BSC 109 1st Edition Lecture 21 Outline of Last Lecture I. The digestive system brings nutrients into the bodyII. 5 basic processes accomplish digestive system functionIII. 2 types of motility aid digestive processesIV. The pharynx and esophagus deliver food to the stomachV. The stomach stores food, digests protein, and regulates deliveryVI. Gastric juice breaks down proteinsVII. The small intestine digests food and absorbs nutrients and waterVIII. Accessory organs aid digestion and absorptionIX. The large intestine absorbs nutrients and eliminates wastesX. How nutrients are absorbedXI. Endocrine and nervous systems regulate digestionXII. Nutrients are used or stored until neededOutline of Current Lecture I. Urinary system contributes to homeostasisA. Excretion: processes that remove wastes and excess materials from the body to maintain homeostasisB. Urinary system (kidneys): excretes nitrogenous wastes, excess solutes, and waterC. The kidneys regulate water levelsD. The kidneys regulate nitrogenous wastes and other solutesII. Organs of the urinary systemA. KidneysB. Ureters: muscular tube that transports urine from kidneys to bladderC. Urinary bladderD. UrethraE. Nephrons produce urineF. The tubule filters fluid and reabsorbs substancesG. Special blood vessels supply the tubuleIII. Formation of urine: filtration, reabsorption, and secretionA. Glomerular filtration: movement of protein-free solution of fluid and solutes from blood into the glomerular capsuleB. Tubular reabsorption: return of most of the fluid and solutes into the bloodC. Tubular secretion: addition of certain solutes from the blood into the tubuleIV. Producing dilute urine: excreting excess waterCurrent LectureThese 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.Chapter 15: The Urinary SystemV. Urinary system contributes to homeostasisA. Excretion: processes that remove wastes and excess materials from the body to maintain homeostasisB. Urinary system (kidneys): excretes nitrogenous wastes, excess solutes, and waterC. The kidneys regulate water levels1. To maintain homeostasis, water intake= water output2. Kidneys adjust water output as necessarya) Water input: food, drink, metabolismb) Water output: lungs, skin, fecesc) Kidneys modify output based on intake and loss (output varies from ½ liter per day to 1 liter per hourD. The kidneys regulate nitrogenous wastes and other solutes1. Protein metabolism produces nitrogenous wastes2. Initially, NH3 (ammonia) is produced during breakdown of amino acids3. Liver detoxifies NH3, producing urea4. Urea is transported from liver to kidneys for disposal5. Other solutes regulated by kidneys: sodium, chloride, potassium, calcium,hydrogen ions, creatineVI. Organs of the urinary systemA. Kidneys1. Principal organ of urinary system2. Cortex: outer portion of the kidney3. Medulla: inner region of the kidney4. Renal pelvis: hollow space in center of kidney where urine collectsB. Ureters: muscular tube that transports urine from kidneys to bladderC. Urinary bladder1. Three layers of smooth muscle, lined with epithelial cells2. Stores urine (600-1000ml)D. Urethra1. Carries urine from bladder to outside of body2. 2 sphincters control urinationE. Nephrons produce urine1. Nephron: functional unit of the kidney2. 2 functional parts: tubule and associated blood supply3. Each nephron consists of a long thin hollow tube (tubule) plus associated blood supply4. Role of nephrons: remove approximately 180 liter of fluid from the blood daily, and return most of it, minus the wastes that are excreted5. Nephron structurea) Glomerular capsule: cuplike end of nephron tubule surrounding glomerulus (network of capillaries)- this is where filtration occursF. The tubule filters fluid and reabsorbs substancesG. Special blood vessels supply the tubule1. Renal artery supplies the kidney2. Renal vein: collects filtered blood from kidneysVII. Formation of urine: filtration, reabsorption, and secretionA. Glomerular filtration: movement of protein-free solution of fluid and solutes from blood into the glomerular capsule1. Filters protein-free plasma fluid from capillaries into glomerular capsule2. Large volume filtration, yet highly selective (impermeable to large proteins and cells)B. Tubular reabsorption: return of most of the fluid and solutes into the blood1. 100% of filtered glucose, amino acids, and bicarbonate and 50% of urea are reabsorbed under normally functions2. Reabsorption of sodium begins the processa) Sodium moved by active transport from tubule cells to interstitial fluid and diffuses to capillariesb) Chloride passively accompanies sodium (balanced charge)c) Water reabsorbed with saltsd) Water moves through aquaporins (water channels)e) Movement of sodium provides energy to transport glucose and amino acids from tubule into surrounding cellsf) Glucose, amino acids then diffuse to the interstitial fluidC. Tubular secretion: addition of certain solutes from the blood into the tubule1. Removes other substances from blood2. Involves the movement of materials from the peritubular capillaries or vasa recta to the tubule3. Purpose:a) Regulation of chemical levels in bodyb) Excretion of harmful chemicals4. Substances secreted: penicillin, cocaine, marijuana, pesticides, preservatives, hydrogen ions, ammonium, potassiumVIII. Producing dilute urine: excreting excess waterA. Kidneys respond to excess water by excreting itB. Mechanism:1. Distal tubule is impermeable to water so water is not reabsorbed here2. NaCl is reabsorbed without the concurrent reabsorption of water3. High volume dilute urine is