Digestive system exam 3

17. Large Intestine a. Describe the structure and discuss the function of the ileocecal valve and the internal and external anal sphincters b. Identify the location and discuss the functions of the cecum and appendix, the ascending, transverse, descending, and sigmoid colon, the rectum, and the anus. c. Identify and discuss the functions of teniae coli, haustra, and epiploic appendages d. List the major functions of the large intestine.

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16. Small Intestine a. Identify the location and discuss the relative length and the functions of the duodenum, jejunum, and ileum. b. Identify and discuss the histology and functions of the plicae circulares, villi, and microvilli. c. Identify Brunner's glands (duodenal glands) in the duodenum and Crypts of Leiberkuhn (intestinal glands) in all portions of the small intestine, and discuss the secretions and functions of these glands. d. State the organ or structure that produces cholecystokinin, the stimulus for its secretion, its target organ, and action. e. State the organ or structure that produces secretin, the stimulus for its secretion, its target organ, and action. f. Define the term segmentation and discuss the role it plays in the various regions of the alimentary canal. g. Briefly explain the processes involved in absorption of monosaccharides, peptides and amino acids, fatty acids and monoglycerides, fat-soluble and water-soluble vitamins and the absorption of vitamin B12. in the small intestine

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11. MOUTH a. Identify the boundaries of the oral cavity

-The mouth is enclosed by the cheeks, lips, palate, and tongue -Its anterior opening between the lips is the oral fissure and its posterior opening into the throat is the fauces -The mouth is lined with stratified squamous epithelium - This epithelium is keratinized in areas subject to the greatest food abrasion, such as the gums and hard palate, and nonkeratinized in other areas such as the floor of the mouth, the soft palate, and the inside of the cheeks and lips.

2. List and define briefly the major processes occurring during digestive system activity: Ingestion, mastication, deglutition, propulsion (peristalsis), absorption, and defecation.

1 - Ingestion - selective intake of food, deglutition 2 - Digestion - mechanical and chemical breakdown of food (can you list the product of chemical protein digestion? Lipids? Carbohydrates?) 3 - Absorption - uptake of nutrient molecules into epithelial cells and then blood or lymph 4 - Compaction - absorbing water and consolidating residue into feces 5 - Defecation - elimination of feces

DIGESTIVE SYSTEM

19 QUESTIONS 31.5 POINTS

10. MOUTH Describe....... A) the gross anatomy B)histology C)physiological functions

A) GROSS ANATOMY -mouth is lined with slightly keratinized stratified squamous cells B) HISTOLOGY -hard plate -soft plate -uvula -tongue -salivary glands -tongue C)FUNCTIONS Its functions include ingestion (food intake), taste and other sensory responses to food, mastication (chewing), chemical digestion (starch is partially digested in the mouth), swallowing, speech, and respiration

13. STOMACH b. Identify the structure and discuss the function of the cardiac region, the fundus, the body and the pyloric region of the stomach

CARDIAC REGION - a small area within about 3 cm of the cardiac orifice FUNDIC REGION (fundus) - the dome superior to the esophageal attachment THE BODY (corpus) - the greatest part distal to the cardiac orifice. PYLORIC REGION - a slightly narrower pouch at the inferior end; it is subdivided into a funnel-like antrum12 and a narrower pyloric canal.

11. MOUTH C. Describe the functions of the tongue, as well as the structures of the tongue, including taste buds and papillae, and discuss their functions

