Exam One Notes
Exam One Notes AN_SCI 3254 - 01
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Date Created: 09/12/15
Exam 1 Notes PART ONE Intro I Physiology is a study of function a Involves many different systems working together b Combination of interaction and integration II There are xed uctuations and regular irregularities a This is because a living organism is in a constant state of dynamic change b Organization remains over time c A living organism has selfsustaining organization or homeostasis III Homeostasis is the most important concept in physiology a Milieu int rieur internal world that remains constant b Walter B Cannon i Father of modern physiology ii Came up with homeostasis IV Claude Bernard father of physiology How to maintain a constant state I 2 important concepts a Rates net gain and net loss i Essential for total body balance b Pool depends on exchanges within the body II Example Cholesterol exchange a Gain i Diet 03 gday from animal fat egg yolk etc ii Synthesis 10 gday by liver adrenals skin etc b Exchange i Stored cells of arteries ii Incorporated into steroid hormones etc c Loss i Breakdown and excretion of bile in feces d Diabetes mellitus bile duct obstruction produces and increase in plasma cholesterol III There are 3 possible states a Loss greater than gain negative balance i Ex Losing heat faster than gain hypothermic b Loss less than gain positive balance i Ex Taking in more calories than losing c Gain equals loss stable state homeostasis Energy Transfer I Energy the capacity to do work a Whenever there is a change in the system energy is transferred II Laws of Thermodynamics a First Law of Thermodynamics also called Law of Conservation of Energy i Energy is neither created nor destroyed only transferred b Second Law of Thermodynamics i All order moves towards disorder ii With any energy conversion there is a decrease in usable energy III Forms of Energy a Types i Light ii Chemical iii Mechanical iv Electrical v Heat most disordered form vi Atomic b What can living animals take in and use i Chemical energy c What can be used for energy transfer within the body i Electrical energy d What can be converted to other forms of energy within the body i Chemical energy e Cells cannot use heat alone for work or convert it to another form f All chemical conversions have heat as the nal product g Any energy conversion decreases usable energy h Forms of energy out ow from body i Chemical ii Heat iii Work Energy Transfer within Cells VI Glucose a 1 mole glucose 02 gt C02 H20 686 kcal released energy b Glucose burned in test tube all is released as heat c Glucose burned in cell some released as heat some captured as ATP Calorie heat required to raise 1g of water 1 C ATP a Energy release is coupled to energy carrier molecules i The primary energy carrying molecule is ATP or adenosine triphosphate b Parts of ATP i Adenine nucleotide base ii Ribose 5carbon sugar iii 3 phosphates c 7 kcal are released or transferred with each phosphate i The addition or removal of phosphate is key in energy transfer d ATP H20 ltgt ADP Pi 7 kcal e The ATP molecule only exists for seconds and is not used for storage only transfer Ef ciency of the Process a In animals it is very ef cient i 55 energy from glucose goes to ATP ii 45 energy from glucose goes to heat b Another example is a car burning gas which is inef cient i 25 energy used for car movement ii 75 energy goes to heat c Why the difference i It is related to the oxidation process or the breakdown in presence of oxygen ii Burning glucose in air yields C02 H20 heat light iii Burning glucose in body yields C02 H20 heat in 2030 intermediate steps iv Differences Slower process Requires enzymes catalysts Lower temperature ATP generated to capture energy PWN Mitochondria a Most aerobic energy transfers in the cell take place in specialized organelles called mitochondria b Cristae folds in mitochondria is the site of enzymes that catalyze oxidative reactions The number of mitochondria vary with energy expenditure of cell Cells using large amounts of ATP cardiac amp skeletal muscle cells have large amounts of mitochondria ex Brown fat i Brown fat a special type of fat found in newborns that has a lot of blood and mitochondria Most is lost during aging e The primary function of mitochondria is to couple ATP production with energy release f ATP production occurs at the mitochondria level i 95 of ATP produced from glucose occurs at this level ii 100 of ATP produced from breakdown of fatty acids occurs at the level of mitochondria Oxidative Phosphorylation a The attachment of phosphate to ADP in the presence of oxygen b Steps i Nutrient breakdown produces hydrogen atoms ii Hydrogen atoms are converted to hydrogen ions and this causes the release of electrons an VII iii The electron transport chain is found along the inner membrane of mitochondria iv Energy is transferred through cytochromes electron acceptors that change color 1 They are iron containing proteins v Hydrogen ions are eventually donated to 02 to produce metabolic H20 1 Some desert animals