A&P Exam 3 PDF

Chapter 23 Respiratory system Craig S Nelson DO Respiratory Anatomy p 892 Major structures of the Respiratory tract f orm a Double Y shaped upper and lower airway Nose and Mouth join at the Pharynx (top of the Y) Pharynx opens into Larynx, which sits on top of Trachea Trachea divides into 2 Bronch...

Chapter 23 Respiratory system Craig S Nelson DO Respiratory Anatomy p 892 Major structures of the Respiratory tract f orm a Double Y shaped upper and lower airway Nose and Mouth join at the Pharynx (top of the Y) Pharynx opens into Larynx, which sits on top of Trachea Trachea divides into 2 Bronchi that connect to the lung (upside down Y) Bronchi divide and divide in the lung, ending with alveoli Alveoli is where the gas exchange occurs UPPER RESPIRATORY SYSTEM P 894 Nasal cavity The f unction of the nasal cavity is to Heat, humidif y, and clean the air coming through the nose Mucous traps particles as air moves in, Nose traps water as the air moves out to use to humidif y the new air coming in Important resonating center f or speech Oral Cavity While not it’s primary f unction, the oral cavity is the Backup airway Tongue plays a vital role in speech by helping to f orm the sounds coming f rom the Larynx Pharynx Connects the 2 cavities and f unnels them into 1 airway at the Larynx LOWER RESPIRATORY SYSTEM P 897 Larynx (Voice box), It is the entrance to trachea and lungs. Epiglottis covers the opening of the larynx and protects it f rom solids or liquids passing through the pharynx Vocal cord vibrates with air passing out and this allows humans to make sounds so we can talk Trachea (Windpipe) The basic structure is that of C shaped bone rings stacked up which are connected by smooth muscle and connective tissue. The opening of the C shaped cartilages is pos terior Carina The carnia is where the trachea divides into 2 primary bronchi, one f or each lung Right bronchi goes of f at less severe angle, aspiration goes down this one Bronchi Subdivisions continue as the bronchi subdivide into smaller and smaller airways ending in the alveoli In the Bronchial tree, the bronchi divide 25 times. The divisions are named as f ollows Primary Bronchi→ Secondary bronchi→Tertiary bronchi → Bronchioles → Terminal bronchioles-> Respiratory bronchioles Alveoli Where the gas exchange occurs. They are microscope squamous epithelial spheres that come of f of the Alveolar ducts The airway continues as Terminal bronchioles → Respiratory bronchioles →Alveolar ducts → Alveoli Lung Right lung is divided into 3 lobes, the Superior, Middle, and Lower lobe. Having 3 lobes gives it 2 f issures, Oblique and a Horizonal Lef t lung is divided into 2 lobes, the Superior and the Lower Having 2 lobes gives it only 1 f issure, Horizonal Apex of the lung is the top, while the Base is the bottom of the lung Hilus is the medial part of the lung where bronchi and blood vessels enter and leave Chapter 23 Respiratory system Craig S Nelson DOp 2 Air Exchange p 866 Lung Lobule Where the circulatory and the respiratory systems meet f or the gas exchanges Terminal bronchioles become respiratory bronchioles deep in the tissue of lobule. Respiratory bronchioles have an epithelium change f rom simple cuboidal to simple squamous. Respiratory bronchioles divide into smaller alveolar ducts which give of f the alveoli There is an Artery, vein, and lymph capillary wrapped around the respiratory structures of the lobule Alveoli They are given of f around the entire circumf erence of the alveolar ducts This is where gas exchange occurs The alveoli are very thin walled sacs surrounded by blood vessels 2 types of cells make up wall of the alveoli Type I alveolar cells – simple squamous cells which allow easy dif f usion of gasesthrough them Type II alveolar cells – (septal cells). These cells secrete a f luid called surf actant Surf actant helps the tiny alveoli stay open Alveolar macrophages (dust cells) in the alveoli help prevent invaders f rom getting into the body Lung anatomy for the Blood supply to the lung Pulmonary Artery brings low O2 blood f rom the Right ventricle Pulmonary Vein returns high O2 Blood to the Lef t atrium p 909 Ventilation-perf usion coupling Lung tries to match the blood f low to the alveoli that are being ventilated. This allows the most ef f icient exchange of gases to occur Hypoxic vasoconstriction is the name of the process that causes the coupling to occur. The precapillary arteriole sphincters direct blood to better ventilated areas that have higher concentrations of O2 If an alveolus is low in O2, the sphincter will close down