Unit 4 - Digestive System PDF

UNIT 4: Levels of organization And the digestive system Levels of organization UNIT B Chapter 8: Human Organization Section 8.1 Types of Tissues Tissues are composed of similarly specialized cells that perform a common function in the body. There...

UNIT 4: Levels of organization And the digestive system Levels of organization UNIT B Chapter 8: Human Organization Section 8.1 Types of Tissues Tissues are composed of similarly specialized cells that perform a common function in the body. There are four major types of tissues in the human body: Epithelial tissue: covers body surfaces, lines body cavities Connective tissue: binds and supports body parts Muscular tissue: moves the body and its parts Nervous tissue: receives stimuli, processes information, conducts nerve impulses TO PREVIOUS SLIDE UNIT B Chapter 8: Human Organization Section 8.2 Organ Systems Organs work together in an organ system, and organ systems work together in the body. TO PREVIOUS SLIDE UNIT B Chapter 8: Human Organization Section 8.2 Figure 8.4 Organ systems Integumentary system of the body. Includes skin, nails, hairs, muscles that move hairs, oil and sweat glands, blood vessels, and nerves leading to sensory receptors Protects body Receives sensory input Helps control temperature Synthesizes vitamin D TO PREVIOUS SLIDE UNIT B Chapter 8: Human Organization Section 8.2 Figure 8.4 Organ systems of the body. Circulatory system Includes heart, blood vessels, and blood Transports blood, nutrients, gases, and wastes Defends against disease Helps control homeostasis TO PREVIOUS SLIDE UNIT B Chapter 8: Human Organization Section 8.2 Figure 8.4 Organ systems Lymphatic and Immune of the body. systems Consist of lymphatic vessels, lymph nodes, lymphatic organs, and lymphocytes Help control fluid balance Absorb fats Defend against infectious disease TO PREVIOUS SLIDE UNIT B Chapter 8: Human Organization Section 8.2 Figure 8.4 Organ systems of the body. Digestive system Includes the mouth, esophagus, stomach, small intestine, large intestine, and associated organs (teeth, tongue, salivary glands, liver, gall bladder, pancreas) Ingests and digests food Absorbs nutrients Eliminates waste TO PREVIOUS SLIDE UNIT B Chapter 8: Human Organization Section 8.2 Figure 8.4 Organ systems Respiratory system of the body. Consists of the lungs and the tubes that take air to and from them Maintains breathing Exchanges gases at lungs and tissues Helps control pH balance TO PREVIOUS SLIDE UNIT B Chapter 8: Human Organization Section 8.2 Figure 8.4 Organ systems Urinary system of the body. Includes the kidneys, urinary bladder, and the tubes that carry urine Excretes metabolic wastes Helps control fluid balance Helps control pH balance TO PREVIOUS SLIDE UNIT B Chapter 8: Human Organization Section 8.2 Nervous system Figure 8.4 Organ systems of the body. Consists of the brain, spinal cord, and associated nerves Receives sensory input Integrates and stores input Initiates motor output Helps coordinate organ systems TO PREVIOUS SLIDE UNIT B Chapter 8: Human Organization Section 8.2 Figure 8.4 Organ systems Musculoskeletal system of the body. Skeletal system o Supports the body and protects body parts o Helps move the body o Stores minerals o Produces blood cells Muscular system o Maintains posture o Moves body and internal organs o Produces heat TO PREVIOUS SLIDE UNIT B Chapter 8: Human Organization Section 8.2 Figure 8.4 Organ systems Endocrine system of the body. Consists of hormonal glands Produces hormones Helps coordinate organ systems Responds to stress Helps regulate fluid and pH balance Helps regulate metabolism TO PREVIOUS SLIDE UNIT B Chapter 8: Human Organization Section 8.2 Figure 8.4 Organ systems of the body. Reproductive system Males: consists of testes and ducts that conduct semen through the penis Females: consists of the ovaries, oviducts, uterus, vagina, and external genitalia Produces gametes Transports gametes Produces sex hormones Nurtures and gives birth to offspring in females TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.1 The Digestive Tract The digestive system is involved in the ingestion and digestion of food and elimination of indigestible material. Digestion takes place within the digestive tract, which begins with the mouth and ends with the anus. Digestion involves mechanical and chemical digestion. o Mechanical digestion: chewing of food, and churning and mixing of food in the stomach o Chemical digestion: enzymes break macromolecules down into small organic molecules TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.1 Figure 9.1 The human digestive tract. The upper part of the tract includes the mouth, pharynx, esophagus, stomach, and small intestine. The large intestine consists of the cecum, the colon (ascending, transverse, descending, and sigmoid colons), the rectum, and the anus. Note also the location of the accessory organs of digestion: the pancreas, the liver, and the gall bladder. TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.1 The Mouth The mouth takes food into the body. Teeth: involved in chewing food Tongue: composed of skeletal muscle and involved in forming the bolus (a mass of food that is ready for swallowing) Roof of the mouth: composed of a hard palate and a soft palate; prevents ingested food from entering the nasal cavity Tonsils: contain