CH 23 digestive system

Describe the anatomy of a typical tooth; how many teeth are found in children vs adults, what are the differences?

- Deciduous teeth - 20 teeth. First appear at 6 months of age - Permanent teeth - 32 teeth. Most erupt by the end of adolescence - teeth lie in sockets (alveoli) in the gum-covered margins of the mandible and maxilla. - Each tooth has two main regions, the exposed crown and the roots in the socket. These regions meet at the neck near the gum line

What is digested in the duodenum? How do the liver/gallbladder and the pancreas aide in the digestion process in the duodenum? What does each of them secrete?

- duodenum is shortest subdivision of small intestine. It receive enzymes from pancreas and bile from liver and gallbladder. It receives partially digested food (known as chyme) from the stomach and plays a vital role in the chemical digestion -Receives digestive enzymes and bile. Main pancreatic duct and common bile ductenter duodenum. Sphincters control entry of bile and pancreatic juices

Mechanical processing

Breaking food into smaller pieces. Chewing & churning. (mouth and stomach)

Labial frenulum

Connects lips to gum

What kinds of digestion occur in the mouth? How does saliva assist in digestion?

Food enters the mouth, where it is chewed, manipulated by the tongue, and moistened with saliva. Saliva dissolves food chemicals so that they can be tasted, wets food, and binds the food together into a bolus.

Function of the esophagus, type of muscle movements occurring here, what is the epithelial type.

Function - propels swallowed food to stmach •Gross anatomy - muscular tube •Begins as a continuation of the pharynx •Joins the stomach inferior to the diaphragm •Microscopic anatomy: - Epithelium is stratified squamous epithelium •When empty - mucosa and submucosa in longitudinal folds and lumen collapses •Mucous glands - primarily compound tubuloalveolar glands •Muscularis externa - skeletal muscle first third of length •Most external layer - adventitia

What is the function of the pancreatic duct, and how is it associated with the common bile duct?

Function: Joins bile duct to form hepatopancreatic ampulla and empties into the duodenum.

What are the names of the ducts that transport bile from the liver and gallbladder into the duodenum?

Hepatic duct then joins with the cystic duct from the gallbladder to form the common bile duct. This runs from the liver to the duodenum (the first section of the small intestine).

Describe the histology of the stomach. What do the chief and parietal cells secrete? What is the purpose of HCl?

Histology: - lining of epithelum of the mucosa is simple columnar epithelium that secrete mucus - surface of stomach mucosa is dotted with gastric pits, which are open into tubular gastric glands Parietal cells - produce hydrochloric acid by pumping hydrogen and chloride ions into th elumen of the gland

What are the two hormones secreted by the pancreas, and what are their functions (which cells secrete the hormones).

Insulin and glucagon: lower and raise blood sugar levels

Excretion

Process by which metabolic wastes are eliminated from the body

Mucosa

The mucosa - innermost layer •Consists of: Epithelium, Lamina propria, Muscularis mucosae The submucosa - external to the mucosa •Contains blood and lymphatic vessels, nerve fibers The muscularis externa - external to the submucosa• Two layers: Circular muscularis and Longitudinal muscularis The serosa - the outermost layer •The visceral peritoneum Nerve plexuses •Myenteric nerve plexus •Submucosal nerve plexus

Absorption

The transport of digested end products from lumen into the blood

Describe the two divisions of the digestive system: alimentary canal (muscular digestive tract) and accessory structures/organs.

alimentary canal (muscular digestive tract) - Mouth, pharynx, and esophagus•Stomach, small intestine, and large intestine (colon) Accessory digestive organs - Teeth and tongue•Gallbladder, salivary glands, liver, and pancreas

Uvula

flap structure that closes nasopharynx during swallowing

Ingestion

intake of food via the mouth

What is the function of accessory digestive structures such as teeth, liver, pancreas, and gallbladder?

liver- bile production Pancreas: Endocrine functions: Insulin (beta cells) and glucagons (alpha cells) Exocrine functions: Acinar cells make, store, and secrete pancreatic enzymes Gallbladder: - Stores and concentrates bile •Expels bile into duodenum •Bile emulsifies fats •Cholecystokinin—released from enteroendocrine cells in response to fatty chyme

Oral cavity

mouth

oropharynx and laryngopharynx

passages for air and food

Lingual frenulum

support the tongue and aid in limiting its movement in different directions

What are mesenteries, where are they found, what is their function?

•A double layer of peritoneum - a sheet of two serous membranes fused together .•Mesenteries hold organs in place, store fat, provise a route for circulatory vesssels and nerves to reach organs •Mesenteries attach to posterior abdominal wall

What are the primary functions of the large intestine? What kind of muscle movement occurs here? How does the wall for large intestine differ from the small intestine? Be able to identify and know the structures of the following items: Cecum, ascending colon, descending colon, transverse colon, sigmoid colon, hepatic flexure, splenic flexure, tenia coli, haustrum, vermiform appendix, rectum anus.

•Digested residue contains few nutrients •Small amount of digestion by bacteria •Main functions - absorb water and electrolytes •Mass peristaltic movements force feces toward the rectum •Subdivided into: •Cecum, vermiform appendix, colon, rectum, anal canal •Special features of large intestine: Teniae coli, haustra, and epiploic appendages •Cecum - a blind pouch •Vermiform appendix - contains lymphoid tissue. Neutralizes pathogens •Colon - divided into distinct segments: Ascending, transverse, descending, and sigmoid colon •Rectum - descends along the inferior half of the sacrum •Anal Canal - the last subdivision of the large intestine Microscopic: •Villi are absent •Contains numerous goblet cells •Lined with simple columnar epithelial tissue •Epithelium changes at anal canal •Becomes stratified squamous epithelium

Hard and soft palate

•Forms the roof of the mouth

How are the omentums related to mesenteries?

•Lesser omentum attaches to lesser curvature of stomach •Greater omentum—a "fatty apron" of peritoneum

What are the primary functions of the small intestine? Describe the structure of the wall of the small intestine. How is the surface area increased? What are circular folds, villi and microvilli?

•Longest portion of the alimentary canal •Site of most enzymatic digestion and absorption •Three subdivisions: Duodenum,Jejunum,Ileum - Circular folds: ridges of mucosa and submucosa. These folds force chyme to spiral through intestinal lumen, slowing its movement and allow time for absorption - Villi: Fingerlike projections that give a velvety texture. Their function is to increase the surface area in order to maximise the absorption of digested food - Microvilli: Contain enzymes that complete final stages of breakdown of nutrient molecule

What is the function of peristaltic movements, as well as segmentation? What areas of the alimentary canal do they occur.

•Mass peristaltic movements force feces toward the rectum Segmentation - Rhythmic local contractions of the intestine. Mixes food with digestive juices

What are the functions of the stomach?

•Site where food is churned into chyme •Protein digestion begins •Secretes pepsin •Functions under acidic conditions