BIOL 2114 Final Exam Review Unit 1 Review PDF
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This document contains lecture notes on the digestive system, including processes like mastication and deglutition.
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LECTURE NOTE UNIT 1 (pg. 53) DIGESTIVE SYSTEM (pg. 1) ○ Explain the following processes: Mastication -the process of chewing food in the oralcavity. Deglutition-the process of swallowing food....
LECTURE NOTE UNIT 1 (pg. 53) DIGESTIVE SYSTEM (pg. 1) ○ Explain the following processes: Mastication -the process of chewing food in the oralcavity. Deglutition-the process of swallowing food. Buccal Phase- compression of the bolus against thehard palate. Tongue retraction forces the bolus into the oropharynx. Pharyngeal Phase- bolus contacts palatal arches andposterior pharyngeal wall. The larynx elevates, the epiglottis folds, and the bolus passes the closed glottis. Esophageal Phase: Pharyngeal muscles push the bolus into the esophagus, and peristaltic waves move it toward the stomach. Include the organs and nerves that are involved. Mastication ○ Organs - teeth, tongue, salivary glands, muscles of mastication ○ Nerves - trigeminal nerve (V) Deglutition ○ Organs - pharynx, esophagus ○ Nerves - glossopharyngeal nerve (IX), vagus nerve (X), trigeminal nerve (V), hypoglossal nerve (XII) ○ Name the structures of the actual GI tract (alimentary canal) from mouth to anus. Oral cavity (mouth) Pharynx Esophagus Stomach Small intestines Large intestines Anus ○ Name the accessory digestive organs and their basic functions. Teeth Tongue Salivary glands Pancreas Liver Gall bladder ○ Describe peritoneum. What types of tissues are found in the peritoneum? Mesothelium: A layer of flat epithelial cells thatproduce peritoneal fluid, reducing friction between moving organs. Areolar Tissue: A supportive connective tissue thatstabilizes the mesothelium and facilitates the passage of essential vessels and nerves. What does it mean to say that an organ is intraperitoneal? Those that are completely surrounded by the visceral peritoneum and are suspended within the peritoneal cavity by mesenteries. Is the peritoneum a serous membrane? What does that mean? Yes; Serous membranes consist of a mesothelium (a layer of squamous epithelial cells) supported by areolar tissue. Name each fold of peritoneum described below: Falciform ligament- connects the liver to the anteriorabdominal wall G reater omentum- hangs from the greater curvature of the stomach Lesser omentum- connects the liver to the stomach Mesentery proper- connects the small intestine tothe posterior wall of the abdominal cavity Mesecolon- connects the transverse colon to the posteriorabdominal wall Name the retroperitoneal and intraperitoneal organs of the GI tract. Intraperitoneal (SALTD PRG) ○ Stomach ○ Appendix ○ Liver ○ Transvercolon ○ Duodenum (1st part) ○ Pancreas (tail) ○ Rectum (upper 3rd part) ○ Gall bladder Retroperitoneal ○ Supradrenal gland ○ Aorta + IVC ○ Duodenum (except 1st part) ○ Pancreas (except tail) ○ Ureters ○ Colon (ascending + descending) ○ Kidneys ○ Esophagus ○ Rectum (except 3rd part) Name the four basic histological layers of organs of the GI tract: ○ mucosa submucosa muscularis externa serosa (Intraperitoneal) / adventitia (retroperitoneal) Describe the types of tissue found in each layer. Mucosa ○ Epithelium- varies ○ Lamina propria- loose connective tissue ○ Muscularis mucosa- smooth muscle (inner circular,outer longitudinal) Submucosa- irregular connective tissue, submucosalplexus & glands Muscularis externa- smooth muscles, Myenteric plexus Serosa/adventitia- connective tissue What is the difference between a serosa and an adventitia? ○ Serosa- smooth, slippery cover that allows organsto glide easily (intraperitoneal) ○ Adventitia- sturdy, fibrous tape that secures the organs in place (retroperitoneal) Describe each of the following terms. Where is each found? What is its significance? ○ Bolus- a small mass of chewed food in the oral cavity.Formed to transport from mouth to stomach. C hyme- a semi-fluid mass of partly digested food in the stomach & small intestine. Used for further digestion and nutrient absorption in the small intestine. Frenulum- small tissue fold found under the tongue and connecting lips to the gums. Helps in the movement and stability of the tongue and lips Uvula- small, extension at the back of the soft palateand hangs in the back of the throat. Plays a role in speech and helps prevent food from entering the nasal cavity. Enamel - the hard outer surface layer of a tooth. Covers the crown of the tooth. Protects the tooth from decay and damage. Dentin- dense, bony tissue forming the bulk of atooth beneath the enamel. Found under the enamel and cementum. Supports enamel and absorbs the pressure from chewing. Incisor- front