The Urinary SystemDorsey SchoolsBIO 102Tanesia Copeland Cynthia ColemanNatalia KicilinskiAccording to “encyclopedia.com under the topic medicine/ urinary system”.
The main purpose of the urinary system is to remove waste products. Included is an detailed description of how this process works. When cells in the body break down proteins into forms in which they can be used and produce ammonia wastes that the liver turns into urea such as a chemical compound of carbon, hydrogen, nitrogen and oxygen. Whereas, when cells break down carbohydrates, water and carbon dioxide are produced as waste products.
However, if these waste products accumulate in the body it would be harmful for the body’s health. Excretion is known as the process of eliminating waste and solids from the body but the urinary system is mainly responsible for waste excretion. Urinary system eliminates water, urea, uric acid, creatinine from blood to be passed from the body in the form of urine.
The urinary system also helps us regulate amount of glucose, salts and water in the blood.There are numerous medical problems and diseases that may affect the urinary system. Included are some of the medical problems and diseases associated with the urinary system followed by specific detailed explanation of each. Urinary tract infection (UTI) is the most common infection in the urinary system. However, women are four times likely to get a UTI than men and a even higher risk if you have diabetes, need a tube to drain bladder, or have spinal cord injury. Symptoms associated with UTI are as followed; pain/ burning when urinating, fever, tiredness, shakiness, urge to urinate frequently, pressure in lower belly, urine smells or looks cloudy or reddish, and pain in back or side below ribs. Treatment for an UTI would be antibiotics. Next, Interstitial cystitis (IC) causes discomfort or pain in bladder and a need to urinate frequently and urgently.
This also is more common in women than men and the symptom worsen in the female during her menstrual and during sexual intercourse. Although, the cause is unknown treatment includes distending or inflating the bladder, bathing the inside of bladder with drug solution, oral meds, electrical nerve stimulation, bladder training, lifestyle changes, physical therapy and in rare cases surgery. Urinary incontinence or loss of bladder control is another medical problem in the urinary system. This happens when muscles are too weak or too active. If the muscles that keep the bladder closed are weak a person may void on themselves if sneezing, laughing, or lifting a heavy object this is known as stress incontinence. Whereas, if the muscles become too active there may be a strong urge to void when there is only a scant amount of urine in the bladder this is known as overactive bladder. However, the symptoms varies from mild leaking to uncontrollable wetting not to mention, women experience this twice as often as men.
Treatment for this medical problem depends on the problem and could include; simple exercises, medicines, special devices or procedures prescribed by physician or surgery. Bladder cancer is a disease of the urinary system which occurs in the lining of the bladder. It’s the sixth most common type of cancer in the United States. A risk for developing bladder cancer include, smoking and exposure to certain chemicals in the workplace, family history of bladder cancer and older caucasian or males have a high risk. Symptoms associated with bladder cancer may be blood in your urine, frequent urge to urinate, pain during urination, and low back pain. Treatments include, surgery, radiation therapy, chemotherapy, and biologic therapy which boost body’s own ability to fight cancer. To conclude the diseases last is Chronic kidney disease which the kidneys are damaged and cannot filter blood that would cause waste build-up in the body.
This disease occurs slowly over many years and treatment cannot cure but may slow the disease progression however, if the kidneys fail person would have to go on dialysis or need a kidney transplant.A detailed explanation of which organs make up the urinary system . The urinary system is responsible for filtering waste from the blood, regulating concentration of substances in the blood, making urine, carrying urine ultimately to be excreted from the body.The major organs of the urinary system include the kidneys, ureters, urinary bladder and the urethra. Kidneys are bean shaped organs present on both sides of the abdomen, in the retroperitoneal cavity. The right kidney is slightly lower than the left one, due to the presence of the liver in the right upper quadrant of the abdomen. They are present in front of the transverse processes of the T12-L3 vertebrae.
They are reddish brown in color and measure about 10cm (length) by 5cm (width) by 2.5cm (thickness). Each kidney is divided into two parts, renal cortex and the medulla.
