Evolution Health Dictionary

a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
p
q
r
s
t
u
v
w
x
y
z

Evolution: From 1 Different Sources

An uninterrupted process of change from one condition, form or state to another. In biological evolution, all varieties of living things are seen as having developed by inheritable, incremental changes from unicellular structures to complex organisms such as humankind. Although the likelihood of some form of evolution had been postulated by scientists in the late 18th and early 19th centuries, the prime contribution to the development of biological evolutionary doctrine came from the British scientist, Charles Darwin, who argued in his book The Origin of Species by Means of Natural Selection (1859) that natural selection resulted in the survival of the ?ttest organisms. The precise biological mechanism of evolution was not unravelled until the 20th century, with the discovery of CHROMOSOMES and GENES and the development of the science of genetics. Charles Darwin’s theory was based on his studies of the varied and unique animal life in the Galapagos Islands in the 19th century. He believed that the diversity of life on the planet could be ascribed to the combined effects of random variation in living things, inherited by succeeding generations.

Health Source: Medical Dictionary
Author: Health Dictionary

Vestigial

An adjective referring to an organ which exists in a rudimentary form and whose function and structure have declined during the course of evolution. An example is the appendix.... vestigial

Bacteria

(Singular: bacterium.) Simple, single-celled, primitive organisms which are widely distributed throughout the world in air, water, soil, plants and animals including humans. Many are bene?cial to the environment and other living organisms, but some cause harm to their hosts and can be lethal.

Bacteria are classi?ed according to their shape: BACILLUS (rod-like), coccus (spherical – see COCCI), SPIROCHAETE (corkscrew and spiral-shaped), VIBRIO (comma-shaped), and pleomorphic (variable shapes). Some are mobile, possessing slender hairs (?agellae) on the surfaces. As well as having characteristic shapes, the arrangement of the organisms is signi?cant: some occur in chains (streptococci) and some in pairs (see DIPLOCOCCUS), while a few have a ?lamentous grouping. The size of bacteria ranges from around 0.2 to 5 µm and the smallest (MYCOPLASMA) are roughly the same size as the largest viruses (poxviruses – see VIRUS). They are the smallest organisms capable of existing outside their hosts. The longest, rod-shaped bacilli are slightly smaller than the human erythrocyte blood cell (7 µm).

Bacterial cells are surrounded by an outer capsule within which lie the cell wall and plasma membrane; cytoplasm ?lls much of the interior and this contains genetic nucleoid structures containing DNA, mesosomes (invaginations of the cell wall) and ribosomes, containing RNA and proteins. (See illustration.)

Reproduction is usually asexual, each cell dividing into two, these two into four, and so on. In favourable conditions reproduction can be very rapid, with one bacterium multiplying to 250,000 within six hours. This means that bacteria can change their characteristics by evolution relatively quickly, and many bacteria, including Mycobacterium tuberculosis and Staphylococcus aureus, have developed resistance to successive generations of antibiotics produced by man. (METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS (MRSA)) is a serious hazard in some hospitals.

Bacteria may live as single organisms or congregate in colonies. In arduous conditions some bacteria can convert to an inert, cystic state, remaining in their resting form until the environment becomes more favourable. Bacteria have recently been discovered in an inert state in ice estimated to have been formed 250 million years ago.

Bacteria were ?rst discovered by Antonj van Leewenhoek in the 17th century, but it was not until the middle of the 19th century that Louis Pasteur, the famous French scientist, identi?ed bacteria as the cause of many diseases. Some act as harmful PATHOGENS as soon as they enter a host; others may have a neutral or benign e?ect on the host unless the host’s natural immune defence system is damaged (see IMMUNOLOGY) so that it becomes vulnerable to any previously well-behaved parasites. Various benign bacteria that permanently reside in the human body are called normal ?ora and are found at certain sites, especially the SKIN, OROPHARYNX, COLON and VAGINA. The body’s internal organs are usually sterile, as are the blood and cerebrospinal ?uid.

Bacteria are responsible for many human diseases ranging from the relatively minor – for example, a boil or infected ?nger – to the potentially lethal such as CHOLERA, PLAGUE or TUBERCULOSIS. Infectious bacteria enter the body through broken skin or by its ori?ces: by nose and mouth into the lungs or intestinal tract; by the URETHRA into the URINARY TRACT and KIDNEYS; by the vagina into the UTERUS and FALLOPIAN TUBES. Harmful bacteria then cause disease by producing poisonous endotoxins or exotoxins, and by provoking INFLAMMATION in the tissues – for example, abscess or cellulitis. Many, but not all, bacterial infections are communicable – namely, spread from host to host. For example, tuberculosis is spread by airborne droplets, produced by coughing.

