Digestive System PDF

9/16/24 CHAPTER 8: DIGESTIVE SYSTEM Contents: I. Activities in the Digestive System II. Layers of the Digestive System III. Organs & Functions of the Digestive System IV.Movements & Secretions in the Digestive System V. Metabolism...

9/16/24 CHAPTER 8: DIGESTIVE SYSTEM Contents: I. Activities in the Digestive System II. Layers of the Digestive System III. Organs & Functions of the Digestive System IV.Movements & Secretions in the Digestive System V. Metabolism 2 3 1  9/16/24 FUNCTIONS OF THE DIGESTIVE SYSTEM: 1. Ingestion (take in food) Food and water are taken into body the body through the mouth. 2. Digestion (break down the food) Is the mechanical and chemical breakdown of foods into smaller components that can be absorbed. Two Processes of Digestion: a) Mechanical Mastication Mechanical digestion breaks down food into smaller particles. b) Chemical Enzymes Chemical digestion consists of hydrolysis reactions that break down dietary macromolecul es into their monomers, which allows for the absorption of nutrients. DVD/MVC copy 4 University of the Assumption FUNCTIONS OF THE DIGESTIVE SYSTEM: 3. Absorption (absorb digested molecules) The small molecules that result from digestion are absorbed through the walls of the intestine for use in the body. 4. Provide Nutrients The process of digestion and absorption provides the body with water, electrolytes, and other nutrients such as vitamins and minerals. 5. Elimination (eliminate wastes) Undigested material, such as fiber from food, plus waste products excreted into the digestive tract are eliminated in the feces. DVD/MVC copy 5 University of the Assumption 2  9/16/24 6 7 3  9/16/24 The Digestive Tract consists of 4 major layers: DVD/MVC copy 8 University of the Assumption 4 Layers of the Digestive Tract 1) MUCOSA Ø The innermost layer. Ø Itis consists of three layers: (1) the mucous epithelium (a tissue producing mucus), which is moist stratified squamous epithelium in the mouth, oropharynx, esophagus, and anal canal and simple columnar epithelium in the remainder of the digestive tract; (2) the lamina propria, which is a loose connective tissue (3) the muscularis mucosa, a thin smooth muscle layer. 9 4  9/16/24 2) Submucosa ØIs a thickconnective tissue layer containing nerves, blood vessels, and small glands that lies beneath the mucosa. ØThe nerves of the submucosa form the submucosal plexus, a parasympathetic ganglionic plexus. 3) Muscularis (Muscular Layer) Ø Itconsists of an inner layer of circular smooth muscle and an outer layer of longitudinal smooth muscle. Ø the myenteric plexus, which consists of nerve fibers and parasympathetic cell bodies, is between these two muscle layers. Ø Together, the submucosal and myenteric plexuses constitute the intramural (meaning, “within the walls”) plexus. This plexus is extremely important in the control of movement and secretion. 5  9/16/24 4) Adventitia or Serosa Ø The fourth layer of the digestive tract is a connective tissue layer called either the serosa or the adventitia Ø it protrude into the peritoneal cavity Ø have a serosa (visceral peritoneum ) as the outermost layer 12 ORGANS & FUNCTIONS OF THE DIGESTIVE SYSTEM The Alimentary tract (7) 1. Oral Cavity (Mouth) i. Tongue ii. Teeth iii. Palate & Tonsils iv. Salivary Glands 2. Pharynx 3. Esophagus 4. Stomach 5. Small Intestine 6. Large Intestine 7. Rectum and Anal canal The Accessory Organs (3) a. Salivary Glands b. Pancreas i) as Exocrine Gland ii) as Endocrine Gland 13 c. Liver and the Biliary Tract 6  9/16/24 ORGANS & FUNCTIONSOF THE DIGESTIVE SYSTEM The Alimentary tract (7) 1. Oral Cavity (Mouth) i. Tongue ii. Teeth iii. Palate & Tonsils iv. Salivary Glands 2. Pharynx 3. Esophagus 4. Stomach 5. Small Intestine 6. Large Intestine 7. Rectum and Anal canal 14 THE ALIMENTARY TRACT 1) Oral Cavity (mouth) Ø Is the first part of the digestive tract. Ø It is bounded by the lips and cheeks and contains the teeth and tongue. These are important in the process of mastication or chewing. 15 7  9/16/24 THE ALIMENTARY TRACT Ø Lips –are muscular structures formed mostly by the orbicularis oris muscle. Ø Cheeks – form the lateral walls of the oral cavity. It also help form words during the speech process. Ø Buccinator muscles – are located within the cheeks and flatten the cheeks against the teeth. 16 Four Parts of the Oral Cavity i. Tongue ØIs a large muscular organ that occupies most of the oral cavity. ØThere is an attachment to the floor of the mouth by a thin fold of tissue called the frenelum. ØPlay a major role in the process of swallowing. ØIs a major sensory organ for taste, as well as one of the major organs of speech. 17 8  9/16/24 The Structure of the TONGUE 18 Four Parts of the Oral Cavity ii. Teeth Ø There are 32 permanent teeth in the normal adult mouth, located in the mandible and maxilla Ø It can be divided into quadrants: right upper right lower left upper left lower Ø In adult, each quadrant contains: one central and one lateral incisor one canine first and second premolars first, second and third molars (wisdom tooth) – they appear in a person’s late teens or early twenties. 