Nervous system is composed of three major parts: the sensory input portion, the central nervous system) or integrated portion), and the motor output portion

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Anatomy and Physiology

The term homeostasis is used to mean maintenance of static or constant conditions in the internal environment in the organism. Essentially all of the organs and tissues of the body perform functions that help to maintain these constant conditions. For instance, the lungs provide oxygen to the extra cellular fluid to replenish oxygen that is being used by the cells; the kidneys maintain constant ion concentrations and the gastrointestinal system provides nutrients.

Not all substances absorbed from the gastrointestinal tract can be used in their absorbed form by the cells. The liver changes the chemical compositions of many of these substances to more useable forms and other tissues of the body – fat cells, gastrointestinal mucosa, kidneys, and endocrine glands - help to modify the absorbed substances or store them until they are needed.

Nervous system is composed of three major parts: the sensory input portion, the central nervous system) or integrated portion), and the motor output portion. Sensory receptors detect the state of the body or the state of the surrounding. For instance, receptors present everywhere in the skin at any point. The eyes are sensory organs that give one a visual image of the surrounding area, for instance human getting image of coming to his direction carriage starts to run to avoid crash. The central nervous system is composed of the brain and spinal cord. The brain is made of three main parts: the forebrain, midbrain, and hindbrain. The forebrain consists of the cerebrum, thalamus, and hypothalamus (part of the limbic system). The midbrain consists of the tectum and tegmentum. The hindbrain is made of the cerebellum, pons and medulla. Often the midbrain, pons, and medulla are referred to together as the brainstem.

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 A large segment of the nervous system is called the autonomic system. It operates at a subconscious level and controls many functions of the internal organs, including level of pumping activity by the heart, movements of the gastrointestinal tract, and glandular secretion. Neurons are cells that act like tiny batteries which power electrical circuits within the body. They can transmit impulses from cell to cell for communication, control, and interpretation of sensory input.

In a typical neuron dendrites respond to stimuli through input to the neuron cell body. When the stimulus is large enough the cell body sends a one ...

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