Infections caused by bacteria are commonly treated with antibiotics, which were widely introduced in the 1950s. However, the con?ict between science and harmful bacteria remains unresolved, with the overuse and misuse of antibiotics in medicine, veterinary medicine and the animal food industry contributing to the evolution of bacteria that are resistant to antibiotics. (See also MICROBIOLOGY.)... bacteria

Bioremediation

The use of the natural properties of living things to remove hazards that threaten human and animal health. When a pollutant ?rst appears in a local environment, existing microorganisms such as bacteria attempt to make use of the potential source of energy and as a side-e?ect detoxify the polluting substance. This is an evolutionary process that normally would take years.

Scientists have engineered appropriate genes from other organisms into BACTERIA, or sometimes plants, to accelerate this natural evolutionary process. For e?ective ‘digestion of waste’, a micro-organism must quickly and completely digest organic waste without producing unpleasant smells or noxious gases, be non-pathogenic and be able to reproduce in hostile conditions. For example, American researchers have discovered an anaerobic bacterium that neutralises dangerous chlorinated chemical compounds such as trichlorethane, which can pollute soil, into a harmless molecule called ethens. But the bacteria do not thrive in soil. So the dechlorinating genes in this bacterium are transferred to bacteria that are acclimatised to living in toxic areas and can more e?ciently carry out the required detoxi?cation. Other research has been aimed at detoxifying the byproducts of DDT, a troublesome and resistant pollutant. Bioremediation should prove to be an environmentally friendly and cost-e?ective alternative to waste incineration or chemically based processes for washing contaminated soils.... bioremediation

Reflex, Primitive

An automatic movement in response to a stimulus that is present in newborn infants but disappears during the first few months after birth. Primitive reflexes are believed to represent actions that were important in earlier stages of human evolution. They include the grasp reflex when something is placed in the hand and the rooting reflex, which enables a baby to find the nipple. The rooting reflex can be evoked by touching the baby’s cheek with the fingertip. These reflexes are tested after birth to give an indication of the condition of the nervous system.... reflex, primitive

Analogous

adj. 1. describing organs or parts that have similar functions in different organisms although they do not have the same evolutionary origin or development. Compare homologous 2. (in ethics) describing a case, justification, or argument that is similar to the case in question and so may be used to help to reach a conclusion. See also analysis; casuistry.... analogous

Breasts, Diseases Of

The female breasts may be expected to undergo hormone-controlled enlargement at puberty, and later in pregnancy, and the glandular part of the breast undergoes evolution (shrinkage) after the menopause. The breast can also be affected by many di?erent diseases, with common symptoms being pain, nipple discharge or retraction, and the formation of a lump within the breast.

Benign disease is much more common than cancer, particularly in young women, and includes acute in?ammation of the breast (mastitis); abscess formation; and benign breast lumps, which may be ?broadenosis – di?use lumpiness also called chronic mastitis or ?brocystic disease – in which one or more ?uid-?lled sacs (cysts) develop.

Women who are breast feeding are particularly prone to mastitis, as infection may enter the breast via the nipple. The process may be arrested before a breast abscess forms by prompt treatment with antibiotics. Non-bacterial in?ammation may result from mammary duct ectasia (dilatation), in which abnormal or

blocked ducts may over?ow. Initial treatments should be with antibiotics, but if an abscess does form it should be surgically drained.

Duct ectasia, with or without local mastitis, is the usual benign cause of various nipple complaints, with common symptoms being nipple retraction, discharge and skin change.

Breast lumps form the chief potential danger and may be either solid or cystic. Simple examination may fail to distinguish the two types, but aspiration of a benign cyst usually results in its disappearance. If the ?uid is bloodstained, or if a lump still remains, malignancy is possible, and all solid lumps need histological (tissue examination) or cytological (cell examination) assessment. As well as having their medical and family history taken, any women with a breast lump should undergo triple assessment: a combination of clinical examination, imaging

– mammography for the over-35s and ultrasonagraphy for the under-35s – and ?ne-needle aspiration. The medical history should include details of any previous lumps, family history (up to 10 per cent of breast cancer in western countries is due to genetic disposition), pain, nipple discharge, change in size related to menstrual cycle and parous state, and any drugs being taken by the patient. Breasts should be inspected with the arms up and down, noting position, size, consistency, mobility, ?xity, and local lymphadenopathy (glandular swelling). Nipples should be examined for the presence of inversion or discharge. Skin involvement (peau d’orange) should be noted, and, in particular, how long changes have been present. Fine-needle aspiration and cytological examination of the ?uid are essential with ULTRASOUND, MAMMOGRAPHY and possible BIOPSY being considered, depending on the patient’s age and the extent of clinical suspicion that cancer may be present.