blood f low to that alveoli. This moves blood away f rom alveoli that are low in O2. If an alveolus has high levels of O2, then the sphincter will dilate, allowing more blood to pass the alveolus. PULMONARY VENTILATION p 912 Mechanics of Ventilation Pulmonary ventilation – This is the term that ref ers to the act of breathing and air movement. Mechanics of air movement Background Physics f act - Pressure is equal to mass per unit volume Pressure = mass / volume There is an indirect relationship between volume and pressure. That means that when one value goes up, the other valve must go down. If you Increase the volume of anything, the pressure inside of the thing will decrease. If you decrease the volume of anything, the pressure inside of the thing will increase. Thorax is the chest cavity and ventilation occurs due to this change in volume causing a change in the pressure. It uses the pressure equation to move air Mass in thorax: Heart, lungs, blood, lymph, AIR Volume in thorax: How large the thoracic cavity is can be changed by respiratory muscles Primary muscles of respiration Diaphragm (major muscle of respiration) moves downward, increasing the volume of the chest Intercostals lif t the ribs up and out, increasing the volume of the chest cavity Secondary muscles of respiration Abdominal muscles pull down on the ribs, increasing the volume of the chest Scalenes and sternocleidomastoid pull up on the ribs, increasing the volume of the chest Chapter 23 Respiratory system Craig S Nelson DO p3 Inspiration This is brought about by the contraction of the respiratory muscles. The alveoli f ill passively 1. The contraction of respiratory muscles increases the volume of the chest cavity 2. Increase in volume of the chest decreases the pressure in the chest. 3. The chest pressure drops below atmospheric pressure 4. The chest is connected to the atmosphere by the airway 5. Atmospheric pressure being higher than chest pressure causes air to move into the chest thru the airways 6. Movement of air causes the alveoli to f ill 7. Eventually the new volume of air causes the chest pressure to equal atmospheric pressure, so the air movement stops The respiratory muscles contract, increasing the volume of the chest cavity, thereby decreasing the pressure in the chest below atmospheric pressure, so the air is sucked into the lung. Expiration This is brought about by the relaxation of the respiratory muscles. The alveoli empty passively 1. 2. 3. 4. 5. 6. 7. The relaxation of respiratory muscles decreases the volume of the chest cavity Decrease in volume of the chest increases the pressure in the chest. The chest pressure raises above atmospheric pressure The chest is connected to the atmosphere by the airway Chest pressure is higher than Atmospheric pressure so the air to moves out of the chest Movement of air causes the alveoli to decrease in their diameter When loss of air causes the chest pressure to equal atmospheric pressure, air movement stops The respiratory muscles relax, decreasing the volume of the chest cavity, thereby increasing the pressure in the chest above atmospheric pressure, so the air is blown out of the lung. Lung volumes Spirogram There is a lab about these important values Total lung capacity - The total amount of air that both lungs can hold together p 917 Residual volume – A small volume that is not under voluntary control to be moved. It keeps the alveoli slightly open, making them easier to expand when the air comes in. Vital capacity –This is the volume of air that can moved voluntarily. The vital capacity is equal to the total lung volume minus the residual volume. VC = TLC – RV Tidal volume – This is the amount of air that is moved during a normal breath in normal ventilation Inspiratory reserve – This volume of air is usually not used. It would require all of the alveoli to inf late to their maximum volume. The body can move this air, but usually does not need too. Expiratory reserve – This is air that is held in the lungs, allowing gas exchange between breaths. It can be moved but it usually is not moved by the body. Functional Residual Capacity - Air lef t in lungs af ter normal breath, and is equal to the Residual volume plus the Expiratory reserve volume RESPIRATION P 919 Respiration is now used to ref er to oxygen movement and utilization External respiration – The process of air getting into the blood through the lung Internal respiration – The process of gas exchange between the blood and the cells. Cellular respiration – The process of the cell utilizing the oxygen f or metabolic reactions Chapter 