9  9/16/24 20 Four Parts of the Oral Cavity iii. Palate and Tonsils The palate or roof of the oral cavity consist of two parts: Hard palate - Anterior part which contain bone Soft palate - The posterior portion consists of skeletal muscle and connective tissue. The uvula is the posterior extension of the soft palate. The tonsils are located in the posterior walls of the oral cavity, in the nasopharynx, and in the posterior surface of the tongue. 10  9/16/24 Four Parts of the Oral Cavity iv. Salivary Glands There are three pairs of salivary glands: 1. Parotid Glands – are serous glands located just anterior to each ear. They are the largest salivary glands. 2. Submandibular Glands – are located below the mandible and they produce more serous than mucous secretions. 3. Sublingual Glands – are located below the tongue and they are the smallest pairs of salivary glands. They produce primarily mucous secretions. Each gland has 10-12 small ducts opening onto the floor of the oral cavity 23 11  9/16/24 Secretions of the Oral Cavity Saliva vContains lysosyme, which has a weak bacterial action and prevents bacterial infection in the mouth by washing the oral cavity vIs secreted at the rate of approximately 1 liter/day vThe serous part of saliva is produced mainly by the parotid and submandibular glands and contains a digestive enzyme called salivary amylase, which breaks down glucose molecules in starch and other polysaccharides to produce disaccharides, maltose and iso-maltose that enhances the sweet taste of food. 24 Secretions of the Oral Cavity Saliva v Secreted from serous and mucous cells of salivary glands Serous: enzymes, ions, and mucin Mucous: produce mucous v 97-99.5% water and slightly acidic solution containing Electrolytes Digestive enzyme: salivary amylase Proteins: mucin, lysozyme, defensins, and IgA Metabolic wastes: urea and uric acid 25 12  9/16/24 THE ALIMENTARY TRACT 2. PHARYNX (throat) Ø connects the mouth with the esophagus. Ø consists of three parts: the nasopharynx, oropharynx and laryngopharynx. THE ALIMENTARY TRACT 3. ESOPHAGUS Ø Connects to the pharynx to the stomach. Ø The upper and lower esophangeal sphincters regulate movement. Ø Is that part of the digestive tube that extends between the pharynx and the stomach. Ø It is about 25 cm long and lies in the mediastinum, anterior to the vertebrae and posterior to the trachea. Ø It passes through the esophageal hiatus (opening) of the diaphragm and ends at the stomach. Ø The esophagus transports food from the pharynx to the stomach through peristalsis. 27 13  9/16/24 28 Movements in the Oral Cavity Mastication ØFood taken into the mouth is chewed or masticated by the teeth (Mechanical breakdown of food) and this is accomplished by the teeth, which cut, tear, and crush the food. Deglutition (swallowing) ØCan be divided into three phases: 1) Voluntary phase a bolus or mass of food, is formed in the mouth. the bolus is pushed by the tongue against the ha rd palate, forcing the bolus toward the poste rior part of the mouth and into the oropharynx. 2) Pharyngeal phase The soft pa late closes the nasopharynx, and epiglottis closes the opening into the la rynx (windpipe) and then move the bolus to the esophagus. The epiglottis covers the windpipe when food or liquid is swallowed enabling it to mov e to the esophagus down to the stomach. 3) Esophageal phase A wave of constriction (pe ristalsis) moves the food down the esophagus to the stomach. 29 14  9/16/24 THE ALIMENTARY TRACT 4. STOMACH Ø It is a J-shaped organ and a temporary “storage tank” where chemical breakdown of proteins begins and food is converted from a bolus to chyme. Ø Gastric glands produce mucus, hydrochloric acid, pepsin, gastrin and intrinsic factor. Ø The openings of the stomach are the Gastroesophageal opening to the esophagus Pyloric orifice to the duodenum The major regions are the a) Cardiac part is connected to the esophagus b) Fundus c) Body d) Pyloric part is continuous with the duodenum through the pyloric sphincter The lateral sides of the stomach consist of greater and lesser curvatures ØThe wall of the stomach consists of a) External serosa b) Muscle layer (longitudinal, circular, and oblique) c) Submucosa d) Simple columnar epithelium Surface mucous ce lls: produce an alkaline mucous with bica rbonate , which coa ts and protects the stomach lining ØAn empty stomach has a volume of 50 mL but can hold about 4 liters of food ØWhen empty one can see the folds called rugae (submucosa and mucosa) ØReflux (backflow) of stomach contents into the esophagus is prevented in part by the tonus of the gastroesophageal sphincter, located at the interior end of the esophagus. 