lymphoid tissue that protect against infections Salivary glands: produce saliva to keep the mouth moist; saliva contains an enzyme that digests starch TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.1 The Pharynx The pharynx is a passageway that receives air from the nasal cavities and food from the mouth. Swallowing (a reflex action) occurs in the pharynx. The soft palate moves back to close off the nasopharynx The trachea moves up under the epiglottis to cover the glottis (the opening to the larynx (voice box)) During swallowing, food enters the esophagus because the air passages are blocked TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.1 Figure 9.2 Swallowing. When food is swallowed, the soft palate closes off the nasopharynx and the epiglottis covers the glottis, forcing the bolus to pass down the esophagus. Therefore, a person does not breathe while swallowing. TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.1 TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.1 The Esophagus The esophagus is a long muscular tube that moves food from the mouth to the stomach by peristalsis. Peristalsis (rhythmic muscular contractions) pushes food along the esophagus and through the digestive tract to the stomach. TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.1 The Stomach The stomach is an organ that receives food from the esophagus, mechanically and chemically digests food, and moves food into the small intestine. TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.1 Structure and Function of the Stomach The human stomach has thick walls with folds that allow it to expand and fill with food. Lining of the stomach has gastric glands that secrete gastric juice containing mucus and digestive enzymes Wall of the stomach: o Three muscle layers (longitudinal, circular, oblique) o Responsible for moving and churning food (mechanical digestion), and mixing food with gastric juice to break it down (chemical digestion) TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.1 Alcohol and other liquids are absorbed in the stomach, but most solid food is not. When food leaves the stomach, it is a thick, soupy liquid called chyme. oChyme enters the small intestine by way of the pyloric sphincter. TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.1 Figure 9.3 Anatomy of the stomach. a. The stomach has a thick wall with folds that allow it to expand and fill with food. b. The mucosa contains gastric glands, which secrete gastric juice containing mucus and digestive enzymes. TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.1 The Small Intestine The small intestine receives chyme from the stomach and completes the digestion of food. Macromolecules are broken down into nutrients, which are absorbed in the small intestine and pass into the blood. TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.1 Structure and Function of the Small Intestine The small intestine is composed of three parts. Duodenum: upper part of the small intestine o Contains a bile duct that delivers bile from the gall bladder and pancreatic juice from the pancreas −Enzymes in pancreatic juice complete food digestion Jejunum: middle part of small intestine Ileum: lower part of small intestine o Contains lymphoid tissues involved in immune response to intestinal pathogens TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.1 Structure and Function of the Small Intestine The wall of the small intestine contains villi, which increase the surface area to improve the absorption of nutrients. Villi: finger like projections that contain microvilli o Microvilli increase the surface area of the villus for the absorption of nutrients o Each villus contains blood capillaries, and a small lymphatic capillary called a lacteal o Nutrients are absorbed into the blood capillaries and the lacteals, which carry them to body cells TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.1 Figure 9.4 Anatomy of the small intestine. The wall of the small intestine has folds that bear finger like projections called villi. Microvilli, which project from the villi, absorb the products of digestion into the blood capillaries and the lacteals of the villi. TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.1 Regulation of Digestive Secretions Digestive secretions are controlled by the nervous system and hormones. After eating a meal: The stomach produces the hormone gastrin o Gastrin: stimulates the gastric glands to secrete more gastric juice The duodenal wall produces the hormones secretin and CCK o Secretin and CCK: stimulate the pancreas to secrete pancreatic juice and the gall bladder to secrete bile TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.1 Figure 9.5 Hormonal control of digestive gland secretions. Gastrin (blue), produced by the lower part of the stomach, enters the bloodstream and thereafter stimulates the stomach to produce more digestive juices. Secretin (green) and CCK (purple), produced by the duodenal wall, stimulate the pancreas to secrete its digestive juices and the gall bladder to release bile. TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.1 The Large Intestine The large intestine absorbs water, salts, and some vitamins. It also stores indigestible material until it is eliminated as feces. TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.1 Structure and Function of the Large