In this article, you will get a great idea about the topic concerned with the central nervous system and the peripheral nervous system. Thus, the students will be beneficial in attaining neural control and coordination class 11 notes.
It is an important topic of human physiology. The nervous system constituting neurons have great significance and one should understand all the basics and functional parts of the nervous systems including classification of neurons in order to perform well in the examinations and this topic is well covered in the NEET MCQs too.
The process through which two or more organs can interact and complement the functions of one another is called coordination. When we are exercising, the supply of oxygen as well as demand of energy increases with increase in muscular activity. When we stop physical exercise, all activities of nerves, heart, lungs and kidney are normalized. Therefore, the functions of all the organs are well coordinated to perform physical exercise and render necessary conditions during the physical exercise. Similarly, in our bodies, the neural system and the endocrine system together coordinate and integrate all the organs’ activities to function in a synchronized manner.
The neural system or nervous system is an organised network of point-to-point connections for quick coordination and the endocrine system is the requirement for a chemical integration through hormones. In this article, we will discuss the human neural system and the mechanisms of neural coordination.
All the following topics are well covered in Neural control and coordination NCERT books for class 11.
Highly specialised cells known as neurons that have the role to detect, receive and transmit various kinds of stimuli are present in the neural system of all animals. In lower vertebrates such as Hydra, the nervous system organisation is very simple with a network of neurons. In insects, it is better organised where the brain consists of numerous ganglia and neural tissues. Ganglia is the collection of cell bodies outside the central nervous system. On the other hand, vertebrates have a more developed nervous system.
Neurons can be unipolar, bipolar and multipolar.
Central nervous system includes the brain and the spinal cord. Also referred as CNS, it is the site for processing information and control.
Brain comprises cerebrum, cerebellum, medulla oblongata, midbrain and brainstem. Brainstem performs vital functions like regulation of temperature and helps hypothalamus in functioning. Cerebrum helps in memory and cerebellum functions in regulation.
Peripheral nervous system includes autonomic nervous system (involuntary) and somatic system (voluntary). It comprises the two kinds of nerve fibers associated with CNS, namely, afferent fibres and efferent fibres.
The somatic neural system (SNS) transmits impulses from the CNS to skeletal muscles and the autonomic neural system (ANS) relays impulses from the CNS to involuntary organs and smooth muscles of the body. ANS is further divided into sympathetic nervous system and parasympathetic nervous system. The former one works during fight, fright and flight (3F) conditions. The latter works during rest or digest conditions.
A neuron is the microscopic structure that consists of three important structures which are the cell body, dendrites and axon.
Cell Body: It contains cytoplasm with typical cell organelles as well as certain granular bodies called Nissl’s granules.
Dendrites: These are the short fibres containing Nissl’s granules that project out of the cell body. Dendrites are responsible to transmit impulses towards the cell body.
Axon: It is a long fibre and its distal end is branched. Each of its branches terminates as a bulb-like structure called synaptic knob that possess synaptic vesicles that have chemicals called neurotransmitters that follow unidirectional flow. The two types of axons are myelinated and non-myelinated nerve fibres; the myelinated one are enveloped with Schwann cells forming a myelin sheath around the axon and found in spinal and cranial nerves. Nodes of Ranvier is the term given to the gaps between two adjacent myelin sheaths. Non-myelinated nerve fibre doesn’t form a myelin sheath around the axon but contains Schwann cells, and is found commonly in ANS and SNS.
The role of axons is to transmit nerve impulses away from the cell body to a synapse or to a neuro-muscular junction.
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Depending on the number of axons and dendrites, the neurons can be classified into three types which are as follows:
Multipolar Neurons: it consists of one axon and 2 or more dendrites and is found in the cerebral cortex.
Bipolar Neurons: It consists of one axon and one dendrite and is found in the retina of the eye.
Unipolar Neurons: It is the cell body with only one axon and is found in the embryonic stage.
This topic is very elaborately explained in the neural coordination chapter in the NCERT books for class 11. Here, we understand a bit of it which can be included in neural control and coordination notes.
Neurons are excitable cells and are called so because they conduct electricity.
Their membranes are polarised and different types of ion channels are present in the neural membrane called axolemma. These ions are selectively permeable to different ions.
Resting membrane potential is the resting state when a neuron is not conducting any impulse. The axonal membrane is more permeable to Potassium ions (K+) and nearly impermeable to sodium ions (Na+).
1. What is a Synapse?
A synapse is nerve impulse transmitted from one neuron to another neuron through junctions. It is formed by the pre-synaptic and post-synaptic neuron membranes. Synapses may or may not be separated by a gap known as synaptic cleft. Two different kinds of synapses called electrical synapses and chemical synapses are known where the former one involves pre-synaptic and post-synaptic neurons in close proximity whereas in the latter, the membranes are separated by synaptic cleft, i.e. a fluid-filled space.
2. What is the Central Neural System?
Brain is the central information processing unit or organ of our body acting as the command and control center. It is under safety as it is protected by the skull and is divided into three major parts, namely, forebrain, midbrain and hindbrain. Brain takes care of the voluntary movements, functioning of vital involuntary organs and helps in balancing the body.