15  9/16/24 Cardiac region Pyloric region 32 Parts of the Stomach 1)Cardiac opening - the opening from the esophagus into the stomach which is near the heart. 2)Fundus – is the most superior part of the stomach. 3)Body – is the largest part stomach forming a greater curvature on the left and lesser curvature on the right. 4)Pyloric opening – the opening from the stomach through the small intestine. 5)Pyloric sphincter – thick ring of smooth muscle that surrounds the pyloric opening. 6)Pyloric region – region of the opening near the pyloric opening. 7)Rugae – large folds when the stomach is empty. 8)Gaspits – tube-like opening for the gastric glands. 9)Epithelial cells of the stomach is divided into five groups: i) Surface mucous cells – produce mucus and protect the stomach ii) Mucous neck cells – produce mucus iii) Parietal cells – produce hydrochloric acid and intrinsic factor vi) Endocrine cells – produce regulatory hormones v) Chief cells – produce pepsinogen (a precursor of the protein-digesting enzyme pepsin) DVD/MVC copy 33 University of the Assumption 16  9/16/24 34 17  9/16/24 SECRETIONS OF THE STOMACH 1. Mucus – lubricates and protects the stomach lining. 2. Hydrochloric acid (HCl) - kills microorganisms and activates pepsin. 3. Pepsinogen - is converted by HCl to an active enzyme Pepsin, which breaks down proteins. 4. Intrinsic factor – binds with vitamin B12 which is important in DNA synthesis and RBC production. 5. Gastrin & Histamine - helps regulate stomach secretions and it also stimulates intestinal motility. These secretions are called “GASTRIC JUICE” DVD/MVC copy 36 University of the Assumption REGULATIONS OF THE STOMACH SECRETIONS 1. Cephalic phase – during this phase, the stomach secretions are initiated by the sight, smell, taste or thought of food. 2. Gastric phase – during this phase, partially digested proteins or distention of the stomach also promotes secretions. 3. Intestinal phase – during this phase, acidic chyme in the duodenum stimulates neural reflexes and the secretion of hormones that induce and then inhibit gastric secretions. (Secretin, gastric inhibitory polypeptide and cholecystokinin inhibit gastric secretion) DVD/MVC copy 37 University of the Assumption 18  9/16/24 MOVEMENT IN THE STOMACH Mixing waves ØMix the stomach contents with the stomach secretions to form chyme. vChyme is ingested food mixed with gastric juice Peristaltic waves ØMove the chyme into the duodenum. Hunger contractions Vomiting Reverse peristalsis 38 39 19  9/16/24 THE ALIMENTARY TRACT 5. SMALL INTESTINE Ø The small intestine is the primary organ of digestion and absorption. Ø The entire small intestine is about 6 m long (range: 4.6–9 m). Ø It consists of three parts: a. Duodenum is about 25 cm or 10-12 inches long. It is where the bile and pancreatic duct empty their secretions. b. Jejunum constituting about 2/5 of the total length of the small intestine, is about 2.5m or 8 ft. long. c. Ileum constituting 3/5 of the small intestine, is about 3.5m or 12 ft. long. Two major accessory glands, the liver and the pancreas, are associated with the duodenum. DVD/MVC copy 40 University of the Assumption 41 20  9/16/24 SECRETIONS OF THE SMALL INTESTINE ØSecretions from the mucosa of the small intestine mainly contain a) mucus, b) ions and c) water. ØIntestinal secretions lubricate and protect the intestinal wall from the acidic chyme and the action of digestive enzymes. ØThey also keep the chyme in the small intestine in a liquid from to facilitate the digestive process. ØMost of the secretions entering the small intestine are produced by the intestinal mucosa, but the secretions of the liver and the pancreas also enter the small intestine and play important role in the digestion process. DVD/MVC copy 42 University of the Assumption Movements in the Small Intestine Peristalsis - A wave of relaxation of the circula r muscles is followed by a wave of strong contra ction of the circula r muscles, which propels the bolus of food through the digestive tract. Segmental contractions – are propagated for only short distances and function to mix intestinal contents. Borborygmus (borborygmi) is the rumbling sound made by gas and fluids moving through the intestines. PERISTALSIS 43 21  9/16/24 Absorption in the Small Intestine Major function of the small intestine is the absorption of nutrients. Most absorption occurs in the duodenum and jejunum, although some absorption also occurs in the ileum. 