FUNCTION- It manipulates food between the teeth while it avoids being bitten, it can extract food particles from the teeth after a meal, and it is sensitive enough to feel a stray hair in a bite of food STRUCTURE Surface- Its surface is covered with nonkeratinized stratified squamous epithelium and exhibits bumps and projections called lingual papillae, the site of most taste buds body- the anterior two-thirds of the tongue that occupies the oral cavity root- posterior one-third of tongue that occupies the oropharynx -lingual tonsils contained in the root The boundary between the root and the body is marked by a V-shaped row of vallate papillae terminal sulcus- the groove behind the row of vallate papillae lingual frenulum- a median fold that attaches the body of the tongue to the floor of the mouth intrinsic muscles-contained entirely within the tongue, produce the relatively subtle tongue movements of speech extrinsic muscles- The extrinsic muscles, with origins elsewhere and insertions in the tongue, produce most of the stronger movements of food manipulation. The extrinsic muscles include the genioglossus, hyoglossus, palatoglossus, and styloglossus serous and mucous lingual glands- secrete a portion of saliva

11. MOUTH f. Describe the main components and functions of saliva. Explain how salivation is regulated.

FUNCTIONS -to cleanse the mouth (with antimicrobial substances), - to dissolve food chemicals so they can be taste, - to moisten the food so it can be compacted into a bolus, and begin the chemical breakdown of carbohydrates. COMPONENTS - salivary amylase, an enzyme needed to break complex sugars into simpler ones. lingual lipase. Lipase breaks down fats

8. Differentiate between intraperitoneal and retroperitoneal..... a) general location of digestive structures b) list of organs

INTRAPERITONEAL Location- When an organ is enclosed by mesentery (serosa) on both sides, it is considered to be within the peritoneal cavity, or intraperitoneal Organs- The stomach, liver, and other parts of the small and large intestines are intraperitoneal RETROPERITONEAL Location- When an organ lies against the posterior body wall and is covered by peritoneum on the anterior side only, it is said to be outside the peritoneal cavity, or retroperitoneal Organs- The duodenum, most of the pancreas, and parts of the large intestine are retroperitoneal

12. Esophagus: Describe the structure and discuss the function of the upper esophageal and lower esophageal (cardiac) sphincters, including the histological differences compared to the rest of the alimentary canal.

LOWER ESOPHAGEAL SPHICTER Its opening into the stomach is called the cardiac orifice (named for its proximity to the heart). Food pauses briefly at this point before entering the stomach because of a constriction called the lower esophageal sphincter (LES). The LES prevents stomach contents from regurgitating into the esophagus, thus protecting the esophageal mucosa from the erosive effect of stomach acid. "Heartburn" has nothing to do with the heart, but is the burning sensation produced by acid reflux into the esophagus. UPPER ESOPHAGEAL SPHINCTER When food is not being swallowed, the inferior constrictor remains contracted to exclude air from the esophagus. This constriction is regarded as the upper esophageal sphincter, although it is not an anatomical feature of the esophagus. It disappears at the time of death when the muscle relaxes. Thus, it is regarded as a physiological sphincter rather than a constant anatomical structure.

9. Identify the mesentery proper and explain its function the mesocolon and explain their function.

MESENTARY Structure- Vertical band of tissue anterior to lumbar vertebrae, function- anchors all small intestine except duodenum MESOCOLON Function- Attaches transvers and sigmoid colon to the posterior abdominal wall

10. In order, list structures through which substances pass through in the GI Tract

Mouth → Upper Esophageal Sphincter (UES) → esophagus → Lower Esophageal Sphincter (LES) → stomach → pyloric sphincter or valve → small intestine (duodenum, jejunum, ileum) → ileocecal sphincter or valve → large intestine (ascending, transverse, & descending colon, sigmoid) → rectum → anal sphincters → anus

11. MOUTH g. Identify the naso-, oro- and laryngopharynx and classify these regions with respect to passage of food and/or air through them

Nasopharynx receives eustachian tube and houses pharyngeal tonsils • It passes only air and is lined by pseudostratified columnar epithelium Oropharynx space between soft palate and epiglottis • passes air, food, drink and is lined with stratified squamous epithelium Laryngopharynx lies posterior to larynx • passes air, food, drink and is lined with stratified squamous epithelium

6. list and describe the enteric nervous system and its two neuron networks.

