the bodily system that consists of the endocrine glands and functions to regulate body activities
any of the bundles of fibres made up of neurons that carry sensory and motor information throughout the body in the form of electrical impulses
a tissue composed of fibres capable of contracting to effect bodily movement
the watery mixture of secretions from the salivary and oral mucous glands that lubricates chewed food, moistens the oral walls, and contains ptyalin
the ability or tendency of an organism or cell to maintain internal equilibrium by adjusting its physiological processes
the part of the central nervous system lodged in the vertebral canal, extending from the foramen magnum to the upper part of the lumbar region
an aggregation of cells specialized to secrete or excrete materials not related to their ordinary metabolic needs
the number of heartbeats per unit of time, usually expressed as beats per minute
any of several complex proteins that are produced by cells and act as catalysts in specific biochemical reactions
the portion of the central nervous system that is enclosed within the cranium
Match the following Ukrainian words and word combinations with the English ones.
пучки нервових волокон
автономна нервова система
to stimulate the secretion of saliva
to increase heart rate
bundles of nerve fibres
parasympathetic nervous system
парасимпатична нервова система
autonomic nervous system
The nervous system is the major controlling, regulatory, and communicating system in the body. It is the centre 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 they 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, and 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. 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.
The nervous system as a whole is divided into two subdivisions: the central nervous system (CNS) and the peripheral nervous system (PNS). The brain and spinal cord are the organs of the central nervous system. Because they are so vitally important, the brain and spinal cord, located in the dorsal body cavity, are encased in bone for protection. The brain is in the cranial vault, and the spinal cord is in the vertebral canal of the vertebral column. Although considered to be two separate organs, the brain and spinal cord are continuous at the foramen magnum.
The peripheral nervous system is composed of nerves and ganglia. Nerves are bundles of nerve fibres, much like muscles are bundles of muscle fibres. Ganglia are collections, or small knots, of nerve cell bodies outside the CNS. The PNS consists of 12 pairs of cranial nerves, which carry impulses between the brain and the head and neck, and 31 pairs of spinal nerves, which carry messages between the spinal cord and the chest, abdomen, and extremities. The peripheral nervous system is further subdivided into an afferent (sensory) division and an efferent (motor) division. The afferent division transmits impulses from peripheral organs to the CNS. The efferent division transmits impulses from the CNS out to the peripheral organs to cause an effect or action. Finally, the efferent division is again subdivided into the somatic nervous system and the autonomic nervous system. The somatic nervous system, also called the somatomotor or somatic efferent nervous system, supplies motor impulses to the skeletal muscles. Because these nerves permit conscious control of the skeletal muscles, it is sometimes called the voluntary nervous system. The autonomic nervous system, also called the visceral efferent nervous system, supplies motor impulses to cardiac muscle, to smooth muscle, and to glandular epithelium. It is further subdivided into sympathetic and parasympathetic divisions. The sympathetic nervous system is involved in the stimulation of activities that prepare the body for action, such as increasing the heart rate, increasing the release of sugar from the liver into the blood, and other activities generally considered as fight-or-flight responses (responses that serve to fight off or retreat from danger). The parasympathetic nervous system activates tranquil functions, such as stimulating the secretion of saliva or digestive enzymes into the stomach and small intestine. Because the autonomic nervous system regulates involuntary or automatic functions, it is called the involuntary nervous system.