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8/28/2011 Chapters 21, 22 & 25: Selected Organ Systems 1. The Digestive System 2. The Respiratory System 3. The Urinary System 1. The Digestive System Digestive System Functions 1) Digest food and absorb nutrients • mechanical breakdown • physical breakdown of food into smaller particles • chemical digestion • breakdown of large molecules (polymers) into smaller ones (monomers) • absorption • transfer of digested material into blood & lymph 2) Waste removal • undigested material & waste from liver 1 8/28/2011 The Digestive System Oral cavity Tongue Mouth Salivary glands Pharynx Salivary glands Mouth Esophagus Esophagus Liver Gallbladder Esophagus Stomach Sphincter Stomach Small intestine Liver Pancreas Sphincter Gallbladder Large intestine Pancreas Rectum Anus A schematic diagram of the human digestive system Small intestine Small intestine Large intestine Rectum Anus Early Digestion Incisors Canine Premolars Molars Mouth (tongue, teeth, salivary glands) Wisdom tooth Tongue Salivary glands • chewing (mastication) of food, mixing with saliva Opening of a salivary gland duct Muscles contract • starch digestion via amylasecontract, in constricting Bolus of saliva passageway food Muscles Muscles relax and pushing bolus down Muscles relax, • swallowing of food bolus allowing Muscles contract passageway to open Muscles relax Esophagus Stomach • muscular tube conducting food bolus from pharynx to stomach Esophagus The Stomach Sphincter Lumen (cavity) of stomach Stomach Gastrin Adds the following to chewed food: Sphincter Small intestine • pepsin Interior surface of stomach (digests protein) Pits Release of gastric juice (mucus, HCl, and pepsinogen) Pepsinogen Epithelium Mucous cells 3 Pepsin (active HCl enzyme) 2 Chief cells Parietal cells (activates pepsin, kills microbes) • mucus 1 Gastric gland Cl– • HCl H+ (protects lining of stomach) produces a mixture called chyme 2 8/28/2011 Completion of Digestion Small Intestine • 3 sections: duodenum > jejunum > ileum • digestion is completed in the duodenum • absorption of nutrients in all sections of small intestine Pancreas • secretes pancreatic juice (enzymes, bicarbonate) to complete digestion Liver Bile Stomach Gallbladder Liver, Gall Bladder • bile fr. liver added to duodenum via gall bladder • emulsifies fats Acid chyme intestinal enzymes pancreatic juice Duodenum of small intestine Pancreas Nutrient Absorption Nutrients are absorbed throughout small intestine. • nutrients are transferred to the blood or the lymph (fats) Vein with blood en route to the liver nutrient absorption Lumen of Intestine nutrient absorption into epithelial cells microvilli epithelial cells amino fatty acids and acids and sugars glycerol lumen muscle layers fats large circular folds villi blood capillaries blood nutrient absorption lymph vessel lymph Epithelial Cells Villi Intestinal Wall Folds, Villi & Microvilli Folds in the intestinal wall as well as villi & microvilli greatly increase surface area for nutrient absorption. • villi are multicellular finger-like projections • microvilli are projections on individual cells 3 8/28/2011 The Large Intestine 3 sections: cecum > colon > rectum • absorption of water, minerals, vitamins • compaction, elimination of waste (undigested material, fiber, bacteria) Large intestine (colon) • houses a variety of beneficial bacteria (aka “probiotics”) Small intestine Sphincter End of small intestine Rectum Anus ***bacteria need to be kept OUT of small intestine*** Nutrient flow Appendix Cecum Essential Amino Acids Methionine Valine (Histidine) Threonine Phenylalanine Leucine Corn Isoleucine Tryptophan Lysine Beans and other legumes Nutrition Info on Food Labels Ingredients: whole wheat flour, water, high fructose corn syrup, wheat gluten, soybean or canola oil, molasses, yeast, salt, cultured whey, vinegar, soy flour, calcium sulfate (source of calcium). 