Human nervous system parts and functions pdf
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The nervous system controls bodily function by gathering sensory input, integrating that information internally, and communicating proper motor output.
The Human Nervous System
The peripheral nervous system PNS is one of two components that make up the nervous system of bilateral animals , with the other part being the central nervous system CNS. The PNS consists of the nerves and ganglia outside the brain and spinal cord. The peripheral nervous system is divided into the somatic nervous system and the autonomic nervous system. In the somatic nervous system, the cranial nerves are part of the PNS with the exception of the optic nerve cranial nerve II , along with the retina. The second cranial nerve is not a true peripheral nerve but a tract of the diencephalon. However, the remaining ten cranial nerve axons extend beyond the brain and are therefore considered part of the PNS. The peripheral nervous system is divided into the somatic nervous system , and the autonomic nervous system.
The nervous system transmits signals between the brain and the rest of the body, including internal organs. The human brain contains about billion neurons. Bundles of axons, called nerves, are found throughout the body. Axons and dendrites allow neurons to communicate, even across long distances. Different types of neurons control or perform different activities. For instance, motor neurons transmit messages from the brain to the muscles to generate movement.
That suggests it is made of two organs—and you may not even think of the spinal cord as an organ—but the nervous system is a very complex structure. Within the brain, many different and separate regions are responsible for many different and separate functions. It is as if the nervous system is composed of many organs that all look similar and can only be differentiated using tools such as the microscope or electrophysiology. In comparison, it is easy to see that the stomach is different than the esophagus or the liver, so you can imagine the digestive system as a collection of specific organs. The nervous system is involved in receiving information about the environment around us sensation and generating responses to that information motor responses. But there is a third function that needs to be included. Sensory input needs to be integrated with other sensations, as well as with memories, emotional state, or learning cognition.
The nervous system is a network of cells called neurons that coordinate actions and transmit signals between different parts of the body. The nervous system is an organ system that coordinates voluntary and involuntary actions and responses by transmitting signals between different parts of our bodies. Central to the functioning of the nervous system is an extensive network of specialized cells called neurons. Neurons feature many thin projecting fibers called axons, which penetrate deep into tissues. They are able to communicate with other cells by chemical or electrical means at synapses. Neuronal function is supported by neuroglia, specialized cells which provide nutrition, mechanical support, and protection.
Human nervous system , system that conducts stimuli from sensory receptors to the brain and spinal cord and conducts impulses back to other parts of the body. As with other higher vertebrates, the human nervous system has two main parts: the central nervous system the brain and spinal cord and the peripheral nervous system the nerves that carry impulses to and from the central nervous system. In humans the brain is especially large and well developed. Almost all nerve cells, or neurons , are generated during prenatal life, and in most cases they are not replaced by new neurons thereafter. Morphologically, the nervous system first appears about 18 days after conception , with the genesis of a neural plate. Functionally, it appears with the first sign of a reflex activity during the second prenatal month, when stimulation by touch of the upper lip evokes a withdrawal response of the head.
The brain and the central nervous system Every cell in the human body, and neurons in particular, contains organic components e.g. proteins (amino acids).
Peripheral nervous system
The nervous system consists of the brain, spinal cord, sensory organs, and all of the nerves that connect these organs with the rest of the body. Together, these organs are responsible for the control of the body and communication among its parts. The brain and spinal cord form the control center known as the central nervous system CNS , where information is evaluated and decisions made. The sensory nerves and sense organs of the peripheral nervous system PNS monitor conditions inside and outside of the body and send this information to the CNS. Efferent nerves in the PNS carry signals from the control center to the muscles, glands, and organs to regulate their functions.
Nervous system , organized group of cells specialized for the conduction of electrochemical stimuli from sensory receptors through a network to the site at which a response occurs. All living organisms are able to detect changes within themselves and in their environments. Changes in the external environment include those of light , temperature , sound , motion, and odour , while changes in the internal environment include those in the position of the head and limbs as well as in the internal organs.
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