rely on this vi The electron transfer releases energy that is ef ciently coupled to ATP synthesis c Numbers i 7 kcal are required to yield ATP from ADP and phosphate ii 3 ATP are produced per pair of hydrogen atoms iii 2 hydrogen ions 12 02 produces H20 metabolic water d The absence of 02 results in less ATP and leads to cell death e Cyanide action on the nal cytochrome of the chain results in no electron transport and no ATP f The absence of a gradient leads to death g 99 of the oxygen used by the cell is used to produce ATP h The universal factor in all death is loss of oxygen at cell or tissue level Discovering the Electron Transport Chain a Heinrich Wieland 18771957 i Studied toadstool poisons ii Received the 1927 Nobel Prize for the structure of steroids iii Thought that cells tore of hydrogen from food then combined with oxygen to produce water b Otto Warburg 18831970 i Received the 1932 Nobel Prize ii Thought respiration occurred because an ironcontaining machine in the cell membrane binds to oxygen then oxygen takes electrons from iron amp iron takes electrons from food iii In 1913 Warburg discovered both cyanide and oxygen bind to iron c David Keilin i Used moths to discover cytochromes cell color ii In the 1960 s he discovered electron electricity generates proton H electricity d Fritz Lipmann 18991986 i Received the Nobel Prize in 1953 for discovering the ATP cycle e John Walker amp Paul Boyer i Received the Nobel Prize in 1997 for discovering the ATP motor 1 Smallest in the world and driven by proton electricity 2 Actually spins with shaft in mitochondrial membrane 3 Forces phosphate onto ADP Body Electricity Electricity a physical phenomenon associated with stationary or moving electrons or protons All the electricity is miniaturized a Electric charges separated by only thickness of membrane 5 nanometers less than 1millionth width of a ngernail b Voltages too small to get a shock 01 volt home voltage 120250 i But 01 volts across 5 nanometers is an electric eld with 20 million voltsmeter Luigi Galvani 1700 s a Used lightening to perform an experiment with frog muscles discovering electricity plays a part in muscle movement PART TWO CELL STRUCTURE AND FUNCTION Cell Compostion Water 85 Protein 10 a Gives structure Lipid 2 IV V a Stores energy Carbohydrate 15 a Energy that we use Inorganic matter 15 Cell Membrane Structure a Semipermeable dynamic uid structure Composition a Protein i Glycoprotein ii Lipoprotein b Lipid i Phospholipid c Made up of doublelayered lipid molecules with embedded protein in a thin lm i Hydrophobic nonpolar tails ii Hydrophilic polar head d The lipid layer prevents most polar ionized molecules from passing through the membrane i Ex Sodium and potassium ions e It is permeable to fatsoluble substances i Ex 02 C02alcohol fatty acids f Water is not lipid soluble and is polar but passes across because it is small enough i Also has kinetic energy ii In addition there are water channels or pores 1 Aquaporin g Glucose is carried across membranes via carrier or transport proteins h No chemical bonds link the phospholipids allowing there to be free movement Some Vocab IV V Oxidative stress a Large connection with oxidative phosphorylation b Oxidizing agent or oxidant is an element or compound that accepts an electron from another element or compound Because it gains electrons electron acceptor it is said to have been reduced The element or compound that had its electrons taken away has been oxidized Free radical a Atom or group of atoms that has at least one unpaired electron and is therefore unstable and highly reactive i In animal tissues free radicals can damage cells and are believed to accelerate cancer cardiac diseases and agerelated diseases b Metabolic activity and environmental factors damage DNA in humans Antioxidants a Terminate free radical chain reactions by removing free radical intermediates and inhibit other oxidation reactions i They do this by being oxidized themselves Oxidation a Chemical reaction that transfers electrons of hydrogen from a substance to a receiver Coenzyme a Enhances the action of an enzyme Membrane Proteins IV V Structural Pumps a Use active transport to move ions across membrane Channels a Pathways for water and watersoluble compounds Receptors a Bind with neurotransmittershormones Enzymes a Catalyze reactions Protein Information l Manufacturing protein is the most energy expensive process in the body a At rest 15th of energy is used to produce protein b During growth 12 of energy is used for producing protein ll 70 of the cell volume is water the 4080 of the remaining space is taken up by proteins lll 1000020000 different types of protein in a cell IV 100000 genes in the human genome have about 100000 different proteins V Over the last 100 years we have determined what 1 of proteins do Transport Mechanisms l Passive Transport a Diffusion of gas or ions from a region of high concentration to low concentration OR from high molecular motion to low molecular motion i Outcome is an equal concentration throughout the medium b Determinants