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Rita Garcia- Gonzalez Digestive & Urinary System Period: 3 - Coggle…

- - - - Urethra
        
        This is a muscular tube that transports urine from the bladder out of the body
        . In males, the urethra is longer and divided into three regions (prostatic, intermediate, and spongy), while the female urethra is shorter
        
        Urinary Bladder
        
        This is a hollow muscular sac that serves as a temporary storage reservoir for urine
        . It is located on the pelvic floor and can expand significantly as it fills; a moderately full bladder can hold approximately 500 ml of urine
        .
        
        Ureters
        
        These are slender, muscular tubes that convey urine from the kidneys to the urinary bladder
        . They enter the base of the bladder through the posterior wall
        .
        
        Kidneys
        
        These are the major excretory organs responsible for maintaining the body's internal environment
        . They perform vital functions such as regulating total water volume and solute concentration, ensuring acid-base balance, and excreting metabolic wastes, toxins, and drugs
        . Internally, the kidneys contain over a million nephrons, which are the structural and functional units that actually form urine
        .
    - - Larynx
        
        The voice box; what makes out voice
        
        Stomach
        
        A temporary storage tank that begins the chemical breakdown of proteins and converts food into a paste called chyme
        
        Esophagus
        
        A flat muscular tube that moves the food bolus from the pharynx to the stomach
        
        Small Intestine
        
        The primary organ for digestion and absorption, subdivided into the duodenum, jejunum, and ileum
        
        Pharynx
        
        Specifically the oropharynx and laryngopharynx, which serve as conduits for food and fluids
        
        Large Intestine
        
        Responsible for absorbing remaining water and electrolytes and propelling feces toward the anus
        . Its regions include the cecum, appendix, colon (ascending, transverse, descending, and sigmoid), rectum, and anal canal
        
        Mouth ( Oral Cavity )
        
        Where ingestion and the initial mechanical and chemical breakdown of food occur
        
        Anus
        
        The terminal opening for the elimination of indigestible substances
      - Accessory Digestive Organs
        
        Tongue
        
        Functions in gripping, mixing food with saliva to form a bolus, and initiating swallowing
        
        Gallbladder
        
        A muscular sac that stores and concentrates bile produced by the liver
        
        Teeth
        
        Used for mastication (chewing) to grind food into smaller fragments
        
        Digestive Glands
        
        These produce secretions that help break down foodstuffs
        
        Liver
        
        The largest gland in the body, which produces bile to act as a fat emulsifier
        
        Pancreas
        
        Supplies enzymes to digest all classes of food and produces bicarbonate to neutralize acidic chyme
        
        Salivary Glands
        
        Cleanse the mouth, moisten food, and begin starch digestion with the enzyme amylase
- - - - Rennin
        
        An enzyme found in infants that breaks down the milk protein casein
      - Pancreatic Proteases
        
        These include trypsin, chymotrypsin, and carboxypeptidase, which are secreted by the pancreas into the small intestine to further digest polypeptides
      - Pepsin
        
        Formed in the stomach when the inactive enzyme pepsinogen (secreted by chief cells) is activated by hydrochloric acid (HCl). It begins the enzymatic digestion of proteins
      - Brush Border Enzymes
        
        Aminopeptidase, carboxypeptidase, and dipeptidase on the small intestine's brush border complete the breakdown of small peptides into individual amino acids
    - - Pancreatic Amylase
        
        Secreted by the pancreas into the small intestine, it continues the breakdown of starch and glycogen
      - Brush Border Enzymes
        
        Located on the microvilli of the small intestine, these include dextrinase, gluco-amylase, lactase, maltase, and sucrase. They break down oligosaccharides and disaccharides into monosaccharides like glucose, galactose, and fructose
        .
      - Salivary Amylase:
        
        Produced by the salivary glands and active in the mouth, it begins the breakdown of starch
    - - Gastric Lipase
        
        Secreted by chief cells in the stomach, it digests about 15% of lipids
      - Pancreatic Lipases
        
        The major fat-digesting enzymes, secreted by the pancreas into the small intestine. They break down triglycerides that have been emulsified by bile into monoglycerides and fatty acids
      - Lingual Lipase
        
        Secreted in the mouth but of minor importance
    - - Pancreatic Nucleases
        
        Include ribonuclease (for RNA) and deoxyribonuclease (for DNA), which are secreted by the pancreas
      - Brush Border Enzymes
        
