The nervous system is the major controlling, regulatory, and communicating system in the body. It is the center of all mental activity including thought, learning, and memory. Together with the endocrine system, the nervous system is responsible for regulating and maintaining homeostasis. Through its receptors, the nervous system keeps us in touch with our environment, both external and internal.
Like other systems in the body, the nervous system is composed of organs, principally the brain, spinal cord, nerves, and ganglia. These, in turn, consist of various tissues, including nerve, blood, and connective tissue. Together these carry out the complex activities of the nervous system.
The various activities of the nervous system can be grouped together as three general, overlapping functions:
- Sensory
- Integrative
- Motor
Millions of sensory receptors detect changes, called stimuli, which occur inside and outside the body. They monitor such things as temperature, light, and sound from the external environment. Inside the body, the internal environment, receptors detect variations in pressure, pH, carbon dioxide concentration, and the levels of various electrolytes. All of this gathered information is called sensory input.
Sensory input is converted into electrical signals called nerve impulses that are transmitted to the brain. There the signals are brought together to create sensations, to produce thoughts, or to add to memory; Decisions are made each moment based on the sensory input. This is integration.
Based on the sensory input and integration, the nervous system responds by sending signals to muscles, causing them to contract, or to glands, causing them to produce secretions. Muscles and glands are called effectors because they cause an effect in response to directions from the nervous system. This is the motor output or motor function.
Answer:
Along with the nervous system, the endocrine system coordinates the body's functions to maintain homeostasis during rest and exercise. The nervous and endocrine systems also work together to initiate and control movement, and all the physiological processes movement involves.
Explanation:
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Of all the body systems, the nervous system is the major control system of homeostasis. It provides monitoring, response, and regulation of all systems in the human body and other organisms. It functions from the tiny level of individual cells to affecting the whole body at once.
Receptors inside and outside the body are constantly monitoring conditions and watching for changes. When a body system leaves a set point and falls outside its normal range, signals are sent through the nervous system which trigger responses to bring the system back into the normal range of functioning. This is the process of homeostasis. These complicated and intricate processes have evolved over millions of years. For example, thermoreceptors and mechanoreceptors in the skin sense changes in temperature and pressure, respectively. Then, signals sent from them to the brain make it possible to detect situations that could cause injury or death. In addition, nerves make muscles contract which moves the bones of the skeleton, making it possible to evade predators and/or fight. This ability to perceive the environment and reacting to it is critical to maintaining homeostasis in the body.
Vision
The nervous system is intricately involved in visual perception which also helps maintain homeostasis. In humans, there is a thin layer of nervous tissue called the retina covering the rear of the inside of the eye. This tissue is populated with millions of photoreceptor cells, ganglion cells, and bipolar cells. The cells detect light and transmit electrical information to the brain via the optic nerve which results in a visual picture. Pupil dilation is also controlled by the nervous system, optimizing the amount of light entering the eye for best vision. Vision allows animals to see and escape danger and find food and mates.
Core Temperature
The nervous system is also responsible for regulating the core temperature of the body. When conditions are too warm and body temperature rises, the blood vessels dilate causing heat loss to the environment. Nerves trigger sweat glands to release fluid that evaporates and cools the skin. Conversely, a drop in core temperature makes blood vessels constrict to conserve heat. The nervous system also triggers muscles to shiver to generate heat and warm the body.
The Autonomic Nervous System
The autonomic nervous system is comprised on the sympathetic and parasympathetic nervous systems which both have critical homeostatic functions. The sympathetic system innervates the heart and increases heart rate and the force of its contractions. It also controls the constriction of blood vessels and dilation of bronchioles in the lungs. The parasympathetic system has the opposite effects on the heart and lungs but is has no effect on blood vessels.
The image above shows the components of the nervous system. Note the green and red dots indicating the structure and function, respectively, within each component.
References
- OpenStax College. [2018]. Anatomy & Physiology. Houston, TX. OpenStax CNX. Retrieved from //cnx.org/contents/
- Nervous System. [n.d.]. In Wikipedia. Retrieved April 8, 2018 from //en.wikipedia.org/wiki/Nervous_system
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Biologydictionary.net Editors. "How Does the Nervous System Maintain Homeostasis." Biology Dictionary, Biologydictionary.net, 15 Apr. 2018, //biologydictionary.net/how-does-the-nervous-system-maintain-homeostasis/.
Biologydictionary.net Editors. [2018, April 15]. How Does the Nervous System Maintain Homeostasis. Retrieved from //biologydictionary.net/how-does-the-nervous-system-maintain-homeostasis/
Biologydictionary.net Editors. "How Does the Nervous System Maintain Homeostasis." Biology Dictionary. Biologydictionary.net, April 15, 2018. //biologydictionary.net/how-does-the-nervous-system-maintain-homeostasis/.