teeth that are sharp and chisel-shaped.Used for cutting and shearing food. Molar-molars are large, flat teeth at the back ofthe mouth. Found back of the back of the oral cavity. Used for grinding and crushing food. ○ Describe each of the following anatomical structures. What is the significance of each? Where are they located? What types of cells/tissues make up these structures? Gingiva- ridges of oral mucosa. Surrounds the baseof each tooth on the alveolar processes of the maxillae and mandible. Provides a protective barrier.TISSUE: stratifies squamous epithelium, connective tissue Epiglottis- flap of tissue that covers the trachea.During swallowing. Located at the entrance of the larynx. Prevents food and liquid from entering the airway during swallowing.TISSUE: stratified squamous, connective tissue (elastic cartilage) Tonsils- lymphoid tissues that play a role in immuneresponse. Three tonsils: pharyngeal, palatine, and lingual tonsils. Traps and destroys pathogens entering the oral or nasal cavities. TISSUE: lymphoid tissue. Periodontal ligament- a group of specialized connectivetissue fibers. Between the tooth and its alveolar socket. Anchors the tooth in its socket and absorbs shock during chewing.TISSUE: dense connective tissue. Name the three major salivary glands: ○ Parotid glands Submandibular glands Sublingual glands D escribe the histology of each gland. Does the gland contain primarily mucus acini, serous acini, or relatively equal amounts of both? Parotid Glands: Contain primarilySEROUSacini. Submandibular Glands:BOTH Sublingual Glands: Contain primarilyMUCUSacini. What is the purpose of mucus and serous acini? ○ Mucus Acini: Produce mucins that hydrate to form mucus,aiding in lubrication and buffering. ○ Serous Acini: Produce a watery solution with enzymes, aiding in digestion. Name 4 components of saliva. Electrolytes (Na+, Cl-, HCO3-) Buffers Glycoproteins (mucins) Enzymes Which salivary gland has the longest duct? Why is that significant? P arotid gland- significant because it allows the secretion of salivary amylase directly into the vestibule at the second upper molar, aiding in the initial digestion of starches. Name the three anatomical parts of the pharynx and the epithelium present in each: ○ Nasopharynx - pseudostratified ciliated columnar epithelium Oropharynx - stratified squamous epithelium Laryngopharynx - stratified squamous epithelium Which parts of the pharynx does food pass through? Oropharynx Laryngopharynx ○ Peristalsis- wave-like muscle contractions that movefood through the digestive tract. Which organs in the GI tract undergo peristalsis? Esophagus Stomach Small intestine Large intestine Which nerve plexus plays a role in peristalsis? Myenteric Plexus How does the autonomic nervous system affect peristalsis? PNS - increases muscle tone and activity; enhancing peristalsis SNS - decreases muscle tone and activity; reducing peristalsis Why are two layers of muscularis necessary for peristalsis? Inner circular layer - contracts behind bolus, narrowing the tract and pushing the bolus forward. Outer longitudinal layer - contract ahead of the bolus. Shortening the segment and making it easier to move. Describe the significance of the upper (UES) and lower esophageal sphincters (LES). ○ When do they open or close during deglutition? UES - opens during swallowing LES - opens to allow bolus to enter the stomach and closes to prevent reflux. What is unique about the muscularis of the esophagus? Muscular Layer Composition: Varies along the length of the esophagus. Upper Third: Contains skeletal muscle fibers. Middle Third: Mixture of skeletal and smooth muscle tissue. Lower Third: Only smooth muscles ○ Name four types of specialized epithelial cells found in the mucosa of the stomach: Mucous cells Parietal cells Chief cells G cells Explain the function of each. Mucous cells- produce mucus that forms a protectivelayer Parietal cells- secrete HCl and intrinsic factors Chief cells- produce pepsinogen G cells- secrete gastrin What is a proenzyme (zymogen)? What activates the proenzyme, pepsinogen? P roenzyme- (aka zymogen) is an inactive enzyme secreted by epithelial cells. The inactive form is important - because prevents the enzyme from digesting the cells that produce it. ○ Chief cells → pepsinogen → pepsin → breakdown proteins Name at least 3 functions of HCl in the stomach. Microorganism destruction Protein denaturation/ Enzyme inactivation Breakdown of plant cell wall & connective tissue What is the significance of intrinsic factors? Vitamin B12 Absorption - important for RBC production How is HCl made by the parietal cell? Increase the concentration of H+ and Cl- ions separately. Ions combine in the lumen of the gastric gland → HCl What stimulates the secretion of HCl from the parietal cell? Histamine, Neural Reflexes (Stretch, Chemoreceptors, Myenteric Plexus), & Gastrin ○ What makes the muscularis externa of the stomach unique? Inner oblique layer - enhances the stomach's ability to churn and mix food Myenteric plexus - contraction (mixing waves) like contents with gastric juices. Explain the control of gastric secretion in the following phases: ○ cephalic phase- triggered by sight, smell, taste,or even the thought of food gastric phase- triggered by food entering the stomach. intestinal phase- triggered by chyme entering thesmall intestine In which of these phases are hormones involved? Name them:GASTRIC & INTESTINAL Gastrin Phase ○ gastrin Intestinal Phase ○ Gastrin Inhibitory peptide (GIP) ○ Secretin ○ CCK Explain the nervous control of each phase. cephalic phase- CNS via PNS gastric phase- local reflexes within the stomachand the PNS intestinal phase- ENS & PNS What is the difference between the enteric and parasympathetic nervous systems? ○ Enteric nervous system - network in the walls of the digestive tract; initiates and coordinates simplex visceral reflexes locally without CNS input. CEPHALIC & GASTRIC PHASE ○ Parasympathetic nervous system - part of ANS like cranial nerves and sacral segments; regulates smooth muscle, cardiac muscle, and glandular secretion. INTESTINAL PHASE ○ For what length of time is food in the stomach? Is any food absorbed in the stomach? 1 - 2 hours No nutrients is absorbed in the stomach. Several clinical conditions are discussed in this chapter. Briefly explain each of the following: ○ Gingivitis- inflmmatio of the gums H iatal hernia- when parts of the stomach pushes up through the diaphragm into chest cavity. Symptoms: heartburn, acid reflux, and difficulty swallowing. Gastroesophageal reflux disease (GERD)- chronic condition;stomach flows back inot the esophagus, causes irritation. Symptoms: heartburn, regurgitation, difficulty swallowing Gallstones- hardened deposits of digestive fluid.Can cause pain, nausea, and vomiting. Can lead to pancreatitis if they block the bile ducts. P yloric stenosis- infants where the passage fromthe stomach to the small intestines (the pylorus) becomes narrowed, causing severe vomiting, dehydration, and weight loss. Lactose intolerance- inability to digest lactose Gastric ulcer- sore that develops the lining of thestomach. Peritonitis- inflammation of the peritoneum. ○ Explain the functions of the following hormones: gastrin (list at least two) Promotes increase stomach motility Stimulates the production of gastic acids & enzymes secretin (list at least two) Increases the secretion of buffers by the pancreas Stimulates bile secretion by the liver CCK (list at least four) Accelerates production & secretion of digestive enzymes Relaxtion of hepatopancreatic sphincter Inhibits gastric activity Reduces sensation of hunger In which organ are these hormones made? Which cells make these hormones? Gastrin Triggers: large amounts of incomplete digested proteins Organ: stomach and duodeum Cells: G- cells Target: stomach Secretin Triggers: arrival of chyme Organ: duodenum Cells: enteroendocrine cells Target: pancreas, liver CCK Triggers: arrival of chyme Organ: Duodenum Cells: enteroendocrine cells Target: panceas, gallbladder, CNS Explain or diagram the difference between microvilli, villi, rugae, and plicae circulares. ○ Microvilli- located epithelial cells lying smallintestine; tiny hair-like projections; increase SA, enhance nutrient absorption, create a “brush border” appearance. Villi- located on the mucosa of small intestine;finger like projections - increase SA, nutrient absorption, blood vessels & lacteals for nutritent transport Rugae- located stomach & gallbladder, folds in mucosa,expansion. Pilcae circulares- small intestine, transverse foldsin mucosa & submucosa, increase in SA, slow down the movement of chyme, allowing nutrients to be absorbed. Which folds include the submucosa? Pilcae circulares ○ Where in the GI tract does mechanical digestion occur? oral cavity, stomach, small intestine, and large intestine ○ Explain the significance of each of the following: Mucosa Paneth cells -aka Crypts of Lieberkuhn; secrete antimicrobialenzymes, playing a role in gut immunity Enteroendocrine cells -epi cells of villi and crypts;release hormones (like CCK and secretin) that regulate various digestive process ○ Ex: gastric emptying, enzyme secretion Lacteal -found in the core of each villus in themucosa. Absorb fats and transport them as chylomicrons to the venous circulation. Submucosa duodenal (Brunner's) glands -(in Duodenum) neutralizestomach acid, protect intestinal lining ○ Where are aggregated lymphoid nodules (Peyer's patches) found?ILEUM What is their significance? protect the small intestines from bacteria that normally inhabit the large intestine. Part of mucosa-associated lymphoid tissue (MALT) ○ Sketch the following