Intestine The large intestine includes the cecum, colon, rectum, and anal canal. Cecum: a small pouch that forms the first part of the large intestine o Contains the appendix which may play a role in fighting infection Figure 9.6 Junction of the small intestine and the large intestine. The cecum is the blind end of the large intestine. The appendix TO PREVIOUS is attached to the cecum. SLIDE UNIT B Chapter 9: Digestive System Section 9.1 Structure and Function of the Large Intestine Colon: includes the ascending, transverse, descending, and sigmoid colon Rectum: the last part of the large intestine; opens at the anus Anus: rectum opening; site of defecation (expulsion of feces) TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.1 Defecation Reflex When feces are forced into the rectum by peristalsis, a defecation reflex occurs Figure 9.7 Defecation reflex. The accumulation of feces in the rectum causes it to stretch, which initiates a reflex action resulting in rectal contraction and expulsion of the fecal material. TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.1 Defecation Reflex Eliminating feces from the body is a way the digestive system maintains homeostasis Feces are about three-quarters water and one-quarter solids o Solids: bacteria, fibre, and other indigestible materials o Bacteria break down some indigestible material, and produce some vitamins that our bodies can absorb o Water that is unsafe for drinking has a high number of coliform (intestinal) bacteria, indicating that a significant amount of feces has entered the water TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.2 Accessory Organs of Digestion The accessory digestive organs are the pancreas, liver, and gall bladder. Figure 9.8 Liver, gall bladder, and pancreas. a. The liver makes bile, which is stored in the gall bladder and sent (black arrow) to the small intestine by way of the common bile duct. The pancreas produces digestive enzymes that are sent (black arrows) to the small intestine by way of the pancreatic duct. TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.2 The Pancreas The pancreas is an organ that has both endocrine and exocrine functions. Exocrine function of the pancreas o Pancreatic cells produce pancreatic juice (to neutralize stomach acid) and digestive enzymes Endocrine function of the pancreas o Pancreas secretes insulin and glucagon, hormones that regulate blood glucose (sugar) levels TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.2 Structure and Function of the Pancreas The pancreas contains pancreatic islets (islets of Langerhans), which are clusters of at least three types of endocrine cells: Alpha cells: produce glucagon Beta cells: produce insulin Delta cells: produce somatostatin TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.2 Structure and Function of the Pancreas Insulin Hormone secreted when blood glucose level is high Stimulates the uptake of glucose by cells (liver, muscle, adipose tissue) to lower blood glucose Glucagon Hormone secreted when blood glucose level is low Stimulates the liver to break glycogen down into glucose to increase blood glucose Stimulates adipose tissue to break fat down to glycerol and fatty acids (to make glucose) TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.2 Structure and Function of the Pancreas Somatostatin A growth-hormone-inhibiting hormone Also produced by cells in the stomach and small intestine Inhibits the release of growth hormone Suppresses the release of insulin and glucagon Decreases the absorption of nutrients TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.2 Figure 9.9 Regulation of blood glucose level. Top: When the blood glucose level is high, the pancreas secretes insulin. Insulin promotes the storage of glucose as glycogen and the synthesis of proteins and fats (as opposed to their use as energy sources). Therefore, insulin lowers the blood glucose level to normal. TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.2 Bottom: When the blood glucose level is low, the pancreas secretes glucagon. Glucagon acts opposite to insulin. Therefore, glucagon raises the blood glucose level to normal. TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.2 The Liver The liver is the largest gland in the body. The liver has many functions, including: Detoxifying blood Making plasma proteins Maintaining blood glucose levels Producing bile, which contains bile salts that emulsify fat in the small intestine Producing urea, a nitrogenous waste product from the breakdown of amino acids TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.2 TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.2 Structure and Function of the Liver The liver contains about 100 000 lobules that serve as its structural and functional units. Three structures are located between the lobules: Bile duct: takes bile away from the liver Hepatic artery branch brings oxygen-rich blood to the liver Hepatic portal vein transports nutrients from the intestines TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.2 Figure 9.8 b. A hepatic lobule. The liver contains over 100 000 lobules, each lobule composed of many cells that perform the various functions of the liver. They remove and add materials to the blood and deposit bile in a duct. TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.2 Figure 9.10 Hepatic portal