APU6 Urinary System

Editor's Notes

• #5: Blood volume and pressure are regulated by adjusting the volume of water lost in the urine.
• #6: 4. The plasma concentrations of sodium, potassium, chloride, and other ions are regulated by controlling the quantities lost in the urine. Blood pH is stabilized by controlling the loss of hydrogen ions (H+) and bicarbonate ions in the urine. 5. As the kidneys filter the blood, they are also indirectly measuring the oxygen levels in the blood. Erythropoietin is released if blood oxygen levels fall, stimulating RBC production in red bone marrow.
• #8: The aorta passes the blood from the heart to the renal arteries, that then pass it to the kidneys for filtration. Once the blood has been filtered, the wastes are passed to the bladder and the filtered blood returns back into circulation.
• #9: A typical kidney is 10 cm long, 5.5 cm wide, 3 cm thick, and 150 g. Right kidney is slightly lower than the left to make room for the liver! The adrenal glands are small glands located on top of each kidney. They produce hormones that you can't live without, including sex hormones and cortisol. Cortisol helps you respond to stress and has many other important functions. 
• #14: Ultrafiltration a type of membrane filtration in which hydrostatic pressure forces a liquid against a semipermeable membrane.
• #17: Plural is calyces.
• #19: The ureters remove the urine from the kidney and pass it to the urinary bladder.
• #20: The bladder is small…roughly the size of a walnut when empty. It can hold up to 800 ml (24 oz) voluntarily; up to 2000 ml (60 oz) when obstructed. As the bladder expands to hold urine, it activates stretch receptors in the wall that monitor volume; when the volume exceeds 200 ml (8 oz) the receptor signals enter our conscious perception …you feel the desire to urinate!
• #21: Both sphincter muscles must open to allow micturition (voiding).
• #22: Females are more prone to UTI’s
• #25: C stands for convoluted
• #28: The renal artery brings blood to the kidney for filtration. The collection of capillaries is called the glomerulus. The Bowman’s capsule is a sac-like projection that surrounds the glomerulus. The glomerulus is nestled inside Boman’s capsule. The glomerulus together with the Boman’s capsule is referred to as the renal corpuscle. As blood is pushed through the tiny capillaries, the high pressure forces some things to pass through the capillary walls…the walls act like a sieve (a filter). During filtration, blood enters the afferent arteriole and flows into the glomerulus where filterable blood components, such as water and nitrogenous waste, will move towards the inside of the glomerulus, and nonfilterable components, such as cells and serum albumins, will exit via the efferent arteriole. These filterable components accumulate in the glomerulus to form the glomerular filtrate. Normally, about 20% of the total blood pumped by the heart each minute will enter the kidneys to undergo filtration; this is called the filtration fraction. The remaining 80% of the blood flows through the rest of the body to facilitate tissue perfusion and gas exchange.
• #29: Most of the filtrate is reabsorbed. Overall, approximately 99% of glomerular filtrate gets reabsorbed – only about 1% of original filtrate actually leaves the body as urine. Needed nutrients are conserved; wastes and toxins are eliminated; blood levels of fluids, acidity, etc are actively regulated. 80% of materials to be reabsorbed are reabsorbed in PCT.
• #30: Additional substances are actively removed from the blood (H+, drugs, steroids)
• #31: Additional substances are actively removed from the blood (H+, drugs, steroids)
• #34: When the concentration of water in the blood decreases, the hypothalamus in the brain signals the posterior pituitary gland to release ADH. Blood carries ADH to the kidney. ADH causes the DCT and collecting ducts to become more permeable and increases water reabsorption. Urine becomes more concentrated, and urine volume decreases.
• #37: Urine is mainly composed of water that has not been reabsorbed, which is the way in which the body lowers blood volume, by increasing the amount of water that becomes urine instead of becoming reabsorbed. Urine is slightly acidic
• #41: Phase 1: Filling and storage During the filling phase the bladder volume increases with very little change to the internal pressure – this is termed compliance. As the bladder fills it becomes spherical and then pear-shaped as it rises up out of the pelvic cavity. During filling the detrusor is relaxed and the bladder neck and external sphincter are contracted maintaining continence. The first desire to void is usually experience at 200ml capacity which can be suppressed by conscious inhibitory control. As the bladder fills up the desire becomes stronger and more difficult to suppress. When the bladder desire is strong the individual will display behaviors to help them hold on ie become restless, hop from one foot to another, fidget, wander…you know…the peepee dance Phase 2: Voiding Voiding is initiated voluntarily and can be delayed until a suitable time and place. The external sphincter and bladder neck relax and simultaneously the detrusor muscle contracts. This is co-ordinated via the spinal-pontine-spinal reflex which involves the micturition control center in the pons of the brain. When the external sphincter relaxes the pressure in the urethra is lowered and the pelvic floor relaxes allowing the bladder neck to descend and open. This is known as funnelling. The parasympathetic nerves stimulate the detrusor contraction, thus increasing the intravesical pressure and the urine is expelled under pressure. Phase 3: Termination of voiding As emptying is completed the flow reduces and ends. External sphincter closes under voluntary control. Urethra contracts forcing urine above the level of the external sphincter back up into the bladder (approximately 10 ml of urine remains). Cortical micturition control center takes control; this inhibition allows the filling cycle to start again.
