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Transcript
Chapter 23 Respiratory System Functions: 1. Provides for gas exchange- intake of O2 for delivery to body cells and elimination of CO2 produced by body cells 2. Helps regulate pH 3. Contains receptors for the sense of smell, filters inspired air, produces vocal sounds, and excretes small amount of water and heat. Structurally Upper respiratory system Lower respiratory system Functionally Conducting zone – conducts air to lungs Respiratory zone – main site of gas exchange NOSE Functions: 1. ________________________________________ 2. ________________________________________ 3. ________________________________________ Pseudostratified Ciliated Columnar Epithelia PHARYNX Starts at internal nares and extends to cricoid cartilage of larynx Contraction of skeletal muscles assists in deglutition Functions: 1. Passageway for air and food 2. Resonating chamber 3. Houses tonsils 3 anatomical regions Nasopharynx - Nose - Soft palate Oropharynx – Soft Palate – Hyoid Bone Laryngopharynx - Hyoid Bone - Esophagus LARYNX 9 pieces of cartilage: Thyroid cartilage or Adam’s apple Cricoid cartilage hallmark for ____________________________________(see figure 23.4) Epiglottis closes off glottis during swallowing Glottis – pair of folds of mucous membranes, vocal folds False vocal cords– superior pair, Hold breath True vocal cords– inferior pair, Vibrate and produce sound with air _______________________– inflammation of the larynx most often caused by a respiratory infection or irritants such as cigarette smoke. Symptoms: Fever, Hoarseness, Swollen lymph nodes or glands in the neck TRACHEA Extends from larynx to superior border of T5 Divides into right and left _______________________________ 16-20 C-shaped rings of hyaline cartilage BRONCHIOLES Right – more vertical, shorter, wide leads to 3 lobes of lung Left – leads to 2 lobes of lung LUNGS Each lung enclosed by double-layered pleural membrane __________________________ – lines wall of thoracic cavity __________________________ – covers lungs themselves Pleural cavity is space between layers Pleural fluid reduces friction, produces surface tension (stick together) Cardiac notch – heart makes left lung 10% smaller than right Carina – Sensitive area cough Alveoli 2 types of alveolar epithelial cells Type I alveolar cells –main site of _____________________ Type II alveolar cells- secrete alveolar fluid Very thin – only 0.5 µm thick to allow rapid diffusion of gases Lungs receive blood from ________________________ - deoxygenated blood _____________________________ – oxygenated blood to perfuse muscular walls of bronchi and bronchioles Pulmonary Ventilation Respiration (gas exchange) steps 1. Pulmonary ventilation/ breathing Inhalation and exhalation Exchange of air between atmosphere and alveoli 2. External (pulmonary) respiration Exchange of gases between alveoli and blood 3. Internal (tissue) respiration Exchange of gases between systemic capillaries and tissue cells Supplies cellular respiration (makes ATP) 1. Inhalation Inhalation is _________________ – Contraction of __________________________– most important muscle of inhalation Responsible for 75% of air entering lungs during normal quiet breathing ___________________________- Contraction elevates ribs 25% of air entering lungs during normal quiet breathing Accessory muscles for deep, forceful inhalation 2. Exhalation Pressure in lungs is _____________than atmospheric pressure Normally _____________________ – muscle relax instead of contract - elastic recoil - Diaphragm relaxes - External intercostals relax Exhalation only active during forceful breathing Inhalation Pressure inside alveoli must become lower than atmospheric pressure for air to flow into lungs 760 millimeters of mercury (mmHg) or 1 atmosphere (1 atm) Achieved by increasing size of lungs Boyle’s Law – pressure of a gas in a closed container is inversely proportional to the volume of the container Air Flow Air pressure differences drive airflow 3 other factors affect rate of airflow and ease of pulmonary ventilation 1. Surface tension of alveolar fluid Causes alveoli to assume smallest possible diameter Accounts for 2/3 of lung elastic recoil Prevents collapse of alveoli at exhalation 2. Lung compliance High compliance means lungs and chest wall expand easily Related to elasticity and surface tension 3. Airway resistance Larger diameter airway has less resistance Regulated by diameter of bronchioles & smooth muscle tone Lung Volumes and Capacities _____________________________________ (MV) = total