23 Respiratory system Craig S Nelson DO Respiratory Physiology p4 p 922 Dif f usion of gases along their concentration gradients Lung alveoli have more O2 and less CO2 in them than the blood passing by in the capillary does So oxygen moves into the blood and CO2 moves into the alveoli down their concentration gradients Tissue systemic arterial capillary blood has more O2 and less CO2 than the interstitial f luid of the tissue does , so O2 and the CO2 move down their concentration gradients. The O2 moves into the tissues and the CO2 moves into the blood. Oxygen that enters the blood is picked up in the lungs, moves onto the hemoglobin. Most of the O2 in the blood is attached to hemoglobin 100 ml high oxygenated arterial blood has 20 ml Oxygen 19.7 ml of oxygen is on hemoglobin Hb normally is completed f illed while breathing room air 0.3 ml of oxygen is dissolved in blood Normal PaO2 of well oxygenated red blood is 100 mm Hg on room air (20 % atm air is oxygen) How the oxygen is delivered to the cells Hemoglobin Disassociation Curve is a knee shaped curve P50 Oxygen 26 mm Hg 100 saturated at 100 mm Hg Hemoglobin has the ability to change its shape, so that it will hold less or more O2 depending on the levels of O2 in the tissues through which it is passing. Hemoglobin and cover oxygen binding sites or uncover them. In tissues of high oxygen, the hemoglobin changes it shape, uncovering oxygen binding sites and will carry more O2. In tissues of low oxygen, the hemoglobin changes it shape, covering oxygen binding sites, f orcing the oxygen on those sites of f , and will carry less O2 Right shif t in the curve is caused by the Hemoglobin being in tissues that have a lower concentration of oxygen than the blood does. The change in the shape of the hemoglobin will cause it to carry less oxygen, thereby releasing O2 Lef t shif t in the curve is caused by the Hemoglobin being in tissues that have a higher concentration of oxygen than the blood does. The change in the shape of the hemoglobin will cause it to carry more oxygen, taking on O2 Byproducts of metabolism in a tissue will make hemoglobin right shif t and release oxygen Increase Heat Increase Acid (pH goes down) Increase CO2 Decrease O2 Hypoxia is a tissue diagnosis, where there is not enough oxygen in the tissue to meet the needs of the cells Trace the air f rom the outside of the body to the cells, and you have the 4 main causes of hypoxia 1. 2. 3. 4. Ventilation problem – The oxygen f rom the outside is not reaching alveoli Dif f usion problem – The oxygen in the alveoli is not not reaching blood Cardiovascular problem – The oxygen in the blood is not being picked up & / or transported Cell metabolic problem – The oxygen is not being used in the cells Chapter 23 Respiratory system Craig S Nelson DO p 5 How the Carbon dioxide is taken from to the cells p 925 Carbon Dioxide is carried in the blood in three main ways 1. 78 % of the CO2 is transported as bicarbonate 2. 13% of the CO2 is transported on the hemoglobin 3. 9% of the CO2 is dissolved in the blood and transported Lung Exchange of CO2 is down its concentration gradients The alveoli has less CO2 than the blood, so the CO2 moves into the alveoli The tissues have more CO2 than the blood, so the CO2 moves into the blood Control of Ventilation p 927 Carbon dioxide control is the most important drive f or ventilation Oxygen control (backup system) Central chemoreceptors sense the CO2 and H+ concentrations Peripheral chemoreceptors sense the CO2 and H+ concentrations but also O2 Located in the Aortic Arch and the Carotid bodies Chapter 24 pg 1 Digestion Craig S Nelson DO Overview of Digestive System Digestion tracts in animals are dif f erent according to the f ood that they eat Herbivore – plants only Carnivore – meat only Omnivore - both Humans are omnivores, but our digestive tract f unctions most like herbivores How the Digestive System works p 942 GI tract is a hollow tube, only absorbed f ood stuffs actually enter into the body , rest is discarded as waste 1. Ingestion – Food enters the system through the mouth 2. Secretion – Fluids are mixed with the f ood. About 7 liters f luid per day are secreted into our Gi tract 3. Propulsion – Mixture of f ood and secretion f rom the stomach down is called chyme. It is pushed through the system By contractions of smooth muscle in a process named peristalsis 4. Digestion – The f ood is broken down by enzymes secreted into the chyme and ones on the walls of the tract. 5. Absorption – The important f ood stuf f s are taken into the body f rom the chyme. 