BIOL2010 A&P II Exam V Study Goals CHAPTERS 24 & 25- THE DIGESTIVE SYSTEM AND METABOLISM, Study Guides, Projects, Research of Biology

Download BIOL2010 A&P II Exam V Study Goals CHAPTERS 24 & 25- THE DIGESTIVE SYSTEM AND METABOLISM and more Study Guides, Projects, Research Biology in PDF only on Docsity! 1 BIOL2010 A&P II Exam V Study Goals CHAPTERS 24 & 25- THE DIGESTIVE SYSTEM AND METABOLISM ❖ DIGESTIVE SYSTEM TERMINOLOGY o 1. Define each of the following terms as they apply to the digestive system. Use each correctly to describe the processes of the digestive system. ▪ Pg 885-886 ▪ Ingestion : • Take in materials by mouth. • Active process involving choices and decision making ▪ Mechanical Digestion: • Mechanical breakdown of food • May not be required before ingestion: liquids ▪ Chemical Digestion: • Chemical breakdown of food molecule by enzymes • Into small organic or inorganic molecules suitable for absorption by digestive system epithelium ▪ Secretion : • Release of water, acids, enzymes, buffers, salts by glandular organs, epithelium of digestive tract and gallbladder, into lumen of digestive tract o The glandular organs and gallbladder secrete their products into ducts that empty into digestive tract ▪ Absorption : • Movement of small molecules across wall of digestive tract into blood or lymph o These materials are absorbed into the interstitial fluid of the digestive tract for distribution to body cells. ▪ Excretion : • Urinating • Removal of metabolic waste products from body fluid ▪ Mastication : pg 898 • Chewing • Mechanical and Chemical digestion occur during this time within oral cavity. • During mastication, you force food from the oral cavity to the vestibule and back, crossing and recrossing the occlusal surfaces of the teeth. • Breaks down tough connective tissues in meat and plant fibers in vegetables. • Also helps saturate the food w/ salivary secretions and enzymes. • Creates bolus ▪ Deglutition : pg 900, figure 24-11 • Swallowing • Initiated voluntarily when you eat but proceeds automatically once it begins. o 3 phases ▪ Buccal Phase ▪ Pharyngeal Phase ▪ Esophageal Phase ▪ Defecation : • Solid waste is eliminated from the body ❖ FUNCTONAL ANATOMY o 2. List organs of the GI tract in order as food passes through and describe the function of each. ▪ Pg 886, figure 24-1 ▪ Oral Cavity (mouth) • Sensory analysis of food before swallowing 2 • Mechanical digestion through the actions of the teeth tongue and palatal surfaces • Lubrication by mixing with mucus and saliva • Limited chemical digestion of carbohydrates and lipids o Teeth o Tongue o Salivary glands ▪ Pharynx (throat) • An anatomical space that serves as a common passageway for solid food, liquid, and air. Specific pharyngeal muscles work w/ muscles of the oral cavity to start swallowing, which pushes the bolus into the esophagus (muscular propulsion of material into esophagus). • 3 regions o Nasopharynx o Oropharynx o laryngopharynx ▪ Esophagus • Transport of materials to the stomach • Innervated by parasympathetic and sympathetic fibers from the esophageal plexus. ▪ Stomach: refer to Q#12-16 • An expandable tube-like organ found in the upper left quadrant of peritoneal cavity. o Temporarily store ingested food received from the esophagus o Chemical digestion of materials by acid and enzymes o Mechanical digestion through muscular contractions ▪ Small Intestine: refer to Q#17 • Enzymatic digestion and absorption of water, organic substrates, vitamins and ions o Primary functions are chemical digestion of chyme from stomach and absorption of nutrients across mucosal surface ▪ Large Intestine • Dehydration and compaction of indigestible materials in preparation for elimination ▪ Rectum - - >Anus • Rectum is expandable organ for the temporary storage of feces • Last portion of rectum is anal canal. • The anus is the exit of the anal canal o 3. List the accessory organs of digestion and briefly describe the function of each. ▪ Teeth • Mechanical digestion by mastication ▪ Tongue • Mechanical digestion by compression, abrasion, and distortion • Manipulation to assist in chewing and to prepare food for swallowing • Sensory analysis by touch, temperature, and