of diffusion rate i Membrane permeability 1 Increase in permeability increases diffusion rate ii Concentration gradient 1 The greater the gradient the faster the diffusion rate iii Electrical charge difference 1 Large charge difference increases diffusion rate iv Kinetic energy or pressure difference 1 The greater the energy or pressure the faster the diffusion rate v Surface area 1 Greater surface area causes faster diffusion vi Molecular weight 1 The larger the weight the more the diffusion rate decreases c Osmosis the movement of solvent usually water to a region of a higher concentrated solute which cannot cross the membrane i This ow is altered by pressure on the solution d Osmotic pressure pressure needed on one side to prevent osmotic ow of water across from a compartment of pure water i Characteristics of solutions with higher osmotic pressure 1 Greater number of particles 2 Lower water concentration 3 Greater osmotic ow water to solution 4 Greater pressure needed to prevent osmotic ow ii Osmotic pressure doesn t really exist in nature It is only an index of the water absorbing power of a solution and is a way to rank solutions iii Types of pressure 1 lsosmotic same osmotic pressure 2 Hyperosmotic solution that has more particles 3 Hyposmotic solution that has fewer particles iv Tonic effective osmotic pressure of a solution relative to blood plasma 1 09 NaCl solution is isotonic isosmotic with blood plasma 2 06 NaCl solution is hypotonic lower osmotic pressure than blood plasma v Example red blood cell 1 A red blood cell in distilled water hypotonic solution will rst swell and then will burst lyse a To start the blood cell is isotonic It is hypertonic compared to distilled water The second before it bursts it is hypotonic 2 A red blood cell in 15 NaCl solution hypertonic solution shrinks crenation a To start the blood cell is isotonic It is hypotonic compared to the solution and is hypertonic after it shrinks ll Active Transport a Movement uphill against concentration electrical or pressure gradients i Energy is needed usually from the breakdown of ATP b Sodiumpotassium pump i Moves 3 Na out of cell and 2 K into cell for each molecule of ATP hydrolyzed ii 1040 of the total energy used by the cell is to transport Na amp K ions across membranes c Other substances transported by active mechanisms i Calcium ii Hydrogen iii Amino acids iv Glucose III Large scale movement of substances between cells a Endocytosis i Plasma membrane engulfs solid or liquid matter ii 2 types 1 Phagocytosis intake of large particulate matter or organisms into cell a Macrophages a type of specialized phagocytic cells found in walls of blood vessels and loose connective tissue i Contain lysosomes singlemembrane sacs within cell with digestive enzymes proteolytic and lipolytic ii Stress increases corticosteroid release from adrenals This suppresses macrophage function to produce respiratory disease 2 Pinocytosis intake of minute particles such as solutes and uids a This is the major means for protein passage into cells b Young animals take in whole proteins adult animals take in amino acids b Exocytosis i Vesicle fuses with plasma membrane and releases contents into extracellular uid 1 Ex Intestinal goblet cell secretes mucus lntercellular Connections I Two activities a Fasten cells together b Allow passage between cells II Types a Desmosome i Dense matter between cells and into cytoplasm ii Rivetlike iii Found in areas of stretchy skin and cardiac muscle b Tight junctions i Occurs around entire cell ii A connection that regulates substance movement iii Found in hollow organs or tubes ex Intestine iv Require special mechanisms for transport c Gap junctions i Protein channels that directly link the cytoplasm of cells together ii It is a low resistance pathway to conduct ions and electrical activity iii Pathway for sodium and potassium ion movement 1 Also sugars and amino acids iv Allows synchrony coordination of electrical and mechanical activity v Found in involuntary muscle bers cardiac and smooth muscle PART THREE ENERGY METABOLISM ATP Production I Oxidative phosphorylation a ADP phosphate energy ATP b Tricarboxylic Acid Cycle TCA Krebs Cycle Citric Acid Cycle c This is the major energyreleasing pathway in the body d Mitochondria contain all enzymes and coenzymes for TCA and oxidative phosphorylation II Glycolysis a 1 glucose goes through the process of glycolysis to form 2 pyruvic acids 2 ATP heat b This is an anaerobic process c Does not need mitochondria i Red blood cells don t have mitochondria and rely on glycolysis Ill The aerobic process begins when pyruvic acid enters the mitochondria IV For each molecule of glucose a 2 ATP formed through the Citric Acid Cycle Kreb s Cycle b 34 ATP formed though oxidative phosphorylation c 2 ATP formed through glycolysis d 38 ATP total V In the absence of oxygen there is only anaerobic glycolysis a 2 ATP pyruvate pyruvic acid lactate lactic acid b Only uses 2 of energy to produce ATP compared to 44 under aerobic conditions c Lactate produced in muscle cells during muscular