Anglický jazyk
7.3 Medical English - The digestive and urinary systems
The digestive system is also called the gastrointestinal tract. The process of digestion begins in the oral cavity = mouth. The mouth contains the tongue and teeth. There are three pairs of salivary glands that produce a fluid called saliva. It is released from the parotid, submaxillary and sublingual glands and poured in the mouth.
Food passes from the mouth to the pharynx which contains the tonsils. They act as a filter to protect the body against microorganisms and produce lymphocytes which are able to fight disease. The pharynx opens in the oesophagus. It is a muscular tube that leads to the stomach.
The stomach has three parts: the fundus, the body with its greater and lesser curvatures, and the antrum. The openings that allow the food go in and out of the stomach are controlled by rings of muscles called sphincters. The cardiac sphincter is at the end of the oesophagus and the pyloric sphincter lets the food go on after digestion. The lining mucous membrane in the stomach secretes a huge amount of mucus, hydrochloric acid and enzymes. Then there are gastric juices secreted that produce an enzyme pepsin to convert proteins to smaller substances called peptones. Hydrochloric acid is necessary for the proper action of pepsin. The stomach serves to prepare food chemically and mechanically for the passage in the small intestine, further digestion and absorption.
The small intestine begins with the duodenum from where the food passes in peristaltic waves to the jejunum and finally to the ileum. The wall of the small intestine is covered with tiny finger-like structures called villi (sg. villus). They have a dense capillary network so they ensure the passage of food nutrients to the blood stream.
The colon = large intestine extends from the ileum to the anus. It is composed of the cecum with the vermiform appendix (blind intestine), the ascending, transverse and descending colon, the pelvic or sigmoid colon, and the rectum. The large intestine receives the fluid by-products of digestion. Water is reabsorbed in the blood stream and solid materials are excreted from the body as faeces = stool in the process of defecation.
The liver, the gallbladder and the pancreas access the digestive system. They are key for proper digestion and absorption of nutrients. The liver produces a thick fluid called bile which is stored in the gallbladder. Without bile, most of the food would remain undigested. The liver also keeps the amount of glucose in blood at a normal level, produces protein substances, destroys worn-out red cells, removes poisons and toxins form the blood, forms antibodies to fight diseases, produces urea, etc.
The pancreas is both an exocrine and endocrine organ. It secretes pancreatic juice which helps to break down food. It produces a hormone called insulin which controls the use of sugars in the body.
|
digestion
|
trávení, zažívání
|
|
salivary glands
|
slinné žlázy
|
|
saliva
|
sliny
|
|
tonsil
|
mandle
|
|
curvature
|
záhyb
|
|
sphincter
|
svěrač
|
|
intestine
|
střevo
|
|
colon
|
tlusté střevo
|
|
vermiform appendix
|
červovitý přívěsek
|
|
ascending
|
vzestupný
|
|
descending
|
sestupný
|
|
solid
|
pevný
|
|
faeces/feces = stool
|
stolice
|
|
bile
|
žluč
|
|
poison
|
jed
|
The urinary system is composed of several parts. The most important are of course the kidneys. They are two bean-shaped organs situated behind the abdominal cavity in the lumbar region. They are embedded in a cushion of adipose tissue and surrounded by fibrous connective tissue for protection. They consist of an outer cortex part and an inner medulla part.
Then there are two ureters which lead urine in peristaltic waves from the kidneys to the urinary bladder. They are muscular tubes lined with mucous membrane.
The urinary bladder is a hollow, muscular, distensible sack in the pelvic cavity. It serves as a temporary reservoir for urine.
Finally, the membranous tube through which urine is discharged from the bladder is the urethra. The discharge is called micturition.
Source: http://s2.hubimg.com/u/7624645_f260.jpg
The kidneys are a very sensitive organ that produces urine. Blood leads to the kidneys directly from the aorta through renal arteries. Each of these arteries branches in many arterioles which are thin so the blood passes through them slowly. Blood flow through the kidneys is essential so they have their own special mechanism to maintain it. If blood pressure falls so that the blood flow decreases, the kidneys produce renin and discharge it in the blood. Renin stimulates the contraction of arterioles so that the blood pressure increases and the blood flow returns to normal.
Each arteriole in the kidney cortex breaks up in tiny intertwined capillaries in the shape of a ball called glomeruli (sg. glomerulus). There are thousands of them in one kidney.
The process of urine formation begins in the glomerulus as water, salts, sugar, urea and other wastes such as creatinin and uric acid filter out in a cup-like structure called Bowman's capsule which encloses each glomerulus. Large molecules such as proteins remain in the blood stream and cannot pass through the walls.
But it is not desirable to discharge water, sugars etc. These substances need to be reabsorbed back in the blood stream. This process takes place through the tubules that lead from Bowman's capsules. They are called renal tubules. Now the fluid is quite concentrated and contains only waste and water. Renal tubules reabsorb about 90% of the primary urine.
Moreover, acids and other unnecessary substances are secreted in the distal renal tubules from the blood stream. They merge and form the renal pelvis, a space that fills most of the kidney medulla. They narrow in the ureter which carries the urine to the bladder. The exit area between the bladder and the urethra is closed by sphincters which keep the urine in the bladder. When it fills up, though, the muscles begin to contract which causes the desire to urinate.
Source: http://www.urologyhealth.org/urology/articles/images/anatomy_Kidney_midsagital.jpg
|
embed
|
uložit
|
|
cushion
|
vycpávka
|
|
surround
|
obklopovat
|
|
cortex
|
kůra
|
|
medulla
|
dřeň
|
|
ureter
|
močovod
|
|
urine
|
moč
|
|
urinary bladder
|
močový měchýř
|
|
urethra
|
močová trubice
|
|
micturition
|
močení
|
|
hollow
|
dutý
|
|
distensible
|
roztažitelný
|
|
discharge
|
vylučovat
|
|
intertwine
|
proplést
|
|
desirable
|
žádoucí
|
|
merge
|
spojit se
|
|
renal pelvis
|
ledvinová pánvička
|
|
narrow
|
úzký, zúžit
|