NERCOUS COORDINATION: INTRODUCTION, DIFFERENCES, COMPONENTS, ORGANIZATIONS, CENTRAL NERVOUS SYSTEM, PERIPHERAL NERVOUS SYSTEM

The nervous system detects and interprets changes in conditions inside and outside the body and responds to them.
All nervous system activities consists of signals passed through pathways of inter connected neurons. Thus nervous co-ordination is the transfer of messages round the body of an organism means of nerves.
The nervous system and the endocrine system work together very closely to bring about co-ordination of activities.

DIFFERENCES BETWEEN THE NERVOUS AND ENDOCRINE CO-ORDINATION
1. Messages pass mainly as electrical impulses along nerves in nervous system while in endocrine systems, messages pass as chemical substances in the bloodstream.
2. In nervous system, transmission is along nerve fibres and is very rapid but in endocrine system, transmission is along the circulatory system and is generally slow.
3. In nervous system, effectors such as muscles and glands receive the message but in endocrine system, target organs receive the message.
4. In nervous system, response is immediate, short lived and very precise but in endocrine system, response is usually slow, long lasting and diffuse.
5. In nervous system, responses are usually localized and temporary but in endocrine system, responses are often widespread and permanent.

COMPONENTS AND ORGANIZATION OF NERVOUS SYSTEM
The nervous system is made up of two main parts- the central nervous system and the peripheral nervous system.

The central nervous system analyses information and initiates responses while the peripheral nervous system gathers information and carries the response signals. Some responses are involuntary while others are dictated by conscious thought.

THE CENTRAL NERVOUS SYSTEM
The central nervous system comprises of the Brain and the Spinal cord.

The spinal cord is a long tubular structure which extends from the medulla oblongata to the tail region. It has a small central canal containing cerebrospinal fluid. Unlike the brain, the spinal cord is made up of grey matter on the inside surrounded by white matter on the outside. The grey matter is H shaped and centrally placed. There are two fissures, namely the dorsal fissure and the ventral fissure.

The ventral fissure is wide while the dorsal fissure is actually a septum. A series of 31 pairs of nerves joined the spinal cord at various points along it. All cell bodies in the spinal cord are found in the ganglia.

FUNCTIONS OF THE SPINAL CORD
1. The centre of reflex action.
2. Transmits impulses to the brain.

COMPONENTS OF THE BRAIN AND THEIR FUNCTION
The mammalian brain
The three main regions of the brain are;
1. The fore brain which consists of the olfactory lobe and cerebrum.
2. The mid brain which consists of the optic lobes where the thalami and hypothalamus are situated.
3. The hind brain which consists of the cerebellum and the medulla.

PARTS OF THE BRAIN AND THEIR FUNCTIONS
THE CEREBRUM: This controls all voluntary actions, intelligence, willpower, memory, learning ability and speech.
THE OLFACTORY LOBE: This interprets smell.
THE CEREBELLUM: This co-ordinates and controls movement of the body muscles.
THE HYPOTHALAMUS: This controls water balance and temperature, regulates emotion, hunger and sleep.
THE MEDULLA OBLONGATA: This controls involuntary movement e.g. respiration, heartbeat, digestion and peristalsis.

THE PERIPHERAL NERVOUS SYSTEM
This is made up of;
The sensory system which consists of sensory receptors and sensory or afferent neurones that connect the receptors to the central nervous systems and;
The motor system which consists of motor or efferent neurones.

The Motor System can be subdivided into
• The somatic nervous system consisting of motor neurones (12 pairs of cranial nerves and 31 pairs of spinal nerves) that transmit impulses from our receptors to the central nervous system or from the central nervous system to all the skeletal and;
• The Autonomic nervous system which consists of motor neurones that carry impulses to involuntary muscles and various glands thus responsible for detecting certain conditions in the internal environment and bringing about appropriate changes in them. The autonomic nervous system is further grouped into
• The Parasympathetic system which operates during normal relaxed circumstances; and
• The sympathetic system which takes over under stressful situations and during emergencies.

Functions
Somatic Nervous System
• It transmits impulses from receptors to the central nervous system and
• From the central nervous system to the skeletal muscles.

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