bile duct passages: right and left hepatic duct, common hepatic duct, cystic duct, common bile duct.SEE IMAGE → What is the hepatopancreatic ampulla (ampulla of Vater)?The hepatopancreatic ampulla is a small, pouch-like structure where the common bile duct and the pancreatic duct meet. It's located in the wall of the duodenum, the first part of the small intestine. What is its significance? ○ Digestion:It plays a crucial role in digestion by allowing the release of bile and pancreatic juice into the duodenum. ○ Nutrient Absorption:Bile aids in the digestion andabsorption of fats, while pancreatic juice contains enzymes essential for the digestion of carbohydrates, proteins, and fats. What is the hepatopancreatic sphincter (sphincter of Oddi)?The hepatopancreatic sphincter is a muscular valve that controls the flow of bile and pancreatic juice from the hepatopancreatic ampulla into the duodenum. What is its significance? ○ Regulates Digestion:It regulates the release of digestiveenzymes and bile, ensuring optimal digestion and nutrient absorption. ○ Prevents Backflow:It prevents the backflow of duodenalcontents into the pancreatic and biliary ducts, protecting these organs from damage. ○ List at least 5 components of bile: Bilirubin cholesterol Water Ions (Bile) salts W here is bile made?LIVER What digestive function does bile have?Emulsifying large lipid droplets into smaller ones, increasing the surface area for pancreatic lipase to act upon. Which component of bile is responsible for fat emulsification?Bile salts What is the significance of bilirubin?Pigment derived from hemogobin + a component of bile. It’s a waste product that needs to be excreted. Where does bilirubin come from?Derived from the breakdown of hemoglobin in RBCs. Elevated bilirubin in the blood is calledJAUNDICE. Explain how elevated bilirubin in the blood may occur in liver disease when there is a blocked bile duct.In liver disease, blocked bile duct can prevent bilirubin from being excreted into the intestine. This causes bilirubin to accumulate in the blood, leading to JAUNDICE. Blackage can be due to gallstones, tunmors, or inflammation, which obstructs the normal flow of bile. ○ Name the histological layers of the gall bladder. MUCOSA- epthelium, lamina propria, muscularis mucosa SUBMUCOSA- connective tissue, blood vessels, and nerves MUSCULAR LAYER -smooth muscle fibers arranges to facilitate contraction and bile expulsion SEROSA- outer layer of connective tissue covered by the visceral peritoneum Which hormone has the muscularis of the gall bladder as its target tissue? CCK - stimulates contraction to release bile into the small intestine. What is a gallstone? Crystals of insoluble minerals and salts. Form when bile becomes too concentrated. Name some common components of gallstones. Common components: cholesterol, bilirubin, & calcium salts What causes colic (relative to the gall bladder)? Caused by gallstones blocking the cystic duct or bile duct, leading to intense pain. What is the danger of an infected gall bladder? An infected gallbladder → cholecystitis → surgery Why is the pancreas such an important digestive organ? ○ Endocrine and exocrine functions. Endocrine secretes insulin and glucagon to regulate blood sugar. Exocrine cells produce pancreatic juice - contains digestive enzymes and bicarbonate. (breakdown carbs, proteins, lipids into smaller molecules) Is the pancreas an endocrine or exocrine organ?BOTH How do enzymes from the pancreas travel to the duodenum? A network of secretory ducts Name 2 pancreatic enzymes that are not proenzymes. Pancreatic alpha-amylase Pancreatic lipase Name 3 pancreatic proenzymes (zymogens). Trypsinogen Chymotrypsinogen Procarboxypeptidase How is each proenzyme (zymogen) activated? TYPSINOGEN→ TYPSIN → CHYMOTRYPSIN & CARBOXYPEPTIDASE Why is bicarbonate an important component of pancreatic juice? NEUTRALIZATIONof acidic chyme (creating an optimal pH for enzyme activity) BUFFERING- maintiains a pH of 7.5-8.8 ○ Why is pancreatic lipase more effective in fat digestion than lingual or gastric lipase? ingual lipase- secreted by glands in the tongue, starts breaking down triglycerides in the mouth and L continues in the stomach. Pancreatic lipase- secreted by the pancreas - acts in the small intestine after chyme mixes with bile. Lingual and Gastric Lipase - limited by the large size of lipid drops and the short time available in the stomach. HOWEVER pancreatic lipase is more effective b/c bile salts emulsifying lipid drops into tiny enzymes. Micelles formation - lipase breaks down triglycerides into monoglycerides & fatty acids, which forms micelles with bile salts, facilitating absorption. ○ Where in the GI tract does most absorption of food occur? SMALL INTESTINE Which organs make enzymes that break down carbohydrates? ○ SALIVARY GLANDS PANCREAS