activity is reconverted in liver into glycogen and made available as a source of energy Cori Cycle Vl We can break down fat to glycerol to generate glucose but we cannot use fatty acids to generate glucose lll l I l l MIMTWE l m ddimn Wealay Lnngnnam inc VII The Cori Cycle Takes place in the liver and muscle Glucose is stored as glycogen Anaerobic Refers to the metabolic pathway in which lactate produced by anaerobic glycolysis in the muscles moves to the liver and is converted to glucose which then returns to the muscles and is metabolized back to lactate 90pm The Cori Cycle 2 ATP 6 ATP 2 Pyruvate 2 Pyruvate 2 Lactate 2 Lactate Liver Muscle VIII Major metabolic fuels a Includes glucose amino acids fatty acids b Metabolic fuels enter immediate paths to produce reduced coenzymes for ATP synthesis c Major processing occurs in the liver i Hepatic portal vein passes from digestive organs and spleen to the liver ii Amino acids carbohydrates and shortchain fatty acids are transported by the hepatic vein iii A major portion of absorbed fat from the intestines enters the lymphatic vessels Liver Functions I Bile secretion II Regulation of carbohydrate and fat metabolism III Synthesis and degradation of proteins and formation or urea and uric acid IV Regulation of hormonal balance a Degrades numerous hormones V Detoxi cation of certain metabolic products VI Blood reserve for up to 25 of liver weight VII Regulation of water balance by generating proteins which contribute to osmotic pressure Glucose I Glucose is the basic metabolic fuel a Preferred fuel consumed by the central nervous system II Nonruminants have direct intake of glucose III Ruminants must rely on glyconeogenesis for glucose a Glyconeogenesis producing glucose from a noncarb source Carbohydrate Metabolism I There are two phases absorptive and nonabsorptive II This differs for ruminants and nonruminants a In nonruminants dietary carbohydrates are broken down to monosaccharides that enter portal circulation for transport to the liver b During the absorptive phase the liver is the major uptake site i There it is processed for storage ii Glucose in the liver 1 Stored as glycogen glycogenesis 2 Produces glycerophosphate for synthesis of lipids Ill Glycerol 3 fatty acids triglyceride triacylglycerol a Triglycerides serve as an important form of energy storage IV Hydrolyzed gt acetylCoA gt fatty acids gt lipids a Instead of going through the TCA cycle excess glucose is converted to fatty acids and lipids b This happens when too much food is eaten V Ruminants do not produce much acetylCoA from ingested glucose a Why Bacteria in the rumen get to it rst b Glucose is scarce in ruminants they must rely on volatile fatty acids produced by microbes i Fatty acids acetate butyrate proprionate c Anaerobic waste is absorbed from the gut VI Volatile fatty acids a Propionate most important glucose precursor in ruminants VII VIII X i Enters at succinyl CoA ii Exits at oxaloacetate for gluconeogenesis iii Does not enter the entire TCA cycle iv From the rumen portal blood goes to the liver for gluconeogenesis and never enters the systemic circulation b Acetate and Butyrate i Go to fatty acid synthesis ketogenesis and TCA cycle Source of glucose a Glycerol triglyceride hydrolyse b Lactate enters the Cori cycle c Selected amino acids alanine glutamate d Propionate Glycogen storage a Location i Liver never exceeds 10 of liver weight ii Skeletal muscle largest tissue mass of the body b Glycogen is the only direct form of glucose storage Liver glycogen produces glucose for the rest of the body Muscle glycogen does not yield glucose but produces substrates pyruvate and lactate for hepatic gluconeogenesis i Can t produce glucose but can release ATP from glycogen 1 Pyruvate and lactate in the muscle can be used by muscle to produce ATP an Glycolysis a The breakdown of glucose to produce ATP b De ning characteristics i Reversible ii Occurs in all cells especially RBC s no mitochondria iii Anaerobic Glucose can also be used for direct synthesis of fatty acids a Liver and adipose tissue b Occurs during absorptive phase when there is abundant acetyl CoA and TCA activity Protein Metabolism Absorptive Phase Fuel Building block a Most amino acids transformed into glucose by liver gluconeogenesis b Protein 75 body solids c Fatty acid production Most amino acids go to liver via hepatic portal circulation a A large amount is removed on the rst pass through the liver b Approximately 75 leaves liver and goes on to other tissues In liver a Amino acids are deaminated to produce keto acids which i Enter carbohydrate paths for energy release ketogenic ii Gluconeogenesis protein synthesis glucogenic iii Fatty acid synthesis b Keto acids are what we get from the breakdown of amino acids in the liver c The amino group is removed and converted to urea n ruminants a Glucose peptides gt VFA NH3 CH4 C02 i Glucose and peptides are broken down by microbes in the rumen to form volatile fatty acids ammonia methane and carbon dioxide b Propionate is the primary glucose source c Amino acids enter the