医学英语课件：Common Knowledge of the Urinary System

1、Common Knowledge of the Urinary System,The major function of the urinary system is to remove urea from the bloodstream so that it does not accumulate in the body and become toxic. Urea is formed in the liver from ammonia, which in turn is derived from the breakdown of simple proteins (amino acids) i

2、n the body cells. The urea is carried in the bloodstream to the kidneys, where it passes with water, salts, and acids out of the bloodstream and into the kidney tubules as urine. Urine then travels down the ureters into the bladder and out of the body.,I . Introduction,In addition to forming urine a

3、nd eliminating it from the body, the kidneys also act as endocrine organs, secreting into the bloodstream substances that act at some distant site in the body. Examples of the kidneys endocrine function include the secretion of renin, a substance important in the control of blood pressure, and eryth

4、ropoietin (poietin = substance that forms), a hormone that regulates the production of red blood cells. The kidneys also secrete an active form of vitamin D, necessary tor the absorption of calcium from the intestine, in addition, hormones such as insulin and parathyroid hormone are degraded and ext

5、racted from the bloodstream by the kidney.,II . Anatomy of the Major Organs,The organs of the urinary system are: (1) Two kidneysbean shaped organs situated behind the abdominal cavity, retroperitoneal, on either side of the vertebral column in the lumbar region of the spine. The kidneys are embedde

6、d in a cushion of adipose and surrounded by fibrous connective tissue for protection. They are fist-sized and weigh about half a pound each. The kidneys consist of a region of outer cortex, which means outer portion or bark, as the bark of a tree and a region of inner medulla, which means marrow or

7、inner portion. The depression on the medial border of the kidney, through which blood vessels and nerves pass, is called the hilum.,Kidney Anatomy,(2) Two uretersmuscular tubes lined with mucous membrane. They convey urine in peristaltic waves from the kidney to the urinary bladder. (3) Urinary blad

8、derhollow, muscular, distensible sac in the pelvic cavity. It serves as a temporary reservoir for urine. The trigone is a triangular space at the base of the bladder where the ureters enter and the urethra leads out. (4) Urethramembranous tube through which urine is discharged from the urinary bladd

9、er. The process of expelling or voiding urine through the urethra is called micturition. The external opening of the urethra is called the urethral or urinary meatus.,Urinary Bladder,III. How the Kidneys Produce Urine,Blood enters each kidney from the aorta by way of the right and left renal arterie

10、s. After the renal artery enters the kidney at the hilum, the artery branches into smaller and smaller arteries. The smallest arteries are called arterioles, which are located throughout the cortex of the kidney. Since the arterioles are small, blood passes through them slowly, but constantly. Blood

11、 flow through the kidney is so essential that the kidneys have their own special device for maintaining blood flow. If blood pressure falls in the vessels of the kidney so that blood flow is diminished, the kidney produces a substance called renin and discharges it into the blood. Renin leads to the

12、 formation of a substance termed angiotensin II , which stimulates the contraction of arterioles so that blood pressure is increased and blood flow in the kidneys is restored to normal.,nephron,Each arteriole in the cortex of kidney leads into a mass of very tiny, coiled and intertwined smaller bloo

13、d vessels called capillaries. The collection of capillaries, shaped in the form of a tiny ball is known as glomerulus. There are thousands of glomeruli in the cortex region of each kidney. As blood passes through the glomeruli, the process of forming urine begins. There are three steps to this proce

14、ss: filtration, reabsorption, and secretion. The walls of the glomeruli are thin enough t0 permit water, salts, sugar, and nitrogenous wastes such as urea, creatinine, and uric acid to filter out of the blood. Each glomerulus is surrunded by a cup-like structure that collects the substances filterin

15、g out of the blood. The cup-like structure is called Bowmans capsule. Large substances like proteins and blood cells cannot pass through the walls of the glomerulus into Bowmans capsule, and thus, if the kidney is healthy, they remain in the blood.,urine,Urine Formation,“refreshed” blood,From the or

16、iginal 1800 g NaCl, only 10 g appears in the urine,Urine,Water- 95% Nitrogenous waste: urea uric acid creatinine Irons: sodium potassium sulfate phosphate,IV. Urinalysis,1. ColoiNormal urine color is yellow (amber) or straw colored. A colorless, pale urine indicates a large amount of water in the ur