taste receptors • Secretion of mucins and the enzyme lingual lipase . ▪ Salivary Glands : refer to Q#8 • Secretion of lubricating fluid containing enzymes that break down carbohydrates ▪ Liver: refer to Q#24 • Secretion of bile o Bile Production • Storage of nutrients • Metabolic & Hematological Regulation ▪ Pancreas: refer to Q#20 • Secretion of pancreatic juice by specialized cells: pancreatic juice is an alkaline mixture of digestive enzymes, water, and ions. o Exocrine cells secrete buffers and digestive enzymes ▪ Pancreatic acini • Lined with simple cuboidal epithelium. • Line the duct system o Endocrine cells secrete hormones into blood ▪ Pancreatic islets • Scattered among the acini 5 the tract (longitudinal layer) 6 ▪ Contractions alter shape of lumen ▪ 2) Submucosa: • Dense irregular connective with…. o Blood vessels o Lymphatic vessels o Exocrine glands secrete enzymes and buffers into the lumen of the digestive tract in some areas • Binds mucosa to the muscular layer • Submucosa Neural Plexus: o Plexus of Meissner o Along outer margin of submucosa and the inner border of the muscular layer o Network of sensory nerve endings, parasympathetic ganglionic neurons, and sympathetic neuron terminals (postganglionic fibers). ▪ Innervate the mucosa and submucosa ▪ 3) Muscular Layer • Smooth muscle cells dominate this region • Muscularis Externa: two layers of smooth muscle cells o Circular Muscle Layer o Longitudinal Muscle Layer o These muscles play role in mechanical digestion and in moving materials along digestive tract ▪ Movements coordinated primarily by sensory neurons, interneurons ,and motor neurons of the enteric nervous system (ENS) ▪ ENS primarily innervated by parasympathetic division of the ANS. Sympathetic postganglionic fibers also synapse here ▪ Many of these fibers continue onward to innervate the mucosa and the myenteric plexus . • Myenteric Plexus: o Network of sensory nerve endings, parasympathetic ganglia neurons, sensory neurons, interneurons, and sympathetic postganglionic nerve terminals o Lies between circular and longitudinal muscle layers. o Parasympathetic stimulation increases muscle tone and activity while sympathetic stimulation decreases muscle tone. ▪ 4) Serosa • Serous membrane that covers the muscular layer along most portions of digestive tract enclosed by the peritoneal cavity. In areas where there is no serosa covering muscular later is a fibrous sheath called adventitia. o 6. Identify neurons that control patterns of movement and secretion within the GI tract. ▪ Pg 891(2): figure 24-5 ▪ Control of movement of food through GI tract and of secretions is mostly local and regulated by the enteric nervous system or “gut brain.” Enteric Nervous System is the network of neurons in the myenteric and submucous plexus. • Local Factors: initial regulation o pH, volume, chemical composition of the intestinal contents have direct effect on digestive activity in that segment of the digestive tract. o Can stimulate localized contractions or release of chemicals • Enteric Neurons Sense….. o Stretching o Chemical Composition of food (pH, fat, or protein content) ▪ Sensory receptors in walls of digestive tract • Visceral motor neurons that control smooth muscle contraction and glandular secretion are located in the myenteric plexus o Considered parasympathetic 7 o Myenteric plexus also contains sensory neurons, motor neurons, and interneurons responsible for local flexes that operate entirely outside the control of the CNS • Short reflexes • Long reflexes • Enteric Neurons and hormones control: 10 • Glycoproteins • Antibodies (IgA) and lysozyme to prevent buildup of bacteria • wastes ▪ Mucins hydrate to form mucus: mucins give saliva its lubricating action. ▪ Salivary Amylase begins digestion of complex carbohydrates ▪ Salivary secretions normally controlled by Autonomic Nervous System • Each gland has parasympathetic and sympathetic innervation. o Parasympathetic efferents originate in the superior salivatory nucleus and the inferior salivatory nucleus of the medulla oblongata and synapses in the submandibular and otic ganglia • Salivation is stimulated by parasympathetic nervous system • Sympathetic