Digestive System test Flashcards
Function of digestive system:
Function of the digestive system is to break down the foods you eat, release their nutrients, and absorb those nutrients into the body
Small intestine is where the majority of digestion occurs, where most of the released nutrients are absorbed into the blood or lymph
Four layers of the alimentary canal
Mucosa
Submucosa
Muscularis
Serosa
Function of the alimentary canal?
Gastrointestinal (GI) tract or gut
Main function of the organs of the alimentary canal is to nourish the body
What does the mucosa consist of?
Innermost lining of the alimentary canal
Epithelium, which is in direct contact with ingested food
lamina propria, a layer of connective tissue analogous to the dermis
In addition, the mucosa has a thin, smooth muscle layer, called the muscularis mucosa
What does the submucosa consist of ?
Immediately beneath the mucosa
Dense connective tissue
Blood & lymphatic vessels: transport absorbed nutrients
Submucosal glands: release digestive secretions
What does the Muscularis consist of ?
Third layer of the alimentary canal
Muscle (skeletal or smooth) layer of the alimentary canal wall
Double layer of smooth muscle: an inner circular layer and an outer longitudinal layer
Contractions of these layers promote mechanical digestion, expose more of the food to digestive chemicals, and move the food along the canal
Peristalsis
What does the submucosa consist of ?
Superficial to the muscularis
layer of loose connective tissus
Present only in the region of the alimentary canal within the abdominal cavity
Serve to hold the alimentary canal in place near the ventral surface of the vertebral column
Which organs are supported by a layer of adventitia rather than serosa?
Mouth
Pharynx
Esophagus
What is the function of Peyer’s patches?
These lymphocyte clusters are particularly substantial in the distal ileum where they are known as Peyer’s patches
Alimentary canal is exposed to foodborne bacteria and other foreign matter and immune system has evolved a means of defending against the pathogens encountered within it
Gastrointestinal (GI) Tract
Mouth to anus
Mouth and anus open to the external environment
Food and wastes within the alimentary canal are technically considered to be outside the body
What is the function of accessory digestive organs?
Aid in the breakdown of food
The mouth, the teeth and tongue begin mechanical digestion
Salivary glands begin chemical digestion
Once food products enter the small intestine, the gallbladder, liver, and pancreas release secretions- bile and enzymes- essential for digestion
What tissue is the mouth, pharynx, esophagus, and anal canal lined with?
Non-keratinized, stratified squamous epithelium, which provides protection
What tissue is the stomach and intestines lined with?
Simple columnar epithelium, which secretes and absorbs
What cells secrete mucus and fluid into the lumen?
Goblet Cells
What cells secrete hormones into the interstitial spaces between cells
Enteroendocrine cells
What is the Lamina Propria lined with?
Loose connective tissue
Blood and lymphatic vessels: transport nutrients absorbed through the alimentary canal to other parts of the body.
Serves an immune function by housing clusters of lymphocytes, making up the mucosa-associated lymphoid tissue (MALT)
What is the Peritoneum?
Digestive organs within the abdominal cavity are held in place by the peritoneum
Broad serous membranous sac made up of squamous epithelial tissue surrounded by connective tissue
What are the 2 regions of the Peritoneum?
Parietal peritoneum: lines the abdominal wall
Visceral peritoneum: enveloping the abdominal organs
Mechanical digestion along the gastrointestinal tract:
Mouth: chewing
Esophagus: Peristalsis
Stomach: Churning & Maceration- (mixing wave)
Small intestine: peristalsis & segmentation
Large intestine: peristalsis
What are the 6 digestive processes?
- Ingestion
- Propulsion
- Mechanical digestion
- Chemical digestion
- Absorption
- Defecation
What processes occurs throughout most of the alimentary canal?
Propulsion
In which part of the alimentary canal does most digestion occur?
Proximal small intestine
Peristalsis:
Series of wave-like muscle contractions that move food through the digestive tract
Segmentation:
Divides and mixes the chyme by alternating between backward and forward movement of the gastrointestinal tract (GI) contents.
What is the function of liver?
Produces bile salts, which emulsify lipids, aiding their digestion and absorption
What is the function of Gallbladder?
Stores, concentrates, and releases bile
What is the function of Pancreas?
Produces digestive enzymes and bicarbonate help neutralize acidic chyme and provide optimal environment for enzymatic activity
What is the structure and function of gastric pits?
Gastric pits lead to gastric glands that secrete gastric juice
Vast number of gastric pits dot the surface of the epithelium, entry to each gastric gland, which secretes a complex digestive fluid referred to as gastric juice
What are the structures in small intestine that increase absorption of nutrients?
3 features of the mucosa and submucosa are unique
- Circular folds
- Villi
- Microvilli
Absorptive surface of the small intestine is vastly enlarged by the presence of circular folds, villi, and microvilli
What is the role of bacterial flora?
Bacteria live within the large intestine and are referred to as the bacterial flora
More than 700 species of these bacteria are nonpathogenic commensal organisms that cause no harm as long as they stay in the gut lumen
Many facilitate chemical digestion and absorption, and some synthesize certain vitamins, mainly biotin, pantothenic acid, and vitamin K
What is the role of bile?
Lipids are hydrophobic, i.e. they do not dissolve in water
Bile is a mixture secreted by the liver to accomplish the emulsification of lipids in the small intestine
Location of the pancreas:
Lies transversely in the retroperitoneum behind the stomach
Mix of exocrine (secreting digestive enzymes) and endocrine (releasing hormones into the blood) functions