system. The hepatic portal vein takes the products of digestion from the digestive system to the liver, where they are processed before entering a hepatic vein. TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.2 The Gall Bladder The gall bladder is a muscular sac attached to the surface of the liver. Excess bile from the liver is stored in the gall bladder Bile leaves the gall bladder and proceeds to the duodenum via the common bile duct o Bile emulsifies fat to prepare it for further breakdown by digestive enzymes TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.3 Digestive Enzymes Digestive enzymes help break down the major components of food: carbohydrates, proteins, nucleic acids, and fats. TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.3 Carbohydrate Digestion by Enzymes The digestion of starch (a carbohydrate) begins in the mouth. Salivary amylase (produced by the salivary glands) digests starch into maltose (a disaccharide) Pancreatic amylase (produced by the pancreas) and maltase (produced by the small intestine) then convert maltose in the small intestine to glucose (a monosaccharide). Glucose can be absorbed by the small intestine. TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.3 Figure 9.11 Digestion and absorption of nutrients. a. The breakdown of carbohydrates, such as starch, involves amylase enzymes. TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.3 Carbohydrate Digestion by Enzymes Other disaccharides, such as lactose, have their own enzyme that digests them in the small intestine. Lactase is an enzyme that digests lactose, a sugar found in milk. o Individuals who have a lactase deficiency often have symptoms of lactose intolerance (diarrhea, gas, cramps) caused by the fermentation of non-digested lactose by intestinal bacteria TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.3 Protein Digestion by Enzymes The digestion of proteins begins in the stomach. Pepsin is an enzyme produced by gastric glands that acts on proteins to produce peptides. Trypsin (produced by the pancreas) and peptidases (produced in the small intestine) break down peptides into amino acids TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.3 Figure 9.11 Digestion and absorption of nutrients. b. Protein digestion involves the action of protease enzymes. TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.3 Fat Digestion by Enzymes Lipase (produced by the pancreas) acts in the small intestine and digests fat molecules in the fat droplets after they have been emulsified by bile salts Glycerol and fatty acids enter the cells of the villi, where they are rejoined and repackaged as lipoprotein droplets before entering the lacteals TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.3 Figure 9.11 Digestion and absorption of nutrients. c. For fat digestion, bile salts emulsify the fats so that lipase enzymes can digest the particles. TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.3 Regulation of Digestive Enzymes Enzymes function best at an optimum temperature and pH that helps maintain the proper shape to fit their substrate. Since the digestive system is maintained at a constant 37ºC, enzymatic activity is largely controlled by pH o The pH of the stomach is between 1 and 2 but can increase to around 7.4 to 7.8 when sodium bicarbonate in pancreatic juice is released from the pancreas o This increase in pH occurs after chyme enters the duodenum, and allows different digestive enzymes to be active depending on the pH TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.4 Disorders of the Digestive System Disorders of the digestive system can be grouped into two categories: Disorders of the digestive tract itself Stomach ulcers, intestinal disorders (diarrhea, Crohn’s disease, constipation), polyps, and colon cancer Disorders of the accessory organs Pancreatic disorders (pancreatitis, pancreatic cancer), diabetes mellitus, hepatitis, cirrhosis, gallstones TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.4 Disorders of the Digestive Tract Stomach Ulcers A stomach ulcer is an open sore in the stomach wall caused by a gradual disintegration of the tissue. o Mainly caused by infection by Helicobacter pylori, a bacterium that impairs the ability of mucous cells to produce protective mucus for the stomach wall o Also caused by viral infections, or overuse of anti- inflammatory medications that damage stomach lining o Can be treated with antibiotics that kill H. pylori bacterium, medications that reduce stomach acid TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.4 Figure 9B Stomach ulcer. Drs. Barry Marshall and Robin Warren won a Nobel Prize in 2005 for discovering that most stomach ulcers are caused by a bacterial infection. TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.4 Intestinal Disorders Diarrhea is loose, watery feces. o Acute: can be caused by infections of the small or large intestine with bacteria, viruses, or protozoans that cause the intestinal wall to be irritated. − Peristalsis increases, and less water is absorbed, resulting in loose, watery feces o Chronic: Persistent inflammation of the intestine due to a misdirected immune response against one’s own intestinal tissues and bacteria (Crohn’s disease) − Genetic predisposition and environmental triggers are factors. TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.4 