The commonest solid benign lump is a ?broadenoma, particularly in women of childbearing age, and is a painless, mobile lump. If small, it is usually safe to leave it alone, provided that the patient is warned to seek medical advice if its size or character changes or if the lump becomes painful. Fibroadenosis (di?use lumpiness often in the upper, outer quadrant) is a common (benign) lump. Others include periductal mastitis, fat NECROSIS, GALACTOCELE, ABSCESS, and non-breast-tissue lumps – for example, a LIPOMA (fatty tissue) or SEBACEOUS CYST. A woman with breast discharge should have a mammograph, ductograph, or total duct excision until the cause of any underlying duct ectasia is known. Appropriate treatment should then be given.

Malignant disease most commonly – but not exclusively – occurs in post-menopausal women, classically presenting as a slowly growing, painless, ?rm lump. A bloodstained nipple discharge or eczematous skin change may also be suggestive of cancer.

The most commonly used classi?cation of invasive cancers has split them into two types, ductal and lobular, but this is no longer suitable. There are also weaknesses in the tumour node metastases (TNM) system and the International Union Against Cancer (UICC) classi?cation.

The TNM system – which classi?es the lump by size, ?xity and presence of affected axillary glands and wider metastatic spread – is best combined with a pathological classi?cation, when assessing the seriousness of a possibly cancerous lump. Risk factors for cancer include nulliparity (see NULLIPARA), ?rst pregnancy over the age of 30 years, early MENARCHE, late MENOPAUSE and positive family history. The danger should be considered in women who are not breast feeding or with previous breast cancer, and must be carefully excluded if the woman is taking any contraceptive steroids or is on hormone-replacement therapy (see under MENOPAUSE).

Screening programmes involving mammography are well established, the aim being to detect more tumours at an early and curable stage. Pick-up rate is ?ve per 1,000 healthy women over 50 years. Yearly two-view mammograms could reduce mortality by 40 per cent but may cause alarm because there are ten false positive mammograms for each true positive result. In premenopausal women, breasts are denser, making mammograms harder to interpret, and screening appears not to save lives. About a quarter of women with a palpable breast lump turn out to have cancer.

Treatment This remains controversial, and all options should be carefully discussed with the patient and, where appropriate, with her partner. Locally contained disease may be treated by local excision of the lump, but sampling of the glands of the armpit of the same side should be performed to check for additional spread of the disease, and hence the need for CHEMOTHERAPY or RADIOTHERAPY. Depending on the extent of spread, simple mastectomy or modi?ed radical mastectomy (which removes the lymph nodes draining the breast) may be required. Follow-up chemotherapy, for example, with TAMOXIFEN (an oestrogen antagonist), much improves survival (it saves 12 lives over 100 women treated), though it may occasionally cause endometrial carcinoma. Analysis in the mid-1990s of large-scale international studies of breast-cancer treatments showed wide variations in their e?ectiveness. As a result the NHS has encouraged hospitals to set up breast-treatment teams containing all the relevant health professional experts and to use those treatments shown to be most e?ective.

As well as the physical treatments provided, women with suspected or proven breast cancer should be o?ered psychological support because up to 30 per cent of affected women develop an anxiety state or depressive illness within a year of diagnosis. Problems over body image and sexual diffculties occur in and around one-quarter of patients. Breast conservation and reconstructive surgery can improve the physical effects of mastectomy, and women should be advised on the prostheses and specially designed brassieres that are available. Specialist nurses and self-help groups are invaluable in supporting affected women and their partners with the problems caused by breast cancer and its treatment. Breast Cancer Care, British Association of Cancer United Patients (BACUP), Cancerlink, and Cancer Relief Macmillan Fund are among voluntary organisations providing support.... breasts, diseases of