44 THE ALIMENTARY TRACT 6. LARGE INTESTINE Ø It is consists of the following: i. Cecum – the proximal end of the large intestine Is a sac that extends inferiorly about 6 cm past the ileocecal junction. Attached to it is the appendix (tube about 9 cm long) ii. Colon – is about 1.5 to 1.8 meters long ( < > 5ft) Consists of four parts: Ascending, Transverse, Descending and Sigmoid colon iii. Rectum Is a straight, muscular tube that begins at the termination of the sigmoid colon ends at the anal canal. iv. Anal canal – the last 2 to 3 cm. of the digestive tract Begins at the inferior end of the rectum and ends at the anus. It forms the internal anal sphincter and external anal sphincter. DVD/MVC copy 45 University of the Assumption 22  9/16/24 THE ALIMENTARY TRACT ØThe large intestine reabsorbs water and electrolytes from chyme remaining in the alimentary canal, and also forms and stores feces. ØIn addition, the large intestine is densely populated with bacterial flora that Ferment indigestible carbohydrates Release irritating acids and gases (flatus) Synthesize B complex vitamins and vitamin K Constitute about 30% of the dry weight of the feces ØThe large intestine, or colon, receives material from the small intestine after nutrients have been absorbed. ØAt the junction of the small and large intestines is a pouch, or cecum, with a finger-like extension called the vermiform appendix. ØThe colon is larger in diameter, but much shorter than the small intestine. ØMuch of the water used in digestion is reabsorbed here, as well as ions. 23  9/16/24 Functions of the Large Intestine 1. Feces production and water absorption. 2. It takes much longer for material to move through the large intestine than the small intestine. 3. In the colon, chyme is converted to feces. 4. Mass movements occur three to four times a day. 5. Defecation is the elimination of feces. 6. Reflex activity moves feces through the internal anal sphincter. 7. Voluntary activity regulates movement through the external anal sphincter. DVD/MVC copy 48 University of the Assumption 49 24  9/16/24 THE ALIMENTARY TRACT 7. RECTUM & ANAL CANAL Ø The rectum is a straight tube that ends at the anal canal Ø The anal canal is surrounded by an internal anal sphincter (smooth muscle) and an external anal sphincter (skeletal muscle) that controls the opening of the rectum or anus. 50 ORGANS & FUNCTIONS OF THE DIGESTIVE SYSTEM The Accessory Organs (3) a. Salivary Glands b. Pancreas i) as Exocrine Gland ii)as Endocrine Gland c. Liver and the Biliary Tract DVD/MVC copy 51 University of the Assumption 25  9/16/24 1) Salivary Glands Ø Digestion begins in the mouth with the mechanical action of teeth and the chemical action of digestive enzymes present in saliva. Ø Salivary amylase breaks starch into the disaccharide maltose. Ø Saliva lubricates the contents of the mouth. Ø The tongue manipulates food into a bolus as it is chewed and initiates the swallowing process. Ø The tongue also secretes lingual lipase, an enzyme that is activated by the acid in the stomach. It chemically digests fat after the food has been swallowed. Ø The salivary glands secrete saliva. 52 1) Salivary Glands Ø This fluid moistens food particles, helps bind them, and begins the chemical digestion of carbohydrates. Ø Saliva is also a solvent, dissolving foods so that they can be tasted, and it helps cleanse the mouth and teeth. Ø Within a salivary gland are two types of secretory cells - serous cells and mucous cells. These cells are present in varying proportions within different salivary glands. Serous cells produce a watery fluid that contains the digestive enzyme amylase. Ø This enzyme splits starch and glycogen molecules into the disaccharide maltose - the first step in the chemical digestion of carbohydrates. Mucous cells secrete a thick liquid called mucus, which binds food particles and lubricates during swallowing. 53 26  9/16/24 SALIVARY GLANDS 54 2) Pancreas v The pancreas is an endocrine and exocrine gland. v Endocrine function > control blood nutrient levels. v Exocrine function > produce bicarbonate ions and digestive enzymes. FUNCTIONS OF THE PANCREAS 1) The pancreas produces bicarbonate (HCO3-) and digestive enzymes 2) Acidic chyme stimulates the release of a watery bicarbonate solution that neutralizes acidic chyme. 3) Fatty acids and amino acids in the duodenum stimulate the release of pancreatic enzymes. DVD/MVC copy 55 University of the Assumption 27  9/16/24 56 3. Liver Ø Weights about 1.36 kg (3 lbs) and is located in the right upper quadrant (RUQ) of the abdomen, tucked against the inferior surface of the diaphragm. Ø It consists of four lobes: Two major lobes (separated by falciform ligament) Left Right Two smaller lobes Caudate Quadrate The liver receives blood from two sources: 1. Hepatic artery – brings oxygenenated blood to the liver which supplies liver cells with oxygen. 