17、ine, whereas a smoky red or brown color of urine is due to the presence of large amounts of blood. Foods, such as beets, and certain drugs can also produce red hues in urine. 2. pH This is a test of the chemical nature of urine. The pH test indicates to what degree a solution, such as urine or blood

18、, is acid or alkaline (basic) . The pH range is from 0 (very acid) to 14 (very alkaline) . Normal urine is slightly acid (6.5) . However, in infections of the bladder, the urine pH may be alkaline, owing to the actions of bacteria in the urine that break down the urea and release an alkaline substan

19、ce called ammonia.,3. Protein Small amounts of protein are normally found in the urine but not in sufficient quantity to produce a positive result by ordinary methods of testing. When urinary tests for protein become positive, albumin is usually responsible. The major protein in blood plasma is albu

20、min, the finding of which is known as albuminuria. It may indicate a leak in the glomerular membrane, which allows albumin to enter the renal tubule and pass into the urine. 4. Glucose Sugar is not normally found in the urine. In most cases, when it does appear, whose condition is termed glycosuria,

21、 it indicates diabetes mellitus. In diabetes mellitus, there is an excess of sugar in the bloodstream termed hyperglycemia, which leads to spilling over of sugar into the urine. The renal tubules are unable to reabsorb all the sugar that filters out through the glomerular membrane.,5. Specific gravi

22、ty The specific gravity of urine reflects the amount of wastes, minerals, and solids in the urine. It is a comparison of the density of urine with that of water. The urine of patients with diabetes mellitus has a higher than normal specific gravity because of the presence of sugar. In kidney disease

23、s such as nephritis , the specific gravity of urine is low because the urine is diluted by large quantities of water that cannot be reabsorbed into the blood. 6. Ketone bodies Ketones sometimes referred to as acetones , which are a type of ketone body are breakdown products from fat catabolism in ce

24、lls. Ketones accumulate in large quantities in blood and urine when fat, instead of sugar, is used as fuel for energy in cells. This happens, for example, in diabetes mellitus when cells that are deprived of sugar must use up their available fat for energy. Also, in starvation, when sugar is not ava

25、ilable, ketonuria and ketosis, that are ketones in the blood, occur as fat is abnormally catabolized. The presence of ketones in the blood is quite dangerous since they increase the acidity of the blood, which is termed acidosis. This can lead to coma and death.,7. Casts These are substances that ap

26、pear in the urine as a sign of various pathological conditions. Casts, composed of materials such as red blood cells, pus, fat globules, and granules, accumulate in the renal tubules and are formed into a mold or shape of the tubule in which they collect. 8. Pus Pyuria gives a turbid (cloudy) appear

27、ance to urine. Large numbers of leukocytes called polymorphonuclears, are present because of infection or inflammation in the kidney or bladder.,9. Phenylketonuria (PKU) Phenylketones are substances that accumulate in the urine of infants bom with a special congenital problem. These infants are bom

28、lacking an important enzyme. The enzyme phenylalanine hydroxylase is necessary in cells to change one amino acid, phenylalanine, to another amino acid, tyrosine. Lack of the enzyme causes phenylalanine to reach high levels in the infants bloodstream, and this will eventually lead to mental retardati

29、on. The PKU test, done just after birth, can detect the phenylketonuria or phenylalanine in the blood. When it is detected , the infant is fed a low-protein diet that excludes phenylalanine so that mental retardation is prevented. This strict diet is necessary until the child is an adult. 10. Bilimb

30、in This pigment substance from hemoglobin breakdown may appear in the urine, darkening it, as an indication of liver or gallbladder disease. The diseased liver has difficulty removing bilirubin from the blood (hyprebilirubinemia), which causes excessive bilirubin to appear in the urine, termed bilir

31、ubinuria.,The Female Reproductive System,Internal Genitalia,Wall of uterus contains three layers Perimetrium Outermost serous membrane layer Myometrium Middle, muscular layer Endometrium Innermost layer, highly vascular,Cervix,The opening from the vagina into the womb allows menstrual blood exit and

32、 sperm in.,External Genitalia,Mons pubis Fatty tissue that covers and cushions symphysis pubis Labia majora Two folds of skin containing fatty tissue and covered with hair Located on either side of the vaginal opening, extending from the mons pubis to the perineum,External Genitalia,Labia minora Two thin folds of tissue located within the folds of the labia majora Extends from the clitoris downward toward the perineum Bartholins glands Located on either side of the vaginal o