Human Anatomy and Physiology PDF Notes (2024)

HUMAN ANATOMY AND PHYSIOLOGY LESSON 14 PART 3: The Digestive System and Body Metabolism MC 1 | BSN - 1M | DOC. JOHN FRANCIS YCONG | SEM 1 2024 ACCESSORY DIGESTIVE ORGANS TEETH SALIVARY GLANDS The role is to masticate TEETH...

HUMAN ANATOMY AND PHYSIOLOGY LESSON 14 PART 3: The Digestive System and Body Metabolism MC 1 | BSN - 1M | DOC. JOHN FRANCIS YCONG | SEM 1 2024 ACCESSORY DIGESTIVE ORGANS TEETH SALIVARY GLANDS The role is to masticate TEETH (chew) food PANCREAS Humans have two sets of LIVER teeth GALL BLADDER ○ Deciduous (baby or milk) teeth ○ 20 teeth are fully formed SALIVARY GLANDS by age two Saliva-producing glands Permanent teeth ○ Parotid glands – located ○ Replace deciduous teeth anterior to ears beginning between the ○ Submandibular glands ages of 6 to 12 ○ Sublingual glands ○ A full set is 32 teeth, but some people do not have wisdom teeth SALIVARY GLANDS Incisors Mixture of mucus and serous ○ bring food into the mouth fluids and cut it Helps to form a food bolus Canines Contains salivary amylase to ○ cut and tear food up begin starch digestion Premolars Dissolves chemicals so they ○ help incisors and canines can be tasted grind and mix food while chewing Molars  ○ teeth that do the most ○ Periodontal membrane chewing work while eating attached to the bone ○ Root canal carrying blood vessels and nerves Periodontal membrane ○ fleshy tissue between tooth and tooth socket that holds the tooth in place, attaches it to the adjacent teeth, and enables it to resist the stresses of chewing. TEETH Crown – exposed part ○ Outer enamel PANCREAS ○ Dentin ○ Pulp cavity Produces a wide spectrum of Neck digestive enzymes that break ○ Region in contact with the down all categories of food gum Enzymes are secreted into the ○ Connects crown to root duodenum Root  Alkaline fluid introduced with PANCREAS: ENDOCRINE enzymes neutralizes acidic FUNCTION (DUCTLESS) chyme islet cells (islets of Langerhans) ○ create and release important hormones directly into the bloodstream ○ glucagon, which acts to raise blood sugar ○ insulin, which acts to lower blood sugar PANCREAS: EXOCRINE FUNCTION Enzymes: ○ trypsin and chymotrypsin → digest proteins ○ amylase → digestion of carbohydrates ○ lipase → break down fats ○ released → pancreatic duct HOMEOSTATIC IMBALANCE joins the common bile duct to form the ampulla of Vater which Pancreatitis is is located at the first portion of inflammation of the the small intestine, called the pancreas that occurs duodenum when pancreatic enzyme pancreatic juices and bile → secretions build up and digest fats, carbohydrates, and begin to digest the organ proteins. itself. It can occur as acute painful attacks  lasting a matter of days, or it LIVER may be a chronic condition that progresses over a period Largest gland IN the body of years. Located on the right side of the body under the 4F’S diaphragm ○ FATS Consists of b suspended ○ FEMALE from the diaphragm and ○ FORTY abdominal wall by the ○ FERTILE falciform ligament Diabetes Type I (IDDM) Connected to the gall ○ insulin dependent bladder via the common ○ incurable hepatic duct ○ genetic Main organ of metabolism Diabetes Type II (NIDDM) ○ genetic and acquired ○ dili i absorb sa cell ang insulin ○ curable through proper diet Gestational Diabetes Mellitus ○ pregnant woman ○ due to the hormones released by the placenta ○ ma cure after giving birth Diabetes Insipidus ○ juvenile diabetes ○ 1L per day ang normal urine 3L if naay sakit  Oval cells CELLS OF THE LIVER ○ differentiate into several Hepatocytes different cell ○ The liver parenchyma is ○ role in the repopulation of primarily comprised of hepatocytes and other hepatocytes hepatic cells (e.g. biliary ○ contain many mitochondria, epithelium) following extensive smooth and rough hepatic injury endoplasmic reticulum and ○ provides everything that Golgi apparatus the liver needs Hepatic = liver Pit cells Ito cells ○ short-lived granular ○ fat storing cells, or lipocytes lymphocytes that ○ storage and maintenance of reside within vitamin A (retinol) hepatic sinusoids ○ production of extracellular and contribute to matrix (collagen types I and immunity. III) ○ regulation of sinusoidal blood flow ○ hepatic tissue repair following injury Kupffer cells ○ Kupffer cells are phagocytes ○ Removes aged red blood cells from circulation ○ removing blood-borne HOMEOSTATIC IMBALANCE: microbes or endotoxins JAUNDICE absorbed from the gastrointestinal tract buildup of bilirubin in the body  sclera mucous membrane Physiologic Jaundice ○ inborn Pathologic Jaundice ○ causes by another health problem BILE Produced by cells in the liver Composition ○ Bile salts ○ Bile pigment (mostly bilirubin from the breakdown of hemoglobin) PROCESSES OF THE DIGESTIVE ○ Cholesterol SYSTEM ○ Phospholipids Ingestion – getting food ○ Electrolytes into the mouth Propulsion – moving GALLBLADDER foods from one region of the digestive system to Sac found in hollow fossa of another liver Peristalsis – alternating Stores bile from the liver by way waves of contraction of the cystic duct Bile is introduced into the duodenum in the presence of fatty food Gallstones/ cholesterol stones can cause blockages  Segmentation Fats are broken to fatty ○ Moving materials back and forth acids and alcohols to aid in mixing Absorption ○ End products of digestion are absorbed in the blood or lymph ○ Food must enter mucosal cells and then into blood or lymph capillaries Defecation ○ Elimination of indigestible substances as feces Mechanical digestion CONTROL OF DIGESTIVE ○ Mixing of food in the mouth by ACTIVITY the tongue ○ Churning of food in the Mostly controlled by stomach reflexes via the ○ Segmentation in the small parasympathetic division intestine Chemical and mechanical Chemical Digestion receptors are located in ○ Enzymes break down food organ walls that trigger molecules into their building reflexes blocks Stimuli include: ○ Each major food group uses ○ Stretch of the organ different enzymes ○ pH of the contents Carbohydrates are ○ Presence of broken to simple sugars breakdown products Proteins are broken to amino acids  Reflexes include: ○ Involuntary transport of the ○ Activation or inhibition of bolus glandular secretions ○ All passageways except to ○ Smooth muscle activity the stomach are blocked Tongue blocks off the mouth DIGESTIVE ACTIVITY OF THE MOUTH Soft palate (uvula) Mechanical breakdown blocks the nasopharynx ○ Food is physically broken down Epiglottis blocks the by chewing larynx Chemical digestion ○ Peristalsis moves the bolus ○ Food is mixed with saliva toward the stomach ○ Breaking of starch into maltose ○ The cardioesophageal by salivary amylase sphincter is opened when food presses against it ACTIVITIES OF THE PHARYNX AND ESOPHAGUS No digestive function Passageways to the stomach DEGLUTITION (SWALLOWING) FOOD BREAKDOWN IN THE STOMACH Buccal phase ○ Voluntary Gastric juice is regulated by ○ Occurs in the mouth neural and hormonal factors ○ Food is formed into a bolus Presence of food or falling pH ○ The bolus is forced into the causes the release of gastrin pharynx by the tongue Gastrin causes stomach glands Pharyngeal-esophageal to produce protein-digesting phase enzymes  Hydrochloric acid makes the The pylorus meters out chyme stomach contents very acidic into the small intestine (30 ml at a time) The stomach empties in four to NECESSITY OF AN EXTREMELY ACID ENVIRONMENT IN THE six hours STOMACH Activates pepsinogen to pepsin for protein digestion Provides a hostile environment for microorganisms DIGESTION IN THE SMALL INTESTINE H-PYLORI bacteria that can strive in an acidic environment Enzymes from the brush border ○ Break double sugars into simple sugars DIGESTION AND ABSORPTION IN ○ Complete some protein THE STOMACH digestion Protein digestion enzymes Pancreatic enzymes play the ○ Pepsin – an active protein major digestive function digesting enzyme ○ Help complete digestion of ○ Rennin (chymosin)– works on starch (pancreatic amylase) digesting milk protein ○ Carry out about half of all The only absorption that protein digestion (trypsin, etc.) occurs in the stomach is of Pancreatic enzymes play the alcohol and aspirin major digestive function (continued) ○ Responsible for fat digestion PROPULSION IN THE STOMACH (lipase) Food must first be well mixed ○ Digest nucleic acids Rippling peristalsis occurs in (nucleases) the lower stomach ○ Alkaline content neutralizes acidic chyme  STIMULATION OF THE RELEASE OF PROPULSION IN THE SMALL PANCREATIC JUICE INTESTINE Peristalsis is the major Vagus nerve means of moving food Local hormones Segmental movements ○ Secretin ○ Mix chyme with digestive ○ Cholecystokinin juices ○ Aid in propelling food FOOD BREAKDOWN