Constipation results in dry and hard feces. o Caused by ignoring the urge to defecate or by inadequate fluid or fibre in the diet o Chronic constipation can lead to hemorrhoids, which are inflamed blood vessels in the anus o Can be prevented by increasing the amount of water and fibre in diet − Laxatives and enemas can be used but can irritate the colon TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.4 Polyps and Colon Cancer Polyps are small growths arising from the epithelial lining in the colon o Can be benign or cancerous o Usually detected by a colonoscopy, where an endoscope is inserted in the colon to enable a viewing of the wall of the large intestine o Colon cancer can be cured if detected early and surgically removed while it is still confined to a polyp TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.4 Disorders of the Accessory Organs Disorders of the Pancreas Pancreatitis is an inflammation of the pancreas. o Caused by excessive alcohol consumption, gallstones that block the pancreatic duct, or other unknown factors o Chronic pancreatitis: digestive enzymes secreted by the pancreas damage the pancreas and decrease insulin secretion o Pancreatic cancer is a cancer that is almost always fatal. o 20% of patients are alive one year after diagnosis o Resistant to treatment and spreads to other organs before symptoms appear TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.4 Diabetes mellitus is a condition that affects the regulation of glucose metabolism. o Type I diabetes: individuals do not produce enough insulin o Type II diabetes: individuals cannot properly use the insulin they produce o In either case, blood glucose levels rise, but the use of glucose by the cells is impaired − Excess glucose in the blood is secreted into the urine − Because blood glucose cannot be used, the body metabolizes fat, which leads to the buildup of ketones − Ketones metabolize into acids, which can build up in the blood and lead to coma and death TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.4 The glucose tolerance test is used to test for diabetes. o Person ingests a known amount of glucose, and blood glucose concentration is measured at intervals o In a person with diabetes, blood glucose rises greatly and remains elevated for hours Figure 9.12 Glucose tolerance test. Following the administration of 100 g of glucose, the blood glucose level rises dramatically in the person with diabetes and glucose appears in the urine. Also, the blood glucose level at 2 hours is equal to or TO PREVIOUS more than 200 mg/100 dL. SLIDE UNIT B Chapter 9: Digestive System Section 9.4 Type 1 Diabetes (individuals do not produce enough insulin) o 10% of individuals with diabetes in Canada have type 1 o Usually begins in childhood (also known as juvenile-onset diabetes) o Can also occur due to a viral infection, autoimmune reaction, or environmental agent that destroys the pancreatic islets that produce insulin o Treatment is through daily insulin injections, which can be administered through an insulin pump TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.4 Figure 9.13 An insulin pump. Insulin pumps administer preprogrammed small doses of insulin throughout the day via an implanted catheter. Most insulin pumps can be worn under clothing. TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.4 Type 2 Diabetes (individuals cannot use insulin properly) o 90% of individuals with diabetes in Canada have type 2. o Can occur in adults or children o Individuals with type 2 diabetes are often overweight or obese, and fat tissue may produce a substance that impairs insulin receptor function o Normally, insulin binds to its receptor on cell surfaces to cause the number of glucose transporters to increase in the plasma membrane. This does not occur in individuals with type 2 diabetes. o Treatment involves weight loss, insulin injections, and medications to increase the effectiveness of the insulin produced TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.4 Disorders of the Liver and Gall Bladder o Hepatitis is inflammation of the liver. o Commonly caused by one of several viruses o Hepatitis A: acquired by consuming food or water that is contaminated with sewage (vaccine is available) o Hepatitis B: spread by sexual contact, blood transfusions, or contaminated needles (vaccine is available) o Hepatitis C: spread by sexual contact, blood transfusions, or contaminated needles (no vaccine, but antiviral drugs are available) TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.4 Cirrhosis is a chronic disease of the liver. o Often seen in alcoholics due to malnutrition and toxic effects of excess amounts of alcohol o Liver becomes infiltrated with fat, and the fatty liver tissue is replaced with non-functioning fibrous scar tissue o Damage to the liver exceeds the rate of liver regeneration o Treatment involves a liver transplant TO PREVIOUS SLIDE UNIT B Chapter 9: Digestive System Section 9.4 Gallstones are small, hard masses that form in the gall bladder. o Cholesterol can precipitate out of the bile and form crystals that can grow into gallstones. o Passage of gallstones from the gall bladder may block the common bile duct and cause jaundice, a yellowing of the skin and eyes due to buildup of bilirubin. o If the gallstones cannot be removed, the gall bladder must be removed. TO PREVIOUS SLIDE