INTESTINAL MUCOSA N ame the enzyme made by each organ. SALIVARY GLANDS -salivary amylase PANCREAS -pancreatic alpha-amylase, pancreatic lipase INTESTINAL MUCOSA -lactase, maltase, and sucrase By what general process do these enzymes work?HYDROLYSIS To be absorbed by the small intestine, carbohydrates must be broken down to MONOSACCHARIDES (absorbed via facilitate diffusion & cotransport) How are carbohydrates absorbed through the epithelial cell of the mucosa? Na+/GLUCOSE SYMPORTER Explain the importance of the Na/glucose symporter. Crucial for absorption of glucose into the epithelial cells of small intestine. Coupling the transport of glucose with Na+ ions, allows glucose to enter the cell against its concentration gradient. Does the Na*/ glucose symporter require ATP? INDIRECTLY Symporter reliwes on sodium gradient maintained by the Na+/K+ ATPase pump - which does use ATP Which organs make enzymes that break down proteins? ○ STOMACH PANCREAS SMALL INTESTINE Name the enzyme made by each organ. Stomach- Pepsin (secreted as pepsinogen) Pancreas- Trypsin (secreted as trypsinogen), Chymotrypsin (secreted as chymotrypsinogen), Carboxypeptidase (secreted as procarboxypeptidase), Elastase (secreted as proelastase) Small Intestine- Dipeptidases By what general process do these enzymes work? HYDROLYSIS Explain why protein-digesting enzymes are secreted as proenzymes (zymogens). To protect the secretory cells from being digested by their own enzymes. Explain how each of the proenzymes (zymogens) from the pancreas and stomach are activated. Note that each is activated differently. Pancreas ENTEROKINASE cleavesTRYPSINOGEN, activating it intoTRYPSIN TRYPSIN→CHYMOTRYPSIN, ELASTASE, & CARBOXYPEPTIDASES A & B Stomach PEPSINOGENis activated toPEPSINby the acidic environment in the stomach. In order to be absorbed, proteins must be broken down toAMINO ACIDS. Is an amino acid a protein?NO- its a building block of proteins. How are amino acids absorbed through the cell of the mucosa? FACILITATED DIFFUSION & COTRANSPORT MECHANISM Explain the importance of the Na/amino acid symporter (cotransporter). Essntial for transporting amino acids into cells against their concentration gradient using energy form sodium ion gradient. ○ Significant fat digestion begins in theDUODENUMwith pancreaticLIPASE. To be absorbed, fats must be broken down toMONOGLYCERIDESandFATTY ACIDS. What is a micelle?Small lipidbile salt complex formed when bile salts emulsify lipid droplets. How are fats absorbed through the cell of the mucosa? Emulsification Digestion Micelle formation Absorption & Resynthesis Chylmoicron formation Lacteal absorption & transport Include the significance of the lacteal and an explanation of chylomicrons. Lacteals essential for absorption of fats. Bypass liver, allows chylomicrons to directly enter the bloodstream. Transported to various tissues for energy storage or use. ○ How are vitamins, minerals, and water absorbed in the small intestine? ○ Vitamins & minerals - absorbed through active transport or facilitated diffusion. ○ Water - absorbed through osmosis gradient Name the fat-soluble vitamins and their functions. Vitamin K Vitamin A Vitamin D Vitamin E Name the water-soluble vitamins and their functions. Vitamin B1, 2, 6, 12 Vitamin C Folic acid Biotin ○ How does the small intestine manage to absorb 9 liters of water every day? How is water absorbed?Due to the osmotic gradient created by the absorption of nutrients. Nutrients are absorbed, water follows by osmosis, moving from the lumen of the intestine into the bloodstream. The villi and microvilli in the small intestine increase the SA for efficient water absorption. ○ Give some examples of minerals. Macrominerals - Ca2+, phosphorus, Mg2+, Na+, K+, Cl-, sulfur Microminerals - Iron, zinc, copper, iodine, selenium, fluoride, chromium, molybdenum How are they absorbed? Passive diffusion - iron and calcium Active transport - sodium and potassium Faciliated diffusion - magnesium ○ W here do amino acids and monosaccharides go once they are absorbed?transported to theLIVER via theHEPATIC PORTAL VEIN. Which important vein brings amino acids and monosaccharides to the liver? HEPATIC PORTAL VEIN What does the liver do with excess amino acids and glucose as they pass through? EXCESS AA -convert excess aa into glucose through gluconeogenesis or store as proteins EXCESS GLUCOSE -stored as glycogen or convert it into fats ○ Where do small fatty acid chains (water-soluble ones) go once they are absorbed in the small intestine? Directly absorbed into bloodstream and transported to the liver via hepatic portal vein Where do chylomicrons go once they are absorbed in the small intestine? To the LYMPHATIC SYSTEM (specifically the LACTEALS) → bloodstream via thoracic duct What is a chylomicron? Lipoprotein Transports dietary fats (triglycerides) from