liver where they are either excreted as urea or are converted to keto acids which are used for energy fatty acids or glucose d Alanine amino acid produces pyruvate keto acid e True carnivores cats minks eat a high protein low carbohydrate diet Fat Metabolism Fat is the major form of stored energy a Energy is stored as triglycerides in adipose tissue i A triglyceride is composed of 3 fatty acid molecules and 1 glycerol molecule ii This is the ideal form of energy storage because 1 They are highly reduced molecules with little oxygen compared to carbon and hydrogen a Concentrated energy source b Twice the caloric value of amino acids and carbohydrates 2 They contain little water a Undiluted by bulky water they can carry more energy Fats are not watersoluble and must have special transport to the blood and lymph a Chylomicrons these are formed in the cells lining the gut and are used to transport fat i Composed of triglyceride phospholipid cholesterol minor dietary lipids proteins on surface ii They are spheres with hydrophobic ends core and hydrophilic ends surface 1 Therefore it is watersoluble iii Enters the blood via lymphatics thoracic duct into vena cava b Fatty acids in the liver are also insoluble in blood i They form a VLDL very light density lipoprotein 1 It is made up of triglycerides phospholipids cholesterol proteins a The protein is on the outside so the fat can be dissolved 2 VLDL are smaller than chylomicrons but similar in structure and function After a fatty meal blood is a milky white color a This is called lipemia and is gone 12 hours after digestion The inner surface capillaries of adipose tissue contain the lipoprotein lipase a This is an enzyme that breaks down proteins and lipids b Lipase hydrolyzes triglycerides to form fatty acids or glycerol i The fatty acids enter the adipocyte to form a new triglyceride molecule ii This then combines with existing fat microdroplets to form a larger droplet Ruminants are different a Glucose is used to produce the glycerol backbone but not for fatty acid synthesis as it is conserved b Instead the fatty acids are derived from acetate a VFA and ketone bodies acetone acetoacetate Bhydroxybutyrate i Ketone bodies are not the same as keto acids 1 Ketone bodies come from fat 2 Keto acids come from amino acids c Fatty acids are only produced in adipose tissue and not in the liver as in nonruminants d In the ruminants almost no digestible carbohydrate goes to the intestine for digestion and absorption as glucose i Ruminants are in a constant state of potential glucose de ciency 1 During peak lactation glucose is needed for lactose milk sugar 2 Dairy cows may get lactational ketosis a Ketosis having a lot of ketone bodies Postabsorption IV V VI Lipids This is primarily nonruminants as this occurs several hours after a meal and ruminants are always ruminating The amount of glucose and amino acids entering the cell is decreased Glycogenolysis begins when glucose is mobilized primarily from liver glycogen a Glycogenolysis the breaking down of glycogen Protein breakdown maintains the amino acid pool and supplies energy to the cell The breakdown of amino acids produces ammonia which is detoxi ed in the liver to produce urea a The liver handles urea formation and glucose synthesis Ruminant a The urea enters the blood and mixes with saliva before moving into the GI tract b Microbes convert urea to ammonia and carbon dioxide c Ammonia is then utilized to synthesize new amino acids that are absorbed and utilized The hydrolysis of stored fat produces glycerol and fatty acids a Hormonesensitive lipases hydrolyze the fats and get it back into blood b This is stimulated by i Growth hormone ii Thyroxine growth and development hormone iii Glucagon causes glucose to release energy iv Cortisol stress hormone c The released fatty acids that are released are bound to albumin in blood II Problem Fatty acids cannot be converted to glucose via gluconeogenesis a Fatty acids do enter mitochondria of the liver muscles and other tissues III Boxidation produces acetyl CoA that enters the TCA cycle for energy release a Excess acetyl CoA is converted into ketone bodies acetone acetoacetate B hydroxybutyrate i Ketone bodies are fatderived watersoluble metabolites b Ketone bodies can leave the mitochondria for other tissues i They are formed in the liver in nonruminants and ruminants and can act as a glucose substitute 1 BUT they cannot be used by the liver for energy ii Ketone bodies are preferred by cardiac muscle over glucose iii Ketone bodies are able to cross the bloodbrain barrier to provide a large portion of energy to the CNS during prolonged starvation 1 Some glucose is still needed IV Ruminants a Produce Bhydroxybutyrate ketone body as an additional energy source i This is produced in the rumen Ketones I If all the ketones are not oxidized they accumulate in the blood to result in ketosis II Metabolic acidosis if the ketones are not buffered it can result in death a Causes of this condition i Starvation ii High fat low carbohydrate diet 1 No conversion of fat to carbohydrate