volume of air inhaled and exhaled each minute Normal healthy adult averages 12 breaths per minute moving about 500 ml of air in and out of lungs (tidal volume) MV = 12 breaths/min x 500 ml/ breath = 6 liters/ min Notes on Board: Problems: 1. Joan’s total volume from one breath is 450ml and she averages 13breaths/min. What is her minute ventilation? What is her tidal Volume? What is her aveolar ventilation rate? 2. Jill has a minute ventilation of 6000ml/min and she averages 11 breaths/min. What is her Tidal volume? That is the anatomic dead space volume? What is the alveolar ventilation rate? 3. Bill’s Tidal volume is 500ml, his functional residual volume is 2400ml, and his inspiratory capacity is 3200ml. What is Bill’s inspritory reserve volume? What is Bill’s total lung capacity? 4. Mark has a tidal volume of 430ml and averages 12breaths/ min. What is Mark’s minute ventilation? What is Mark’s anatomic dead space volume? What should Mark’s weight average if he is in good shape? 5. Martha has an expiratory reverve volume of 1101ml, and a residual volume of 1100ml. What is Matha’s functional residual volume? What is the importance of the functional residual volume? Dalton’s Law -Each gas in a mixture of gases exerts its own pressure as if no other gases were present -Atmospheric pressure (________________ mmHg) = PN2 + PO2 + PH2O + PCO2 + Pother gases -Partial pressure greater Partial pressure less - The greater the difference, the faster the rate of diffusion Henry’s law -Quantity of a gas that will dissolve in a liquid is proportional to the partial pressures of the gas and its solubility -Higher partial pressure of a gas over a liquid and higher solubility, more of the gas will stay in solution -CO2 is 24 times more soluble than O2 External Respiration vs. Internal Respiration At rest, only about ________% of the available oxygen is used Deoxygenated blood would retain _________% of its oxygen capacity Rate of Pulmonary and Systemic Gas Exchange Depends on: 1. _____________________________________ Alveolar PO2 must be higher than blood PO2 for diffusion to occur – problem with increasing altitude 2. _____________________________________ 3. ______________________________________ occurs before hypercapnia Oxygen transport 1.5% dissolved in plasma 98.5% bound Heme Oxyhemoglobin Only dissolved portion can diffuse out of blood into cells Oxygen must be able to bind and dissociate from heme 4. ____________________________________ O2 has a lower molecular weight and should diffuse faster than CO2 except for its low solubility - when diffusion is slow, hypoxia Relationship between Hemoglobin and Oxygen Partial Pressure Higher the PO2, More O2 combines with Hb Fully saturated – Percent saturation expresses average saturation of hemoglobin with oxygen Oxygen-hemoglobin dissociation curve In pulmonary capillaries, O2 loads onto Hb In tissues, O2 is not held and unloaded 75% may still remain in deoxygenated blood (reserve) Oxygen-hemoglobin Dissociation Curve Hemoglobin and Oxygen Other factors affecting affinity of Hemoglobin for oxygen Each makes sense if you keep in mind that metabolically active tissues need O2, and produce acids, CO2, and heat as wastes 1. __________________________ 2. __________________________ 3. __________________________ Bohr Effect -As acidity increases (pH decreases), affinity of Hb for O2 decreases Increasing acidity enhances unloading Shifts curve to right -PCO2 Also shifts curve to right As PCO2 rises, Hb unloads oxygen more easily Low blood pH can result from high PCO2 -Temp Within limits, as temperature increases, more oxygen is released from HbqDuring hypothermia, more oxygen remains bound 2,3-bisphosphoglycerate BPG formed by red blood cells during glycolysis Helps unload oxygen by binding with Hb Fetal hemoglobin Fetal hemoglobin has a higher affinity for oxygen than adult hemoglobin Hb-F can carry up to 30% more oxygen Maternal blood’s oxygen readily transferred to fetal blood Carbon Dioxide Transport Dissolved CO2 Smallest amount, about 7% Carbamino compounds About 23% combines with amino acids including those in Hb Carbaminohemoglobin Bicarbonate ions 70% transported in plasma as HCO3Enzyme carbonic anhydrase forms carbonic acid (H2CO3) which dissociates into H+ and HCO3- CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3Chloride shift HCO3- accumulates inside RBCs as they pick up carbon dioxide Some diffuses out into plasma To balance the loss of negative ions, chloride (Cl-) moves into RBCs from plasma Reverse happens in lungs – Cl- moves out as moves back into RBCs Chapter 