Anglický jazyk
10.3 Medical English - Genetics and reproduction
Genetic factors, DNA and the genes that it carries play key roles in morphologic and physiologic abnormalities that characterize disease entities. Techniques of chromosomal analysis and nuclear sex determination have shown correlations with abnormal sex differentiation, Down's syndrome, mental retardation, somatic defects, infertility and metabolic disorders. The recognition of heterozygote carriers of latent genetic abnormalities may be of great value in directing prophylactic measures (special dietary controls, use of appropriate medication, avoidance of aggravating drugs and environmental factors) and in marriage counselling.
The nucleus of the normal human cell contains 46 chromosomes. Two of these are sex chromosomes – XX in women and XY in men. The remainder can be classified on the basis of physical appearance and segregated into 22 pairs. With technology, it is possible to discern alterations in form and number of chormosomes in cells obtained from blood, bone marrow, skin, mucosa, and othe tissues of specific interest. Recent advances in staining techniques have led to the identification of many normal variants.
The sperm and the ovum normally contain one autosomal chromosome from each pair and one sex chromosome, that is 23 unpaired (haploid) chromosomes. Upon fertilization, the full number of 46 diploid chromosomes is reconstituted. In the normal state, the chromosomal pattern (karyotype) of somatic cells is identical.
Each chromosome is composed of thousands of genes arranged in regular order. The corresponding genes (alleles) on a chromosome carry identical gene instruction (homozygous) or dissimilar instruction (heterozygous). If the genes are heterozygous one may be expressed as a bodily characteristic (dominant), while the other is unexpressed (recessive).
At fertilization, the reassortment of chromosomes is purely random so that either one of a pair of chromosomes from one parent has an equal chance of combining with either one of the corresponding pair from the other parent. Normal as well as abnormal characteristics are inherited in the same way, either as autosomal dominant, autosomal recessive or x-linked (sex-linked). The term genotype denotes the hereditary constitution or combination of genes that characterizes a give individual or group of genetically identical organisms. The term phenotype denotes the recognizable morphologic or functional characteristics expressed by a genetic trait.
Genes may undergo transformations (mutations) that may produce new somatic or functional characteristics. The older the parenteral age, the greater the incidence of such fresh mutations. They might be inapparent but in many circumstances they can be correlated with the sudden appearance of heritable disease. The mutations are in number or shape of chromosomes, e.g. Down's syndrome appears when the 21st chromosome is tripled.
Genetic counselling is the process of managing the problems associated with the occurence or risk of occurence of a genetic disorder in a family. An appropriately trained proffesional counsellor attempts to help an individual or a family to understand the diagnosis of a genetic disorder, its cause and the available methods of treatment, the contribution of heredity to the disorder, and the risk of reoccurence in specific blood relatives. Informed genetic counselling often requires the use of diagnostic services such as karyotyping, biochemical tests for inborn errors of metabolism, syndrome recognition and amniotic fluid analysis.
Example of a hereditary genetic trait.
Pregnancy and childbirth
The process by which the fetus and the placenta are pushed out of the uterus is called labour. It is divided into four stages. Labour can be premature, prolonged, spontaneous, induced or also false. Childbirth is also referred to by doctors as parturition. Delivery is the process of helping the child to be born. A spontaneous vaginal delivery (SVD) is a normal delivery. If there are complications, the baby may be delivered by caesarian section (surgically removed).
A full-term pregnancy is 40 weeks, divided into three trimesters. A baby born before this is premature, born after this is postmature. A baby who is born dead, for example because the umbilical cord is around its neck, is stillborn. The expected date of delivery is the date on which a woman is expected to give birth to the child she is carrying (pregnant with). It is calculated by adding 280 days or 40 weeks to the first day of the last menstrual period. A pregnancy may end before term spontaneously with a miscarriage (spontaneous abortion) or be deliberately terminated with an induced abortion.
Fetal lie is the position of the fetus in the uterus. The normal lie is longitudinal, and the abnormal lie is transverse. Fetal presentation refers to the part of the fetus which occupies the central pelvic canal and which the examining finger feels on vaginal examination. The normal presentation is with the head (vertex presentation). Breech presentation means the buttocks are presenting. Abnormal presentation may require delivery with forceps.
The field of medicine that deals with pregnancy and childbirth is called obstetrics and the doctor is an obstetrician. If women experience troubles becoming pregnant they undergo assisted conception in specialized centres.
Ultrasound scan (pregnancy sonogram) of a fetus.
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entity
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ucelená jednotka
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infertility
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neplodnost
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carrier
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nositel
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prophylactic
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ochranný
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avoid
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vyhnout se
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aggravate
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zhoršit
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counsel
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radit
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remainder
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zbytek
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discern
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rozlišit
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alteration
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změna
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staining techique
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barvicí technika
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dissimilar
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různý, nestejný
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reassortment
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znovuuspořádání
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random
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náhodný
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denote
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označovat
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hereditary
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dědičný
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trait
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vlastnost, znak
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undergo
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podstoupit
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parenteral age
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stáří plodu
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inapparent
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nezjevný
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occurence
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výskyt
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premature
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předčasný, nevyspělý
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prolonged
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prodloužený
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induced
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indukovaný
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caesarian section
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císařský řez
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umbilical cord
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pupeční šňůra
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forceps
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kleště
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conception
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početí
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