BIOL 1140 1st Edition Lecture 23Outline of Last LectureI. Digestive SystemII. Gastrointestinal TractIII. Digestive TractIV. Salvitory Glands of the MouthV. Digestive Tract ContinuedVI. Digestion and Absorption of NutrientsVII. OrgansVIII. Hormonal Control of Digestive SecretionsOutline of Current LectureI. Urine System FunctionII. Urinary System StructuresIII. Kidney StructureIV. Anatomy of a NephronV. Urine FormationVI. Hormonal Control of Functions VII. Problems with Kidney FunctionVIII. Dialysis for Treatment of Kidney FailureCurrent Lecture I. Urinary System Functiona. Excretion of nitrogenous wastes, excess solutes, and water from bodyi. Blood is filteredii. Urine is formed, then eliminatedb. As urine is being produced, the kidneys are maintaining homeostasisi. Regulation of metabolic wastes1. Amino acid breakdown yields ammonia, converted to urea in liver2. Excess salts, ammonium, creatinine, and uric acid are also excretedii. Maintain water content of blood, and thus blood volume and blood pressureiii. Maintain acid-base balance of the bloodII. Urinary System Structuresa. Kidneys - primary organs of the urinary system and produce urine b. Ureters- carry urine from the kidneys to the bladderc. Urinary bladder - stores urine, gradually expands as urine entersd. Urethra - carries urine from the urinary bladder to an exterior openingi. Sphincters control elimination of urineIII. Kidney StructureThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.a. Three major regionsi. Renal cortexii. Renal medullaiii. Renal pelvisb. Kidney is composed of about a million filtration units called nephronsi. Sit partially in the cortex and partially in the medullaii. Filter about 180 L of fluid from blood per day, return most of it, and excrete the rest as urineIV. Anatomy of a Nephrona. Composed of several partsi. Glomerularii. Proximal tubuleiii. Loop of Henleiv. Distal tubulev. Collecting ductb. Each collecting duct gathers urine from multiple nephrons and drains it into the renal pelvisc. Urine then flows into a ureterd. Has own blood supplyi. Blood enters from the renal arteryii. Renal artery branches into smaller arterioles, which lead to the glomerulus capillaries inside Bowman's capsuleiii. Blood then flows to a capillary network which surrounds the nephroniv. Blood exits the kidney through the renal vein V. Urine Formation a. Urine formation is divided into four stepsi. Filtration1. At the glomerulus and bowman's capsuleii. Reabsorption 1. Mainly in proximal tubule and loop of Henleiii. Secretion1. Distal tubule iv. Concentration1. Collecting ductb. Filtrationi. Arteriole brings blood into the Glomerulus, a knot of capillaries inside Bowman's capsule that acts like a sieveii. Blood pressure forces small components of blood out of capillary and into the capsuleiii. Large components remain in capillary c. Reabsorptioni. In the proximal tubule, the good stuff is moved out of the tubule and back into bloodstreamii. Amino acids, glucose, saltsiii. Some h20 is also reabsorbediv. Via active transport and facilitated diffusiond. Reabsorption i. In the loop of Henle1. Reabsorption h20 and salt2. Loop passes through medulla, which is very salty3. H20 moves out of tubule by osmosis in the descending part of the loop4. NaCl is actively transported into the medulla in the ascending part of the loopa. Maintains high salt concentration in the medullae. Secretion - in the distal tubulei. Some drugs, toxins, and foreign substances are secreted from the blood into the tubule1. Penicillin, marijuana, cocaine, pesticides, preservatives2. By active transport or diffusion ii. Blood pH is maintained by reabsorbing bicarbonate ions and exerting hydrogen ions asneeded1. Metabolic reactions in body make H+2. H+ is acidic and must be eliminatedf. Concentrationi. Dilute urine enters collecting duct; contains urea and other wastes, drugs and toxins, some h20ii. Additional h20 may leave duct by osmosis1. Depends on water content of bloodConcentrated urine empties into renal pelvis, which empties into ureterVI. Hormonal Control of Functionsa. Maintenance of blood volumei. Heart senses blood volume and the hypothalamus in the brain senses solute concentration in bloodii. Antidiuretic hormone is released by the posterior lobe of the pituitary1. ADH increases permeability of Collecting Duct to h20a. Therefore causes more water to be reabsorbed into blood and less urine to form iii. Diuretics increase urine flow by decreasing reabsorption of h201. Caffeine inhibits sodium reabsorption; sodium is therefore excreted in urine, causing more h20 to go with it2. Alcohol inhibits ADH release3. Some drugs help reduce blood volume and therefore blood pressure for hypertension treatment b. Maintenance of salt balancei. Kidneys regulate blood's salt balance by controlling excretion and reabsorption of salts1. Aldosterone causes more sodium to be reabsorbed into blood from distal tubuleand collection ducta. Made in adrenal glandsb. If more sodium is reabsorbed, then more h20 is also reabsorbedc. In turn raises blood volume and blood pressureii. Renin is secreted by the kidney when blood pressure is too low for proper filtration1. A protein called angiotensinogen is made by liver, found in bloodstream 2. Renin = enzyme that converts angiotensinogen into angiotensinogen I3. An enzyme in lung tissue converts angiotensinogen I into angiotensinogen II4. II is a vasoconstrictor = raises blood pressureiii. Renin also stimulates aldosterone releaseiv. Atrial Natriuretic hormone inhibits renin, and inhibits aldosterone1. Released by cells in the heart when they are stretched by too much blood volume2. ANH decreases reabsorption of Na+, therefore it promotes excretion of Na+ (lostin urine)3. Less water is reabsorbed into the bloodstream and instead lost in urinea. Decreases blood volume and blood pressureVII. Problems with Kidney Functiona. Kidney stones: crystals formed from urine made of calcium, phosphorus, uric acid, and proteini. May block ureters ii. May cause urine to back up into nephrons and destroy themb. UTIi. If they move up the urethra, bladder or into the kidney, can damage the nephrons1. Urethritis - localized infection of the urethra2. Cystitis -infection in the bladder3. Pyelonephritis - infection of the kidneysc. Hypertension i. Damages the glomerulus and bowman's capsuled. Diabetes - causes 50% of kidney