innervation is unclear o 10. Briefly describe the process of swallowing and indicate which steps are controlled by voluntary muscle. ▪ Pg 900: figure 24-11 ▪ Also called Deglutition • Buccal Phase- Voluntary o Tongue pushes bolus against hard palate and toward pharynx o Soft palate rises to block nasopharynx • Pharyngeal Phase- Involuntary o Swallowing reflex begins o Bolus is pushed through pharynx to entry to esophagus. o Raising of larynx forces epiglottis down to block entry to trachea • Esophageal Phase- Involuntary o Bolus is pushed through esophagus by peristalsis. ▪ A dry or poorly lubricated bolus travels much more slowly and may require a series of secondary peristaltic waves. These waves are local reflexes triggered by the stimulation of sensory receptors in the esophageal walls. o 11. Describe the location and function of the uvula and the epiglottis. ▪ Uvula • Posterior of soft palate • Prevents food from entering pharynx too early • Seals off the nasopharynx ▪ Epiglottis • Apart of larynx. Projects superior to the glottis and forms a lid over it. • Prevents food from entering larynx 11 • Bends over glottis so that bolus can glide across into the esophagus. ❖ STOMACH o 12. Describe the location of gastric pits and gastric glands . Identify secretions of the specialized cells found there. ▪ Pg 901-904: Figure 24-13 ▪ Stomach has 4 parts: The Cardia, Fundus, Body, Pyloric part ▪ Gastric pits : which are shallow depressions that open onto the gastric surface of the stomach is embedded within mucosa layer and is lined with simple columnar epithelium. • Epithelium is secretory sheet, which produces a carpet of mucus that covers the interior surface of the stomach, • Mucus cells are at base, or neck, of gastric pit ▪ Gastric glands In the fundus and body of the stomach, each gastric pit communicates with several gastric glands, which extend deep into the underlying lamina propria. • Within fundus & body: secret most of the acid and enzymes involved in gastric digestion o Within pyloric part: secrete mucus and important digestive hormones, including gastrin, a hormone that stimulates gastric glands o 13. List and describe the function of each of the factors secreted by cells in the gastric mucosa. o Pg 904 ▪ Remember that in the fundus and body of the stomach, each gastric pit communicates with several gastric glands. o Gastric glands are dominated by Two types of secretory cells: parietal and chief ▪ Parietal : • Common along proximal portion of each gastric gland • Secretes intrinsic factor o A glycoprotein that helps absorb vitamin B12 across intestinal lining. ▪ pernicious anemia • indirectly secretes hydrochloric acid (HCl): refer to Q#14 o THEY DO NOT PRODUCE HCl IN CYTOPLASM: it would erode a secretory vesicle and destroy the cell. o These cells create the conditions for increasing the concentrations of both H+ and Cl-. Each ion exits parietal cells independently by different mechanisms. o HCl keeps stomach contents at pH of 1.5-2.0 ▪ Kills most of the microorganisms ingested w/ food. ▪ Denatures proteins and inactivates most of the enzymes in food ▪ Helps break down plant cell walls and the connective tissues in meat. ▪ Acidic environment is also necessary for the function of chief cells. ▪ Chief : • Most abundant near the base of a gastric gland. • Secrete pepsinogen o An inactive proenzyme o Acid in the gastric lumen converts pepsinogen to pepsin, an active proteolytic, or protein-digesting enzyme. o Pepsin functions most effective in pH of 1.5-2.0 ▪ IN NEWBORNS • IN ADDTION TO THE OTHER CELLS. They produce rennin, also called chymosin, and gastric lipase o These enzymes are Important for the digestion of milk ▪ Rennin coagulates mill proteins ▪ Gastric lipase initiates the digestion of milk fats o Remember that glands in pyloric part primarily produce mucus secretions rather than enzymes or acids. ▪ Enteroendocrine cells are scattered among mucus secreting cells within pyloric 12 part. Produces 7 hormones o Gastrin most notable: produced by G cells , which are the most abundant in the gastric pits of the pyloric antrum. 