        Nucleosidases and phosphatases break down the resulting units into pentose sugars, nitrogen-containing bases, and phosphate ions
- - - - innermost layer that lines the lumen. It is generally composed of three sublayers: an epithelium, a lamina propria, and a muscularis mucosae. Its primary functions are to secrete mucus, digestive enzymes, and hormones; absorb the end products of digestion; and protect against infectious disease.
      - Stomach Modifications: The stomach's mucosa consists of simple columnar epithelium made entirely of mucous cells that secrete a protective two-layer coat of alkaline mucus. It is dotted with gastric pits that lead into gastric glands, which produce gastric juice. Additionally, when the stomach is empty, the mucosa collapses into large, longitudinal folds called rugae.
    - - This layer consists of areolar connective tissue. It contains a rich supply of blood and lymphatic vessels, lymphoid follicles, and the submucosal nerve plexus. It also has abundant elastic fibers, which allow organs like the stomach to regain their shape after storing a large meal.
    - - This muscle layer is primarily responsible for segmentation and peristalsis. Typically, it consists of an inner circular layer (which can thicken to form sphincters) and an outer longitudinal layer of smooth muscle.
      - Stomach Modifications: The stomach contains an extra third layer of smooth muscle called the oblique (diagonal) layer. Together, these three layers allow the stomach to not only move and mix chyme but also to "pummel" it, physically breaking it down before delivering it to the small intestine.
    - - The serosa is the outermost layer of the intraperitoneal organs. It is formed by the visceral peritoneum and is composed of areolar connective tissue covered with a single layer of squamous epithelial cells (mesothelium). In the stomach, mesenteries (like the greater and lesser omenta) extend from this layer at the curvatures to tether the organ to the body wall and other digestive organs.
- - - - Small intestine . Amino acids are absorbed primarily via cotransport with Na +
  - - - Small intestine
        . Most fatty acids and monoglycerides enter intestinal cells via diffusion, are repackaged as chylomicrons, and then enter the lacteals (lymphatic capillaries)
        .
  - - - Small intestine . Glucose and galactose are absorbed via cotransport with Na + , while fructose moves via facilitated diffusion .
  - - - Small intestine
        . The resulting units enter intestinal cells via active transport using membrane carriers
        .
- - - - Renal Corpuscle: Located in the renal cortex, it consists of two parts
        
        Glomerulus: A tuft of highly porous, fenestrated capillaries that allow for efficient filtrate formation
        
        Glomerular (Bowman’s) Capsule: A hollow structure surrounding the glomerulus . Its visceral layer features branching epithelial podocytes with filtration slits that allow filtrate to pass into the capsular space
        
        Renal Tubule: This 3 cm-long tube is divided into three major regions
        
        Nephron Loop (Loop of Henle): A U-shaped structure with a descending limb (thin segment, simple squamous epithelium) and an ascending limb (thick segment, cuboidal or columnar cells)
        
        Distal Convoluted Tubule (DCT): Farthest from the corpuscle; it functions more in secretion than reabsorption and has very few microvilli
        
        Proximal Convoluted Tubule (PCT): Closest to the corpuscle; its cuboidal cells have dense microvilli (brush border) to increase surface area for reabsorption and secretion
        
        Collecting Duct: While not part of a single nephron, it receives filtrate from many nephrons . It contains principal cells (maintaining water and Na + balance) and intercalated cells (maintaining acid-base balance)
    - - Tubular Secretion: This is "reabsorption in reverse," where selected substances (such as K + , H + , creatinine, and certain drugs) are moved from the peritubular capillaries into the filtrate . It is vital for disposing of drugs, eliminating undesirable substances like urea, ridding the body of excess K + , and controlling blood pH .
        
        Associated Blood Vessels
        
        Blood enters the nephron through the afferent arteriole, which feeds into the glomerulus for filtration . The remaining blood leaves via the efferent arteriole, which then supplies the peritubular capillaries or vasa recta—vessels that stay close to the renal tubules to facilitate the exchange of water and solutes during reabsorption and secretion
        
        The Three Major Renal Processes
        
        The kidneys process approximately 180 L of fluid daily, but only about 1.5 L becomes urine
        . This transition involves three steps
        
        Glomerular Filtration: This is a passive process where hydrostatic pressure forces fluids and solutes (blood plasma minus proteins) through the filtration membrane into the glomerular capsule
        
        Tubular Reabsorption: This process reclaims most of the filtrate's contents and returns them to the blood
        
        Nephron Loop: The descending limb reabsorbs water, while the ascending limb reabsorbs Na + , Cl − , and K + .
        
        PCT: Reabsorbs about 65% of filtrate volume, including all organic nutrients (glucose, amino acids) and most electrolytes
        
        DCT and Collecting Duct: Reabsorption here is hormonally regulated; for example, aldosterone increases Na + reabsorption and ADH increases water reabsorption .
- - - - Gastroesophageal Reflux Disease: a chronic disease that orccurs when the esophageal shinetes relaxes allowing flu condends of the stomach
        
        Symptoms: chest pain, heartburn, and difficulty swallowing
        
        Treatment: surgery, prescription medication, and over the counter medication
        
        causes: weakened esophageal shinoter and obesity
      - Peptic Ulcer: sores that develop in the lining of the stomach duadenum
        
        Symptoms: heartburn, chest pain, nausea
        
        Treatment: Life changes, medication, and endosecopic surgery
        
        causes: Bacterial infection, alcohol abuse, and excess acid production
  - - - Kidney Stones: when urine has high levels of minerals and salts
        
        Symptoms: sharp pain, intense need to urine, and burning feeling while urinating
        
        Treatment: wait to pass, medication, and surgery
        
        causes: to much calcium in urine, acidic urine, and too much cystin in urine
      - Bladder Cancer: rare cancer in the lining of the bladder
        
        Symptoms: blood in pee and pain when peeing
        
        Treatment: surgical removal
        
        Causes: Smoking, radiation exposure, and chemotherapy