2. Hepatic portal vein – carries blood that is unoxygenated but rich in absorbed nutrients and othe r substances from the digestive tract to the liver. DVD/MVC copy 57 University of the Assumption 28  9/16/24 58 Functions of the Liver 1.It produces Bile, which contains bile salts that emulsify fats. FBile plays an important role in digestion by diluting and neutralizing stomach acid. It also plays part in fat digestion and absorption. FThe liver secretes about 700mL of bile /day FBile or gall is a bitter yellow or green alkaline fluid secreted by the liver and is stored in the gallbladder (between meals and upon eating is discharged into the duodenum where the bile aids the process of digestion of lipids.) FBile salts emulsify fats, breaking fat globules into smaller droplets FBile also contains excretory products such as bile pigments, cholesterol and fats. FBilirubin is a yellow bile pigment that results from the breakdown of hemoglobin. FBilirubin is excreted in BILE, and its levels are elevated in certain diseases. It is responsible for the yellow color of BRUISES and the yellow discolorations in JAUNDICE (yellow coloration of the skin due to increase bilirubin level in the blood) DVD/MVC copy 59 59 University of the Assumption 29  9/16/24 Functions of the Liver 2. It stores and processes nutrients – liver cells remove sugar from blood and store it in the form of glycogen. It also stores fat, vitamins A, B12, D, E and K, copper and iron. liver cells convert amino acids to lipids or glucose, fats to phospholipids, vitamin D to its active form. 3. Detoxifies harmful chemicals or molecules – liver cells remove ammonia and convert it to urea, which is eliminated in the urine. Other substances are detoxified and secreted in the bile or excreted in the urine. 4. Produce new molecules - the liver synthesizes blood proteins such as albumins, fibrinogen, globulins and clotting factors. DVD/MVC copy 60 University of the Assumption The Liver-Gallbladder-Pancreas & Duct System 1. The hepatic ducts from the liver lobes combine to form the common hepatic duct 2. The common hepatic duct combines with the cystic duct from the gallbladder to form the common bile duct. 3. The common bile duct and the pancreatic duct combine to form the hepatopancreatic ampulla. 4. The hepatopancreatic ampulla empties into the duodenum at the duodenal papilla. 5. The accessory pancreatic duct also empties pancreatic secretions into the duodenum DVD/MVC copy University of the Assumption 61 30  9/16/24 62 Metabolism Metabolism is the total of all the chemical reactions that occur in the body. ØAnabolism – is the energy- requiring process by which small molecules are joined to form larger ones. ØCatabolism – is the energy-requiring process by which large molecules are broken down into smaller ones. 63 31  9/16/24 Digestion – is the breakdown of food to molecules that are small enough to be absorbed into the circulation 2 Types of Digestion: 1.Mechanical Digestion – breaks large food particles down to smaller ones and takes place in the oral cavity. 2.Chemical Digestion – involves breaking of covalent chemical bonds in organic molecules by digestive enzymes where carbohydrates are broken down into monosaccharides, proteins into amino acids and fats into fatty acids and glycerol. Absorption vbegins in the stomach, where small lipid-soluble molecules can diffuse through the stomach epithelium into the circulation. vMost absorption occurs in the duodenum and jejunum, although some also occurs in the ileum. Transport – requires carrier molecules and includes facilitated diffusion, cotransport and active transport. DVD/MVC copy University of the Assumption 64 65 32  9/16/24 Water & Minerals / ions Ø Approximately 9 liters of water enters the digestive tract each day. Ø About 2 liters is ingested in food and drinks and the remaining 7 liters is from digestive secretions. Ø About 92% of the water is absorbed in the small intestine and 7% is absorbed in the large intestine and 1% leaves the body in the feces. Ø Can move either direction across the intestinal wall, depending on osmotic conditions. Ø Approximately 99% of the water entering the intestine is absorbed. Ø Most minerals are actively transported across the intestinal wall. 66 33  9/16/24 Chapter 9: Circulatory System: The Heart, Blood, Blood Vessels, Circulation 68 Chapter 9: BLOOD 69 34  9/16/24 Blood is the primary transport medium of the body. Ø Oxygen enters blood in the lungs and is carried to cells and tissues of the body. üAround 98.5% of O2 is transported in the body by the RBC. Ø CO2 (produced by cells) is carried in blood to the lungs, where it is expelled. üAround 23% of CO2 is transported in the body by the RBC. 70 ØIngested nutrients, electrolytes, & H2O are transported by the blood from the digestive tract to cells ØWaste products are transported from cells via the blood to the kidneys for elimination in urine. DVD/MVC copy University of the Assumption 71 35  9/16/24 FUNCTIONS OF BLOOD 1. Transport of gases, nutrients, waste products, processed molecules and regulatory molecules. 2. Regulation of pH, fluid and ion balance. 3. Maintenance of core body temperature. 4. Protection against foreign substances such as microorganisms and toxins. 