Human Biological Systems, Co-ordination & Control - Essay Example

Different Parts of the Nervous System The human nervous system includes three main parts. These are central nervous system, peripheral nervous system and the autonomic nervous system. The CNS consists of brain and spinal cord while the other two are formed by neurons clusters known as ganglia. The brain is comprised of three major parts. The cerebrum controlling the human senses of touch etc, the cerebellum which controls coordination and balance and the brain stem that provides the linkage between brain and spinal cord as well as controls breathing, heartbeat and digestion.

Spinal Cord is a tube consisting of neurons that move up the spine and links to the brain stem. The signals from the body parts are first conveyed to the spinal cord, from where they are either responded in case of autonomic responses or else are conveyed to the brain. 2. Types of Neurons The neurons or nerve cells are classified on the basis of their function as motor neurons, sensory neurons and inter- neurons. Motor neurons dispatch signals from the CNS to the other body parts. Thus carries a message that has been send by the CNS to generate an appropriate response, sensory neurons convey the external stimuli that triggered the nerve impulse to the CNS.

These stimuli may be sense of taste, hearing, sight, smell, touch and pain. While inter neurons relay information among groups of neurons or neurons for information processing to occur within the brain in a similar way as computer’s logic circuits. They also convey information within the CNS. 3. Nerve Impulse Initiation Animals have various kinds of mechanical stimuli receptors. Each receptor begins nerve impulses within the sensory neurons on going thru a physical deformation introduced by an external stimulus like pressure, touch, stretching, sound waves and motion.

A nerve impulse starts within a living cell by receptor cells. These all possess exceptional voltage-gated sodium channels, but are gated instead by the suitable stimulus either directly or indirectly. For instance: In tongue the sodium channels are chemical-gated which opens the taste receptors on coming in contact with a particular food chemical while sodium channels in the inner ear hair cells are mechanically-gated that are disturbed by sound vibrations. In either case the right stimulus leads to the opening of sodium channel, leading the flow of sodium ions into the cell, causing membrane potential depolarization and ultimately influences the voltage-gated channels of sodium located nearby and initiates an action potential.

Nerve impulses transmission Electrical transmission Neurons receive and send messages from and to one another and the body. This communication takes place via