interests to other body parts Composed of triglyceride, cholesterol, phopholipids, and proteins ○ Name the anatomical valves that mark the beginning and end of the small intestine. BEGINNING OF SMALL INTESTINES- pyloric sphincter END OF SMALL INTESTINE- ileocecal valve ○ Why does the ileum need Peyer's patches? Peyer’s patches - are clusters of lymphatic nodules found in the ileum Crucial role in immue function by monitoring intestinal contects for pathogens and initiating an immune response. Are lymphatic nodules found elsewhere in the GI tract? YES - tonsils, appendix, throughout small intestine ○ Name all of the major anatomical parts of the large intestine. CECUM APPENDIX COLON Ascending Transverse Descending Sigmoid RECTUM ANUS What are haustra? Punches formed by the contraction of taeniae coli What are taeniae coli? 3 bands of longitudinal smooth muscle that run the length of the colon. They contract to form haustra. ○ What are two important functions of the fecal bacteria in the large intestine? Vitamin production Digestion of fiber ○ Name 4 components of feces. Undigested food matter Bacteria Water mucus ○ Contrast and compare these movements: Peristalsis- rhythmic contractions; propel food forward through digestive tract Segmentation- contractions that mix and churn food, increasing exposure to digestive enzyme Gastroilealreflex- reflex thatr increases peristalsis in the ileum, pushing chyme into the cecum. Mass peristalsis (mass movement)- strong, prolonged contractions that move a large amount of material through the colon Haustral churning- slow, segmenting contractions that mix contents. ○ Does the large intestine have a digestive function? No - not in chemical digestion. Bacteria in the colon ferment undigested carbs, producing short-chain fatty acids that can be absorbed and used for energy What is the purpose of the large intestine? Water absorption Electrolyte absorption Formation & storage of feces Bacterial fermentation ○ Explain how defecation occurs. Make sure to include the nerves as well as the internal and external anal sphincters in your response. FILING OF THE RECTUM -as feces piles up, stretch receptors in the rectal eall are activated DEFECATION REFLEX INVOLUNTARY PHASE- stretch receptors send signals to spinal cord initiating the defecation reflex. CONTRACTION OF REACTAL MUSCLES/ RELAXATION OF INTERNAL ANAL SPHINCTER VOLUNTARY PHASE- brain singals to you the need to defecate. Inhibit the reflex by contracting the external anal spincter. Faciliatet the reflec by reflaxing the external anal sphincter and contracting abdominal muscles to increase intra-abdominal pressure. EXPULSION OF FECES -external anal sphincter relaxes and abdominla muscles contract, feces is expelled throuhg the anus. Would a person still defecate if the spinal cord was completely severed at T12? LOSS OF VILUNTARY CONTROL- lose the ability to consciouslty control the external anal sphincter. INTACT INVOLUNTARY REFLEX- internal anal spincter and rectal muscles, controlled by the autonomic nervous system, would still function. METABOLISM (pg. 27) (50%) ○ In what form are most carbohydrates in the diet?Most carbs in the diet are in the form of POLYSACCHARIDES (ex. starches), and DISACCHARIES (ex. sucrose). Most absorption is done through MONOSACCHARIDES (ex. glucose) What is the major function of carbohydrates in the body?PRIMARY SOURCE OF ENERGY What is the general formula for a monosaccharide?(CH2O)n (n can be 3-7) Are there essential carbohydrates?NO; because the body can make glucose from other nutrients What does the liver do if large amounts of monosaccharides pass through the sinusoids?The liver stabilizes blood glucose levels by STORING EXCESS GLUCOSE AS GLYCOGEN (glycogenesis) or CONVERTING IT TO FAT. Which organ is especially dependent on a constant supply of glucose in the blood?BRAIN What hormone is needed to move glucose into many body cells?INSULIN By what process does glucose move into body cells?FACILIATED DIFFUSIOn Does that process require ATP?NO Why is glucose phosphorylated once it gets into a cell?Glucose is phosphorylated to glucose-6-phosphate to PREVENT IT from leaving the cell and to prepare it METABOLISM. ○ Write the reactants and products for the following reactions: Glycogenesis(formation of Glycogen) Glucose + UTP → Glycogen + UDP + P Glycogenolysis(breakdown of Glycogen) Glycogen + Pi → Glucose-1-phosphate + Glycogen (with one less glucose unit) Glycolysis(breakdown of Glucose) Glucose + 2 ATP + 2NAD+ → 2 Pyruvate + 2ATP + 2NADH ○ Under anaerobic conditions, glucose is converted to lactic acid. Write the overall reaction below. Glycolysis(breakdown of Glucose) Glucose + 2 ATP + 2NAD+ → 2 Pyruvate + 2ATP + 2NADH Lactic Acid Formation 2 Pyruvate → lactic acid (C3H6O3) NADH is oxidized back to NADH+, which is necessary for glycolysis to