5. Blood clotting prevents fluid and cell loss and is part of tissue repair. DVD/MVC copy University of the Assumption 72 COMPOSITIONS OF BLOOD Ø Blood is a type of connective tissue that consists of 1) plasma – liquid portion 2) formed elements – RBC/WBC/platelets Ø Blood isa sticky, opaque fluid with a metallic taste Ø Color varies from scarlet to dark red Ø ThepH of blood is 7.35–7.45 Ø Temperature is 38 °C Ø Blood accounts for approximately 8% of body weight Ø Average volume: 5–6 L for males, and 4–5 L for females 73 36  9/16/24 COMPOSITIONS OF BLOOD 1) PLASMA Ø Pale yellow fluid containing over 100 solutes Ø Mostly water (91%) Ø Contains proteins (7%) a) Albumin (58% of the plasma proteins) Helps maintain osmotic pressure b) Globulins (38% of the plasma proteins) Immunity: antibodies and complement Transport: bind to molecules such as hormones Clotting Factors c) Fibrinogen (4% of the plasma proteins) Converted to fibrin during clot formation DVD/MVC copy University of the Assumption 74 COMPOSITIONS OF BLOOD 1) PLASMA ØOther substances (2%) i. Ions (electrolytes): sodium, potassium, calcium, chloride, bicarbonate ii. Nutrients: glucose, carbohydrates, amino acids iii. Waste products: lactic acid, urea, creatinine iv. Respiratory gases: oxygen and carbon dioxide DVD/MVC copy University of the Assumption 75 37  9/16/24 76 Hematocrit: the % of RBCs out of the total blood volume 77 38  9/16/24 COMPOSITIONS OF BLOOD 2) FORMED ELEMENTS a) Erythrocytes or red blood cells (RBCs) About 95% of formed elements RBCs have no nuclei or organelles b) Leukocytes or white blood cells (WBCs) Most of the remaining 5% of formed elements Only WBCs are complete cells Five types of WBCs c) Platelets v Just cell fragments Ø Most formed elements survive in the bloodstream for only a few days DVD/MVC copy University of the Assumption 78 79 39  9/16/24 DVD/MVC copy University of the Assumption 80 40  9/16/24 Production of Formed Elements ØMost blood cellsdo not divide but are renewed by stem cells (hemocytoblasts) in bone marrow. Hematopoiesis: is blood cell production that occurs in different locations before and after birth; Fetus F Liver, thymus, spleen, lymph nodes, and red bone marrow After birth F In the red bone marrow of the P Axial skeleton and girdles P Epiphyses of the humerus and femur F Some white blood cells are produced in lymphatic tissues ØHemocytoblasts give rise to all formed elements Growth factors determine the type of formed element derived from the stem cell DVD/MVC copy University of the Assumption 82 Hematopoiesis 83 41  9/16/24 Types of Blood Cells 1. (RBC) Red Blood Cells or Erythrocytes 2. (WBC) White Blood Cells or Leukocytes 3. Platelets or Thrombocytes 84 i) RBC or Erythrocytes Ø The main component of a RBC is pigmented protein hemoglobin (Hb). v Oxygen content determines blood color P Oxygenated: bright red P Deoxygenated: darker red Ø Each protein called a globin, is bound to one heme, red-pigmented molecule. Ø The heme molecules are converted to bilirubin, a yellow pigmented molecule taken up by the liver and released into the small intestine as part of the bile. üThe heme group in red blood cells contain IRON. üOld heme molecules are removed from the body in the form of Bile pigments in the feces. Ø If the liver is not functioning normally, flow is hindered; bilirubin builds up in the circulation and produces jaundice (a yellower color of the skin.) One RBC contains 250 million Hb groups thus it can carry 1 billion molecules of O2 85 42  9/16/24 i) RBC or Erythrocytes Ø Normal RBC are biconcave disks about 7.5 cm in diameter with edges that are thicker than the center of the cell. Ø Compared with a flat disk of the same size, the biconcave shape increases the surface area of the RBC. Ø The greater surface area makes the movement of gases into and out of the RBC more rapid. Ø In addition, the RBC can bend or fold around its thin center, decreasing its size and enabling it to pass more easily through small blood vessels. Ø Dying RBCs are “engulfed” by macrophages located in the spleen or liver 86 i) RBC or Erythrocytes Transport of Oxygen and Carbon Dioxide Ø Oxygen Transported bound to hemoglobin ~98.5% Dissolved in plasma ~1.5% Each Hb molecule binds four oxygen atoms in a rapid and reversible process Ø Carbon dioxide Dissolved in plasma ~7% Transported as bicarbonate(HCO3 –) ~70% Chemically bound to hemoglobin ~23% DVD/MVC copy University of the Assumption 87 43  9/16/24 RBC Production ØIn response to decreased blood oxygen (hypoxemia), the kidneys release the hormone erythropoietin. Ø Erythropoietin stimulates erythrocyte production in the red bone marrow. This process increases blood oxygen levels 88 Lifespan / Destruction of RBC & other blood components: RBC WBC 89 44  9/16/24 ii) (WBC) White Blood Cells or Leukocytes Ø Are the formed elements in the blood that are involved in “immunity” Ø WBC are spherical cells that lack hemoglobin. Ø They are less numerous but larger than RBC and each has a nucleus. Ø Make up 1% of the total blood volume Ø Can leave the blood and by amoeboid movement through the tissues. Functions of WBC: FTo protect the body against invading microorganism. FTo remove dead cells and debris from the tissues by phagocytosis Phagocytosis – is the process of ingestion and digestion of cells of substances such as cells, bacteria, cell debris, and foreign particles. 