AND ABSORPTION IN THE LARGE INTESTINE No digestive enzymes are produced Resident bacteria digest remaining nutrients ABSORPTION IN THE SMALL ○ Produce some vitamin K and INTESTINE B Water is absorbed along the ○ Release gases length of the small intestine Water and vitamins K and B End products of digestion are absorbed ○ Most substances are absorbed Remaining materials are by active transport through cell eliminated via fece membranes PROPULSION IN tHE LARGE ○ Lipids are absorbed by INTESTINE diffusion Sluggish peristalsis Substances are transported to Mass movements the liver by the hepatic portal ○ Slow, powerful movements vein or lymph ○ Occur three to four times per ○ Categories of nutrients day ○ Carbohydrates Presence of feces in the rectum Most are derived from causes a defecation reflex plants ○ Internal anal sphincter is Exceptions: lactose from relaxed milk and small amounts of Defecation occurs with glycogens from meats relaxation of the voluntary ○ Lipids (external) anal sphincter Saturated fats from animal Endoscopy products Unsaturated fats from nuts, seeds, and vegetable HOMEOSTASIS: UPPER AND LOWER GI BLEEDING oils Cholesterol from egg yolk, Esophagogastroduodenoscop meats, and milk products y (EGD) ○ Proteins Colonoscopy and Complete proteins – Sigmoidoscopy contain all essential amino UPPER GIT BLEEDING acids ○ Hematemesis - blood vomit Most are from animal ○ Melena - dark feces products LOWER GIT BLEEDING Legumes and beans also ○ Melena have proteins, but are ○ Hematochezia - fresh red incomplete blood feces ○ Vitamins Most vitamins are used as NUTRITION cofactors and act with enzymes Nutrient – substance used by Found in all major food the body for growth, groups maintenance, and repair ○ Mineral  Play many roles in the body Carbon leaves cells as Most mineral-rich foods are carbon dioxide (CO2) vegetables, legumes, milk, Hydrogen atoms are and some meats combined with oxygen to ○ Water form water Energy produced by these reactions adds a phosphorus METABOLISM to ADP to produce ATP Chemical reactions ATP can be broken down to necessary to maintain life release energy for cellular Catabolism – substances use are broken down to simpler substances METABOLIC PATHWAYS INVOLVED IN Anabolism – larger CELLULAR RESPIRATION molecules are built from smaller ones Glycolysis – energizes a Energy is released during glucose molecule so that it catabolism can be split into two pyruvic The body’s preferred source acid molecules and yield ATP to produce cellular energy (ATP) Glucose (blood sugar) is the major breakdown product and fuel to make ATP Krebs cycle CELLULAR RESPIRATION ○ Produces virtually all the carbon dioxide and water Oxygen-using events take resulting from cell respiration place within the cell to create ○ Yields a small amount of ATP ATP from ADP  Electron transport chain ○ Hydrogen atoms removed during glycolysis and the Krebs cycle are delivered to protein carriers ○ Hydrogen is split into hydrogen ions and electrons in the mitochondria ○ Electrons give off energy in a series of steps to enable the production of ATP TRANSITION REACTION ○ converts pyruvate into acetyl CoA (acetyl coenzyme A ) producing Co2 and NADH 4 STAGES OF CELLULAR RESPIRATION GLYCOLYSIS KREBS CYCLE ○ The first pathway used in the ○ Series of reaction that takes breakdown of glucose to acetyl CoA and produces extract energy. NADH, FADH and ATP ○ It takes place in the ○ The Krebs cycle is an aerobic cytoplasm process, meaning it requires ○ Glucose is converted into a oxygen to work, so the Krebs more usable form called cycle gets to business right pyruvate away mixing carbon and oxygen in the respiration pathway  ELECTRON TRANSPORT CHAIN FAT METABOLISM The electron transport chain is a cluster of proteins that transfer Handled mostly by the electrons through a membrane liver within mitochondria to form a ○ Use some fats to make gradient of protons that drives ATP the creation of adenosine ○ Synthesize triphosphate (ATP). ATP is used lipoproteins, by the cell as the energy for thromboplastin, and metabolic processes for cellular cholesterol functions. ○ Release breakdown products to the blood Body cells remove fat and cholesterol to build membranes and steroid hormones USE OF FATS FOR ATP SYNTHESIS Fats must first be broken down to acetic acid  Within mitochondria, acetic acid The liver converts is