includes esophagus, stomach, intestines o Debatably part of the ANS Two networks of neurons: Submucosal (Meissner) plexus - in submucosa • Controls movement of the musclaris mucosae and glandular secretions Myenteric (Auerbach) plexus - between layers of the muscularis externa • Controls peristalsis and contractions of muscularis externa

3. Distinguish between mechanical and chemical digestion.

mechanical- happens in mouth. physical breakdown Chemical- happens when the chemical composition changes

5. describe the function of mucosa and list its parts

o Mucosa Epithelium • simple columnar epithelium in stomach and intestines • non-keratinized stratified squamous oral to esophagus and again in lower anal canal o abrasion Lamina propria • loose connective tissue • MALT - lymphocytes and lymphatic nodules o Peyer's patches in distal ileum In what way could MALT help protect the body against disease? Muscularis mucosae • thin smooth muscle o tenses mucosa to enhance surface area

1. Alamentary canal list organs overall composition length

o Organs of the Digestive Tract • Mouth • Pharynx • Esophagus • Gastrointestinal Tract • Stomach • Small intestine • Large intestine definition- a muscular tube extending from mouth to anus length- It measures about 5 m (16 ft) long in a living person, but about 9 m (30 ft) in the cadaver due to the loss of muscle tone at death

1. list accessory organs of the digestive system

o Teeth o Tongue o Salivary Glands o Liver o Gallbladder o Pancreas

13. STOMACH c. Discuss the significance of rugae

The mucosa and submucosa are flat and smooth when the stomach is full, but as it empties, these layers form conspicuous longitudinal wrinkles called gastric rugae

13. STOMACH d. Discuss the function of the oblique muscle layer of the stomach.

The muscularis externa has three layers, rather than two: outer longitudinal, middle circular, and inner oblique layers ++++++++

6. describe blood supply of gastrointestinal system

Two functions: • Supply organs with nutrients and oxygen • Transport nutrients absorbed by mucosal cells Arteries • Anterior - branches of aortic arch and thoracic aorta • Celiac trunk • Superior and inferior mesenteric arteries Veins • Hepatic portal system to liver to process or store nutrients

5. describe the function of serosa and list its parts

•begin at lower esophagus and ends just before rectum (only in abdominal cavity) • Areolar tissue - thin layer • Mesothelium (visceral peritoneum) - Simple squamous • Adventitia - pharynx, most of esophagus, rectum (replaces serosa) • Fibrous connective tissue

11. MOUTH h. List the structures involved in the process of deglutition and explain how they function, including the changes in position of the glottis and larynx that prevent aspiration.

ORAL PHASE is under voluntary control. During chewing, the tongue collects food, presses it against the palate to form a bolus, and pushes it posteriorly. Food thus accumulates in the oropharynx in front of the blade of the epiglottis. When the bolus reaches a critical size, the epiglottis tips posteriorly and the bolus slides around it, through a space on each side, into the laryngopharynx. The PHARYNGEAL PHASE is involuntary. The soft palate and root of the tongue block food and drink from entering the nasal cavity or reentering the mouth. To prevent choking, breathing is automatically suspended, the infrahyoid muscles pull the larynx up to meet the epiglottis and cover the laryngeal opening, and the vocal cords adduct to close the airway. These actions also widen the upper esophagus to receive the food. The pharyngeal constrictors contract in order from superior to middle and inferior, driving the bolus downward into the esophagus. The EPSOPHAGEAL PHASE is a wave of involuntary contractions called peristalsis, controlled jointly by the brainstem swallowing center and the myenteric plexus in the esophageal wall. The bolus stimulates stretch receptors that feed into the plexus, which transmits signals to the muscularis externa above and below the bolus. The circular muscle layer above the bolus constricts and pushes the food downward. Below the bolus, the circular muscle relaxes while the longitudinal muscle contracts. The latter action pulls the wall of the esophagus slightly upward, making it a little shorter and dilating it to receive the descending food. When one is standing or sitting upright, most food and liquid drop through the esophagus by gravity faster than the peristaltic wave can keep up with it. Peristalsis, however, propels more solid food pieces and ensures that you can swallow regardless of the body's position—even standing on your head! Liquid normally reaches the stomach in 1 to 2 seconds and a food bolus in 4 to 8 seconds. As a bolus reaches the lower end of the esophagus, the lower esophageal sphincter relaxes to let it pass into the stomach

