BIO 202: Digestive system
Explain why the stomach does not digest itself
- The structure of stomach protects itself from digesting itself. First, the gastric mucosa is covered with surface epithelial cells. These epithelial cells produce a thick mucus with an alkaline pH; thus neutralize the gastric acid that might flow through that part. Second, epithelial cells are connected by tight junctions. These cell-cell adhesions act as a barrier, so molecules or chemicals would not pass through easily into the stomach lining. Third, damaged epithelial cells are replaced at a rapid rate. Cell division in this area occurs every three days to promote protection of the stomach from digesting itself.
Explain where and how the following are absorbed from the digestive tract: carbohydrates
-digested in the mouth, stomach and small intestine -digestive system breaks a complex carbohydrate (starch) back down into its component glucose molecules so that the glucose can enter your bloodstream -When you eat carbs, your body breaks them down into simple sugars, which are absorbed into the bloodstream
Describe the functions of saliva and how autonomic innervation affects its secretion
1) lubricate ingested food 2) hydrolysis and solubilization of food 3) protect mucosa from dehydration, inflamm, infection 4) prevent dental caries (aka bactericidal) Sympathetic stimulation dominates during stress, resulting in dryness of the mouth parasympathetic stimulation promotes continuous secretion of a moderate amount of saliva, which keeps the mucous membranes moist and lubricates the movements of the tongue and lips during speech
Explain the role of various pancreas secretions in the digestive system
1. Acinar Cell Basal Secretion (Intralobular Secretion) 2. Secretin Stimulated Secretion (Extralobular Secretion) 3. Regulatory Duct Cells (Main Pancreatic Duct regulation)
Describe the gross anatomy of the gall bladder and bile duct system
1. The liver has left and right lobes; the left lobe includes a quadrate lobe and a caudate lobe. The gallbladder is a sac located in a depression on the posterior surface of the liver that stores and concentrates bile. 2. The lobes of the liver are made up of lobules that contain hepatocytes (liver cells), sinusoids, stellate reticuloendothelial (Kupffer) cells, and a central vein. 3. Hepatocytes produce bile that is carried by a duct system to the gallbladder for concentration and temporary storage. 4. Bile's contribution to digestion is the emulsification of dietary lipids. 5. The liver also functions in carbohydrate, lipid, and protein metabolism; processing of drugs and hormones; excretion of bilirubin; synthesis of bile salts; storage of vitamins and minerals; phagocytosis; and activation of vitamin D.
Describe the gross anatomy of the pancreas and its duct system
1. The pancreas consists of a head, a body, and a tail and is connected to the duodenum via the pancreatic duct and accessory duct. 2. Endocrine pancreatic islets secrete hormones, and exocrine acini secrete pancreatic juice. 3. Pancreatic juice contains enzymes that digest starch (pancreatic amylase), proteins (trypsin, chymotrypsin, carboxypeptidase, and elastase), triglycerides (pancreatic lipase), and nucleic acids (ribonuclease and deoxyribonuclease).
Know the 3 different types of lingual papillae and their general function
1. fungiform: contains tastebuds 2. foliate: taste buds 3. circumvallatae 4. filiform: contribute to texture of the tongue
Describe the gross anatomy of a tooth
A typical tooth consists of three principal regions: crown, root, and neck. Teeth are composed primarily of dentin and are covered by enamel, the hardest substance in the body. There are two dentitions: deciduous and permanent.
Explain the types of hepatitis that can occur and their effects
A: loss of appetite, malaise, nausea, diarrhea, fever, and chills B: produce cirrhosis and possibly cancer of the liver C: produce cirrhosis and possibly cancer of the liver D: severe liver damage and has a higher fatality rate E: very high mortality rate among pregnant women
Explain the basic processes of the digestive system: motility
Alternating contractions and relaxations of smooth muscle in the walls of the GI tract mix food and secretions and move them toward the anus
Explain how hepatic and gallbladder activity are coordinated; explain the role of CCK, secretin, the autonomic nervous system, circulating bile salts
CCK- inhibit stomach and causes gallbladder to squeeze. Circulating bile salts- once they are reabsorbed back into hepatic portal circuit they go back to the liver and that stimulates the liver to make more bile salts and Emulsify lipids Autonomic nervous system- gets things turned on prior to ingesting meal, cephalic reflex. Secretin- shut down gastric glands and help turn on pancreas and bile production
Explain how pancreatic activity is coordinated; explain the role of: CCK secretin duodenal distension acidity of chyme
CCK-Causes pancreatic enzymes and bile secretion and contributes to satiety. secretin- Slows gastric activity and stimulates basic (High pH) pancreas secretion. Duodenal distension- turns on endocrine cells as well. Stimulates g cells. Acidity of chyme- turns on the duodenal endocrine cells and you get more of those hormones.