continue Overll RXN Glucose + 2ADP → 2 C3H6O3 + 2ATP ○ Under aerobic conditions, glucose is converted to water and carbon dioxide. Write the overall reaction for cellular respiration below. Glucose + 6 O2 → 6 CO2 + 6 H2O Cellular respiration occurs in four major steps. Write the name of each step, the reactants and products of each step, as well as where the step occurs in the cell: GLYCOLYSIS ○ Reactants:Glucose, 2 ATP, 2 NAD+, 4 ADP, 4 Pi ○ Products:2 Pyruvate, 2 NADH, 4 ATP ○ Location:Cytosol PYRUVATE OXIDATION ○ Reactants:2 Pyruvate, 2 CoA, 2NAD+ ○ Products:2 acetyl-CoA, 2 CO2, 2 NADH ○ Location:Mitochondrial Matrix KREB CYCLE (TCA Cycle) ○ Reactants:2 acetyl-CoA, 6 NAD+, 2 FAD, 2 ADP, 2 Pi ○ Products:2 ATP, 2 FADH2, 4 CO2, 6 NADH ○ Location:Mitochondrial Matrix ELECTRON TRANSPORT CHAIN ○ Reactants:10 NADH, 2 FADH2, O2, ADP, Pi ○ Products:38 ATP, H2O 2 ATP (net) in glycolysis 2 ATP in kreb cycle 34 ATP in electron transport chain ○ Location: Inner Mitochondrial Membrane Which of these steps is/ are irreversible? GLYCOLYSIS KREB CYCLE (TCA Cycle) ○ What are the general characteristics of enzymes? Name at least four. Speeds up rxn Sensitive to changes in pH and temperature Specifity (lock and key) Reusable How does a coenzyme differ from an enzyme? Conenzymesare nonprotein organic molecules that function as cofactors, aiding enzymes in catalysis. Enzyme- proteins that catalyze biochemical rxn Name 3 coenzymes and the vitamin from which each coenzyme is derived. Also, give the function of each coenzyme in metabolism: NAD+ (derived from Vitamin B3) - electron carrier in redox rxn FAD (derived from Vitamin B2) - electron carrier, involved in the TCA cycle and ETC Coenzyme A (derived from Vitmamin B5) - essential for the synthesis and oxidation of fatty acids in the Krebs Cycle What does it mean to say a compound is oxidized?Oxidation is the LOSS of electrons, hydorgens, or ○ gain of oxygen. REsults in a decrease in potential energy. Is glucose oxidized or reduced during cellular respiration? Glucose (C6H12O6) is oxidized to carbon dioxide (CO2) If one compound is oxidized, is another always reduced? REDOX reactions; always paired. When one compound is oxidized, another one is reduced. Name a compound that is reduced during cellular respiration. NAD+ FAD Oxygen Comparing the structures of pyruvic acid and lactic acid, which is oxidized? P yruvate is REDUCED to lactate when oxygen is lacking, While NADH is OXIDIZED to NAD+. P yruvic Acid (Pyruvate): CH3—CO—COO− Lactic Acid (Lactate): CH3—CHOH—COO− ○ Explain how ATP is generated in the electron transport chain. The electron transport chain (ETC) is a series of protein complexes embedded in the inner mitochondrial membrane. Electrons, carried by NADH and FADH2 from the citric acid cycle, are passed along a chain of electron carriers. As electrons move down the chain, they release energy, which is used to pump protons (H+) from the mitochondrial matrix to the intermembrane space. This creates a proton gradient. Explain the general role of oxygen and the electron carriers. Oxygen - final electron acceptor in ETC lectron carriers - facilitate the transfer of electron and pumpoing of protons. E Explain (in general terms) the process of chemiosmosis. The process by which ATP is synthesize using energy stored in the proton gradient. Protons flow back into the mitochondrial matrix throuhg a protein channel called ATP synthase. This flow of protons power the rotation of ATP synthase, which phosphorylates ADP to form ATP. Why is the formation of ATP called oxidative phosphorylation? The process of generating ATP by utilizng the energy releases from oxidation of molecules (like glucose) to phosphorylate ADP. ○ Write out the reaction for the formation of ATP from ADP. ADP + Pi + energy → ATP + H2O Diagram the general structure of an amino acid and explain how its composition differs from a ○ monosaccharide.Monosaccharides are carbohydrates composed of C, H, and O atoms. Amino acids have a linear structure with a central carbon atom. What is deamination? Removal of an amino group (-NH2) from an amino acid. Why does deamination occur in the metabolism of amino acids? If the body needs energy and there are no carbs present, the body will turn to amino acids. What does the liver do with the NH2 (amine) group? Liver converts the amine group into urea, which is less toxic. Urea is then excreted in urine. Are there essential amino acids? Yes there are 9 essential amino acids What happens if a non-essential amino acid is missing from the diet? The body can usually synthesize it from other compounds. Name a structural protein, a protein hormone, and several protein enzymes. Structural - collagen Hormone - insulin Enzymes - amylase, pepsin, trypsin Making glucose from amino acids occurs by the general process calledGLUCONEOGENSIS. ○ What