Nervous System PDF

## Coordinated Functions of Nervous and Endocrine System ### Objectives: - At the end of this lesson, I will be able to - Describe the parts and functions of the nervous system - Differentiate the role of the nervous and endocrine systems together - Recognize the importance of coordinat...

## Coordinated Functions of Nervous and Endocrine System ### Objectives: - At the end of this lesson, I will be able to - Describe the parts and functions of the nervous system - Differentiate the role of the nervous and endocrine systems together - Recognize the importance of coordinated functions of the nervous and endocrine system in maintaining the balance in our body ### Sense Organs - These sense organs are constantly receiving information from the environment and sending messages to the brain. - These senses aid in the survival of human beings. ### Stimuli vs Response - **Stimulus** refers to any factor in the environment that may trigger a nerve impulse. - Stimulus is received by the body and a response is made. - **Response**, on the other hand, is a reaction to a stimulus. - Messages do not travel in both directions along the same neuron. ### Reaction Time - Reaction time is the length of time between the application of a stimulus and the detection of a response. ### Nervous System - The nervous system is composed of: - Brain - Spinal cord - Nerve cells - There are two main parts of the nervous system: - **Central nervous system:** Brain and spinal cord - **Peripheral nervous system:** Nerves that connect the central nervous system to the rest of the body ### Nerve Cells - The nerve cell is the basic unit of the nervous system, also called **neurons**. - There are billions of neurons in the body. - Some exist alone. - Others are joined together to form organs like the brain and spinal cord. - In one part of the brain alone, there are 12-14 billion neurons. - Neurons are specially intended for information processing and signaling - They relay and receive messages (impulse) between the brain and the body, and within the brain and spinal cord. - **Dendrites** carry impulses towards the cell body. - Dendrites are tree-like extensions at the beginning of a neuron that help increase the surface area of the cell body. - **Cell body (soma)** is where the signals from the dendrites are joined and passed on. - The soma and the nucleus do not play an active role in the transmission of the neural signal. - Instead, these two structures serve to maintain the cell and keep the neuron functional. - **Axon** carries impulses away from the cell body. - Axon passes impulses to the dendrites of other neurons or cell body of muscle cells. - Axons can be grouped together into a combination of an electrical charge and a chemical reaction. ### Nerve Impulse - A nerve impulse is a combination of an electrical charge and a chemical reaction. - A nerve impulse is not a flow of electricity, but an electrochemical signal moving along a neuron. - The nerve impulse cannot jump from one neuron to another. - When a nerve impulse comes to an end of an axon, it produces the chemical, called **neurotransmitter**, to be released.  - The chemical crosses the space between neurons called **synapse** and stimulates the nerve impulse to start in the next dendrite.