Explain the digestive fate of carbohydrates
Carbohydrates-through amylase to monosaccharides.
Describe the structural adaptations in the small intestine which enhance absorption of nutrients
Circular Folds: Permanent, transverse ridges of the mucosa and submucosa. Increases the absorptive surface area. Forces the chyme to spiral through the intestinal lumen, slowing its movement and allowing time for complete absorption of nutrients Villi: Fingerlike projections of the mucosa. Velvety texture. Covered by a simple columnar epithelium made of absorptive cells. Absorptive cells: specialized for absorbing digested nutrients. Within the core of the lamina propria in the villus is a network of blood capillaries and a wide lymphatic capillary called a lacteal. End products of carbohydrates and proteins enter the blood capillaries. Absorbed fats enter the lacteals. In the core of each villus is a slip of smooth muscle from the muscularis mucosae that allows the villus to move during digestion. The movements increase the absorption efficiency and squeeze the lymph through the lacteals. Microvilli: Located on the apical surfaces of the absorptive cells. Increase the absorptive surface. Its plasma membrane contains enzymes that complete the final stages of the breakdown of nutrient molecules
Understand the role of the dentition in mechanical digestion
Dentition (teeth) physically breaks down food by cutting and grinding (chewing) the food into smaller pieces.
Understand the nutritional role of: fibers
G.I. motility. Can't digest but promotes peristolsis for motility normalize bowel movements, lower cholesterol and helps control blood sugar levels
Explain the difference between mechanical and chemical digestion
Mechanical digestion involves physically breaking the food into smaller pieces. Mechanical digestion begins in the mouth as the food is chewed. Chemical digestion involves breaking down the food into simpler nutrients that can be used by the cells. Chemical digestion begins in the mouth when food mixes with saliva.
Explain the digestive fate of triglycerides
Proteins- through pepsin to amino acids
Explain the role of salivary amylase in chemical digestion
Salivary amylase is the enzyme present in the mouth. It comes from the salivary glands in the mouth. The salivary amylase breaks the chemical bonds between sugar monomers and starches, making the food easier to chew and swallow.
Explain the difference between endocrine and exocrine secretion
Secretions of endocrine glands diffuse into interstitial fluid and then into the blood; exocrine secretions flow into ducts that lead into body cavities or to the body surface.
Explain the role of the gall bladder
Stores and concentrates bile, and then releases it into the duodenum to help absorb and digest fats
Explain the role of the appendix
The function of the appendix is unknown. One theory is that the appendix is designed to protect good bacteria in the gut. That way, when the gut is affected by a bout of diarrhea or other illness that cleans out the intestines, the good bacteria in the appendix can repopulate the digestive system and keep you healthy
Explain what gastric juice digests
The hydrochloric acid in the gastric juice breaks down the food and the digestive enzymes split up the proteins
Explain the role of the liver in the digestive system
The liver also functions in carbohydrate, lipid, and protein metabolism; processing of drugs and hormones; excretion of bilirubin; synthesis of bile salts; storage of vitamins and minerals; phagocytosis; and activation of vitamin D.
Explain the digestive fate of triglycerides
Triglycerides through lipase turn to glycerol, and fatty acids.
Understand the nutritional role of: triglycerides
a type of fat (lipid) found in your blood. When you eat, your body converts any calories it doesn't need to use right away into triglycerides. The triglycerides are stored in your fat cells. Later, hormones release triglycerides for energy between meals
Describe the basic secretory, digestive, and absorptive activities of the: large intestine
absorb some water and electrolytes from the chyme. Full of bacteria. Enhance ability to absorb you have plicae circularis but not vili. has bacteria which produces vitamin K.
Describe the basic secretory, digestive, and absorptive activities of the: oral cavity
begin processing food. chewing. mechanical digestion And digestive enzyme amylase that breaks down starch.
Understand the following digestive system activities and know where they occur: chemical digestion
breaking of chemical bonds; any time there is an enzyme (occurs: mouth, stomach, small intestine)
Describe the gross anatomy of the stomach including the various areas and layers
cardia: surrounds the opening of the esophagus into the stomach fundus: rounded portion superior to and to the left of the cardia body: Inferior to the fundus is the large central portion of the stomach pyloric part: three regions -pyloric antrum, connects to the body of the stomach. -pyloric canal, leads to the third region -pylorus: connects to the duodenum
Understand the following digestive system activities and know where they occur: propulsion
churning and movement of food through GI tract (occurs: all over)
explain the basic functions of the: submucosa
consists of areolar connective tissue that binds the mucosa to the muscularis
explain the basic functions of the: myenteric plexus
controls GI tract motility. located between the longitudinal and circular smooth muscle layers of the muscularis
Describe the role of: molars
crushing/grinding -prepare for swallowing
Describe the role of: incisors
cutting into food
Understand the following digestive system activities and know where they occur: defecation
elimination of feces in GI tract
Explain the function of bile
emulsification of dietary lipids -digestion and absorption of fats and fat-soluble vitamins in the small intestine
Understand the nutritional role of: carbohydrates
fuel. source for chemical energy for cellular respiration provide energy, store energy, build macromolecules, and spare protein and fat for other uses
explain the basic functions of the: mucosa
inner lining of GI tract, mucous membrane. Composed of epithelium, lamina propria, muscularis mucosa
Describe the basic secretory, digestive, and absorptive activities of the: small intestine
most chemical digestion occurs. Digestive nutrients will be absorbed. Mechanical digestion= peristalsis.
