Anatomy 2 2
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- What are the organs of the digestive system?
- mouth, pharynx, esophagus, stomach, small intestine, large intestine
- Accessory organs of the digestive system:
- tongue, teeth, salivary glands, liver, gall bladder, pancreas.
- Activities of the (GI) tract:
- ingestion, propulsion (peristalsis), mechanical digestion, chemical digestion, absorption, defecation.
- What is peristalsis?
- It is propulsion, an activity of the GI tract, its the major means of propulsion, involves alternate waves of contraction and relaxation of muscles in the organ walls. It squeezes food along tract, some mixing occurs as well. Very powerful.
- Where is most of the GI tract housed?
- In the abdominal cavity
- Visceral peritoneum:
- This is a serous membrane that surround the organs of the digestive tract in the abdominal cavity.
- Parietal peritoneum:
- A serous membrane that lines the abdominal wall and is continuous with the visceral peritoneum.
- The peritoneal cavity is the same as the...
- abdominal cavity
- What consists of double layers of parietal peritoneum?
- The mesenteries that attach the GI tract to the abdominal wall.
- What attaches the GI tract to the abdominal wall?
- Mesenteries
- Peritonitis
- Inflammation of peritoneal (abdominal) cavity. Occurs when bacterial get into the cavity through an opening, external or internal. Must be treated quickly or life threatening.
- Four basic layers of digestive tract: (from lumen to the exterior)
- Mucosa, Submucosa, Muscularis Externa, Serosa
- Mucosa
- Epithelial membrane that lines the lumen of the GI tract from mouth to anus.
- What are the functions of mucosa:
- secretion, absorption, protection.
- What are the 3 sublayers of mucosa:
- surface epithelium (simple columnar), lamina propria, muscularis mucosae.
- Lamina propria consists of:
- consists of loose areolar connective tissue containing blood vessels and lymphatic tissues.
- Muscularis:
-
thin layer of smooth muscle cells that produce isolated movements of the mucosa.
- one of 3 sublayers of mucosa - Submucosa consists of
- dense connective tissue with elastic connective tissue fibers. There are blood vessels, various components of lymphatic tissues and nerve fibers.
- Muscularis externa consists of:
- an inner layer of circular muscle and an outer layer of longitudinal muscle.
- Sphincter muscles are formed from:
- thickening of the circular muscle layer.
- Serosa is also known as:
- visceral peritonium.
- Serosa consists of:
- areolar connective tissue covered by a single layer of squamous epithelial cells (the mesothelium)
- What are the two nerve plexuses in the wall of the GI tract?
- the submucosal nerve plexus, and the myenteric nerve plexus.
- What do the two nerve plexuses in the wall of the GI tract do?
- Control glandular secretions, and muscle movements by way of local reflex arcs.
- The neural components of the two nerve plexuses in the wall of the GI tract are innervated by:
- sensory and motor fibers of the autonomic nervous system.
- Function of digestion:
- to break down food materials into small melecules by enzymatic digestion, and to absorb the end products of digestion into blood or lymph.
- What 3 things are digested into monosaccharides?
- Polysaccarides, oligosaccharides and disaccharides
- What is digested into fatty acids and monoglycerides: (give an example)
- Nuetral fats, such as triglycerides
- What is digested into fatty acids and lysolecithin? (give an example)
- Phospholipids, such as lethocin.
- What is digested into amino acids?
- Proteins and peptides
- What is digested into nucleotides?
- Nucleic acids (dna and rna)
- What are the nucleotides digested into?
- a pentose sugar, a purine or pyrimidine base, and a phosphate.
- What are the final end products of digestion? 8
- monosaccharides, amino acids, fatty acids, monoglycerides, lysolecithin, purine or pyrimidine bases, pentose sugar, and phosphate.
- What are hydrolytic enzymes?
- Digesive enzymes
- Why are digestive enzymes known as hydrolytic enzymes?
- Because the chemical bonds are broken by splitting and adding water.
- What is digestion also known as?
- enzymatic hydrolysis
- What is enzymatic hydrolysis?