24: The Digestive System 6 functions of the digestive system 1. ___________________________ 2. ___________________________ of water, acid, buffers, and enzymes into lumen 3. ___________________________ 4. ___________________________ - Mechanical digestion churns food - Chemical digestion – hydrolysis 5. ___________________________ – passing into blood or lymph 6. ___________________________ – elimination of feces 2 groups of organs compose the digestive system A. Gastrointenstinal (GI) tract or alimentary canal – B. Accessory digestive organs – Organs of the digestive system Fig 24.4 Layers of the GI tract Wall of GI tract from lower esophagus to anal canal has same basic 4 layers 1. ___________________________ – inner lining a. Epithelia -b. Lamina Propria – c. Muscularis Mucosa – 2. ___________________________ 3. ___________________________ Voluntary skeletal muscle found in mouth, pharynx, upper 2/3 of esophagus, and anal sphincter Involuntary smooth muscle elsewhere 4. ___________________________ Outermost covering of organs suspended in abdominopelvic cavity Esophagus lacks serosa – has adventitia Peritoneum Largest serous membrane of the body Divided into Parietal peritoneum – Visceral peritoneum – 5 major peritoneal folds -Greater omentum -falciform ligament -lesser omentum -mesentery -mesocolon Mouth Oral Cavity Mechanical Digestion -Mastication Chemical Digestion Saliva Mostly water 99.5% 0.5% solutes – ions, dissolved gases, urea, uric acid, mucus, immunoglobulin A, lysozyme, and salivary amylase (acts on starch) Salivation6 glands 3 pairs 1) __________________: - located anterior and inferior to ear - produce salivary amylase 2) __________________ : - medial inferior to mandible -buffer, mucin, salivary amylase 3) __________________ beneath the tongue - buffer, mucin, salivary amylase Tongue and Teeth Tongue -Accessory digestive organ Lingual gland – ___________________ Teeth (Fig 24.8) - Accessory digestive organ - 3 major regions – crown, root, and neck (label in image) Dentin of crown covered by enamel 2 dentitions – deciduous and permanent teeth Deglutition 9 sec to reach stomach Act of swallowing Facilitated by secretions of saliva and mucus Involves mouth, pharynx, and esophagus 3 stages Voluntary – bolus passed to oropharynx Pharyngeal – involuntary passage through pharynx into esophagus Esophageal – involuntary passage through esophagus to stomach Esophagus Secretes mucous, transports food – no enzymes produced, no absorption Peristalsis – Esophageal Sphincter Stomach Serves as mixing chamber and holding reservoir 4 main regions 1. ___________________ – smallest part of the stomach, mucus glands to prevent acid damage 2. ___________________ – upper bulge 3. ___________________ - largest region of the stomach, gastric glands 4. ___________________ – is the curve of the J, region that connects the stomach to the duodenum Gastric Glands of the Fundus and Body Gastric Glands ______________________: HCl and Intrinsic Factor which facilitates the absorption of Vitamin B12 (hematopoiesis) - H and Cl are independent pH _________________ _____________________: - most abundant neat the base of gastric gland - secrete _______________________ - secrete gastric lipase - in newborn secretes rennin and gastric lipase to digest milk Pancreas Histology 99% of cells are acini Exocrine Secrete pancreatic juice 1% of cells are pancreatic islets (islets of Langerhans) Endocrine Secrete hormones Pancreatic juice 1200-1500ml daily Mostly water Sodium bicarbonate – buffers acidic stomach chyme Enzymes Liver Liver is the heaviest gland of the body Liver is composed of Hepatocytes – major functional cells of liver Bile canaliculi – ducts between hepatocytes that collect bile Exits livers as common hepatic duct, joins cystic duct from gallbladder to form common bile duct see page 949 for list of liver functions Gallbladder Storage of Bile produced by Liver Contraction bilecystic duct Bile- bile salts, water, cholesterol, bile pigments, ions pH - 7.6-8.6 Hepatic Blood Flow Small intestine 3 regions: 1. _____________________ – 10 inches, the shortest region, from pyloric sphincter to jejunum 2. _____________________ – 3 ft. From duodenum to ileum 3. _____________________ – 6ft, joins to large intestine called the iliocecal sphincter Special structural features increase surface area for digestion and absorption -Circular folds -_____________- Contains arteriole, venule, blood capillary, and lacteal -______________ - Projects of apical membrane of absorptive cells, Intestinal juice and brush-border enzymes Brush border enzymes