4 8/28/2011 2. The Respiratory System The Respiratory System Nasal cavity Pharynx (Esophagus) Larynx Left lung Trachea Right lung • uptake of O2, removal of CO2 Bronchus Bronchiole Diaphragm (Heart) Respiratory System Organs Nasal Cavity Pharynx Larynx Epiglottis Trachea Lungs Diaphragm warms & moistens air passage for air, food/water vocal chords; where air, food separate blocks airway when swallowing connects airway to lungs site of gas exchange muscle used for “inhaling” 5 8/28/2011 Inhalation & Exhalation Rib cage expands as rib muscles contract air inhaled Rib cage gets smaller as rib muscles relax air exhaled lung diaphragm Diaphragm contracts (moves down) Diaphragm relaxes (moves up) Inhalation Exhalation The Lungs The bronchi of the lungs branch into smaller and smaller bronchioles which terminate in alveoli. Oxygen-rich blood Oxygen-poor blood • alveoli are the sites of gas exchange Bronchiole Alveoli • arrangement maximizes the surface area for gas exchange Blood capillaries Gas Exchange in the Alveoli O2 and CO2 simply diffuse from higher to lower concentration across the capillary, alveolar epithelia • O2 is more concentrated in the lungs than in the blood • CO2 is more concentrated in the blood than in the lungs *situation reversed in body tissues* 6 8/28/2011 Summary of Gas Exchange Inhaled air Exhaled air Alveolar epithelial cells Deoxygenated blood from tissues returns to the right atrium & ventricle of the heart which pumps it to the lungs. Air spaces CO2 O2 Alveolar capillaries CO2-rich, O2-poor blood O2-rich, CO2-poor blood Heart Tissue capillaries O2 CO2 Interstitial fluid In the alveoli of the lungs blood is oxygenated and flows back to the left atrium & ventricle of the heart, from which it is pumped back to the body. Tissue cells throughout body 3. The Urinary System The Urinary System Kidneys • removal of waste, excess in blood Ureters • conduct urine from kidneys to bladder Bladder • holds, expels urine Urethra • conducts urine from bladder “out” 7 8/28/2011 The Kidney Organized into functional units called nephrons Bowman’s capsule Tubule Renal cortex Renal artery Renal vein Collecting duct Renal medulla To renal pelvis Bowman’s capsule Arteriole from renal artery 1 Proximal tubule Glomerulus Capillaries Arteriole from glomerulus Nephron Structure 3 Distal tubule From another nephron Branch of renal vein Collecting duct 2 Loop of Henle with capillary network Filtration in the Kidney Blood Filtrate composition H2O NaCl HCO3– H+ Urea Glucose Amino acids Some drugs Proximal tubule Bowman’s Nutrients H2O capsule NaCl HCO3– 1 Distal tubule H2O NaCl K+ Some H+ drugs and poisons HCO3– H+ 3 Collecting duct Cortex Medulla Loop of Henle 2 NaCl NaCl H2O Reabsorption Urea Secretion NaCl Filtrate movement H2O Urine (to renal pelvis) 8 8/28/2011 Water & Salt Homeostasis Antidiuretic Hormone (ADH) regulates water resorption in the kidneys: • released by the pituitary gland • “sensors” in brain and heart regulate ADH release • increases permeability of kidney tubules, greater water resorption Aldosterone released from the adrenal cortex regulates “salt” levels: • stimulates retention of sodium ions (Na+), excretion of potassium (K+) in kidneys Hemodialysis Line from artery to apparatus Pump Tubing made of a selectively permeable membrane Dialyzing solution Line from apparatus to vein Fresh dialyzing solution Used dialyzing solution (with urea and excess ions) It’s all about diffusion! Key Terms for Chapters 21, 22 & 25 • villi, microvilli, chyme, pepsin, bile • pharynx, larynx, epiglottis, diaphragm, alveoli • nephron, glomerulus, tubule, hemodialysis Relevant Review Questions: Ch. 21: 1 Ch. 22: 1, 2, 5, 7 Ch. 25: 2, 4 9
