The Nervous System


Sensory. The sensory function of the nervous system involves collecting information from sensory receptors that monitor the body's internal and external conditions. ...

Integration. ...


Parts of the system



Spinal Cord

5 Interesting/fun facts

Did you know....

- There are more nerve cells in the human brain than there are stars in the Milky Way.
- If we lined up all the neurons in our body it would be around 600 miles long.
- There are 100 billion neurons in your brain alone.
- A newborn baby's brain grows almost 3 times during the course of its first year.
- The left side of human brain controls the right side of the body and the right side of the brain controls the left side of the body.
- A New born baby
loses about half of their nerve cells before they are born.
- As we get older, the brain loses almost one gram per year.
- There are about 13, 500,00 neurons in the human spinal cord.
- The total surface area of the human brain is about 25, 000 square cm.

How the system helps to maintain homeostasis?

Since the nervous system does not store nutrients, it must receive a continuous supply from blood. Any interruption to the flow of blood may bring brain damage or death. The nervous system maintains homeostasis by controlling and regulating the other parts of the body. A deviation from a normal set point acts as a stimulus to a receptor, which sends nerve impulses to a regulating center in the brain. The brain directs an effector to act in such a way that an adaptive response takes place. If, for example, the deviation was a lowering of body temperature, the effector acts to increase body temperature. The adaptive response returns the body to a state of normalcy and the receptor, the regulating center, and the effector temporarily cease their activities. Since the effector is regulated by the very conditions it produced, this process is called control by negative feedback.

This manner of regulating normalcy results in a fluctuation between two extreme levels. Not until body temperature drops below normal do receptors stimulate the regulating center and effectors act to raise body temperature. Regulating centers are located in the central nervous system, consisting of the brain and spinal cord . The hypothalamus is a portion of the brain particularly concerned with homeostasis; it influences the action of the medulla oblongata, a lower part of the brain, the autonomic nervous system, and the pituitary gland.

The nervous system has two major portions: the central nervous system and the peripheral nervous system (table 3). The peripheral nervous system consists of the cranial and spinal nerves. The autonomic nervous system is a part of peripheral nervous system and contains motor neurons that control internal organs. It operates at the subconscious level and has two divisions, the sympathetic and parasympathetic systems. In general, the sympathetic system brings about those results we associate with emergency situations, often called fight or flight reactions, and the parasympathetic system produces those effects necessary to our everyday existence

How the systems work with the other systems?

Skeletal system

Cardiovascular system

Muscular System

Endocrine System

Lymphatic System

Respiratory System

Digestive System

Reproductive System

Urinary System

Integumentary System