90 Two Main Types of Leukocytes (WBC) 1) GRANULOCYTES – are those containing large granules. Three kinds of Granulocytes: a) Neutrophils Ø the most common type of white blood cells. Ø have small cytoplasmic granules that stain with both acidic and basic dyes. Ø remain in the blood for a short time (10-12 hours), move into other tissues, and phagocytize microorganisms (bacteria slayers) and other foreign substances. Ø dead neutrophils, cell debris and fluid can accumulate as pus at site of infections. DVD/MVC copy University of the Assumption 91 45  9/16/24 Two Main Types of Leukocytes (WBC) b) Basophils Ø the least common among of all white blood cells. Ø contain large cytoplasmic granules that stain blue or purple with basic dyes. Ø release histamine that promote inflammation. Ø they also release heparin, which prevents the formation of clots. DVD/MVC copy University of the Assumption 92 Two Main Types of Leukocytes (WBC) c) Eosinophils Øcontain cytoplasmic granules that stain brick red with eosin, an acidic stain. Ørelease chemicals that reduce inflammation. ØIn addition, chemicals from eosinophils are involved with the destruction of certain worm parasites. DVD/MVC copy University of the Assumption 93 46  9/16/24 Three kinds of GRANULOCYTES 94 Two Main Types of Leukocytes (WBC) 2) AGRANULOCYTES – are those with very tiny granules that cannot be seen with the light microscope. Two Kinds of Agranulocytes: a) Monocytes > Are the largest of the white blood cells. > After they leave the blood and enter tissues, they enlarged and become macrophages which phagocytize bacteria, dead cells, cell fragments, and any other debris within the tissues. DVD/MVC copy University of the Assumption 95 47  9/16/24 Two Main Types of Leukocytes (WBC) b) Lymphocytes > are the smallest of the white blood cells and they play an important role in the body’s immune response such as production of antibodies and other chemicals that destroy microorganisms, contribute to allergic reactions, rejects grafts, control tumors and regulate the immune system. ØThere are two types of lymphocytes: T cells and B cells ü B cells Stimulated by bacteria or toxins Give rise to plasma cells, which produce antibodies P T cells Protect against viruses and other intracellular microorganisms Attack and destroy the cells that are infected DVD/MVC copy University of the Assumption 96 Two kinds of AGRANULOCYTES 48  9/16/24 iii) Platelets or Thrombocytes Ø are minute fragments of cells, each consisting of a small amount of cytoplasm surrounded by a cell membrane. Ø There are approx. 200,000 – 500,000 platelets/uL of blood. Ø They are produced in the red bone marrow from megakaryocytes (large nucleus cell). Ø They play an important role in blood clotting that is accomplished in 2 ways: a)the formation of platelet plugs, which seal holes in small vessels b)the formation of clots, which help seal off larger wounds in the vessels. 98 TERMINOLOGIES Transfusion Ø Is the transfer of blood or blood components from one individual to another. Infusion Ø Is theintroduction of a fluid other than blood, such as saline or glucose solution, into the blood. Agglutination Ø The process to which cells stick together to form clumps. Hemolysis Ø The rupture of red blood cells. Donor ØA person who gives blood Recipient ØA person who receives blood DVD/MVC copy University of the Assumption 99 49  9/16/24 TERMINOLOGIES Antigens ØAre molecules on the surfaces of the red blood cells. ØA substance that when introduced into the body stimulates the production of an antibody. ØAntigens include toxins, bacteria, foreign blood cells, and the cells of transplanted organs. ØSelf-antigens are produced by the body, and foreign antigens are introduced into the body. TERMINOLOGIES Antibodies or Immunoglobulins (Ig) Ø Are proteins found in the plasma that are responsible for anti-body mediated immunity; bind specifically to an antigen. Ø are gamma globulin proteins that are found in blood or other bodily fluids, and are used by the immune system to identify and neutralize foreign objects, such as bacteria and viruses. 