11. MOUTH b. Identify the hard and soft palates and discuss their functions.

PALATE FUNCTION - The palate, separating the oral cavity from the nasal cavity, makes it possible to breathe while chewing food HARD/BONY PALATE -supported by the palatine processes of the maxillae and by the smaller palatine bones -It has transverse ridges called palatine rugae that aid the tongue in holding and manipulating food SOFT PALATE -has a more spongy texture and is composed mainly of skeletal muscle and glandular tissue, but no bone -has a conical medial projection, the uvula, visible at the rear of the mouth. -The uvula helps to retain food in the mouth until one is ready to swallow.

11. MOUTH e. Describe the location of the parotid, submandibular, and sublingual glands and their respective ducts.

PARATHYROID GLAND located just beneath the skin anterior to the earlobes. The parotid duct passes superficially over the masseter muscle, pierces the buccinator muscle, and opens into the mouth opposite the second upper molar tooth. Mumps is a parotid inflammation and swelling caused by a virus. SUBMANDIBULAR GLAND located halfway along the body of the mandible, medial to its margin, just deep to the mylohyoid muscle. The submandibular duct empties into the mouth at a papilla on the side of the lingual frenulum, near the lower central incisors SUBLINGUAL GLANDS located in the floor of the mouth. They have multiple ducts that empty into the mouth posterior to the papillae of the submandibular ducts

13. Stomach: a. Describe the structure and discuss the function of the cardiac and pyloric sphincters.

PYLORIC SPHINCTER STRUCTURE- A thick ring of smooth muscle that surrounds the pylorus FUNCTION- which regulates the passage of chyme into the duodenum. CARDIAC SPHINCTER Back to our bolus of food in the esophagus...the UES relaxes allowing the bolus to enter the esophagus. Then the bolus moves down the esophagus via peristalsis. When it reaches the LES (cardiac sphincter), the sphincter relaxes and the bolus drops into the stomach

7. Describe the histology of the visceral and parietal peritoneum.

Parietal peritoneum - lines abdominal wall Visceral peritoneum - envelops organs (five major folds) • Greater omentum o Superficial to small intestine and transverse colon • Falciform ligament o Anchors liver to anterior abdominal wall and inferior diaphragm • Lesser omentum o Suspends stomach from inferior liver, pathway for structures • Mesentery o Vertical band of tissue anterior to lumbar vertebrae, anchors all small intestine except duodenum • Mesocolon o Attaches transvers and sigmoid colon to the posterior abdominal wall

5. describe the function of muscular externa and list its parts

Smooth muscle • two layers in small intestines 1. Inner circular layer • Form valves in some places (sphincters) • Propels food and residue 2. Outer longitudinal layer • Propels food and residue • Modified proximal and distal o Stomach has third oblique muscle o Colon has longitudinal layer segregated into three parallel bands • Skeletal muscle in proximal and distal alimentary canal • Offers voluntary control over swallowing and defecating

13. STOMACH e. Identify the structure of a gastric gland including the location of the chief (zymogenic) cells, parietal (oxynic) cells, enteroendocrine (Gcells) cells, and mucous cells. Discuss the composition of gastric juice and explain the function of each component produced by eachof these different cell types.

