| 释义 |
lactation
lac·ta·tion L0010250 (lăk-tā′shən)n.1. Secretion or formation of milk by the mammary glands.2. The period during which the mammary glands secrete milk.
lac·ta′tion·al adj.lactation (lækˈteɪʃən) n1. (Physiology) the secretion of milk from the mammary glands after parturition2. (Physiology) the period during which milk is secreted lacˈtational adj lacˈtationally advlac•ta•tion (lækˈteɪ ʃən)
n. 1. the secretion of milk. 2. the period of milk production. [1660–70; < Late Latin lactātiō the act of giving suck < lactā(re) to give suck, derivative of Latin lac, s. lact- milk] lac•ta′tion•al, adj. lac·ta·tion (lăk-tā′shən) The secretion or production of milk by the mammary glands, occurring in female mammals after giving birth.lactation1. the secretion of milk by a mammary gland.
2. the period during which secretion takes place.See also: Bodily FunctionslactationMilk production by the mammary glands.Thesaurus| Noun | 1. | lactation - the period following birth during which milk is secreted; "lactation normally continues until weaning"period, period of time, time period - an amount of time; "a time period of 30 years"; "hastened the period of time of his recovery"; "Picasso's blue period" | | 2. | lactation - the production and secretion of milk by the mammary glandsbodily function, bodily process, body process, activity - an organic process that takes place in the body; "respiratory activity" | | 3. | lactation - feeding an infant by giving suck at the breastsucklingalimentation, feeding - the act of supplying food and nourishment |
Translationslactation
lactation1. the secretion of milk from the mammary glands after parturition 2. the period during which milk is secreted Lactation The function of the mammary gland providing milk nourishment to the newborn mammal. This process is under the control of the endocrine and nervous systems. It involves transformation of an inactive duct system to a lobuloalveolar glandular structure during pregnancy, cellular production of the components of milk (galacto-poiesis), secretion into the ducts, and ejection under the stimulus of milking or suckling. Lactation makes demands on the maternal regulation of calcium metabolism. Resorption of bone increases in lactating rats and women, and there is a marked increase in the absorption of calcium from the intestine. The elevated need for calcium results in an increased role for parathyroid hormone, calcitonin, and vitamin D in the regulation of the absorption and utilization of calcium. In humans a concomitant phenomenon frequently associated with lactation is amenorrhea. Consequently in some societies prolonged nursing is used as a birth control technique. See Mammary gland, Milk Lactation the process of the formation, accumulation, and periodic release of milk in man and mammals. Lactation begins after parturition. Only a mammary gland that has gone through particular stages of development in the course of pregnancy is capable of secreting milk. The milk forms in the secretory epithelial cells of the alveoli of the mammary gland from component parts of the blood. There are four stages of lactation: the absorption of the precursors of milk from the blood by the mammary gland, the synthesis of the component parts of the milk in the secretory cells of the gland, the formation and accumulation of the synthesized products in the cytoplasm of the secretory cells, and the secretion of the milk into the cavities of the alveoli and other spaces of the mammary gland, such as the cisternae. The milk proteins are synthesized from amino acids; the milk sugar, or lactose, from glucose; and the butterfat, from the neutral fat and free fatty acids of the blood. The hypothalamus and the pituitary gland play a fundamental role in the regulation of lactation. Lactogenic hormone is secreted in large quantities during pregnancy. A hormone of the posterior pituitary lobe, oxytocin, also participates in the process of milk production. In man. On the first day after parturition, only a few drops of colostrum can be drawn from the mammary glands. Subsequent increases in secretion proceed variously: in some cases, the quantity of milk increases gradually: in others, the influx of milk occurs suddenly and vigorously. In some women (mainly primaparas) the milk appears late; secretion begins only by the fifth or sixth day, or even as late as the beginning of the second week, developing slowly by the third week. The secretion increases gradually and continuously from the moment of influx, reaching a maximum between the tenth and 20th week and remaining at that level until the end of lactation. The amount of breast milk may fluctuate in the same woman on different days and at different hours of the same day (after sleep there is more; after a sleepless night, at the end of the day, or after strenuous work, there is less), but, in general, the amount is approximately the same for every 24-hour period. If the mammary gland has a high lactation capacity and the woman is nursing two or more children, the daily amount may reach 2,000–3,000 g. A fully balanced diet for the mother is necessary for successful lactation. A nursing mother should consume a daily average of 110–130 g of protein, 100–130 g of fat, 450–500 g of carbohydrates, 2 mg of vitamin A, 3.5 mg of riboflavin, 25 mg of nicotinic acid, 4 mg of pyridoxine, and 100–120 mg of ascorbic acid. She should take an increased quantity of fluids—to 1.5–2l, depending on the amount of milk she is producing. Milk (but not more than 0.5 l) and milk products (for example, cottage cheese) and meat, fish, and eggs are obligatory components of the nursing woman’s diet. The most frequent disturbance of lactation is hypogalactia, or insufficient lactation. A complete absence of milk secretion, called agalactia, is very rare and occurs as a result of hormonal disturbances. An involuntary discharge of milk is sometimes observed, at nursing time or independent of nursing, that arises not from an abundance of milk but as a functional disturbance of mammary activity in women with heightened nervous excitability; this requires no special treatment but generally fortifying measures. Decreased lactation is observed with all chronic wasting diseases in the mother (diabetes, nephritis, cancer), with acute illnesses accompanied by high temperatures and loss of appetite (for example, mastitis), with chronic infections (especially tuberculosis), and with diarrhea. Medicines taken by the nursing mother only slightly reflect on lactation; however, quantities may decrease under the influence of laxatives, diuretics, camphor, and atropine. In animals. Lactation increases in animals during the early period after parturition and then gradually decreases. Cows produce the greatest amount of milk at the end of the first month and during the second month after calving. In some animals (cows, mares, goats), lactation decreases with a new pregnancy. In order to obtain higher milk yields during the next lactation, the cow is not milked for 1.5–2 months before calving (the dry period). This should be begun even earlier with mares and goats. The period from the beginning of lactation (after parturition) until the end of milk production is called the lactation period. In cows, this period averages 300 days; in goats, eight to ten months; in sheep, four to five months; in mares, nine months or more; and in sows, 60 to 70 days. The duration of the lactation period and the amount of milk obtained depend on the species, breed, feeding schedule, feed content, time of onset of the new pregnancy, and length of the dry period. Disturbances of lactation are observed with mastitides, involuntary milk discharge, and milking difficulties. REFERENCESEspe, D. Sekretsiia moloka. Moscow, 1950. (Bibliography; translated from English.)
