arising from the cell body. They conduct impulses towards the cell body and conduct electric impulses outside the cell body
Axon − It is a single, unbranched cylindrical projection that arises from the cyton. The axon is covered with a myelin sheath. It carries impulses away from cyton.
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Responsible for control, command, and coordination in our body− The network of neurons is responsible for receiving and transferring the message and thereby controlling and coordinating the different parts of body
Associated intelligence, thinking, consciousness, memory, imagination, reasoning, and willpower− Our intelligence, thinking, consciousness, memory, imagination, reasoning, and willpower are all controlled by the cerebrum
Controls body balance and voluntary movement− The cerebellum is responsible for body balance and all voluntary movements
Responsible for reflex action− Spinal cord control by spinal cord.
Control involuntary responses to peripheral nerve stimulation− Medulla oblongata controls all involuntary responses like respiration, cardiovascular activity, gastric secretion vomiting, and salivation
The brain is enclosed within the skull and further, it is suspended in a special fluid which is known as the cerebrospinal fluid. It protects the brain from damage and acts as a shock−absorbing fluid. Apart from this it supplies nutrients and removes waste products from the brain
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Nerves are categorized on the basis of their function, structure, and presence and absence of myelin sheath.
Function
Afferent or Sensory Neurons− They carry impulses to CNS from sense organs.
Efferent or Motor Neurons− They carry impulses to effector organs from CNS.
Interneurons or Association− It conducts impulses between afferent and efferent neurons
Structure
Unipolar Neurons− The cell body gives rise to only one nerve possess which act as both dendron and axon.
Bipolar Neurons− The cell body gives rise to two nerve processes of which one acts as an axon while another as a dendron
Multipolar Neuron− The cell body gives rise to an axon and many dendrons.
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Myelin Sheath
Myelinated nerve fiber− Myelin sheath has covered the axon
Non−myelinated nerve fiber− Myelin sheath does not cover the axon.
The nervous system is the most completed network system in the human body. It consists of the central, peripheral, and autonomic nervous systems. It helps us do everyday activities, complex processes, and automatic activities of our body. The nervous system is a communication network that carries messages to and from the brain and spinal cord to all the parts of the body with the help complex network of nerves. The cerebrospinal fluid which is present in the brain help the brain from damage. The neuron is the important unit of life. Neurons are further sub−divided on the basis of functions, structure, and presence and absence of myelin sheath. Nerve−related disorders include numbness, Parkinson's, epilepsy, etc. The disorders affect the nerves as well as the brain. These can be treated by medicines, stimulation, therapy, rehabilitation, and spinal surgery
1. What is the function of the spinal cord?
Ans− Spinal cord controlled the reflex action of the body. It conducts sensory information and motor impulses to and from the brain.
2. What is the location and position of the hypothalamus?
Ans. Hypothalamus is located at the base of the thalamus. Its function is to control involuntary functions. Hormonal secretion, hunger, thirst, sleep, sweating, anger, fear, water balance, and blood pressure are controlled by the hypothalamus.
3. Why is the person under the influence of alcohol not able to maintain correct posture?
Ans− The cerebellum is affected due to the consumption of alcohol. We know the cerebellum is responsible for maintaining body balance. The person under the influence of alcohol is unable to maintain correct posture as the cerebellum functions are affected by alcohol
4. What is a central canal?
Ans− The cerebrospinal fluid-filled cavity of the spinal cord is known as the central canal. It lies below and is connected to the ventricular system of the brain.
5. What is epilepsy?
Ans− Epilepsy is a central nervous system disorder. The person suffering from epilepsy shows periods of abnormal behaviors and sensations. In the case of extreme epilepsy person will lose awareness
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