1. Peripheral Nervous System 2. Central Nervous System Nervous System

Human nervous system consists of billions of interconnected cells. Most of these cells are neurons that control and coordinate the whole human behavior. The nervous system is divided into two main parts. 1. The Peripheral Nervous System 2. The Central Nervous System

Peripheral Nervous System 1. The Somatic Nervous System 2. The Autonomic Nervous System Somatic Nervous System; The part of the nervous system that controls voluntary movement. It is the system which directs the organs and muscles to action, such as to move the arm, looking up, running and so on. Autonomic Nervous System; The part of the nervous system that controls involuntary movement( the actions of heart, lungs and other organs).

Autonomic Nervous System It also has two subdivions 1. Sympathetic System 2. Parasympathetic System Sympathetic System; It acts to prepare the body in stress or emergency situations.This response takes the form of “fight or flight”. e.g. a person saw the snake in his path, his sympathetic nervous system cause the increase in heart rate,blood pressure and breathing.

Autonomic Nervous System 2.Parasympathetic Nervous System; It acts to calm the body after the emergency situation is resolved. It causes heart rate to slow down,blood pressure to drop and breathing to become normal. Sympathetic and parasympathetic divisions work in opposition to each other. If one system is arousing the body, the other system is relaxing the body.

The Central Nervous System The central nervous system has two parts 1. The Spinal Cord 2. The Brain Spinal Cord; It is encased in the backbone and has a number of functions to perform. 1. It receives sensory input through the peripheral nerves. 2. It controls all the body’s activities and movements. 3. It control reflexes (Involuntary and rapid actions).

Brain It is also divided into three parts 1. The Brain Stem/ Hindbrain 2. Midbrain 3. The Forebrain The Brain Stem/Hindbrain; It extends from spinal cord and gradually changes into the brain stem, near the junction of the skull. It consists of three parts.

Brain stem/ Hindbrain 1. Medulla; It is important in many activities as heart rate, blood pressure and other bodily actions. It controls tongue movements, taste, touch and position of limbs. 2.Pons; The sensory neurons in the pons receive input from hearing receptors and head position receptors. The pons control jaw movement, certain eye movements and muscle movements involved in facial expressions.

Brainstem/Hindbrain 3.The Cerebellum; This structure receives sensory and other inputs from the spinal cord, brain stem processes this information to many parts of the brain to help make our movements precise, coordinated and smooth. In other words, It is involved in coordination of the motor activity, maintenance of physical postures and the body balance.

2. Midbrain Midbrain; It is relatively small region that connects the hind brain with the forebrain. It appears to function mainly as railway station for messages coming into the brain. It also contains structures that play a role in seeing,hearing and movement.

3. The Forebrain It influences many of the basic life support functions, and higher level behaviors as perception, thought, memory, speech, motivated behavior and fine control of motor movements. Four major regions are as under; 1. Thalamus 2. Hypothalamus 3. Limbic System 4. Cerebrum

The Forebrain 1.Thalamus; It primarily acts as a relay station, mostly messages concerning sensory information,from eyes, ears and skin travel to the thalamus to be communicated upward to higher parts of the brain. 2. Hypothalamus; It helps provide a constant body temperature and monitors the amount of food stored in the cells. It also produces and regulates behavior that is important to survival like eating, drinking,fighting and so on.

The Forebrain 3. Limbic System; Certain structures of the limbic system are involved in emotional behavior like expression of aggression and feelings of pleasure. It is also important for memory.

Cont’d 4.Cerebrum;It is divided into two halves: the right and left hemispheres. The left hemisphere controls the right side of the body and receives impulses from the right side of the body and of the external world ; the right hemisphere controls left side and receives impulses from it.

The Forebrain There are four sections or lobes in each hemisphere 1. The Frontal Lobe; Located at the front center of cortex, containing motor and speech, reasoning and remembering. E.g,in class room giving answer to the questions, you are using your frontal lobes. 2. The Parietal Lobe; It is responsible for interpreting senses such as touch, pain and temperature. 3. The Temporal Lobe; It’s major function is related to hearing e.g, when you hear someone talking, you temporal lobes are operating.

The Forebrain 4.The Occipital Lobe; Located at the back of the brain. It’s major function is related to vision e.g., occipital lobes allow you to interpret what you see in the environment.