iii Diabetes mellitus especially in dogs 1 Lack of insulin high blood glucose What Happens During Starvation I Glucose is the preferred energy source a But the total supply is used up in a few hours II Glycogen in the liver and skeletal muscles is converted to glucose in the liver and is released to the tissue a Hepatic glycogen release of glucose is limited i 612 hours for a human with low exertion ii 20 minutes under heavy exertion III Gluconeogenesis a Pyruvate and other intermediates of the TCA cycle are generated by the deamination of amino acids IV Fat is converted to fatty acids then ketones a This is what happens during dieting V Protein breakdown during nal stage a Body weakens and eventually death occurs PART FOUR DIGESTIVE SYSTEM Functions of the Digestive System I Ingestion II Grinding food III Digestion IV Absorption of food V Elimination of waste Mouth I Function grinding food and mixing with saliva to increase surface area II Mastication decreases food particle size and mixes with saliva III Remastication important in ruminants which take in large amounts of food over a short pedod IV Bolus food from mouth V Chyne food from stomach Vl Saliva a Salivary glands i Parotid below and front of ear 1 Stimulated saliva ii Submandibular underjaw 1 Unstimulated saliva iii Sublingual under tongue 1 Mainly mucus b Ruminants have a fourth in their inferior molar Saliva pH 70 Functions i Lubricant ii Dissolves some food iii Taste iv Neutralize pH e Composition of saliva i Water 9899 ii Mucus holds food together in bolus for swallowing iii Salivary amylase ptyalin starch splitting to glucose 1 Occurs in humans horses swine and dogs 2 This is the start of carbohydrate digestion Amylase is destroyed in the stomach environment but up to 50 starch digestion begins in the mouth a Most carbohydrate digestion is in the small intestine 3 This makes food taste sweet and more interesting 4 Not important in ruminants as there is little amylase in them iv Sodium bicarbonate phosphate buffers food to reduce acidity and keep teeth intact 1 Ruminants produce large amounts of saliva equal to extracellular uid volume per day 2 Must absorb water and electrolytes f Humans have two kinds of saliva i Stimulated parotid 1 Comes mainly from the parotid gland 2 7090 of the 23 pints of saliva generated daily 3 Primary function dilute acidity ii Unstimulatedsubmandibular 1 Has laments due to mucins longchained amino acids in webs that produce saliva s viscosity elasticity and stickiness a This yields a protective lm for teeth and also traps bacteria which are swallowed and destroyed in stomach 2 Has antimicrobial properties that are superior to mouthwash histatins which speed wound closure and some components that make viruses ineffective an Vll Tooth decay a Anything below pH 4 will dissolve calcium phosphate which is a key component of tooth enamel Anything acidlike produces instant saliva from parotid b Sugar contributes to tooth decay because bacteria in the mouth digest sugar Waste products metabolites from the bacteria are highly acidic and destroy enamel Not directly due to sugar Vlll Newborn saliva a They lack teeth to keep saliva in the mouth b They have a high fat 100 whole milk diet Newborn saliva has lipase that breaks down fat Adults get lipase mainly from pancreas since salivary lipase decreases once the baby s diet changes lX Laundry detergent a High end detergents contain i Amylase to break down starch stains ii Protease for protein iii Lipase for grease stains Swallowing or Deglutition Stomach I Swallowing is accomplished through use of a peristaltic wave or a moving ring of contraction Swallowing starts in the pharynx and propels food into the esophagus a Pharynx common passage for air and food b Epiglottis prevents food from entering trachea c Esophagus muscular tube that passes through the thoracic cavity and diaphragm into the stomach The esophagus has two parts a Upper region skeletal muscle under voluntary control b Lower region smooth muscle under involuntary control Gastroesophageal sphincter a Physiological barrier between esophagus and stomach Anatomically the lower gastroesophageal sphincter is not different than the rest of the esophagus but it is physiologically very different c Caves in or closes because of a difference in pressure i Subatmospheric pressure in thoracic cavity 5 to 10 mmHg ii Abdominal pressure due to compression of contents 5 to 10 mmHg If there was no sphincter re ux would get into the esophagus e In the last 5 months of pregnancy there is a displaced terminal segment into the thoracic cavity causing acid re ux f During heartburn stomach contents HCI goes into the esophagus and causes contractile spasms of smooth muscle g Newborns have no intrabdominal segment and may have regurgitation Vomiting a Very complex coordinated re ex by the vomit center in the medulla b Actions i Relaxation of the muscles of the stomach and lower esophageal sphincter along with closure of the pyloric sphincter between stomach and small intestine ii Contraction of the abdominal muscles to increase