Ch. 22

Describe the composition and functions of saliva.

99.5⁠% water plus electrolytes, mucus, white blood cells, epithelial cells, enzymes (such as amylase and lipase), antimicrobial agents such as secretory IgA, and lysozymes.

Explain the role of microbes in the large intestine.

Bacteria have nutrients and a stable environment within the large intestine, in return they produce vitamins and other molecules that are beneficial to the body. Some are irritants that cause contraction of small intestine, some oare oily and leave colon slippery.

Trace the production and flow of bile.

Bile is produced in the liver, then flows through the right and left hepatic ducts to enter common hepatic duct, then flows to cystic duct and is stored in gallbladder. The gallbladder then constricts and bile flows back to cystic duct and into common bile duct, which empties into duodenum.

Digestion

Breakdown of food substances into simpler forms that can be absorbed and used

Describe the structural and functional relationships between the liver/gallbladder, pancreas, and the small intestine.

Chemical digestion in the small intestine relies on the activities of three accessory The liver digests food by producing bile to break down fats, removing toxins and breaking down and storing some vitamins and minerals. The pancreas produces enzymes to help break down proteins, fats and carbohydrates. The gall bladder stores the bile that is produced by the liver.

Explain the role of pancreatic juice in digestion.

During digestion, your pancreas makes pancreatic juices called enzymes. These enzymes break down sugars, fats, and starches. Your pancreas also helps your digestive system by making hormones. These are chemical messengers that travel through your blood.

Describe the histology (tissue types and cell types) and secretions of small intestine.

Exocrine cells in the mucosa of the small intestine secrete mucus, peptidase, sucrase, maltase, lactase, lipase, and enterokinase. Endocrine cells secrete cholecystokinin and secretin. The most important factor for regulating secretions in the small intestine is the presence of chyme.

Explain the homeostatic imbalances that lead to the following: acid reflex/GERD/heartburn, gastric ulcers, jaundice, gallstones, celiac disease, diarrhea/constipation.

Homeostatic imbalance occurs when cells in the body experience a deficiency, such as nutritional deficiencies resulting from an unhealthy diet or when cells are exposed to toxins. Homeostatic imbalances may result from three main influences - 1) Internal influences such as aging and genetics. 2) External influences such as nutrition deficiencies, physical activity, mental health , drug and alcohol abuse. 3) Environmental influences such as exposure to toxins.

Stomach

It is a continuation of the esophagus and receives our churned food from it. Therefore, the stomach serves as a kind of connection between the esophagus and the small intestine, and is a definite pit stop along our alimentary canal.

Describe the mechanical and chemical digestive processes that occur in the mouth.

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. Saliva contains an enzyme (amylase) that begins the breakdown of carbohydrates.

Contrast mechanical and chemical digestion

Mechanical digestion: the physical breakdown of food into smaller particles; achieved by the cutting and grinding of the teeth Chemical digestion: a series of hydrolysis reactions that break dietary macromolecules into their monomers

Describe the blood supply of the lower digestive system including some of the major arteries and veins that would be carrying blood to and from the lower digestive organs.

The digestive system is supplied by the celiac artery. The celiac artery is the first major branch from the abdominal aorta, and is the only major artery that nourishes the digestive organs. There are three main divisions - the left gastric artery, the common hepatic artery and the splenic artery.

Describe the location and the role of the gallbladder.

The gallbladder is a pear-shaped organ located on the undersurface of the liver. The gallbladder functions as a concentrating reservoir for bile, which it delivers to the duodenum in response to meals.

Explain the protective significance of the hepatic portal system.

The hepatic portal system is the venous system that returns blood from the digestive tract and spleen to the liver (where raw nutrients in blood are processed before the blood returns to the heart).

Describe the histology (tissue types and cell types) and secretions of large intestine.

The large intestine also secretes mucus, which aids in lubricating the intestinal contents and facilitates their transport through the bowel. Each day approximately 1.5 to 2 litres (about 2 quarts) of chyme pass through the ileocecal valve that separates the small and large intestines.