50  9/16/24 Two Types of Blood Groups 1) A-B-O Blood Group ØThe ABO blood groups consists of: Two antigens (A and B) on the surface of the RBCs Two antibodies in the plasma (anti-A and anti-B) ANTIGENS ANTIBODIES Blood type Present Present A B Anti-A Anti-B AB + + – – B – + + – A + – – + O – – + + Two Types of Blood Groups 2) Rh Blood Group Ø Rh(+) blood has Rh antigens, whereas Rh(-) does not. Ø Antibodies against the Rh antigen are produced when an Rh(-) person is exposed to Rh(+) blood. Ø The Rh blood group is responsible for hemolytic disease of the newborn, which can occur when the fetus is Rh(+) and the mother is Rh(-). DVD/MVC copy University of the Assumption 103 51 9/16/24 52  9/16/24 Preventing Blood Loss ØWhen a blood vessel is damaged, blood can leak into other tissues and interfere with normal tissue function, or blood can be lost from the body. ØA small amount of blood loss from the body can be tolerated, and new blood is produced to replace it. ØIf a large amount of blood is lost, death can occur CLOT FORMATION 106 HEMOSTASIS Hemostasis is the stoppage of bleeding, which is vitally important when blood vessels are damaged. > Following an injury to blood vessels, several actions may help prevent blood loss: (a) The vasoconstriction reduces blood loss (b) Platelets adhere to the exposed collagen fibers of a vessel wall, forming a platelet plug. (c) A clot forms as platelets and erythrocytes become enmeshed in fibrin threads. DVD/MVC copy University of the Assumption 107 53  9/16/24 (3) Stages of Blood Clot Formation Stage 1: Ø Damage to tissue or blood vessels activates clotting factors that activate other clotting factors, which leads to the production of prothrombinase. Stage 1 can be activated in 2 ways: a. Extrinsic pathway is initiated when clotting factors are released by the damaged blood vessel and perivascular tissue (i.e., the factors come from sources other than the blood). b. Intrinsic pathway is initiated when factor XII is activated or released when platelets degranulate (i.e., everything needed to initiate the pathway is present in the blood or platelets). Stage 2: Prothrombin is activated by prothrombinase to form thrombin. Stage 3: Fibrinogen is activated by thrombin to form fibrin, which forms the clot. DVD/MVC copy University of the Assumption 108 108 109 54  9/16/24 Control of Clot Formation vAnticoagulants – prevent clotting factors from forming clots such as antithrombin and heparin. Clot Retraction and Dissolution (Fibrinolysis) vAfter a clot has formed, it begins to condense to a more compact structure by a process known as clot retraction pulling the edges of the damaged tissue closer together. vSerum (a plasma without the clotting factors) is squeezed out of the clot during clot retraction. vFibrinolysis is clot breakdown or dissolution is accompanied by plasmin. DVD/MVC copy 110 University of the Assumption 55  9/16/24 Diagnostic Blood Tests: 1) COMPLETE BLOOD COUNT A) Red blood cell count (million/µL) D) White blood cell count Male 4.6-6.2 million/µL (WBCs/µL) Female 4.2-5.4 million/µL Male and Female 5000-9000 B) Hemoglobin Measurement WBCs/µL (grams of hemoglobin per/100mL of E) Differential white blood cell blood) count (the % of each type of WBC) Male 14-18 g/100mL Neutorphils – 60%-70% Female 12-16 g/100mL Lymphocytes – 20%-25% C) Hematocrit measurement (% volume of RBCs) Monocytes – 3%-8% Male 40%-52% Eosinophils – 2%-4% Female 38%-48% Basophils – 0.5%-1% Diagnostic Blood Tests: 1) COMPLETE BLOOD COUNT a)Red Blood Count (million/uL) Ø A drop of blood is approximately 50uL b) Hemoglobin Measurement (gms of hemoglobin/ 100ml of blood) Anemia is an abnormally low hemoglobin measurement which is either decrease RBC or decrease hemoglobin in each RBC 113 56  9/16/24 Diagnostic Blood Tests: c) Hematocrit Measurement (% volume of RBC) Ø A decreased hematocrit can result from a decreased number of normal-sized RBC or a normal number of small-sized RBCs. The hematocrit (Ht or HCT) or packed cell volume (PCV) or erythrocyte volume fraction (EVF) is the % of RBCs out of the total blood volume. d) White Blood Count (million/uL) Normal WBC count = 5000-9000 WBC/uL of blood. Leukopenia – lower than normal WBC count indicating decreased production or destruction of the red bone marrow. Leukocytosis – an abnormally high WBC count due to bacterial infections which increase the number of neutrophils. Leukemia – is a cancerous tumor of the red bone marrow. Centrifuge blood in the hematocrit tube at 10,000 rpm for 5 minutes 57  9/16/24 Diagnostic Blood Tests: 2) TYPE & CROSSMATCH Ø Blood Typing determines the ABO and Differential white blood cell Rh blood groups of a blood sample. count (the % of each type of WBC) Ø Crossmatch tests for agglutination reactions between donor and recipient Neutorphils – 60%-70% blood. Lymphocytes – 20%-25% Monocytes – 3%-8% 3) DIFFERENTIAL WHITE BLOOD Eosinophils – 2%-4% COUNT Ø Determines the percentage of each of Basophils – 0.5%-1% the five kinds of white blood cell count. 116 Diagnostic Blood Tests: 4) CLOTTING Ø Platelet Count & Prothrombin Time measure the ability of the blood to clot. Ø Normal platelet count = 250,000-400,000 platelets/uL of blood Ø Thrombocytopenia – decrease in platelet count resulting to bleeding through small vessels and capillaries. Ø Prothrombin time is a measure of how long it takes for the blood to start clotting, which is normally 9-12 seconds. 5) BLOOD CHEMISTRY vThe composition of materials dissolved or suspended in plasma (eg. Glucose, urea, nitrogen, bilirubin and cholesterol) can be used to assess the functioning of many body’s systems. 117 58  9/16/24 The BLOOD 118 Y O u 59