15 • Gastric phase o Begins w/ the arrival of food in the stomach and builds on stimulation provided during the cephalic phase. o May continue for 3-4 hrs while the acid and enzymes process the ingested materials. o Stimuli that initiate the gastric phase are ▪ 1) distension of the stomach ▪ 2) an increase in the pH of the gastric contents ▪ 3) The presence of undigested materials in the stomach, especially proteins and peptides. • Intestinal Phase o Begins when chime first enters the small intestine. o Function of this phase is to control the rate of gastric emptying to ensure that the secretory, digestive, and absorptive functions of the small intestine can proceed w/ reasonable efficiency. o Arrival of chime also triggers other neural and hormonal events that coordinate the activities of the intestinal tract, pancreas, liver, and gallbladder. o 16. Describe control of chyme delivery to the duodenum from the stomach. Describe the effects of each of these hormones secreted by the duodenum on the stomach and on accessory organs of digestion. gastrin, CCK, secretin, GIP, VIP. ▪ Pg 919: figure 24-22;23 -22 Major Hormones of the Duodenum. Major Hormenes of the Duodenum Gastrin is secreted by G cells in the duodenum when they are exposed to large quantities of incompletely digested proteins. The functions of gastrin include promoting increased stomach motility and stimulating the production of gastric acids and enzymes. (Gastrin is also produced by the stomach.) ‘Secretin Secretin is released when chyme arrives in the duodenum. Secretin's primary effect is an increase in the secretion of bile (by the liver) and butters (by the pancreas), which in turn act to increase the pH of the chyme. Among its secondary effects, secretin reduces gastric motility and secretory rates. Gastric Inhibitory Peptide (GIP) Gastric inhibitory peptide is secreted when fats and carbohydrates— especially glucose—enter the small intestine. The Inhibition of gastric activity is accompanied by the stimulation of insulin release at the pancreatic islets. GIP has several secondary effects, including stimulating duodenal gland activity, stimulating lipid synthesis in adipose tissue, and increasing glucose use by skeletal muscles. Cholecystokinin (CCK) Cholecystokinin is secreted when chyme arrives in the duodenum, especially ‘when the chyme contains lipids and partially digested proteins. In the pancreas, CCK accelerates the production and secretion of all types of digestive enzymes. It also causes a relaxation of the hepatopancreatic sphincter and contraction of the gallbladder, resulting in the ejection of bile and pancreatic juice into the duodenum. Thus, the net effects of CCK are to increase the secretion of pancreatic enzymes and to push pancreatic secretions and bile into the duodenum. The presence of CCK in high concentrations has two additional effects: It inhibits gastric activity, and it appears to have CNS effects that reduce the sensation of hunger. Vasoactive Intestinal Peptide (VIP) Vasoactive intestinal peptide stimulates the secretion of intestinal glands, dilates regional capillaries, and inhibits acid production in the stomach. By dilating capillaries in active areas of the intestinal tract, VIP provides an efficient mechanism for removing absorbed nutrients. Enterocrinin is released when chyme enters the duodenum. It stimulates mucin production by the submucosal glands. 16 17 ❖ SMALL INTESTINE, LIVER, GALL BLADDER, PANCREAS o 17. List and describe the main function(s) of each the three divisions of the small intestine. ▪ Pg 915 ▪ Small intestine is a long muscular tube where chemical digestion is completed and the products of digestion are absorbed. 90%. Fills much of peritoneal cavity. Stabilized by mesentery proper. Has 3 segments: Duodenum, Jejunum, & Ileum. ▪ Duodenum : • Closest to the stomach • Mixing area for chyme and secretions from the pancreas and liver (mixing bowl) o Receives chyme from the stomach and digestive secretions from the pancreas and liver. ▪ Jejunum : • Bulk of chemical digestion and most nutrient absorption occurs here ▪ Ileum • Largest part of small intestine • Ends at ileocecal valve between small and large intestine: controls the flow of material from the ileum to the cecum of the large intestine • Mainly absorption of water. • Distal end contains many Peyer’s patches ( or MALT) to protect small intestine from bacteria in large intestine o 18. Describe the structure, location, and function of the plicae circularis and intestinal villi . What is the purpose of these folds? ▪ Pg 915 (16) ▪ Plicae circulares: • Level 1 of the folding of the small intestine • Does not unfold as intestine stretches. 