Large intestine.

The last section of the digestive system, where water is absorbed from food and the remaining material is eliminated from the body responsible for absorbing water from indigestible food. Measuring approximately six feet long, the large intestine is made up of four main parts: the cecum, the colon, the rectum, and the anus.

Contrast the parts of the pharynx that are used for digestion vs. respiration.

The most superior, the nasopharynx, is involved only in breathing and speech. The other two subdivisions, the oropharynx and the laryngopharynx, are used for both breathing and digestion.

Relate the structure of the small intestine with its function (how its structural features allow for increased absorption...one of its main functions).

The muscles of the small intestine mix food with digestive juices from the pancreas, liver, and intestine, and push the mixture forward for further digestion. The walls of the small intestine absorb water and the digested nutrients into your bloodstream.

Absortion

The process by which nutrient molecules pass through the wall of the digestive system into the blood

Describe the location, basic anatomy, and function of the esophagus

a long, thin, and muscular tube that connects the pharynx to the stomach. It forms an important piece of the gastrointestinal tract and functions as the conduit for food and liquids that have been swallowed into the pharynx to reach the stomach.

Describe the location, basic anatomy, and function of the mouth

also called oral cavity or buccal cavity, in human anatomy, orifice through which food and air enter the body. The mouth opens to the outside at the lips and empties into the throat at the rear; its boundaries are defined by the lips, cheeks, hard and soft palates, and glottis.

Small intestine

an organ in the gastrointestinal tract where most of the end absorption of nutrients and minerals from food takes place. It lies between the stomach and large intestine, and receives bile and pancreatic juice through the pancreatic duct to aid in digestion.

Trace the flow of blood away from the veins of the lower digestive organs until it reaches the inferior vena cava and makes it into general circulation.

blood flow away from the gastric and mesenteric veins merge to from hepatic portal vein through the liver out of the liver through the hepatic veins hepatic vein then dumps the blood back into circulation via the inferior vena cava

Explain the role of bile in digestion AND as an excretory product.

breaks down fat Bile emulsifier

Describe the basic process of absorption for carbohydrates, proteins, and lipids that have been digested (broken down).

broken down into subunits that are small enough to be absorbed by the lining of the alimentary canal. This is accomplished by enzymes through hydrolysis.

Describe chemical digestion in the stomach, small intestine, and large intestine; be able to tell me where the different enzymes come from and what they are used to break down.

chemical digestion

Describe the location, basic anatomy, and function of the pharynx

cone-shaped passageway leading from the oral and nasal cavities in the head to the esophagus and larynx. The pharynx chamber serves both respiratory and digestive functions. Thick fibres of muscle and connective tissue attach the pharynx to the base of the skull and surrounding structures.

Explain what peristalsis is and list locations/examples of where it occurs.

coordinated waves of contraction that squeeze food through the GI tract esophagus, stomach, and intestines

Defecation

elimination of feces from the digestive tract through the anus

Describe the mechanical processes that occur in the stomach, small intestine, and large intestine (think peristalsis).

mechanical digestion

GI tract (alimentary canal) organs

mouth, pharynx, esophagus, stomach, small intestine, large intestine

Ingestion

taking in food

Accessory digestive organs

teeth, tongue, salivary glands, gall bladder, liver and pancreas

Propulsion

the action of driving or pushing forward through the GI tract

List the four layers of the GI tract and mention tissue types that were noted in the slides.

the mucosa - epithelium, lamina propria, and muscular mucosae the submucosa the muscularis propria - inner circular muscle layer, intermuscular space, and outer longitudinal muscle layer and the serosa

Describe the histology (tissue types and cell types) and secretions of the stomach.

the stomach secretes water, electrolytes, hydrochloric acid, and glycoproteins, including mucin, intrinsic factor, and enzymes gastric motility and secretion are regulated by neural and humoral mechanisms.