Inserted into plasma membrane of absorptive cells Some enzymatic digestion occurs at surface rather than just in lumen α-dextrinase, maltase, sucrase, lactase, aminopetidase, dipeptidase, nucleosidases and phosphatases Chemical digestion Carbohydrates Pancreatic amylase α-dextrinase, sucrase, lactase, maltase in brush border Ends with monosaccharides which can be absorbed Proteins Trypsin, chymotrypsin, carboxypeptidase, and elastase from pancreas Aminopeptidase and dipeptidase in brush border Lipids Pancreatic lipase most important in triglyceride digestion Emulsification by bile salts increases surface area Amphipathic – hydrophobic and hydrophilic regions Nucleic acids Ribonuclease and deoxyribonuclease in pancreatic juice Nucleosidases and phosphatases in brush border Large intestine Overall function to complete absorption, produce certain vitamins, and form and expel feces 4 major regions 1. Cecum – expanding pouch, contain the appendix 2. Colon – Ascending Transverse Descending Sigmoid 3. Rectum – (Last 15cm of digestive tract) Internal sphincter – involuntary External sphincter – voluntary 4. Anus Mechanical digestion Haustral churning Peristalsis Mass peristalsis – drives contents of colon toward rectum Chemical digestion Final stage of digestion through bacterial action Ferment carbohydrates, produce some B vitamins and vitamin K Mucus but no enzymes secreted Remaining water absorbed along with ions and some vitamins Chapter 25: Metabolism and Nutrition Metabolism – refers to all chemical reaction occurring in body Catabolism – break down complex molecules _________________– produce more energy than they consume Anabolism – combine simple molecules into complex ones __________________- consume more energy than they produce Adenosine triphosphate (_______) “energy currency” ADP + P + energy ↔ ATP Role of ATP in linking anabolic and catabolic reactions Energy transfer Oxidation-reduction or redox reactions Oxidation – removal of electrons Decrease in potential energy Dehydrogenation – removal of hydrogens Liberated hydrogen transferred by coenzymes Nicotinamide adenine dinucleotide (NAD) Flavin adenine dinucleotide (FAD) Glucose is oxidized Reduction – addition of electrons Increase in potential energy 3 Mechanisms of ATP generation 1. ______________________________ Transferring high-energy phosphate group from an intermediate directly to ADP 2. _______________________________ Remove electrons and pass them through electron transport chain to oxygen 3. _______________________________ Only in chlorophyll-containing plant cells Carbohydrate metabolism Fate of glucose depends on needs of body cells ATP production or synthesis of amino acids, glycogen, or triglycerides GluT transporters bring glucose into the cell via facilitated diffusion Insulin causes insertion of more of these transporters, increasing rate of entry into cells Glucose trapped in cells after being phosphorylated Glucose catabolism / cellular respiration Glycolysis __________________________ respiration – does not require oxygen Formation of acetyl coenzyme A Krebs cycle reactions Electron transport chain reactions Aerobic respiration – requires oxygen Overview of cellular respiration 1. Glycolysis Splits 6-carbon glucose into 2 3-carbon molecules of pyruvic acid Consumes 2 ATP but generates 4 10 reactions Fate of pyruvic acid depends on oxygen availability - If oxygen is scarce (_________________), reduced to lactic acid - ______________________ can convert it back to pyruvic acid - If oxygen is plentiful (aerobic), converted to acetyl coenzyme A Cellular respiration begins with glycolysis The 10 reactions of glycolysis 2. Formation of Acetyl coenzyme A Each pyruvic acid converted to 2-carbon acetyl group Remove one molecule of CO2 as a waste product Each pyruvic acid also loses 2 hydrogen atoms NAD+ reduced to NADH + H+ Acetyl group attached to coenzyme A to form acetyl coenzyme A (acetyl CoA) Fate of pyruvic acid 3. The Krebs cycle Also known as citric acid cycle Occurs in matrix of mitochondria Series of redox reactions 2 decarboxylation reactions release CO2 Reduced coenzymes (NADH and FADH2) are the most important outcome One molecule of ATP generated by substrate-level phosphorylation The Krebs Cycle 4. Electron transport chain Series of electron carriers in inner mitochondrial membrane reduced and oxidized As electrons pass through chain, exergonic reactions release energy used to form ATP ______________________ Final electron acceptor is oxygen to form _______________________ Carriers act as proton pumps to expel H+ from mitochondrial