6. Def ecation – The waste material is eliminated through the rectum. Layers of GI tract 4 main layers make up the digestive tract P 943 1. Mucosa The inner most lining of the GI tract - Non-kernatinized Squamous epithelial tissue lines the tract where protection is important Mouth, pharynx, esophagus, anus - Simple columnar epithelial tissue lines the tract where absorption and secretion is important Stomachs and intestines - MALT (mucosa –associated lymph tissue) is present throughout the tract Provides Immune cells that will attempt to protect the body f rom invaders. - Blood vessels and Lymph are present to absorb nutrients into body f rom the tract - Folds in the mucosa, increase the absorptive area by increasing the surf ace area of the GI tract 2. Submucosa Binds mucosa layer above it to muscular layer below it. - Contains connective tissue with Blood and lymph vessels passing through it 3. Muscularis Muscular portion of GI tract Two dif f erent types of muscle are present in this muscularis layer Skeletal muscle used f or swallowing, chewing, and def ecation are in the mouth, pharynx, esophagus, and anus Smooth muscle used f or peristalsis is in the stomach and intestines 4. Serosa - This is the outer most layer of the tract and provides a superf icial covering. - Visceral peritoneum (Esophagus lacks a serosa) CNS control of GI tract p 945 Enteric Nervous system controls the GI tract, Motor side - arranged in 2 plexus Myenteric plexus (Auerbach) -in-between muscle layers, controls contractions Submucosal plexus - (Meissner) - control gland secretions Sensory side - 2 main types Chemoreceptors - respond to dif f erent chemicals in gut Stretch receptors - respond to stretch and movement of gut Chapter 24 2 Digestion Craig S Nelson DO page Peritoneum p 946 - Largest serous membrane of body and it lines the entire abdominopelvic cavity Parietal peritoneum is that portion which lines walls of the abdomen Visceral peritoneum is the layer that is directly on the organs - Several major f olds of peritoneum help hold the GI tract in place inside the abdomen Greater omentum – f olds over intestines and whose exact purpose is debated Falcif orm ligament – attaches liver to anterior wall of abdomen and diaphragm Lesser omentum – suspends stomach and duodenum f rom liver Mesentery – attaches small intestine posterior wall of the abdomen Mesocolon – attaches the large intestine to the posterior wall of the abdomen Parts of our digestive tract Mouth P 948 Opening that allows the f ood to be placed into the GI tract Nerves send inf ormation about the f ood being eaten to the brain so the brain can determine if the f ood going to be swallowed or spit back out It starts digestive process by secreting amylase (digests carbohydrates) in the salvia Food is chewed up to mechanically breakdown the f ood and to start digestion Lips and cheeks These structures help hold f ood in the mouth so that it can be chewed Nerves send inf ormation about the f ood being eaten to the brain so the brain can determine if the f ood going to be swallowed or spit back out Palates chewing Hard palate is made up of part of maxillary bone and all of the palatine bone. It aids in Sof t palate and uvula are made of muscle, and moves superiorly in swallowing to pro vent f ood f rom Being pushed up into the nasal cavity Salivary Glands p 949 - Salvia is made up of 99% water - Moistens the f ood and allows aids in tasting by dissolving the tastants. - Some enzymes start digestion of f ood, amylase works on starch, some lipase work on f at - Its f ormation is controlled by ANS, Daily total 1000 – 1500 ml - 3 main glands Parotid - watery f luid with amylase Sublingual – thicker mucous f luid, less amylase Submandibular – thicker than parotid f luid Tongue p 951 - The tongue is vital in taste as the largest group of taste buds are on tongue - Strong muscle that moves f ood around the mouth that aids in chewing - Used in speech - Pushes f ood bolus back into pharynx and aids in swallowing the f ood Chapter 24 Digestion Craig S Nelson DO page 3 Teeth p 952 - The teeth are made up of 3 parts Crown (visible part) Neck (connects other 2) Root (invisible part in jaw) - Located in sockets in bone of both jaws in the mouth - The teeth are held in place by periodontal ligament that makes up a f ibrous joint - Gingivae is a thin tissue layer that covers the edge of socket and part of the tooth - Blood supply and nerve supply thru roots Dentitions (2 sets of teeth) First – deciduous teeth ( baby, milk, primary) 20 teeth (6 months to 6 years) Second – permanent (secondary) 32 teeth 3rd