completely oxidized to harmful ammonia to produce water, carbon dioxide, urea which can be and ATP eliminated in urine PROTEIN METABOLISM Proteins are conserved by body cells because they are used for most cellular structures ROLE OF THE LIVER IN METABOLISM Ingested proteins are broken down to amino acids Several roles in digestion Cells remove amino acids to Detoxifies drugs and build proteins alcohol ○ Synthesized proteins are Degrades hormones actively transported across Produce cholesterol, cell membranes blood proteins (albumin Amino acids are used to make and clotting proteins) ATP only when proteins are Plays a central role in overabundant or there is a metabolism shortage of other sources METABOLIC FUNCTIONS OF THE PRODUCTION OF ATP FROM LIVER PROTEIN Glycogenesis – Amine groups are removed formation of glycogen from proteins as ammonia from sugar The rest of the protein molecule ○ Glucose molecules are enters the Krebs cycle in converted to glycogen mitochondria ○ Glycogen molecules are stored in the liver  Glycogenolysis – breakdown CHOLESTEROL METABOLISM of the molecule glycogen into glucose Cholesterol and fatty ○ Glucose is released from acids cannot freely the liver after conversion circulate in the from glycogen bloodstream Gluconeogenesis They are transported by ○ Glucose is produced from lipoproteins (lipid-protein fats and proteins complexes) Fats and fatty acids are picked ○ Low-density up by the liver lipoproteins (LDLs) ○ Some are oxidized to transport to body cells provide energy for liver ○ High-density cells lilpoproteins (HDLs) ○ The rest are broken down transport from body into simpler compounds cells to the liver and released into the blood BODY ENERGY BALANCE CHOLESTEROL METABOLISM Energy intake = total Functions of cholesterol energy output (heat + ○ Serves as a structural basis work + energy storage) of steroid hormones and ○ Energy intake is vitamin D liberated during food ○ Is a major building block of oxidation plasma membranes ○ Energy output Most cholesterol is produced in Heat is usually the liver and is not from diet about 60% Storage energy is in the form of fat or glycogen  ○ The amount of REGULATION OF FOOD INTAKE thyroxine produced is Body weight is usually relatively the most important stable control factor ○ Energy intake and output ○ More thyroxine means remain about equal higher metabolic rate ▪Mechanisms that may regulate food intake TOTAL METABOLIC RATE (TMR) ○ Levels of nutrients in the blood Total amount of ○ Hormones kilocalories the body ○ Body temperature must consume to fuel ○ Psychological factors ongoing activities TMR increases with an increase in body activity METABOLIC RATE AND BODY HEAT TMR must equal calories PRODUCTION consumed to mainta Basal metabolic rate (BMR) – homeostasis and amount of heat produced by maintain a constant the body per unit of time at rest weight Factors that influence BMR ○ Surface area – small body BODY TEMPERATURE REGULATION usually has higher BMR ○ Gender – males tend to Most energy is released have higher BMR as foods are oxidized Factors that influence BMR Most energy escapes as (continued) heat ○ Age – children and The body has a narrow adolescents have a higher range of homeostatic BMR temperature  ○ Must remain between 35.6° to 37.8°C (96° to 100° F) ○ The body’s thermostat is in the hypothalamus DEVELOPMENTAL ASPECTS OF THE Initiates heat-loss or heat- DIGESTIVE SYSTEM promoting mechanisms The alimentary canal is a continuous tube by the fifth HEAT PROMOTING MECHANISMS week of development Digestive glands bud from Vasoconstriction of blood vessels the mucosa of the ○ Blood is rerouted to deeper, more alimentary tube vital body organs The developing fetus Shivering – contraction of receives all nutrients muscles produces heat through the placenta In newborns, feeding must HEAT LOSS MECHANISMS be frequent, peristalsis is inefficient, and vomiting is Heat loss from the skin via common radiation and evaporation Teething begins around age ○ Skin blood vessels and capillaries six months are flushed with warm blood Metabolism decreases with ○ Evaporation of perspiration cools old age the skin Middle age digestive problems BODY TEMPERATURE REGULATION ○ Ulcers ○ Gall bladder problems Activity of digestive tract in old age ○ Fewer digestive juices ○ Peristalsis slows ○ Diverticulosis and cancer are more common