Continuity Of Care

A term describing a system of medical care in which individuals requiring advice on their health consult a named primary care physician (GENERAL PRACTITIONER (GP)) or partnership of practitioners. The availability of an individual’s medical records, and the doctor’s knowledge of his or her medical, family and social history, should facilitate prompt, appropriate decisions about investigations, treatment or referral to specialists. What the doctor(s) know(s) about the patient can, for example, save time, alert hospitals to allergies, avoid the duplication of investigations and provide hospitals with practical domestic information when a patient is ready for discharge. The traditional 24-hours-aday, 365-days-a-year care by a personal physician is now a rarity: continuity of care has evolved and is now commonly based on a multi-disciplinary health team working from common premises. Changing social structures, population mobility and the complexity and cost of health care have driven this evolution. Some experts have argued that the changes are so great as to make continuity of care an unrealistic concept in the 21st century. Nevertheless, support inside and outside conventional medical practice for HOLISTIC medicine – a related concept for treating the whole person, body and mind – and the fact that many people still appreciate the facility to see their own doctors suggest that continuity of care is still a valid objective of value to the community.... continuity of care

Dna

DNA is the abbreviation for deoxyribonucleic acid, one of the two types of NUCLEIC ACID that occur in nature. It is the fundamental genetic material of all CELLS, and is present in the nucleus of the cell where it forms part of the CHROMOSOMES and acts as the carrier of genetic information. The molecule is very large, with a molecular weight of several millions, and consists of two single chains of nucleotides (see NUCLEIC ACID) which are twisted round each other to form a double helix (or spiral). The genetic information carried by DNA is encoded along one of these strands. A gene, which represents the genetic information needed to form protein, is a stretch of DNA containing, on average, around 1,000 nucleotides paired in these two strands (see GENES).

To allow it to ful?l its vitally important function as the carrier of genetic information in living cells, DNA has the following properties. It is stable, so that successive generations of species maintain their individual characteristics, but not so stable that evolutionary changes cannot take place. It must be able to store a vast amount of information: for example, an animal cell contains genetic information for the synthesis of over a million proteins. It must be duplicated exactly before each cell division to ensure that both daughter cells contain an accurate copy of the genetic information of the parent cells (see GENETIC CODE).... dna

Human Genome

In simple terms, this is the genetic recipe for making a human being. GENOME is a combination of the words gene and chromosome, and a genome is de?ned as all the genetic material – known as deoxyribonucleic acid, or DNA – in a cell. Most genes encode sequences of AMINO ACIDS, the constituents of proteins, thus initiating and controlling the replication of an organism. The identi?cation and characterisation of the human genetic puzzle have been a key bioscience research target. The Human Genome Project was launched in 1990 (and completed in 2003) to produce a full sequence of the three million base pairs that make up the human genome.

Carried out as two separate exercises – one by a privately funded American team; another by an international joint venture between tax-funded American laboratories, a charitably funded British one and several other smaller research teams from around the world – the ?rst results were announced on 26 June 2000. In February 2001 the privately funded American group, known as Celera Genomics, announced that it had identi?ed 26,558 genes. At the same time the Human Genome Project consortium reported that it had identi?ed 31,000. Allowing for margins of error, this gives a ?gure much lower than the 100,000 or more human genes previously forecast by scientists. Interestingly, genes were found to make up only 3 per cent of the human genome. The remaining 97 per cent of the genome comprises non-coding DNA which, though not involved in producing the protein-initiating genetic activity, does have signi?cant roles in the structure, function and evolution of the genome.

One surprise from the Project so far is that the genetic di?erences between humans and other species seem much smaller than previously expected. For example, the Celera team found that people have only 300 genes that mice do not have; yet, the common ancestor of mice and men probably lived 100 million years or more in the past. Mice and humans, however, have around twice as many genes as the humble fruit ?y.

Cells die out when they become redundant during embryonic development: genes also die out during evolution, according to evidence from the Genome Project – a ?nding that supports the constant evolutionary changes apparent in living things; the Darwinian concept of survival of the ?ttest.

Apart from expanding our scienti?c knowledge, the new information – and promise of much more as the Genome Project continues – should enhance and expand the use of genetic engineering in the prevention and cure of disease. Studies are in progress on the gene for a receptor protein in the brain which will shed light on how the important neurotransmitter SEROTONIN in the brain works, and this, for example, should help the development of better drugs for the treatment of DEPRESSION. Another gene has been found that is relevant to the development of ASTHMA and yet another that is involved in the production of amyloid, a complex protein which is deposited in excessive amounts in both DOWN’S (DOWN) SYNDROME and ALZHEIMER’S DISEASE.... human genome

Carcinogenesis

n. the evolution of an invasive cancer cell from a normal cell. This is a multistep process characterized by successive genetic mutations caused by carcinogens. Intermediate stages, sometimes called premalignant, preinvasive, or noninvasive, may be recognizable, but the interchangeable use of these terms can be confusing, and they have been replaced by *carcinoma in situ.... carcinogenesis