Emel’ianov, A. S. Laktatsionnaia deiatel’nost’ korov i upravlenie eiu. Vologda, 1953.
Grachev, I. I. Reflektornaia reguliatsiia laktatsii. Leningrad, 1964.
Azimov, G. I. Kak obrazuetsia moloko [2nd ed.] Moscow, 1965.
Neirogormonal’naia reguliatsiia laktatsii. Moscow-Leningrad [1966].lactation[lak′tā·shən] (physiology) Secretion of milk by the mammary glands. lactation
Lactation DefinitionLactation is the medical term for yielding of milk by the mammary glands which leads to breastfeeding. Human milk contains the ideal amount of nutrients for the infant, and provides important protection from diseases through the mother's natural defenses.DescriptionEarly in a woman's pregnancy her milk-producing glands begin to prepare for her baby's arrival, and by the sixth month of pregnancy the breasts are ready to produce milk. Immediately after the baby is born, the placenta is delivered. This causes a hormone in the woman's body (prolactin) to activate the milk-producing glands. By the third to fifth day, the woman's breasts fill with milk.Then, as the baby continues to suck each day, nursing triggers the continuing production of milk. The baby's sucking stimulates nerve endings in the nipple, which signal the mother's pituitary gland to release oxytocin, a hormone that causes the mammary glands to release milk to the nursing baby. This is called the "let-down reflex." While the baby's sucking is the primary stimulus for this reflex, a baby's cry, thoughts of the baby, or the sound of running water also may trigger the response. Frequent nursing will lead to increased milk production.Breast milk cannot be duplicated by commercial baby food formulas, although both contain protein, fat, and carbohydrates. In particular, breast milk changes to meet the specific needs of a baby. The composition of breast milk changes as the baby grows to meet the baby's changing needs. Most important, breast milk contains substances called antibodies from the mother that can protect the child against illness and allergies. Antibodies are part of the body's natural defense system against infections and other agents that can cause disease. Breast milk also helps a baby's own immune system mature faster. As a result, breast-fed babies have less diarrhea and fewer ear infections, rashes, allergies, and other medical problems than bottle-fed babies.There are many other benefits to breast milk. Because it is easily digested, babies do not get constipated. Breast-fed babies may have fewer speech impediments, and breastfeeding can improve cheekbone development and jaw alignment.Breastfeeding is also good for the mother. The act of breastfeeding releases hormones that stimulate the uterus to contract, helping it to return to normal size after delivery and reducing the risk of bleeding. The act of producing milk is thought to burn more calories, helping the mother to lose excess weight gained during pregnancy. However, research in 2004 disputed this belief when body composition changes of lactation and non-lactating women were compared at intervals for six months postpartum. Breastfeeding may be related to a lower risk of breast cancer, ovarian cancer, or cervical cancer. This benefit is stronger the younger a woman is when she breastfeeds; women who breastfeed before age 20 and nurse for at least six months have a 50% drop in the risk for breast cancer.In addition, breastfeeding does not involve any formulas, bottles and nipples, or sterilizing equipment. Breast milk is free, and saves money by eliminating the need to buy formula, bottles, and nipples. Because breast-fed babies are healthier, health care costs for breast-fed infants are lower.ProcedureBreastfeeding should begin as soon as possible after birth, and should continue every two to three hours. However, all babies are different; some need to nurse almost constantly at first, while others can go much longer between feedings. A baby should be fed at least 8-12 times in 24 hours. Because breast milk is easily digested, a baby may be hungry again as soon as one and one-half hours after the last meal.Mothers should wear comfortable, loose, front-opening clothes and a good nursing bra. Mothers should find a comfortable chair with lots of pillows, supporting the arm and back. Feet should rest on a low footstool, with knees raised slightly. The baby should be level with the breast. The new mother may have to experiment with different ways of holding the baby before finding one that is comfortable for both the mother and baby.Some babies have no trouble breastfeeding, while others may need some assistance. Once the baby begins to suck, the mother should make sure that the entire dark area around the nipple is in the baby's mouth. This will help stimulate milk flow, allowing the baby to get enough milk. It will also prevent nipple soreness.Breastfeeding mothers will usually offer the baby both breasts at each feeding. Breastfeeding takes about 15-20 minutes on each side. After stopping the feeding on one side, the mother should burp the baby before beginning the feeding on the other breast. If the baby falls asleep at the breast, the next feeding should begin with the breast that was not nursed.Mothers can tell if the baby is getting enough milk by checking diapers; a baby who is wetting between four to six disposable diapers (six to eight cloth) and who has three or four bowel movements in 24 hours is getting enough milk.Nursing problemsNew mothers may experience nursing problems, including:- Engorged breasts. Breasts that are too full can prevent the baby from sucking. Expressing milk manually or with a breast pump can help.