20 absorbed. ▪ Amylase : pancreatic alpha-amylase (carbohydrase) 21 • Enzyme that breaks down certain starches. ALMOST identical to salivary amylase ▪ Nucleases : • Breaks down DNA or RNA ▪ Proteolytic enzymes : • 70% of pancreatic enzymes • Breakdown proteins and peptides. Are secreted as inactive proenzymes and then converted to active enzymes in duodenum. • Includes proteases- - > break apart large protein complexes • Includes peptidases- - > break small peptide chains into individual amino acids o 22. Describe the function of the gall bladder . ▪ Pg 914(15) ▪ The major function of the gallbladder is BILE STORAGE . • Bile is released into the duodenum only under the stimulation of intestinal hormone CCK. ▪ Bile modification • When gallbladder becomes too full, much of water is absorbed and bile salts and other components of bile become increasingly concentrated. o Gallstones o Cholecystitis o 23. Describe the pathway blood flow from digestive organs to the liver, and the venous system. ▪ Blood flows from… the digestive organs via the hepatic portal vein to the liver and then to the inferior vena cava via the hepatic vein. ▪ The hepatic artery only supplies oxygenated blood to the liver. o 24. List all functions of the liver. Relate the normal functions of the liver to symptoms of liver failure. ▪ Pg 912-14 ▪ Metabolic Regulation: Liver is primary organ involved in regulating the composition of circulating blood. All blood leaving the absorptive surfaces of the digestive tract enters the hepatic portal system and flows into the liver. The liver then extracts nutrients or toxins from blood before it reaches systemic circulation through the hepatic veins. The liver removes and stores excess nutrients and corrects nutrient deficiencies via the following activities • Carbohydrate Metabolism o Stabilizes blood glucose levels at 90mg/dL ▪ Provides glucose by breaking down glycogen AND by making glucose from other organic molecules (gluconeogenesis) ▪ Stores excess glucose as glycogen • Lipid Metabolism o Regulates circulating levels of fatty acids, triglycerides, cholesterol • Amino Acid Metabolism o Removes excess amino acids ▪ Converts ammonia, a toxic waste product of amino acid breakdown, to urea for excretion by kidneys. • Waste Removal • Vitamin Storage o Stores fat-soluble vitamins (vitamins A, D, E, K, B12) • Mineral Storage o Converts iron to ferritin for storage • Drug inactivation o Removes and breaks down many circulating drugs ▪ Rate of removal by liver must be taken into account when determining drug dosage ▪ Hematologic Regulation: Liver is the largest blood reservoir in the body. As blood passes through it, the liver performs the following functions • Phagocytosis and Antigen Presentation o By Kupffer Cells 22 • Synthesis of Plasma Proteins o Including albumins 25 ▪ The microvilli make up the brush border because they project from the epithelium like the bristles on a brush. • This arrangement increases the total area for absorption. ▪ Brush Border enzymes • Integral membrane proteins on the surfaces of intestinal microvilli. They break down materials that come in contact with the brush border. The epithelial cells then absorb the breakdown products. Once the epithelial cells are shed, they disintegrate within the lumen, releasing both intracellular and brush border enzymes. An example: Enteropeptidase that enters the lumen and activates the key pancreatic proenzyme, trypsinogen. o 29. Describe the forms in which carbohydrates, proteins, and lipids are absorbed at the brush border. ▪ Figure 24-27 ▪ Carbohydrates • Only monosaccharides • Enzymes associated w/ breakdown of carbs o Maltase ▪ Splits bonds between glucose molecules of the disaccharides maltose o Sucrase ▪ Breaks the disaccharide sucrose into glucose and fructose o