matrix Creates ______________________________ – concentration gradient and electrical gradient Gradient has potential energy – proton motive force As H+ flows back into matrix through membrane, generates ATP using ____________________ The actions of the three proton pumps and ATP synthase in the inner membrane of mitochondria Summary of cellular respiration Glucose anabolism Glucose storage: _________________________________ Polysaccharide that is the only stored carbohydrate in humans Insulin stimulates hepatocytes and skeletal muscle cells to synthesize glycogen Glucose release: ________________________________ Glycogen stored in hepatocytes broken down into glucose and release into blood Glycogenesis and glycogenolysis Formation of glucose from proteins and fats: gluconeogenesis Glycerol part of triglycerides, lactic acid, and certain amino acids can be converted by the liver into glucose Glucose formed from noncarbohydrate sources Stimulated by cortisol and glucagon Lipid metabolism Transport by lipoproteins Most lipids nonpolar and hydrophobic Made more water-soluble by combining them with proteins to form lipoproteins Proteins in outer shell called apoproteins (apo) Each has specific functions All essentially are transport vehicles Apoproteins Apoproteins categorized and named according to density (ratio of lipids to proteins) a. Chylomicrons i. Form in small intestine mucosal epithelial cells ii. Transport dietary lipids to ______________________ b. Very low-density lipoproteins (VLDLs) i. Form in hepatocytes ii. Transport endogenous lipids to __________________ c. _______________________ (LDLs) – “bad” cholesterol i. Carry 75% of total cholesterol in blood ii. Deliver to body cells for repair and synthesis iii. Can deposit cholesterol in fatty plaques d. ________________________ (HDLs) – “good” cholesterol i. Remove excess cholesterol from body cells and blood ii. Deliver to liver for elimination 2 sources of cholesterol in the body 1. Present in foods 2. Synthesized by hepatocytes As total blood cholesterol increases, risk of coronary artery disease __________________________ Treated with exercise, diet, and drugs Lipids can be oxidized to provide_____________ Stored in ______________ if not needed for ATP Major function of adipose tissue to remove triglycerides from chylomicrons and VLDLs and store it until needed ______% of all body energy reserves Lipid catabolism: ____________________________ Triglycerides split into ___________________ and ___________________ Must be done for muscle, liver, and adipose tissue to oxidize fatty acids Enhanced by epinephrine and norepinephrine Lipid anabolism:_______________________ Liver cells and adipose cells synthesize lipids from glucose or amino acids Occurs when more calories are consumed than needed for ATP production Pathways of lipid metabolism Protein metabolism Amino acids are either oxidized to produce___________ or used to synthesize __________________ Excess dietary amino acids are not excreted but converted into glucose (gluconeogenesis) or triglycerides (lipogenesis) Protein catabolism Proteins from worn out cells broken down into amino acids Before entering Krebs cycle amino group must be removed – ________________________ Produces ammonia, liver cells convert to urea, excreted in urine Various points at which amino acids enter the Krebs cycle for oxidation Protein anabolism Carried out in ribosomes of almost every cell in the body _____ essential amino acids in the human Must be present in the diet because they cannot be synthesized Complete protein – contains sufficient amounts of all essential amino acids – beef, fish, poultry, eggs Incomplete protein – does not – leafy green vegetables, legumes, grains 10 other nonessential amino acids can be synthesized by body cells using transamination Key molecules at metabolic crossroads 3 molecules play pivotal roles in metabolism Stand at metabolic crossroads – reactions that occur or not depend on nutritional or activity status of individual 1. __________________________ a. Made shortly after glucose enters body cell b. 4 fates – synthesis of glycogen, release of glucose into blood stream, synthesis of nucleic acids, glycolysis 2. __________________________ a. If there is enough oxygen, aerobic cellular respiration occurs b. If there is not enough oxygen, anaerobic reactions can produce lactic acid, produce alanine or gluconeogenesis 3. __________________________ a. When ATP is low and oxygen plentiful, most pyruvic acid goes to ATP production via Acetyl CoA b. Acetyl CoA os the entry into the Krebs