abdominal pressure iii Expansion of the chest cavity to decrease intrathoracic pressure iv Relaxation of the upper esophageal sphincter v Glottis closes to protect lungs c Stimuli i Mechanoreceptors in the pharynx ii Pressure and chemoreceptor stimuli in stomach and duodenum iii Drugs and toxins d Retching i Occurs following gastric irritation or distention gastric contents enter esophagus but not pharynx e Chronic vomiting i Metabolic alkalosis with loss of chloride and hydrogen ions f Species differences i Ruminants vomiting rear and impractical since rumination includes regurgitation ii Horses lack ability to vomit can t relax lower esophageal sphincter iii Pigs vomit but physiologically not well understood iv Dogscats vomiting is a welldeveloped re ex 9 Function a Regulates the rate at which chyme uids enzymes food particles enters the small intestine Regions of the stomach a Cardiac simple and compound glands which produce mucus b Fundic between cardiac and pyloric regions c Pyloric produces mucus Motility a Two layers of smooth muscle run through the entire gastrointestinal tract i Longitudinal and circular b Movement is controlled by basic electrical rhythm BER from pacemaker cells i Located at the esophageal entrance c The stomach moves in a slow wave with synchronized contractions to the pylorus i This is possible because of the gap junctions ii These contractions send food to the duodenum region at a controlled rate IV Pyloric sphincter a Usually open but with an antral contraction the sphincter closes b This forces the contents back into the stomach and is the primary mixing force V Control of gastric emptying a Internal nerve plexus network b External nerves vagus i Affects contractions of the stomach c Hormonal in uence d Most control of gastric motility comes from receptors in the duodenum VI Secretions a Three types of cells i Mucus neck cells 1 Secrete mucus for lubrication ii Parietal cells 1 Produce HCL and intrinsic factors a Intrinsic factor needed for vitamin Bl2 absorption iii Chief cells 1 Produce pepsinogen 2 HCI acts on pepsinogen to produce pepsin which is used for protein digestion b Protein digestion begins in the stomach i Gastric lipase produced by the mucosal lining hydrolyzes fat into fatty acids and glycerol c Gastrin is produced in the stomach by G cells to increase secretion of HCI i Stimulated by protein d Stimulation of secretions i Cephalic phase 1 Neural stimulation sight smell taste thought 2 Parasympathetic nervous system a Specially the vagus nerve 3 Sends impulses to the stomach to increase secretions and motility 4 Vagotomy is relief for ulcer patients ii Gastric phase 1 Presence of food in stomach to increase secretion of HCI and enzymes 2 Mechanical stimulation distension 3 Chemical stimulation a Protein releases gastrin from antrum 4 Gastrin causes increased HCI 5 Before dinner sometimes you drink alcohol or eat a soup with protein to increase acid release to prepare the stomach iii Intestinal phase 1 Reduces the activity of the stomach 2 Enterogastric re ex releases hormones to decrease HCI a Controlled with the central nervous system and the endocrine pathway 3 All decrease gastrin and HCI release in stomach Ruminant Stomach I Digestive system is large with space for processing large quantities of bulky forage II Four chambers of stomach reticulum rumen omasum abomasum a Reticulorumen i Ideal ecosystem for microbes ii This structure is a large fermentation vat for cellulose breakdown 1 6090 of total digestion occurs here iii This region has no secretory function but some absorptive function iv Composed of smooth muscle with vagus innervation 1 Blood from reticulorumen enters portal vein to liver b Omasum i Epithelium has lea ike folds and enormous absorptive ability c Abomasum i True stomach similar to monogastric stomach with some secretory ability ii Also has pyloric sphincter III Digestion a Carbohydrates i In form of cellulose ii Microbe population mainly anaerobic produces volatile fatty acids acetate propionate butyrate 1 600 required for energy for cow and are absorbed across rumen wall b Proteins i Also digested by microbes c Lipids i Also broken down d Microbes in rumen synthesize all Bcomplex vitamins and all essential amino acids Vertebrate Fermenters I Foregut a Ruminants sheep antelopes cattle goats camelids moose deer giraffes and buffalo b Nonruminant herbivores that are foregut fermenters kangaroos hippos sloths coobus monkey II Hindgut a Have fermenting microbes in the area of the large intestine and cecum b Examples rabbits horses zebras some herbivorous birds III Midgut a Between foregut and hindgut b Mainly sh tilapias carps and cat sh Small Intestine I Site of most absorption II Duodenum to jejunum to ileum III Contains folded mucosa IV Villus center contains both capillary network and lymphatic vessel V Duodenum a Both secretin and cholecystokinin CCK are produced in the duodenum and move into the bloodstream and then the stomach b Actions i Decreased stomach motility ii Decreased gastrin release iii Decreased HCI secretion