- Sore nipples. In the early weeks nipples may become sore; a nipple shield can ease discomfort.
- Infection. Soreness and inflammation on the breast surface or a fever in the mother, may be an indication of breast infection. Antibiotics and continued nursing on the affected side may solve the problem.
PrognosisThere are no rules about when to stop breastfeeding. A baby needs breast milk for at least the first year of life; as long as a baby eats age-appropriate solid food, the mother may nurse for several years.PreventionMost common illnesses can not be transmitted via breast milk. However, some viruses, including HIV (the virus that causes AIDS) can be passed in breast milk; for this reason, women who are HIV-positive should not breastfeed.Many medications have not been tested in nursing women, so it is not known if these drugs can affect a breast-fed child. A nursing woman should always check with her doctor before taking any medications, including over-the-counter drugs.These drugs are not safe to take while nursing:- Radioactive drugs for some diagnostic tests
- Chemotherapy drugs for cancer
- Bromocriptine
- Ergotamine
- Lithium
- Methotrexate
- Street drugs (including marijuana, heroin, amphetamines)
- Tobacco.
Key termsBromocriptine — A drug used to treat Parkinson's disease that can decrease a woman's milk supply.Ergotamine — A drug used to prevent or treat migraine headaches. This can cause vomiting, diarrhea, and convulsions in infants.Lithium — A drug used to treat manic depression (bipolar disorder) that can be transmitted in breast milk.Methotrexate — An anticancer drug also used to treat arthritis that can suppress an infant's immune system when taken by a nursing mother.ResourcesPeriodicalsWosje, Karen S., and Heidi J. Kalkwarf. "Lactation, Weaning, and Calcium Supplementation: Effects on Body Composition in Postpartum Women." American Journal of Clinical Nutrition August 2004: 676.OrganizationsInternational Lactation Consultants Assoc. 201 Brown Ave., Evanston, IL 60202. (708) 260-8874.La Leche League International. 1400 North Meacham Rd., Schaumburg, IL 60173. (800) LA-LECHE.National Alliance for Breastfeeding Advocacy. 254 Conant Rd., Weston, MA 02193. (617) 893-3553.lactation [lak-ta´shun] 1. the secretion of milk by the breasts; it is thought to be brought about by action of progesterone and estrogen and specific pituitary hormones, such as lactogenic hormone (prolactin). It does not begin until at least 3 days after the birth of the baby; before that, and immediately after birth, the breast secretes colostrum. Stimuli for lactation. From Applegate, 2000.2. the period of weeks or months during which a woman is lactating and a baby can be breast-fed; see breastfeeding.lac·ta·tion (lak-tā'shŭn), Avoid the illegitimate variant lactancy.1. Production of milk. 2. Period following birth during which milk is secreted in the breasts. [L. lactatio, suckle] lactation (lăk-tā′shən)n.1. Secretion or formation of milk by the mammary glands.2. The period during which the mammary glands secrete milk.
lac·ta′tion·al adj.lactation 1. Milk secretion–the production and secretion of milk by the mammary glands.2. The time during which a ♀ provides breast milk to an infant. See Breast feeding, Weaning.lac·ta·tion (lak-tā'shŭn) 1. Production of milk. 2. Period following birth during which milk is secreted in the breasts. [L. lactatio, suckle]lactation The secretion and production of milk in the breasts (MAMMARY GLANDS) after childbirth.lactation the production of milk by the adult female mammal from the mammary gland, in order to suckle its young. Lactation is induced by LUTEOTROPIC HORMONES from the anterior PITUITARY GLAND. see COLOSTRUM.lactation
Related to lactation: BreastfeedingSynonyms for lactationnoun the period following birth during which milk is secretedRelated Words- period
- period of time
- time period
noun the production and secretion of milk by the mammary glandsRelated Words- bodily function
- bodily process
- body process
- activity
noun feeding an infant by giving suck at the breastSynonymsRelated Words |