The gastric glands produce 2 to 3 L of gastric juice per day, composed mainly of water, hydrochloric acid, and pepsin ++++++++++++++++

14. Liver and Gall Bladder: a. Identify the individual lobes of the liver b. Identify the coronary ligament, falciform ligament, and round ligament (ligamentum teres). c. Identify the hepatic artery, hepatic portal vein, and hepatic vein and discuss the function of each of those blood vessels. d. Identify the histological components of a liver lobule (including hepatocytes, hepatic sinusoids, Kupffer cells, bile canaliculi, central vein, and the components of a hepatic triad) and discuss the function of each. e. Identify the hepatic duct, cystic duct, gallbladder, common bile duct, sphincter of the hepatopancreatic ampulla (ampulla of Vater and sphincter of Oddi) and discuss the roles of those structures in the flow of bile. f. List the major functions of the liver g. List the major components and functions of bile h. Define emulsification and describe the process. List the organs and structures of the digestive system that function in the process of emulsification.

a) screenshot B) same screenshot c)identify in same picture hepatic artery-The liver receives 30% of its blood from the hepatic arteries hepatic portal vein-The liver receives blood from two sources: about 70% from the hepatic portal vein receives blood from the stomach, intestines, pancreas, and spleen, and carries it into the liver at the portal hepatis hepatic vein-Blood from the central veins ultimately converges in the right and left hepatic veins, which exit the superior surface of the liver and empty into the nearby inferior vena cava. d) e) f) It has a tremendous variety of functions, but only one of them, the secretion of bile, contributes to digestion g) Bile is a green fluid containing minerals, cholesterol, neutral fats, phospholipids, bile pigments, and bile acids. The principal pigment is bilirubin, derived from the decomposition of hemoglobin. Bacteria of the large intestine metabolize bilirubin to urobilinogen, which is responsible for the brown color of feces. In the absence of bile secretion, the feces are grayish white and marked with streaks of undigested fat (acholic feces). Bile acids (bile salts) are steroids synthesized from cholesterol. Bile acids and lecithin, a phospholipid, aid in fat digestion and absorption, as discussed later h) Emulsification The breakdown of large lipid globules into a suspension of small lipid globules, which presents a large surface area that allows pancreatic lipase to more rapidly digest fat

15. Pancreas: a. Identify the head, body and tail of the pancreas b. Identify the pancreatic acini and discuss their functions c. Identify the pancreatic islets and discuss their functions d. Identify the pancreatic duct and the hepatopancreatic sphincter and discuss their roles in the flow of pancreatic enzymes e. Identify components of pancreatic juice and their functions in the digestive processes.

a)picture b) c) its endocrine part is the pancreatic islets, which secrete insulin and glucagon d) e)In the jejunum and ileum, the succus entericus, or digestive juice, contains to act on the chyme breaking disaccharides into monosaccharides and peptides into di- and mono-peptides (amino acids). +++++++++

11. MOUTH d. Identify the anatomical structures of a tooth

teeth are collectively called the dentition From the midline to the rear of each jaw, there are two incisors, a canine, two premolars, and up to three molars on each side INCISORS - chisel-like cutting teeth used to bite off a piece of food CANINES - more pointed and act to puncture and shred it. -They serve as weapons in many mammals but became reduced in the course of human evolution until they now project barely beyond the other teeth -The premolars and molars have relatively broad surfaces adapted for crushing, shredding, and grinding. -Each tooth is embedded in a socket called an alveolus, forming a joint called a gomphosis between the tooth and bone The alveolus is lined by a periodontal ligament, a modified periosteum whose collagen fibers penetrate into the bone on one side and into the tooth on the other. This anchors the tooth firmly in the alveolus but allows for slight movement under the stress of chewing. The gum, or gingiva , covers the alveolar bone. Regions of a tooth are defined by their relationship to the gingiva The crown is the portion above the gum the root is the portion below the gum, embedded in alveolar bone the neck is the point where the crown, root, and gum meet The space between the tooth and gum is the gingival sulcus Most of a tooth consists of hard yellowish tissue called dentin, covered with enamel in the crown and cementum in the root. Dentin and cementum are living connective tissues with cells or cell processes embedded in a calcified matrix.

5. describe the function of submucosa and list its parts

•Thicker loose connective tissue w/ vessels, lymphatics, nerve plexus, +/- glands and MALT