The medulla is divided into renal pyramids, which ultimately empties out urine into the renal pelvis. The primary functional unit of the kidney is a Nephron. Nephrons process blood and make urine in the process. Each nephron consists of (in order), the renal corpuscle (comprising of the glomerulus and the Bowmans capsule), the proximal convoluted tubule, the descending loop of Henle, ascending limb of Henle (thin followed by thick), distal convoluted tubule and the collecting duct, which open into the renal papillae. All nephrons are predominantly located in the renal cortex. The medulla is responsible for transporting urine from the cortex to the renal pelvis and also for making urine through the loops of Henle. Each renal pyramid is made up of multiple units of the renal collecting ducts. Urine drains from the renal papillae located at the tips of the renal pyramids into the minor calyx.
Each kidney has about 7-9 minor calices. Each minor calyx drains into the major calyxes which in turn drain into the renal pelvis. The renal pelvis drains into the ureters. The kidney is a very vascular organ. It receives blood from the renal artery (which branches off of the aorta) and blood is taken from the kidneys into the inferior vena cava through the renal veins. The renal hilum comprises of the renal artery, vein, lymphatics and the renal pelvis. Urine is carried from each kidney to the urinary bladder by the ureters.
The ureters are long muscular tubes (about 22-30cm in length), usually divided into three sections; upper third (from the renal pelvis to the upper edge of the sacrum), middle third (from the top to lower edge of the sacrum) and distal third (from lower edge of the sacrum to the urinary bladder). There are three physiologic areas of narrowing in the ureters, which are clinically important; upper (transition between the renal pelvis and the ureter), middle (where the ureters cross the iliac vessels ventrally) and the lower (transition of the ureters into the urinary bladder). Various blood vessels supply the ureters in a longitudinal fashion and the venous drainage is paired with the arteries. Ureters have their own pacemaker that governs peristalsis; however, it is also supplied by the autonomic nervous system. Parasympathetic nervous input is derived from the S2-4 segments of the spinal nerve roots. Pain sensation received through noiceceptors is carried through the sympathetic nervous system and referred pain can proceed from ipsilateral ribs down to scrotum or labia as the pain travels down the length of the ureter. Ureters are lined (from the inside to outside) by the transitional epithelium, the lamina propria and the muscularis (inner longitudinal and outer circular smooth muscle fibers) and the adventitia which harbours the vascular supply.
The urinary bladder is an extraperitoneal reservoir for collecting urine, prior to voiding, that lies behind the pubic symphysis (space of Retzius). The dome is covered by peritoneum. It is supported by the pelvic muscles and ligaments. At its apex, lies the medial umbilical ligament which courses along the anterior abdominal wall to the umbilicus. The bladder neck serves as an opening to the urethra and acts as an internal sphincter. The neck is surrounded by the pelvic floor muscles which act as the external sphincter. The trigone is a triangular portion of the bladder (its three vertices include the two ureteral openings and the third one being the bladder neck). The bladder wall has three muscular layers called the detrusor (inner longitudinal, middle circumferential and outer longitudinal layer).
Blood supply is through the iliac vessels. The external sphincter is supplied by the pudendal nerve. The innervation of the detrusor is through the parasympathetic nervous system (S2-4). The sympathetic nervous system to the bladder neck constricts the neck until voiding happens.
The urethra is a tube that transports urine from the bladder neck to outside of the body. Males and females have a different anatomy for the urethra. The male urethra is about 20cm long. It is divided into three parts: prostatic, membranous and spongy (penile) urethra.
Prostatic urethra is surrounded by the prostate and can get constricted in males with benign prostatic hyperplasia. Membranous urethra is the shortest segment of the urethra and the least distensible. It is part of the pelvic floor and forms the external sphincter. The spongy urethra is surrounded by the corpus spongiosum of the penis. It opens to the outside of the body from the urinary meatus. The female urethra is shorter in length (about 4cm). The proximal portion lies within the pelvic diaphragm. Distally it is surrounded by the urogenital glands.
The pelvic blood vessels from the iliac vessels supply the urethra. Lymph drains from the urethra into the deep and superficial inguinal lymph nodes. On cross-section, the inner lining consists of the transitional epithelium. Distally, it is lined by the squamous epithelium closer to the urethral meatus. Functions of the urinary system: 1. Kidneys:The kidneys are important organs that facilitate removal of waste from the blood in the form of urine and regulating water fluid levels in the body. The whole blood from the body passes through the kidneys every 4-5 minutes.
