Neural Control and Coordination

aflutter run across AND CO-ORDINATION Co-ordination It is the process through which 2 or more organs interact and complement the functions of each other. neuron It is the functional and structural unit of nervous system. Therefore, the nervous system is also known as NEURAL SYSTEM. Neurons with longer projections atomic number 18 said to be the longest cells in our body. There are about coke billion neurons and almost of them exist in the thinker. Some neurons have flask-shaped and are called Purkinje cells. They are found in the cerebellum of brain. Shortly after birth neurons do not develop.A neuron has two main parts to wit a) Cell body or Cyton or Soma It may be up to 13. 5 m in diameter and may be irregular, oval, rounded, etc. Neuroplasm and neurolemma are its cytoplasm and cell membrane. A cyton consists of cell organelles like other cells. Besides, it also has neurofibrils, neurotubules and Nissls granules or bodies. Neurofibrils take part in transmission of itc h Nissls granules or bodies are irregular masses of rough displaceoplasmic reticulum on which free ribosomes and polysomes are attached. Nissls granules probably synthesize protein for the cell. ) Cytoplasmic processes or neuritis They are of two types. 1. Dendrites or dendrons They contain neurofibrils, neutubules and Nissls granules. They conduct nerve propensity towards the cell body and are called afferent processes (receiving processes). They may be one to several. 2. Axon or axis vertebra It is a single long process of uniform thickness. The part of cyton from where the axon arises is called Axon hillock and is the most sensitive part of a neuron. An axon does not have Nissls granules, golgi complex, ribosome, etc. So cyton supplies protein to axon.Its cell membrane and cytoplasm are known as axolemma and axoplasm respectively. Axon ends in a group of branches called terminal arborizations (axon terminals or telodendria). They have synaptic knob to form synapse where ax on and dendrite of two successive neurons can meet. Motor end plate The part of sarcolemma that lies beneath the axon terminals (nerve endings). Axon conducts nerve impulses away from the cell body therefrom called efferent processes. TYPES OF AXON There are two types such as myelinated (medullary) and non-myelinated (non-medullary) In myelinated neurons, the axon is surrounded by myelin sheaths.Myelin sheaths have regular interruptions called node of Ranvier. The space between two successive node of Ranvier is called internodes. Around the myelin sheaths, there is a delicate sheath made up of nucleated cells called Schwann cells. VARIOUS PARTS OF NEURAL SYSTEM It can be divided as important Nervous System (CNS) and Peripheral nervous system (PNS). Central Nervous System The CNS comprises brain and spinal cord. BRAIN It is the anterior most part of the CNS. It lies inside the cranial cavity of the skull. It weighs from 1220 to 1400gms. It has membranes called meninges (sing. eni nx), they are 1) Pia matted It is thin and innermost membrane Sub arachnoid space lies between piamater and arachnoid membrane. Cerebro Spinal unruffled (CSF) is found in this space . It provides medium for exchange of food materials, wastes, respiratory gases, etc. 2) Arachnoid mater It is thin and spider webby. It is the middle membrane. Subdural space lies between arachnoid mater and dura mater. 3) Duramater It is the outermost fibrous membrane. **Fontanales Membranous areas between the cranial bones of foetal skull. Structure of human brain It has triplet parts viz. ) Forebrain or Prosencephalon It includes olfactory lobe, cerebrum and diencephalon Olfactory lobe It lies in the secular lobe. * Function It receives impulses from the nose. Cerebrum It is the largest and most complicated part of the brain . Its outer portion is called the outer cortex and it forms the colour MATTER. Beneath the grey matter, there are millions of medullated (myelinated) nerve fibres. Th ey form white matter. * Function -It creates ideas, touch, perception, reasoning, determination making. * Diencephalon Hypothalamus is located here. Hypothalamus maintains homeostasis.It is also called therefore called THERMOREGULATORY CENTRE OR THERMOSTAT. It keeps body temperature at roughly 37C. 2) Mid-brain or Mesencephalon It comprises cerebellum, pons varolii and medulla oblongata. Cerebellum It is the second largest part of brain and it has purkinje cells. * Function It controls rapid muscular activities like running, talking and typing. Pons varolii It is located above the medulla oblongata. Pneumotaxic centre is present here. **Pneumotaxic centre limits inspiration. medulla oblongata oblongata It continues with spinal cord. * Function It regulates heart rate, blood pressure, etc.