Hippocampal Formation

a curved band of cortex lying within each cerebral hemisphere: in evolutionary terms one of the brain’s most primitive parts. It forms a portion of the *limbic system and is involved in the complex physical aspects of behaviour governed by emotion and instinct.... hippocampal formation

Homologous

adj. 1. (in anatomy) describing organs or parts that have the same basic structure and evolutionary origin, but not necessarily the same function or superficial structure. Compare analogous. 2. (in genetics) describing a pair of chromosomes of similar shape and size and having identical gene loci. One member of the pair is derived from the mother; the other from the father.... homologous

Oncologist

A doctor who specialises in the treatment of cancers (see CANCER; ONCOLOGY). Increasingly, cancer is being treated by multidisciplinary teams which include surgeons, physicians, radiotherapists and oncologists. The latter are non-surgical cancer specialists and are divided into clinical and medical branches: clinical oncologists concentrate mainly on RADIOTHERAPY treatments; medical oncologists are trained in the medical management of cancer patients – diagnosing and classifying cancers and arranging drug, psychosocial and palliative care. The latter claim a pivotal role in liaising with primary-care services, clinical oncologists and those providing palliative care, as well as other medical and surgical colleagues involved in the treatment and care of patients with cancer. With the constant evolution of cancer care and the introduction of new treatments such as GENE THERAPY, the role of oncologists and their relation with other specialists dealing with cancer will also evolve; but the strategic aim will remain to provide patients with up-to-date, comprehensive, coordinated care in hospitals and the community.... oncologist

Penicillin

The name given by Sir Alexander Fleming, in 1929, to an antibacterial substance produced by the mould Penicillium notatum. The story of penicillin is one of the most dramatic in the history of medicine, and its introduction into medicine initiated a new era in therapeutics comparable only to the introduction of ANAESTHESIA by Morton and Simpson and of ANTISEPTICS by Pasteur and Lister. The two great advantages of penicillin are that it is active against a large range of bacteria and that, even in large doses, it is non-toxic. Penicillin di?uses well into body tissues and ?uids and is excreted in the urine, but it penetrates poorly into the cerebrospinal ?uid.

Penicillin is a beta-lactam antibiotic, one of a group of drugs that also includes CEPHALOSPORINS. Drugs of this group have a four-part beta-lactam ring in their molecular structure and they act by interfering with the cell-wall growth of mutliplying bacteria.

Among the organisms to which it has been, and often still is, active are: streptococcus, pneumococcus, meningococcus, gonococcus, and the organisms responsible for syphilis and for gas gangrene (for more information on these organisms and the diseases they cause, refer to the separate dictionary entries). Most bacteria of the genus staphylococcus are now resistant because they produce an enzyme called PENICILLINASE that destroys the antibiotic. A particular problem has been the evolution of strains resistant to methicillin – a derivative originally designed to conquer the resistance problem. These bacteria, known as METHICILLINRESISTANT STAPHYLOCOCCUS AUREUS (MRSA), are an increasing problem, especially after major surgery. Some are also resistant to other antibiotics such as vancomycin.

An important side-e?ect of penicillins is hypersensitivity which causes rashes and sometimes ANAPHYLAXIS, which can be fatal.

Forms of penicillin These include the following broad groups: benzylpenicillin and phenoxymethyl-penicillin; penicillinase-resistant penicillins; broad-spectrum penicillins; antipseudomonal penicillins; and mecillinams. BENZYLPENICILLIN is given intramuscularly, and is the form that is used when a rapid action is required. PHENOXYMETHYLPENICILLIN (also called penicillin V) is given by mouth and used in treating such disorders as TONSILLITIS. AMPICILLIN, a broad-spectrum antibiotic, is another of the penicillins derived by semi-synthesis from the penicillin nucleus. It, too, is active when taken by mouth, but its special feature is that it is active against gram-negative (see GRAM’S STAIN) micro-organisms such as E. coli and the salmonellae. It has been superceded by amoxicillin to the extent that prescriptions for ampicillin written by GPs in the UK to be dispensed to children have fallen by 95 per cent in the last ten years. CARBENICILLIN, a semi-synthetic penicillin, this must be given by injection, which may be painful. Its main use is in dealing with infections due to Pseudomonas pyocanea. It is the only penicillin active against this micro-organism which can be better dealt with by certain non-penicillin antibiotics. PIPERACILLIN AND TICARCILLIN are carboxypenicillins used to treat infections caused by Pseudomonas aeruginosa and Proteus spp. FLUCLOXACILLIN, also a semi-synthetic penicillin, is active against penicillin-resistant staphylococci and has the practical advantage of being active when taken by mouth. TEMOCILLIN is another penicillinase-resistant penicillin, e?ective against most gram-negative bacteria. AMOXICILLIN is an oral semi-synthetic penicillin with the same range of action as ampicillin but less likely to cause side-effects. MECILLINAM is of value in the treatment of infections with salmonellae (see FOOD POISONING), including typhoid fever, and with E. coli (see ESCHERICHIA). It is given by injection. There is a derivative, pivmecillinam, which can be taken by mouth. TICARCILLIN is a carboxypenicillin used mainly for serious infections caused by Pseudomonas aeruginosa, though it is also active against some gram-negative bacilli. Ticarcillin is available only in combination with clarulanic acid.... penicillin