molars of ten lack room in jaw bones, so they twist (impacted) Carnivores – Teeth f unction only to cut f ood into pieces. There is no chewing Herbivores – Teeth f unction to grind down plant cells wall. Takes intensive chewing to do this. Omnivores – Teeth must do both cutting and chewing, so they have both types of teeth Typical tooth Periodontal ligament - Dense f ibrous connective tissue that helps holds teeth in the socket of jaw Gingivae is the Gums Inside of tooth Enamel - Covers the visible crown to protect it, -hardest substance in body (Ca++ phosphate & carbonate Dentin - majority of the tooth, Calcif ied connective tissue, -harder than bone due to higher Ca++ content Pulp cavity - contains blood vessels, lymph, and nerves, Pharynx p 955 Muscles of pharynx and tongue f orce f ood down into esophagus Voice box and trachea protected by epiglottis, a f lap that covers opening (glottis) Swallowing can be divided into 3 stages 1. Voluntary stage f ood bolus passed into oropharynx 2. Pharyngeal stage (involuntary) f ood bolus passed into esophagus 3. Esophageal stage f ood bolus passed into stomach via peristalsis (involuntary muscular contractions move bolus) Esophagus p 955 Muscular tube that connects pharynx with stomach Food moves down the esophagus by waves of contractions called peristalsis Sphincter muscle are located at the top and the bottom to control the f ood movement The upper esophageal sphincter regulates f ood leaving pharynx and entering esophagus The lower esophageal sphincter keeps f ood in stomach f rom returning to esophagus Muscularis layer of the esophagus has the type of muscle change Top 1/3 skeletal muscle Middle 1/3 mixed Chapter 24 Digestion Bottom 1/3 smooth muscle Craig S Nelson DO page 4 Stomach p 958 - Expandable sac-like structure connected to the end of the esophagus, it is J-shaped, like a comma. Cardia - surrounds the opening f rom the esophagus Fundis - area of stomach above and to the side of the cardia Body - main and largest portion of the stomach Lesser curature - edge that is the shortest Greater curature - edge that is the largest and longest Pylorus connects the stomach to the Small Intestines (duodenum) Contains pyloric sphincter, which controls chime entering the Small intestine Pyloric anthrum → Pyloric canal → Pyloric sphincter → small intestine -Located right below the diaphragm -Changes size - f rom f ull at 4 liters of f ood down to empty at 50 ml -It f unctions are 1. Storage f acility, holding f ood until it is slowly released into the small intestines. 2. It continues digestion by secreting gastric juice into the f ood it is holding. 3. Through muscle contractions, it mixes the f ood with the gastric juices. Mechanical and Chemical Digestion in the stomach Chyme - Mixture of f ood and gastric juices Gastric juices HCl - This is secreted f rom the parietal cells and it gives the stomach contains a pH 1 Gastrin is the hormone that controls the secretion of HCl Serves to denature the proteins in the f ood to aid in digestion Kills most of the bacteria on f ood. Enzyme – pepsinogen - This is secreted f rom the chief cells in an inactive f orm which is activated inside stomach cavity Is turned into the active enzyme pepsin in the stomach where it breaks down proteins Enzyme – gastric lipase - This is secreted f rom the chief cells. It breaks down lipids Gastric glands Parietal cells - HCl and intrinsic f actor (B12) Chief cells – pepsinogen and gastric lipase Mucous neck cells – mucous (protects f rom acid) G cells - secretes the hormone gastrin, Gastrin is the hormone that controls gastric secretions and mobility Stomach and HCl acid The HCl acid is strong enough to dissolve you completely so the stomach must be protected. A protective layer of mucous helps protect the stomach f rom the acid. If the acid gets through this protective layer, it will destroy any tissue Ulcers - when the acid eats into tissue wall. Stomach, esophagus, or small intestine. Mucous layers in the esophagus and duodenum (small intestine) are thinner, easier to damage Gastrin secretion of Acid G cells secrete gastrin, the hormone that stimulates the parietal cells to release HCl. Histamine is involved it is a H2 receptor that gastrin stimulates the parietal cell H2 blockers – Pepcid, Tagament, block this receptor and thereby decrease acid secretion Chapter 24 Digestion Craig S Nelson DO page 5 Stomach sphincter muscles and the control of acid Stomach has sphincter at each end to control acid Esophageal sphincter prevents acids f rom ref luxing into the esophagus (heart burn) Many f ood groups