cycle c. Can also be used for synthesis of certain lipids Metabolic adaptations During the absorptive state ingested nutrients are _________________________________ o Glucose readily available for ATP production During postabsorptive state ________________________________________________________________ o Energy needs must be met by fuels in the body o Nervous system and red blood cells depend on glucose so maintaining steady blood glucose critical o Effects of _________________________ dominate Metabolism during absorptive state o Soon after a meal nutrients enter blood Glucose, amino acids, and triglycerides in chylomicrons o 2 metabolic hallmarks 1. Oxidation of glucose for ATP production in all body cells 2. Storage of excess fuel molecules in hepatocytes, adipocytes, and skeletal muscle cells o Pancreatic beta cells release insulin Promotes entry of glucose and amino acids into cells Principal metabolic pathways during the absorptive state Metabolism during postabsorptive state About 4 hours after the last meal absorption in small intestine nearly complete Blood glucose levels start to __________________ Main metabolic challenge to maintain normal blood glucose levels ___________________________ Breakdown of liver glycogen, lipolysis, gluconeogenesis using lactic acid and/or amino acids __________________________ Oxidation of fatty acids, lactic acid, amino acids, ketone bodies and breakdown of muscle glycogen Principal metabolic pathways during the postabsorptive state Hormones and autonomic nervous system regulate metabolism during postabsorptive state As blood glucose decline, insulin secretion falls Glucagon – increases release of glucose into blood via gluconeogenesis and glycogenolysis Sympathetic nerve endings of ANS release norepinephrine and adrenal medulla releases epinephrine and norepinephrine Stimulate lipolysis, glycogen breakdown Heat and energy balance Heat – form of energy that can be measured as temperature and can be expressed in calories calorie (cal) – amount of heat required to raise 1 gram of water 1°C Kilocalorie (kcal) or Calorie (Cal) is 1000 calories Metabolic rate – overall rate at which metabolic reactions use energy Some energy used to make ATP, some lost as heat Basal metabolic rate (BMR) – measurement with body in quiet, resting, fasting condition Body temperature homeostasis Despite wide fluctuations in environmental temperatures, homeostatic mechanisms maintain normal range for internal body temperature Core temperature (37°C or 98.6°F) versus shell temperature (1-6°C lower) Heat produced by exercise, some hormones, sympathetic nervous system, fever, ingestion of food, younger age, etc. Heat can be lost through Conduction to solid materials in contact with body Convection – transfer of heat by movement of a gas or liquid Radiation – transfer of heat in form of infrared rays Evaporation exhaled air and skin surface (insensible water loss) Hypothalamic thermostat in preoptic area Heat-losing center and heat-promoting center Thermoregulation If core temperature declines Skin blood vessels constrict Release of thyroid hormones, epinephrine and norepinephrine increases cellular metabolism Shivering If core body temperature too high Dilation of skin blood vessels Decrease metabolic rate Stimulate sweat glands Ch 25 (cont) Nutrition Nutrients are chemical substances in food that body cells use for growth, maintenance, and repair 6 main types 1.______________________– needed in largest amount 2.______________________ 3.______________________ 4.______________________ 5.______________________ 6.______________________ Essential nutrients must be obtained from the diet Guidelines for healthy eating Basic guidelines Eat a variety of foods Maintain a healthy weight Choose foods low in fat, saturated fat and cholesterol Eat plenty of vegetables, fruits and grain products Use sugars in moderation only -Inorganic elements that occur naturally in Earth’s crust -Eat foods that contain enough calcium, phosphorus, iron and iodine -Excess amounts of most minerals are excreted in urine and feces -Major role of minerals to help regulate enzymatic reactions Vitamins Organic nutrients required in small amounts to maintain growth and normal metabolism Do not provide energy or serve as body’s building materials Most are ______________________________ Most cannot be synthesized by the body Vitamin K produced by bacteria in GI tract No single food contains all the required vitamins 2 groups Fat-soluble – ______,_______,_______,_______ Water-soluble – several B vitamins and vitamin C End of Chapter 25