Neocerebellum

n. the middle lobe of the *cerebellum, excluding the pyramid and uvula. In evolutionary terms it is the newest part, occurring only in mammals.... neocerebellum

Neopallium

n. an enlargement of the wall of each cerebral hemisphere. In evolutionary terms it is the newest part of the cerebrum, formed by the development of new pathways for sight and hearing in mammals.... neopallium

Palaeocerebellum

n. the anterior lobe of the cerebellum. In evolutionary terms it is one of the earliest parts of the hindbrain to develop in mammals.... palaeocerebellum

Palaeothalamus

n. the anterior and central part of the *thalamus, older in evolutionary terms than the lateral part, the neothalamus, which is well developed in apes and humans.... palaeothalamus

Pallium

n. the outer wall of the cerebral hemisphere as it appears in the early stages of evolution of the mammalian brain. In the modern brain it corresponds to the *cerebral cortex.... pallium

Phylogenesis

n. the evolutionary history of a species or individual.... phylogenesis

Combinations, Formulae

In the evolution of herbal medicine it was discovered that some remedies have affinities and assist others in therapeutic action. An older generation of herbalists learnt how to ‘blend’ herbs according to their properties. Although empiric, such intelligent observation over centuries has developed into lore handed down as traditional medicine.

Use of herbs in combination enhances activity of the mild ones and modifies effects of the strong. Volatile properties of one may be kept in balance by opposing alkaloids, glycosides, etc.

Present practice views with disfavour the combination of several remedies, approval being given to a maximum of no more than four plant substances.

Herbs may be combined in equal parts or in specific proportions; i.e. Elder 4, Ladies’ Mantle 3 and Pulsatilla 1: represent Elder 4 parts, Ladies’ Mantle 3 parts and Pulsatilla 1 part.

The object of combining medicines is (a) to augment, correct or modify the action of a remedy, (b) to obtain a joint operation of two or more remedies, (c) to obtain a new medicine and (d) to afford a suitable form for administration.

“A combination of similar remedies will produce a more certain, speedy and considerable effect than an equivalent dose of any single one.” (Fordyce) Some herbs used singly may be of little use, their true value lying in a correct combination. Referred to as polypharmacy where a number of remedies are used in one prescription. ... combinations, formulae

Aggression

A general term for a wide variety of acts of hostility. A number of factors, including human evolutionary survival strategies, are thought to be involved in aggression. Androgen hormones, the male sex hormones, seem to promote aggression, whereas oestrogen hormones, the female sex hormones, actively suppress it. Age is another factor; aggression is more common among teenagers and young adults. Sometimes, a brain tumour or head injury leads to aggressive behaviour.

Psychiatric conditions associated with aggressive outbursts are schizophrenia, antisocial personality disorder, mania, and abuse of amfetamines or alcohol.

Temporal lobe epilepsy, hypoglycaemia, and confusion due to physical illnesses are other, less common, medical causes.... aggression

Preparedness

n. (in psychology) a quality of some stimuli that makes them much more likely to trigger a pathological fear. For example, animals or high places are much more likely to become the subject of a *phobia than are plants or clothes. One theory is that individuals are genetically predisposed to *conditioning of fear to objects that have been a biological threat during human evolution.... preparedness

Rhinencephalon

n. the parts of the brain, collectively, that in early stages of evolution were concerned mainly with the sense of smell. The rhinencephalon includes the olfactory nerve, olfactory tract, and the regions now usually classified as belonging to the *limbic system.... rhinencephalon

Health Encyclopedia

Recent Searches