loosen this sphincter, increasing the change of ref lux Caf f eine, citric acid, Nicotine, peppermint, Alcohol Pyloric sphincter opens and closes allowing chyme to exist stomach into small intestine Emesis or vomiting Vomiting center in medulla oblongata causes vomiting Stomach contraction and relaxation of esophageal sphincters project chyme out of mouth Brain input and local stimuli can also cause vomiting Small Intestine p 971 The place where the nutrient molecules are absorbed. Molecules are absorbed thru the intestinal wall and enter blood stream or lymph Digestion causes the large molecules to be broken down into smaller molecules so they are easier to absorb Enzymes f or digestion come mostly f rom the Pancreas and but some are in wall of Small Intestine Vili are extensions of wall of small intestine that increase surf ace area f or absorption Microvilli are estimated to be as numerous as 200 million per square millimeter of the small intestinal wall Small intestine is 20 f eet long but microvilli give it the same surf ace area as a 300 square f oot swimming pool Inside the Villi are the blood and lymph vessels (lacteal is the term f or the lymph vessels inside the villi. General anatomy Duodenum - f irst 25 cm small intestine, and this is where pancreas and liver secretions enter the small intestine Jejunum - next 2 f eet but it serves the same absorption f unctions as the ileum (In Latin it means empty because f or some unknown reason in a cadaver, this section is always empty of f luid) Ileum - remaining 15 f eet, is where the majority of the absorption occurs Small Intestine peristalsis MMC (migrating motility complex) is the term f or the small moving pockets of chyme in the intestine Small portions of chyme move down intestine together taking 90 to 120 min reach ilieum Brush border of the intestine greatly increases the surf ace area f or absorption 200 MILLION villi per square millimeter are located on the wall of the intestine Lymph tissue in mucosa is present MALT - mucosa associated lymphoid tissue) Solitary lymph nodules Peyers patches (groups of nodules) Small Intestine absorption Water soluble nutrients move into the blood stream by dif f usion or active transport Fat soluble nutrients take one of 2 routes into the body Small f atty acids can go in the blood stream Long chain f atty acids and monoglycerides must go into lacteals (Lymph) Water absorption is via Osmosis Small Intestine Enzymes Major chemicals used in the small intestine come f rom the Pancreas Stomach acid is neutralized by the secretion of base by the liver and pancreas Liver also secretes bile salts which aid in the aid absorption of f at There are some enzymes in the small intestine wall Chapter 24 Digestion Craig S Nelson DO page 6 Large intestine p 983 Receives chyme f rom small intestine, and continues moving it by peristalsis Major concern is water conservation f rom unwanted ingested material 5 f eet long f rom the beginning at the cecum to the end at the anus Large intestine Has no villi as there is no major absorption of anything but water in the large intestine Haustra are tonic (continuous) contractions that give the colon a segmented appearance Gastroileal ref lex, af ter eating, peristalsis intensif ies and empties colon Major regions Cecum is the portion where the small intestine attaches Appendix is a small appendage near cecum, whose f unction is unknown Colon major portion of the large intestine, and is divided into sections , and its contains change f rom a liquid to a solid as it passes through the Large Intestine Ascending (liquid waste) → Transverse → Descending (semi – solid) → Sigmoid Colon (solid f eces) → Rectum Rectum empties into the anal canal Two Rectal sphincter muscles Internal (involuntary) and an External (Voluntary) Defecation Empties Distention of rectal wall, ref lex Abdominal muscles increase pressure Final stage of digestion via bacteria that live in colon. Cause f latulence if excessive Diarrhea – increased Constipation - decreased Liver p 966 Heaviest gland in the body, weighing about 3 pounds It is made up of 2 lobes , a small lef t and a larger right lobe Falcif orm ligament separates lobes and help hold them in place in the abdomen Round ligament (ruminants of umbilical vein) is f ree edge of f alcif orm ligament Liver Lobule is the f unctional unit of liver, it contains - Hepatocytes which are the cells that make up the liver - Sinusoids capillaries that carry blood through the liver lobule and send the blood to the Central vein - Bile Canaliculi, carries bile into bile duct Duel blood