It filters about 180 liters of blood and reabsorbs 178.5L of fluid back into the blood every day. The deficit of around 1.5L is excreted in the form of urine from the body. The process by which it does it is called glomerular filtration and the basic unit of kidneys which facilitate this process is called a nephron. Each nephron is composed of the Bowman’s capsule (which surrounds the glomerular tuft), proximal convoluted tubule, loop of Henle (descending limb, thin ascending limb and thick ascending limb), and distal convoluted tubule.
Urine formation occurs through three main steps:Filtration: During filtration, blood flows through the afferent arteriole into the glomerulus. Water and small molecules are filtered through the wall of the glomerular epithelium (composed of podocytes and basement membrane) into the Bowman’s capsule and large molecules like albumin and other proteins are retained in the blood and flow into the efferent arteriole.Reabsorption: During reabsorption, molecules, electrolytes and ions will be absorbed back into the blood depending on the osmotic and the diffusion gradient. Each component of the nephron (proximal, distal convoluted tubule and the loop of Henle) is responsible for absorbing different components and electrolytes. Secretion: In secretion, some components from the blood like creatinine, hydrogen ions, drugs etc are removed from the body actively against the osmotic or diffusion gradient using energy in the form of ATP with the tubular cells.The sum process of all these activities results in the formation of urine which is taken from the nephron into the collecting system and then subsequently into the renal papillae and ultimately, ureters. Other important functions of the kidneys:a.
Renin Angiotensin system: Renin, produced by the kidneys gets converted to Angiotensin I, which subsequently is converted to Angiotensin II. It regulates blood pressure, body water content and sympathetic stimulation by regulating the concentration of aldosterone and vasopressin in the body. The former promotes absorption of sodium and the latter, water.b. Countercurrent multiplier: Responsible for water and electrolyte absorption from the loop of Henle and in concentrating urine.c. Production of erythropoietin: Important for generation of red cells in the body and haemoglobin.
d. Production of calcitriol (1, 25 dihydroxycholecalciferol) which is the active form of Vitamin D and is responsible for calcium absorption in the rest of the body, which subsequently promotes bone formation. 2. Ureters: Ureters are responsible for transporting urine from the kidneys to the urinary bladder in small spurts called peristalsis. Ureteral valves prevent backflow of urine from the bladder into the ureters 3. Urinary bladder: It is responsible for storage of urine before it is ultimately excreted.
As urine accumulates in the bladder, its walls stretch, promoting the micturation reflex. The brain is able to inhibit the external sphincter of the bladder to prevent urination in the early stages of bladder filling. However, when the urine in the bladder reaches around the 400-450cc mark, the micturation reflux is so pronounced that it promotes relaxation of the internal urethral sphincter at the apex of the bladder. When the external sphincter also relaxes, it promotes micturation (urination).
The parasympathetic nervous system promotes internal sphincter constriction whereas the sympathetic nervous system promotes relaxation. The bladder also has a mild temperature regulation. Heat leaves the body in the form of urine. 4.
Urethra. The urethra carries urine from the urinary bladder to the urethral meatus and ultimately, out of the body. The urinary system is a unique system.
This system works well with other systems of the body. The urinary system works by cleaning the blood of waste products produced by other body systems. The circulatory system circulates oxygen and glucose throughout the body to help cells work properly. Waste from the blood must pass through one of the two kidneys. Water, uric acid and urea are removed from the blood and than most of the water is returned to the circulatory system. Waste is removed from the blood to produce urine.The muscular and skeletal system provide protection and smooth muscle bladder for the urinary bladder.
The smooth muscle is a layer in the urinary bladder wall that’s made of smooth muscle fibers. This muscle assist the bladder to expel urine. Nutrients are provided by the digestive system to help kidneys clean and eliminate waste produced by other body systems. The adrenal glands; which are part of the endocrine system secretes a chemical that helps the kidneys to effectively regulate fluids in the body (homeostasis). The nervous system will receive a message from the brain when it’s time to release urine.The bladder muscles and the urethra helps the bladder to retain the urine until we can find a bathroom. All systems in the body work together to maintain balance in the body.
The urinary system compensates for water loss due to sweating. The integumentary system and the urinary system also are involved with the production of vitamin D. The urine elimination from the bladder is controlled by the muscular system. The nervous systems tells the bladder when to produce and release urine. The kidneys replenishes fluids lost by the digestive system. The ph of the internal environment is controlled by the lungs and the urinary system. Fluids lost from the female and male reproductive system are restored by the urinary system.
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