Lactase ▪ Hydrolyzes the disaccharide lactose into a molecule of glucose and one of galactose. ▪ If intestinal mucosa stops producing lactase, the person become lactose intolerant ▪ Proteins • Only single amino acids ▪ Lipids • Fatty acids and monoglycerides cross membrane of epithelial cells leaving bile salts in the lumen • Enzymes associated w/ breakdown of lipids o lingual lipase from glands of the tongue o Pancreatic lipase from the pancreas ▪ Lipases are water-soluble enzymes therefore lipases can only interact w/ the exposed surfaces of the lipid drops. Lipid drops are large and available time is short. Therefore need assistance of bile salts. ▪ Bile salts improve chemical digestion by emulsifying the lipid drops into tiny emulsion droplets, therefore providing better access for pancreatic lipase. The emulsification takes place only after the chyme has been mixed with bile in the duodenum. - - > monoglycerides and fatty acids ▪ The monoglycerides and fatty acids mix with bile salts within chyme to for small lipid-bile salt complexes called micelles. • Micelles contacts intestinal epithelium, the lipids diffuse across the plasma membrane and enter the cytoplasm. • Intestinal cells synthesize new triglycerides and are coated with proteins: chylomicrons. o Intestinal cells secrete chylomicrons into interstitial fluid by exocytosis. The protein coat keeps them suspended in the interstitial fluid and are generally too large to diffuse into capillaries. Most diffuse into intestinal lacteals which lack basement membranes and have large gaps between adjacent endothelial cells. o 30. List compounds that are absorbed at the stomach. ▪ Pg 905 ▪ Alcohol (ethanol), Aspirin, and some lipids ❖ METABOLISM 26 o 31. Define metabolism, anabolism, catabolism. ▪ Pg 940-942 27 ▪ Metabolism : All of the body’s chemical reactions occurring at one time. Sum of all chemical and physical changes that occur within body tissues. • Chemical rxns are used to.. o Breakdown large organic molecules into smaller molecules for recycling o Build large organic molecules from smaller molecules o Convert small organic molecules from one form to another o Breakdown small organic molecules to provide energy to make ATP o Carry out processes such as secretion, contraction, cell division and many more. ▪ Anabolism : smaller molecules - - -> larger molecules • Used to build new large molecules • ATP produced by mitochondria provides energy to support both anabolism and other cell functions. • Used to store energy in chemical bonds (formation of new chemical bonds) • Used to store small energy molecules as part of larger molecules ▪ Catabolism : larger molecules - - -> smaller molecules • Used to breakdown and recycle large molecules • Used to release energy stored in chemical bonds o Covalent bonds are broken to obtain energy o Two type of nutrients broken down for energy for ATP ▪ Monosaccharides (glucose) ▪ Fatty acids ▪ Amino acids are used for energy only if not enough monosaccharides and fatty acids o 32. List the major types of molecules found in the nutrient pool. ▪ Pg 940: figure 25-1 ▪ Carbohydrates ▪ Lipids ▪ Proteins o 33. Compare and contrast break down of simple sugars (glucose), fatty acids, and amino acids by cellular respiration . Compare speed, number of ATP created, waste products, and location. ▪ Pg 943 ▪ Cellular Respiration: a set of metabolic reactions and processes that take place in the cells of organisms to convert biochemical energy from nutrients into adenosine triphosphate (ATP), and then release waste products. ▪ Glucose • Glycolysis: first step o glucose (6 C) is broken into two molecules of pyruvate (3 C each) o no O2 required o makes 2 molecules of ATP per glucose o occurs in cytosol • Aerobic Cellular respiration: finishes job o pyruvate converted to Acetyl CoA (2 C) o pyruvate completely broken down into CO2 + H2O o requires O2 o complete breakdown of one glucose molecule provides energy for 32-38 ATP o occurs in mitochondria ▪ Fatty Acids • Aerobic Cellular respiration only! o converted to acetyl CoA in 2 carbon pieces o formation of ATP from fatty acids requires O2 o For each 2-carbon fragment cell makes 17 ATP (example: 144 ATP from