Be able to trace some food through the alimentary canal mentioning the accessory organs as well
mouth, pharynx, larynx, esophagus, stomach, duodenum (liver/gallbladder/pancreas), dedunum, ileum, cecum, ascending, transverse, decending, sigmoid colon, rectum, anus
Explain where and how the following are absorbed from the digestive tract: proteins
occurs in the stomach and duodenum in which 3 main enzymes, pepsin secreted by the stomach and trypsin and chymotrypsin secreted by the pancreas, break down food proteins into polypeptides that are then broken down by various exopeptidases and dipeptidases into amino acids Digestion of proteins in the stomach is helped by stomach acid, which is strong hydrochloric acid
explain the basic functions of the: muscularis externa
of the mouth, pharynx, superior/middle parts of esophagus contains skeletal muscle that produces voluntary swallowing
Understand the following digestive system activities and know where they occur: absorption
passage of digested products from GI tract into blood and lymph (occurs: mouth, stomach, **small intestine)
Define peristalsis and segmentation
peristalsis is smooth muscle of wave contractions move food in one direction along GI tract Segmentation smooth muscle back and forth contractions to mix and break food further down.
Understand the following digestive system activities and know where they occur: mechanical digestion
physical breaking down of foods, larger to smaller particles (occurs: mouth, stomach, small intestine)
explain the basic functions of the: serosa
portions of the GI tract that are suspended in the abdominal cavity have a superficial layer (serosa) serous membrane composed of areolar connective tissue and simple squamous epithelium
Understand the basic anatomy of gastric glands; explain the secretions (and their functions) secreted by the: chief (zymogenic) cells
produce digestive enzyme pepsinogen. when activated digests protein
Understand the nutritional role of: proteins
raw material for building our own proteins. Chemical energy Producing vital body structures -Maintaining fluid balance -Contributing to acid -base balance -Form hormones, enzymes and neurotransmitters -Contributing to immune function-Transporting nutrients -Forming glucose -Providing energy
Understand the following digestive system activities and know where they occur: secretion
release of waters, acids, buffers, and enzymes into lumen of GI tract (occurs: all along the pathway)
know the dental formula:
represents the typical number of each type of tooth found in the upper and lower arcade: - "I" for incisor, "C" for canine, "P": for premolar, and "M" for molar. -letters are upper case for adult teeth and lower case for deciduous teeth
Understand the basic anatomy of gastric glands; explain the secretions (and their functions) secreted by the: G cells
secrete hormone called gastrin. Tells parietal and chief cells to make more gastric juice
Understand the basic anatomy of gastric glands; explain the secretions (and their functions) secreted by the: parietal cells
secrete hydrochloric acid which activates pepsinogen into pepsin
Understand the basic anatomy of gastric glands; explain the secretions (and their functions) secreted by the: mucous cells
secrete mucous which protects the stomach from digesting itself.
Describe the basic secretory, digestive, and absorptive activities of the: pancreas
secretes most of digestive enzymes (Pancreatic Lypase, Pancreatic Amylase, Deoxy/ribonuclease, and proteolytic enzymes) and a bunch of sodium bicarbonate Doesn't absorb anything just secretes
Describe the basic secretory, digestive, and absorptive activities of the: stomach
secretes mucous, gastrin, HCl, and pepsinogen which when activated into pepsin digests proteins. Mechanical and chemical digestion occurs as the stomach churns and mixes the bolus with the gastric juices
Explain where and how the following are absorbed from the digestive tract: triglycerides
small intestine -triglycerides are broken down into monoglycerides and free fatty acids, then imported across the intestinal mucosa. Once across, the triglycerides are resynthesized and transported to the liver or adipose tissue.
Understand the following digestive system activities and know where they occur: ingestion
taking food into mouth (occurs: mouth)
Describe the role of: canines
tear and shred food
Describe the gross anatomy of the large intestine and appendix
the regions of the large intestine are the cecum, colon, rectum, and anal canal. -extends from the ileocecal sphincter to the anus. appendix: Attached to the cecum is a twisted, coiled tube, measuring about 8 cm (3 in.) in length