VI Enterogastric re ex a Inhibitor b High fat meal eggs and milk may be in gut after 6 hours c High carbohydrate meal out in 3 hours d Fat keeps material in the stomach longer VII Motility a Mixing contraction i Oscillating contraction relaxation smooth muscle ii Chyme divided into segments forced up and down and mixed b Propulsive contraction i Local distention produces contraction of distended portion and relaxation of forward region ii Mediated via myenteric plexus c External nerve involvement i Parasympathetic vagus increases contraction activity stimulated by hostility ii Sympathetic decreased contraction activity fear People I Ivan Pavlov a Dog and bell experiment ll William Beaumont a Father of gastrointestinal physiology b Did experiments with guy with hole in gut Small Intestine Digestion I Pancreas involvement Produces a Proteases proteolytic b Amylases starch splitting c Lipases fat breakdown d Bicarbonate buffer II Carbohydrates a Enzymes from both salivary and pancreatic amylases release glucose i Glucose is taken up by active transport Ill Protein a Digestion begins in the stomach with pepsin along with pancreatic proteolytic enzymes b Amino acids are used for uptake through active transport IV Lipids a Bile is produced in the liver and stored in the gall bladder b Bile acts as a detergent and causes decreased surface tension causing emulsi cation of fats i Emulsi cation breakdown into smaller particles c Pancreatic lipase causes further breakdown of free fatty acids and glycerol d Bile salts form micelles i Composed of FFA monoglycerides and cholesterol ii In this form they can enter solution and diffuse across membrane iii If they didn t go into solution they would remain as fat droplets e Triglycerides formed in epithelial cells are encased in protein coat and become chylomicrons i They then enter lacteals part of the lymphatic system f All fat digestedabsorbed in the upper part of the small intestine V Sphincter of Oddi controls entry of pancreatic enzymes and bile Re exes of Small Intestine I Tip The rst part of the word is where it starts and the second part of the word is where it ends II Gastroileal a Stimulatory b Increased stomach emptying causes increased contraction of ileum III Illeogastric a Inhibitory b Distention of ileum causes decreased stomach motility IV Intestino a Inhibitory b Large distentions wall injury bacterial infection causes complete cessation of motor activity Ileocecal Valve I Sphincter that is normally closed to prevent the back ow of fecal contents ll Distended cecum increases sphincter contraction Large Intestine I Storage and concentration no digestive enzymes ll Functions a Absorption of water and electrolytes i Sodium ions actively transported out followed by water b Storage of feces c Fermentation of organic matter i Major determinant of colon size ii Provides some energy VFA iii Colonic fermentation found in horses rabbits rats wine guinea pigs 1 Begins at cecum VI 2 The cecum is very important in the horse because it contains microorganisms that aid in ber breakdown a Most digestion for the horse occurs in the cecum 3 Results in digestion of cellulose to volatile fatty acids Parts a Ascending colon transverse colon descending colon b Terminates at rectum and anus c Longitudinal muscles of large intestine are incomplete i The walls are folded into sacs called haustra Movement a Segmentation i Not propulsive ii Very slow 1 every 30 minutes b Mass movement i 34 times per day ii Large increase in motility iii Simultaneous contraction of transverse and descending colons iv Material propelled 1334 length of the colon in a few seconds Diarrhea a Most of the deaths around the world are due to this b Two possible causes i Fluid enters colon faster than absorbed 1 Normally 2 liters of water absorbed per day across colon 2 Drink 26 liters per hour causes 15 liters per hour output from rectum 3 Enteritis infected GI tract large intestine and distal end of ileum a Mucosa irritated by bacteria or virus causing an increased secretion rate b Increases motility and causes a large uid output 4 Cholera toxin outpouring of large volume isotonic solution into jejunum ileum and colon a Death in one day the only therapy is to replace uid and electrolytes ii Diarrhea of intestinal origin 1 Contents delivered at normal rate but colon is not absorbing 2 Magnesium sulfate laxative is poorly absorbed Control of Defecation a Both internal smooth involuntary and external skeletal voluntary anal sphincters b Distension of walls of rectum causes defecation re ex c Stimulation of mechanoreceptors causes the urge to defecate d Relaxation of internal anal sphincter contraction of external anal sphincter and increased peristaltic activity in sigmoid colon e Eventually the pressure in rectum causes the relaxation of external anal sphincter f Brain centers can override the re ex i If this happens reverse peristalsis can happen causing the movement of contents back into the sigmoid ii Urge then decreases until next mass movement
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