To defend the body against attack Healing, regeneration and nourishing the body Overall Effect Catabolic breaks down the body Anabolic builds up the body Organs and Glands It Activates The brain, muscles, the insulin pancreas, and the thyroid and adrenal glands The liver, kidneys, enzyme pancreas, spleen, stomach, small intestines and colon Hormones and Substances It Increases Insulin, cortisol and the thyroid hormones Parathyroid hormone, pancreatic enzymes, bile and other digestive enzymes Body Functions It Activates Raises blood pressure and blood sugar, and increases heat production Activates digestion, elimination and the immune system Psychological Qualities Fear, guilt, sadness, anger, willfulness, and aggressiveness. The sympathetic branch mediates this expenditure while the parasympathetic branch serves a restorative function.
Stimulus-response coordination The simplest type of response is a direct one-to-one stimulus-response reaction. A change in the environment is the stimulus ; the reaction of the organism to it is the response.
In single-celled organisms, the response is the result of a property of the cell fluid called irritability. In simple organisms, such as algaeprotozoansand fungia response in which the organism moves toward or away from the stimulus is called taxis.
In larger and more complicated organisms—those in which response involves the synchronization and integration of events in different parts of the body—a control mechanism, or controller, is located between the stimulus and the response.
In multicellular organisms, this controller consists of two basic mechanisms by which integration is achieved—chemical regulation and nervous regulation.
In chemical regulation, substances called hormones are produced by well-defined groups of cells and are either diffused or carried by the blood to other areas of the body where they act on target cells and influence metabolism or induce synthesis of other substances.
The changes resulting from hormonal action are expressed in the organism as influences on, or alterations in, form, growthreproductionand behaviour. Plants respond to a variety of external stimuli by utilizing hormones as controllers in a stimulus-response system.
Directional responses of movement are known as tropisms and are positive when the movement is toward the stimulus and negative when it is away from the stimulus.
When a seed germinates, the growing stem turns upward toward the light, and the roots turn downward away from the light. Thus, the stem shows positive phototropism and negative geotropism, while the roots show negative phototropism and positive geotropism. In this example, light and gravity are the stimuli, and directional growth is the response.
The controllers are certain hormones synthesized by cells in the tips of the plant stems. These hormones, known as auxinsdiffuse through the tissues beneath the stem tip and concentrate toward the shaded side, causing elongation of these cells and, thus, a bending of the tip toward the light.
The end result is the maintenance of the plant in an optimal condition with respect to light. In animalsin addition to chemical regulation via the endocrine systemthere is another integrative system called the nervous system.
A nervous system can be defined as an organized group of cells, called neurons, specialized for the conduction of an impulse—an excited state—from a sensory receptor through a nerve network to an effector, the site at which the response occurs.
Organisms that possess a nervous system are capable of much more complex behaviour than are organisms that do not. The nervous system, specialized for the conduction of impulses, allows rapid responses to environmental stimuli.
Many responses mediated by the nervous system are directed toward preserving the status quo, or homeostasisof the animal. Stimuli that tend to displace or disrupt some part of the organism call forth a response that results in reduction of the adverse effects and a return to a more normal condition.
Organisms with a nervous system are also capable of a second group of functions that initiate a variety of behaviour patterns. Animals may go through periods of exploratory or appetitive behaviour, nest building, and migration. Although these activities are beneficial to the survival of the species, they are not always performed by the individual in response to an individual need or stimulus.
Finally, learned behaviour can be superimposed on both the homeostatic and initiating functions of the nervous system. Intracellular systems All living cells have the property of irritability, or responsiveness to environmental stimuli, which can affect the cell in different ways, producing, for example, electrical, chemical, or mechanical changes.
The responsiveness of a single cell can be illustrated by the behaviour of the relatively simple amoeba. Unlike some other protozoans, an amoeba lacks highly developed structures that function in the reception of stimuli and in the production or conduction of a response.
The amoeba behaves as though it had a nervous system, however, because the general responsiveness of its cytoplasm serves the functions of a nervous system. An excitation produced by a stimulus is conducted to other parts of the cell and evokes a response by the animal. An amoeba will move to a region of a certain level of light.
It will be attracted by chemicals given off by foods and exhibit a feeding response. It will also withdraw from a region with noxious chemicals and exhibit an avoidance reaction upon contacting other objects.
Page 1 of The nervous system is an organ system containing a network of specialized cells called neurons that coordinate the actions of an animal and transmit signals between different parts of its body.
In. Risk of HIV and Sexually Transmitted Infections. The relationship between HSV-2 and the risk of acquiring other sexually transmitted infections (STIs) has long been recognized. IntroductionEmbedded in the mammalian nervous system are neuroanatomical structures related to the expression and experience of social and emotional behavior.
Autonomic Nervous System Testing (ANS) The autonomic nervous system (ANS) regulates physiologic processes, such as blood pressure, heart rate, body temperature, digestion, metabolism, fluid and electrolyte balance, sweating, urination, defecation, sexual response, and other processes.
The nervous system is the body’s prime communication and coordination network and is constantly alive with electricity. The nervous system comprises of three systems, which are defined by anatomy and function.
The three systems are: the central nervous system (CNS), the peripheral nervous system (PNS) and the autonomic nervous system (ANS).
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