Psychology
Hormones
Hormones are chemical messengers produced by the endocrine system that regulate various bodily functions and behaviors. In psychology, hormones play a crucial role in influencing emotions, stress responses, and overall mood. They can impact cognitive processes, such as memory and learning, and are also involved in the regulation of sleep and appetite.
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6 Key excerpts on "Hormones"
eBook - ePub- Gail Anderson(Author)
- 2019(Publication Date)
- CRC Press(Publisher)
7 The chemistry of the body The effects of Hormones on behavior Introduction This chapter is one of several that considers the areas of biology that do not directly deal with genetics, although Hormones and neurotransmitters are controlled by genes. It first provides a brief overview of the normal function of Hormones and how they influence behavior. There is a very fine control kept on hormone levels through negative feedback mechanisms, and this system in turn is one of the controls of behavior. One of the most hotly contested areas in biological criminology relates to the so-called male and female Hormones, as well as their relationships with other Hormones. Hormone imbalances are treated medically every day, which means that as greater understanding is achieved, better interventions may be developed. The functions of Hormones Hormones (from the Greek word hormon, meaning to excite or to set in motion) are chemical signals. They are released into the blood by endocrine cells (the building blocks of the endocrine system, which include the hypothalamus, pituitary, and thyroid glands) and neurosecretory cells, which are specialized nerve cells that also make Hormones. These cells sometimes release the Hormones directly, but they also often store them in a gland for later release (for example, the digestive glands or the pancreas). Once something gets into the bloodstream, it will reach every cell in the body, because that is what the blood is designed to do—to take oxygen and nutrients to every single cell and take away waste products, such as carbon dioxide and nitrogenous waste. However, although the Hormones will get to every cell, only certain types of cells, the target cells for that particular hormone, will respond. The other cells will ignore it
eBook - ePubStress and Your Health
From Vulnerability to Resilience
- Hymie Anisman(Author)
- 2015(Publication Date)
- Wiley-Blackwell(Publisher)
5 Hormones and What They DoHormonal release to deal with stressors
Humans and animals have exquisitely well-integrated adaptive neurobiological systems that allow us to deal with stressors. We even have compensatory processes that kick in when a primary system stops operating effectively. Yet, each of us has weaknesses owing to genetic factors, prenatal or early postnatal experiences, or responses that developed over time when the stress load became excessive. The weak link in one individual might not be the same as that in a second, and thus identical stressors may elicit different outcomes. For one individual this might comprise processes leading to psychological disturbances, and for another it might promote the development of immunological, cardiovascular, muscular, or gastrointestinal illnesses. In some unfortunate individuals stressors might increase vulnerability to several pathological conditions.Hormones comprise biochemical substances that are secreted from glands or cells in the body and in the brain in response to internal signals, such as altered sugar levels in the blood, as well as environmental stimuli, such as stressors. They operate to help the body meet its needs, including the activation of metabolic processes, initiation and cessation of eating, regulation of immune activity, preparing the body for transitional phases of life (puberty, parenting, bonding, menopause), and the functioning of reproductive processes, and they contribute to cell growth and the normal course of cell death. They also affect our ability to contend with stressful events by influencing our readiness to make appropriate behavioral or emotional responses, modifying cognitive processes and promoting physiological changes, including energy regulation, as well as immune and heart functioning. That’s a pretty impressive load for these tiny chemical molecules, but weak links may be present so that hormonal dysfunctions might occur in the context of stressful situations, thereby increasing vulnerability to illnesses of one form or another.
eBook - ePubAdaptive Origins
Evolution and Human Development
- Peter LaFrenière(Author)
- 2011(Publication Date)
- Psychology Press(Publisher)
CHAPTER 6 Hormones and Behavior* Hormones represent a group of neurochemicals that is quite distinct from the neurotransmitters discussed in the preceding chapter. Hormones are produced by the endocrine system which interacts with the nervous system mainly through connections between the hypothalamus and the pituitary just beneath it. The hypothalamus produces some Hormones, such as oxytocin, and sends them via its axons as neurotransmitters to the pituitary for storage and release into the bloodstream where they can act on their target tissues. The hypothalamus also produces releasing Hormones that reach the pituitary through special arteries and that stimulate the pituitary to produce various other Hormones of its own (see Figure 6.1). Most of these pituitary Hormones act on other endocrine glands to stimulate them to produce Hormones that act on final target tissues. An example is the HPA (hypothalamus-pituitary-adrenal cortex) system. The hypothalamus produces the releasing hormone CRF, which stimulates the pituitary to produce ACTH, which in turn stimulates production of the adrenal corticosteroid Hormones, such as cortisol, which cause adjustments to stressful situations. Because they travel via the bloodstream, Hormones usually require more time to have an impact on the body than neurotransmitters whose impact on the generation of an action potential in the neuron’s axon occurs in nanoseconds. FIGURE 6.1 Many Hormones are produced by the hypothalamus and the pituitary. □ Evolution of Hormones In comparing Hormones and neurotransmitters, it is useful to understand their evolution. The current evolutionary model (Snyder, 1985) is presented in Figure 6.2. The first and most basic form of chemical communication (model a) evolved to provide a primitive form of intercellular communication so that the organism could behave as a unit rather than a collection of uncoordinated cells