- Digestion
- Mechanical digestion?
- Chewing food, occurs in the mouth.
- A very small amount of what occurs in the mouth?
- Chemical digestion
- Salivary glands:
- Has secretions caused by sight, thought, and smell of food, occurs in the mouth, and also occurs while food is in mouth.
- What are the components of saliva:
- Mucin protein, chemical buffers, antibacterial agents, salivary amylase.
- Mucin protein:
- a protein in saliva that lubricates food for swallowing.
- Chemical buffers in saliva:
- Nuetralize acids.
- What are some antibacterial agents in saliva:
- lysozyme, and IgA antibodies.
- Salivary amylase is also known as:
- Ptyalin
- What is function of salivary amylase:
- partially digests starch
- The tongue is used for:
- tasting, to manipulate food for chewing, to shape food into a ball termed as a "bolus".
- Bolus:
- ball of food shaped by tounge.
- Swallowing reflex is initiated:
- when the tongue pushes a bolus into the pharynx. This is voluntary.
- Is swallowing reflex voluntary or involuntary:
- voluntary
- The pharynx connects:
- the mouth to the esophagus.
- The eppiglotis is located in the
- pharynx
- The function o fthe epiglottis is to:
- cover the glottis during swallowing to prevent food from entering the trachea.
- The esophagus connects:
- the pharynx to the stomach
- the upper one third of the sophagus and the pharynx contain _________ muscle.
- skeletal.
- Contractions of the pharynx and upper one third of the esaphagus are ________ during swallowing.
- voluntary
- Swallowing initiates:
- reflex contractions of the lower two thirds of the esophagus to propel food thru it.
- The lower two thirds of the esophagus contain... and the contractions are.....
- smooth muscle, involuntary.
- Contractions of the pharynx and esophagus occur with a wave like motion termed _________.
- Peristalsis
- Gastroesophageal sphincter:
- guards the junction of the esophagus and stomach to prevent food from regurgitating backwards into the esophagus.
- What kind of digestion occurs in the stomach?
- Mechanical and some chemical
- _________ storage of food may occur in the stomach.
- temporary
- The stomach holds about ___ liters for up to __ hours.
- 2, 6
- The stomach secretes ___
- HCl
- The pH of the stomachs contents is __.
- 2
- What does HCl dissolve:
- the intercellular cement between plant and animal cells.
- HCl kills:
- most bacterial swallowed with food
- Pepsin is produced where:
- in the stomach
- Pepsin is secreted as:
- innactive form pepsinogen
- Pepsin is converted to active form by... and ... itself
- HCl, pepsin
- Pepsin has its optimum activity at pH __.
- 2
- pepsin digests proteins into smaller ....
- polypeptides.
- In addition to pepsinogen, and HCl, the stomach also secretes:
- Mucus proteins.
- Mucus proteins:
- secreted by stomach, the protect stomach wall from digestion by pepsin and HCl.
- Lesions of the inner lining of the stomach or duodenum cause ________.
- peptic ulcers
- gastric ulcers are in the ________.
- stomach
- duodenal ulcers are peptic ulcers in the ________.
- duodenum.
- Gastric ulcers are due to
- lack of secretion of mucus proteins
- Duodenal ulcers may be caused by:
- too much HCl from the stomach
- NSAIDS are thought cause
- gastric ulcers
- NSAIDS inhibit:
- prostaglandin synthesis.
- What is the function of prostaglandins:
- to inhibit the secretion of gastric juices. (pepsin/pepsinogen, HCl, mucus proteins)
- What is the major cause of peptic ulcers:
- infection of bacterium Helicobacter pylori. Can be treated with antibiotics.
- What can be given to suppress HCl secretion:
- Drugs such as tagamet. These drugs are antagonistic to H2 histamine receptors.
- What is stimulated by secretion of HCl
- H2 receptors by histamine
- Digestion in the stomach produces a fluid known as
- acid chyme
- How is acid chyme released
- the stomach empties bye waves of peristalsis which open the pyloric sphincter to release it.
- How long does it take for the stomach to empty?
- two to six hours.