is the difference between the fats listed below? saturated fat- single bonds btw carbon atoms unsaturated fat- double bonds between carbon atoms trans fat- unsaturated fats What are HDL and LDL? HDL (high density lipoproten)- removes excress cholesterol from blood stream. Primarily made in small liver. Aka “good cholesterol” LDL (low density lipoprotein)- high levels can contribute to heart disease. Primarily made in liver. Aka “bad cholesterol” Where is each made and what is the significance of each lipoprotein? HDL (high density lipoproten)- made in the liver & small intestine Aka “good cholesterol” LDL (low density lipoprotein)- made in the liver Aka “bad cholesterol” Write out the general reaction for beta-oxidation. Fatty acid + CoA + NAD+ + FAD → Aceytl-CoA + NADH + FADH2 + H+ Is beta-oxidation reversible? NO - its IRREVERSIBLE When does beta-oxidation occur? ccurs in the mitochondria when the body needs energy from fatty acids. O What are ketones and why do they form when fats are broken down for ATP? Ketones - acid compounds by prouduct of when the body breaksdown fatty acids Build up in the bloodstream People are prolonded fasting People who diabetes Leads toKETOACIDOSIS Can the body make glucose from fatty acids? Why or why not? NO - not directly b/c of irreversible nature of beta-oxidation Can the body make glucose from glycerol? Why or why not? GLUCONEOGENESIS What is glycerol? Glycerol is a three-carbon alcohol that is a component of truglycerides Describe each of the following processes: ○ Deamination- removal of an amino group from an amino acid Gluconeogenesis- synthesis of glucose from non-carb sources like amino acids and glycerol Glycolysis- breakdown of glucose into pyruvate Glycogenolysis- breakdown of glycogen into glucose Ketogenesis- formation of ketone bodies from fatty acids Glycogenesis- synthesis of glycogen from glucose Beta-oxidation- breakdwon of fatty acids into acetyl-CoA Lipogenesis- synthesis of fatty acids Decarboxylation- removal of carboxyl group from a molecule Phosphorylation- addition of a phophate grou to a molecule CARBOHYDRATES, FATS, & PROTEINS (pg. 47) ○ How many ATP and NADH or FADH, are formed during the following: Glycolysis ATP -2 NADH -2 conversion of glucose to lactic acid ATP -2 NADH -0 (NADH is used up) formation of acetyl CoA ATP -0 NADH -2 Krebs cycle ATP - 2 NADH - 6 FADH -2 electron transport chain ATP - 28 - 32 (depends on efficiency of the cell) ○ Approximately how much ATP would be formed from 6 NADH and 5 FADH, entering the electron transport chain? 18 ATP from 6 NADH 10 ATP from 5 FADH ○ Name two conditions when ketosis occurs and why it occurs. POSTABSORPTIVE STATE of METABOLISM- body replies on stored nutrients for energy PROLONGED STARVATION- increased production of ketone bodies to provide energy, as gluclose levels are insufficient. Why does ketosis sometimes lead to ketoacidosis? Excessive Ketone Bodies- increased production of ketone bodies to provide energy, as gluclose levels are insufficient. This can exceed then buffering capacity of the blood, leading to a dangerous drop in pH. Acidification of Blood- high levels of ketone bodies lower blood pH, casuing ketoacidosis. This condition can disrupt tissue function and lead to sever health issues like coma or cardiac arrhythmias. ○ What is meant by the term, basal metabolic rate? Basal metabolic rate (BMR)- rate at which your body expands energy while at rest to maintain vital functions like breathing, circulation, and maintaining body temperature. How is it measured?1 kcal per hour for each kilogram of body weight What hormone plays a major role in the regulation of metabolic rate?THYROXINE ○ Name several metabolic processes that occur in the absorptive state. NUTRIENT ABSORPTION GLUCOSE UTILIZATION PROTEIN SYNTHESIS FAT STORAGE How long does the absorptive state typically last? Typical last 4 hours after a meal Focuses on nutrient absorption and stroage Name several metabolic processes that occur in the postabsorptive state. GLYCOGENOLYSIS GLUCONEOGENESIS LIPID CATABOLISM PROTEIN CATABOLISM What is the body's chief concern during the postabsorptive state? Maintaining blood gluclose levels to meet the needs of the NERVOUS TISSUE. Which part of the brain regulates body temperature?HYPOTHALAMUS(pre-optic area) ○ Give examples of how the body releases heat through radiation, conduction, convection, and evaporation. Radiation- warmth of sun, losing body heat to the environment Conduction- sit on cold chair Convection- heat lost through air; when the aire warms up and rises, carrying heat away from your skin. Evaporation- sweat evaporates from the body. In order to release heat, blood vessels in the skin willDILATE, alowing more warm blood to flow to the surface of the boady, where heat can be lost through radiation, convection, and evaporatinon.