eBook - PDF- Stefan Silbernagl, Agamemnon Despopoulos(Authors)
- 2015(Publication Date)
- Thieme(Publisher)
The receptors on the target cells pick out the substances specifically intended for them from a wide variety of different mes-senger substances in their environment. Hormones work closely with the nervous system to regulate digestion, metabolism, growth, physical and mental development, maturation, reproduction, adaptation, and the internal milieu of the body ( homeostasis ) ( A ). Most of these actions are predominately autonomous functions subject to central con-trol by the hypothalamus , which is controlled by higher centers of the brain ( p. 348). Neurotransmitters released at chemical synapses of nerve endings transmit signals to postsynaptic nerve fibers, muscles or glands ( p. 54ff.). Some neuropeptides released by presynaptic neurons also exert their effects in neighboring synapses, resulting in a kind of “paracrine” action. Neurons can also secrete Hormones, e.g., epinephrine, oxytocin, and antidiuretic hor-mone. Some transmitter substances of the im-mune system, e.g., thymosin and various cy-tokines, also have endocrine effects. Integrative Systems of the Body 281 11 Hormones and Reproduction Plate 11.1 Integrative Systems of the Body Psychological factors Signals from the environment Messages from within the body (e.g., feedback control) Endocrine system autonomic nervous system somatic nervous system Neurosecretion Hypothalamus Anterior lobe of pituitary Posterior lobe of pituitary Kidneys Thyroid gland Parathyroid glands Ovaries Testes Adrenal cortex Adrenal medulla Pancreas Nutrition Circulation Growth and maturation Metabolism Temperature Water and electrolyte balance Reproduction Immune system Behavior Control and regulation of Peripheral nervous system Motoricity Defense Hormone release Aglandular Hormones Sympathetic and parasympathetic nervous systems A. Regulation of autonomic nervous system functions (overview)
eBook - PDF- J. M. M. Brown, G. G. Járos(Authors)
- 2013(Publication Date)
- Butterworth-Heinemann(Publisher)
CHAPTER 12 The Endocrine control of Physiological processes — The Vitamins The regulating role of Hormones has been mentioned several times in the earlier chapters. Hormones can be defined as substances produced by certain tissues called endocrine glands and which are released into the blood and carried to other parts of the body where they exert a regulating effect on various physiological processes. The study dealing with hormonal regulation is known as Endocrinology. In the present chapter only those aspects of endocrinology are discussed which have a direct bearing on bio-chemical processes in the body. It must be noted at this point that Hormones perform their regulating functions in close association with the autonomic nervous system. A list of the most important endocrine glands and the Hormones which they secrete is given in Table 12.1. TABLE 12.1 The endocrine glands and their secretions Gland Hormones Hypothalamus releasing factors ADH, oxytoxin (both released in the neurohypophysis) Adenohypophysis STH, TSH, AGTH gonadotrophins Pars intermedia MSH Thyroid T 3 , T 4 , thyrocalcitonin Parathyroid parathormone Islands of Langerhans insulin, glucagon Adrenal medulla adrenalin, noradrenalin Adrenal cortex glucocorticoids, mineralocorticoids, androgens, oestrogens Follicle of Graaf oestrogens Corpus luteum progesterone Testes testosterone Placenta chorionic gonadotrophin Digestive tract gastrin, secretin, pancreozymin, enterocrinin, villikinin, enterogas-trone Kidneys 1,25-DHC erythropoietin renin Tissues (general) prostaglandins, histamine, bradykinin Parasympathetic nerves acetylcholine 12:2 Elementary Medical Biochemistry The action of Hormones — The negative feedback mechanism The term hormone is derived from the Greek word hormaein meaning to arouse or stimulate. When the term was coined all the Hormones were known to stimulate, i.e., to increase the activity of the tissues or organs on which they acted.
eBook - PDF- P Karlson(Author)
- 1975(Publication Date)
- Academic Press(Publisher)
C H A P T E R Hormones 1. Principles of Hormonal Regulation Humoral or hormonal control means that peripheral tissue is influenced by substances with specific effects. The active substances are formed in specialized glands or tissues (endocrine glands) and secreted into the blood stream. This can also be called internal secretion the substances produced by endocrine (or endo-secretory) glands are the Hormones. T h e concept hormone has been applied m o r e o r less b r o a d l y in the past. A h u n d r e d years ago, C . B e r n a r d coined the t e r m internal s e c r e t i o n to describe the p r o d u c t i o n of glucose b y the liver. T h e example has been d r o p p e d , but the t e r m has been kept. T h e situation is similar w i t h Starling's s e c r e t i n , w h i c h occasioned the f o r m u l a t i o n of the t e r m hormone. Secretin is not a h o r m o n e of the endocrine glands, but rather one of the tissue h o r m o n e s , w h i c h t o d a y constitute a separate g r o u p . A critical discussion of the h o r m o n a l concept is given b y V e r z a r . 1 The Principle of the Master Gland. Several hypophyseal ( = pituitary) Hormones act on peripheral endocrine glands. The activity of the hypophysis is itself regulated by yet another hormone, 2 so that there evidently exists a hierarchy of hormone glands, which comprises three levels in the case of the hypophyseal-adrenocortical system (see Fig. XX-1). Certain centers of the midbrain elaborate a neurosecretion that travels through the pituitary stalk to the anterior lobe of the hypophysis, where it stimulates the release of the adrenocorticotropic hormone (ACTH). ACTH is itself a glandotropic hormone ; its target is the adrenal cortex, which is stimulated to produce increased amounts of the so-called corticosteroids and to release them to the blood circulation. A feedback system controls the master gland, the hypophysis, in 1 F.
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