The Brain and its Functions
The brain is the anterior-most part of the central nervous system. It is located inside the cranial cavity. It weighs 1220-1400 grams. It has the following meninges/protective coverings.1)Dura mate...
Autonomic Nervous System and Peripheral Nervous System
The part of the nervous system that regulates the involuntary activities of the human body parts is called autonomic nervous system. It supplies stimulation to involuntary muscles and two clans of the body via and motor nerves. The activities of autonomic nervous system is controlled by medulla oblongata and hypothalamus of the brain. Physiologically, it is divisible into two separate systems which have opposite effects on the same organs they are sympathetic and parasympathetic nervous system.
| Sympathetic Nervous System | Para-sympathetic Nervous System |
| Its action is a quick response. | Its action is a slow response. |
| It generates excitatory homeostatic effects. | It generates inhibitory homeostatic effects. |
| Pre-ganglionic fibers are short. | Pre-ganglionic fibers are long. |
| Post-ganglionic fibers are long. | Post-ganglionic fibers are long. |
| Ganglia are nearer to the spinal cord. | Ganglia are farther from the spinal cord. |
| Post-ganglionic fibers are found in large numbers. | Post-ganglionic fibers are found in fewer numbers. |
| It covers a large area of the body. | It covers the smaller area in the body. |
| It increases the rate of glycogen breakdown. | It decreases the rate of glycogen breakdown. |
| It increases the activity of the digestive system. | It decreases the activity of the digestive system. |
Peripheral Nervous System
1) Cranial nerves: The nerves arising from the brain are called cranial nerves. There are 12 pairs of cranial nerves in humans. They arise from the ventral side of the brain.
2) Spinal nerves: The nerves arising from the spinal cord are called spinal nerves. There are 31 pairs in humans. Spinal nerves emerge from sides of the spinal cord and find their way through the vertebra into the corresponding muscle segments.