supply to the Liver - blood f rom both systemic arteries and veins Hepatic Artery brings oxygenated blood aorta to the sinusoid Hepatic portal vein brings nutrient rich venous blood f rom digestive tract - Both the artery and the vein dump blood into Hepatic sinusoid which runs to Hepatic Vein - Hepatic Vein carries blood to Inf erior Vena Cava Chapter 24 Digestion Craig S Nelson DO page 7 Liver functions 1. Liver makes Bile which Emulsif ies the absorbed f at. This makes the f at more water soluble, and easier to absorb and transport in the blood Bile is secreted by hepatocytes into bile canaliculated which lead into duct system Every day hepatocytes secret 1 liter of bile Contains the Conjugated bilirubin, which is the primary pigment in bile (bilirubin is f rom hemoglobin metabolism) Bile made is made all of the time and is stored in the Gall bladder and then used when it is needed During a meal, the hormone CCK relaxes Sphincter of Oddi and contracts gall bladder, expelling the bile 2. Provides sugar f or the body by placing the sugar in the blood When glucose is needed, the liver can break down all 4 macromolecules to f orm glucose 3. Builds up the body through anabolic reactions Energy is not needed it can make all f our basic macromolecules (Carbohydrates, Lipids, Proteins, Amino Acids) 4. Makes many essential enzymes and proteins that are used in the body 5. Detoxif ies any chemicals that the body does not what in the blood 6. Excretion of bilirubin – hemoglobin metabolism product which is secreted in the bile 7. Storage – The liver stores glycogen, vitamins, and minerals, 8. Phagocytosis – Kupf f er cells clean blood of old worn out blood cells and debris 9. Activation of Vitamin D occurs in the liver Pancreas p 964 Anatomy of the pancreas 1. Head – near duodenum 2. Body – narrowing middle 3. Tail – tapers to point Ductal system Pancreatic duct joins Common Bile duct, Enters Small Intestine through the Sphincter of Oddi Exocrine gland – 99% of the cells in the pancreas are f or this purpose (Acini are clusters of cells that serve this f unction) The pancreas is main f unction is that of Exocrine gland, secreting enzymes into the duodenum Endocrine gland – 1% of the cells in the pancreas are f or this purpose. The pancreas makes two especially important digestive hormones in the Islets of Langerhans Alpha cells make Glucagon, the f asting hormone that raises low blood serum glucose levels Beta cells make Insulin, the digesting hormone that lowers high blood serum glucose levels Pancreatic Juice 1 to 1.5 liters day is produced and it is a mixture of water, salt, bicarbonate ion, and enzymes It has an enzyme that will break down every one of the 4 major macromolecules Many enzymes are secreted in an inactive f orm (so that they don’t dissolve the pancreas) and are activated in the small intestine Chapter 24 Digestion Craig S Nelson DO page 8 Ductal system for Liver and Pancreas Both empty into the duodenum (2% of humans have them empty separately) through common opening System of ducts Right hepatic \ Lef t hepatic / Small Intestine >Common hepatic \ > Common Bile → Hepatopancreatic duct → Sphincter of Oddi → / Gall Bladder → Cyst duct / | | ^ . | Pancreatic duct -----------------------------------------------PHASES OF DIGESTION P 988 3 major digestive hormones 1. Gastrin – major - gastric secretion and motility minor – constricts esophageal sphincters. Relaxes pyloric and ileocecal sphincters Made in G cells of stomach 2. Secretin – major – secretion of pancreatic juices and bile f rom liver, HCO3- neutralizes HCl minor – inhibits gastric juice secretion Made in S cells of Small Intestine 3. Cholecystokinin – major – ejection of bile gall bladder, increases pancreatic juice secretion - relaxes sphincter of Oddi, opening of gall bladder duct into small intestine - induces f eeling of being f ull in the brain Minor – inhibits gastric motility Made in C cells of Small Intestine At least 10 other hormones in digestion, but these are the important ones Gastric Motility p 943 3 phases of gastric motility are known and they are all caused by dif f erent stimuli 1. Cephalic phase – Brain tells stomach to get ready because f ood is going to be eaten. Parasympathetic NS controls the gastric secretion and motility 2. Gastric phase – Food reaches stomach and it directly stimulates the secretion and motility 3. Intestinal phase – Food into the small intestine stimulates and secretion f rom the small intestine secretin and CCK which slow gastric secretion and motility prevents the small intestine f rom being overloaded.