• #42: When bladder fills with 200 ml of urine, stretch receptors transmit impulses to the CNS and produce a reflex contraction of the bladder.
• #45: A thorough urinalysis may provide more information about the general condition of the body than any other set of tests.
• #46: Oliguria less than 400 ml/day, seen in dehydration, shock, renal failure Polyuria, more than 2000 ml/day, seen in increased water ingestion, diabetes mellitus and insipidis Anuria less than 100 ml/day, seen in renal shut down
• #47: Color due to metabolic breakdown of hemoglobin by bile or bile pigments Colorless may indicated diabetes or taking diuretics Pale yellow may indicate diabetes insipidus, granular kidney or simply indicate the ingestion of copious amounts of water. Reddish colors may be due to food pigments (such as beets) certain drugs, or blood in the urine. Greenish colors indicate either bile pigment (jaundice) or certain bacterial infections. Brown/Black urine can indicate phenol or metallic poisonings, or hemorrhages due to conditions such as renal injury or malaria.
• #48: A milky appearance may indicate fat globules, or pus corpuscles resulting from a UTI.
• #49: Odor is due to nitrogenous waste in urine Diabetes will be sweet, ketonuria will be fruity, there is a maple syrup urine disease Some initial symptoms characteristic of classic MSUD are: lethargy. poor appetite. weight loss. weak sucking ability. irritability. a distinctive maple sugar odor in earwax, sweat, and urine. irregular sleep patterns. alternating episodes of hypertonia (muscle rigidity) and hypotonia (muscle limpness)
• #50: pH reflects ability of kidney to maintain normal hydrogen ion concentration The acidicy or alkalinity can fluctuate depending on the type of food ingested. High protein = acidic; vegetables & wheat = alkaline Pathological conditions can also affect the pH of urine. Fevers and acidosis lower the pH, whereas anemia, vomiting, and ischuria (urine retention) raise the pH.
• #51: The more concentrated the urine, the higher the urine specific gravity, and the more likely that kidney stones will form
• #52: Mg/dl is milligrams per deciliter Albumin is a plasma protein
• #54: Catabolized – broken down
• #55: URINE is sterile because it contains no living organisms, unless the person that produces is unlucky enough to have a urinary tract or bladder infection. There are less bacteria in urine than in tap water, for example. Epithelial cells are found in urine as they are the cells that line the urinary tract. A large number of crystals, or certain types of crystals, may mean kidney stones are present or that there is a problem with how the body is using food.
• #58: Kidneys show lots of atrophy in old age. From ages 25 to 85 the number of nephrons decline by 30-40 percent; up to 1/3rd of remaining glomeruli become atherosclerotic, bloodless, and nonfunctional Kidneys of 90 year old man are 20-40% smaller than those of a 30 yr old and receive only half as much blood. Water balance Micturition Problems – urethral sphincters lose muscle tone leading to incontinence in older women. The ability to control micturition (due to stroke/Alzheimer’s). Urinary retention leading to infections (enlarged prostate compresses the urethra and reduces urine flow, making it harder to empty bladder)
• #59: URINE is sterile because it contains no living organisms, unless the person that produces is unlucky enough to have a urinary tract or bladder infection. There are less bacteria in urine than in tap water, for example. CLARIFICATION: In the bladder, that is. But as soon as it leaves your body, it can pick up bacteria from the urethra and air. Ancient Roman doctors actually told their patients to rinse their mouths with pee for whiter teeth. And surprisingly, this wasn't an entirely crazy idea — the ammonia in urine can actually make your teeth whiter, but good luck finding the courage to swish it around in your mouth. Ancient Roman spies used urine as invisible ink to write secrets between the lines of their official documents, hence the saying: “read between the lines.” The messages appeared only when heated.[1] And in pre-industrial times, urine was used in cleaning fluids because of the ammonia. If you happen to be lost in the desert without water, do not drink your urine. It's full of salt, which can actually make you more dehydrated instead of quenching your thirst. In fact, the US Army Field Manual strictly advises against drinking urine for survival. The World Record for the longest pee is 508 seconds.That's almost 8.5 minutes. Urine therapy, or drinking one’s own urine, is very popular in several countries. In Germany for example, nearly 5 million people regularly drink the liquid. In China, over 3 million people drink urine. Singers Jim Morrison and John Lennon and political activist Gandhi were also advocates. Boy George drank his own urine for six months and even consumed it in public. Urine therapists suggest that urine should be sipped, not guzzled, and it should be morning urine caught in midstream. A person doing urine therapy also needs to avoid salty foods and drink plenty of water. Women typically urinate in a wider stream than men due to having sex and giving birth. Centuries ago, the stream of the urine was used as a test to determine a woman’s virginity. If she urinated like a man, she was thought to be a virgin.[2]Men who pierce their penis may alter their urine stream. The piercing may cause spraying, split stream, and so on. Some men need to cover the piercing hole with a hand to urinate in a consistent stream.