Sunday, December 4, 2016

ch. 14 | the digestive system, nutrition, & metabolism

  • ingestion: taking food into the mouth
  • secretion: releasing water/acid/buffers/enzymes into lumen of GI tract
  • mixing & propulsion: churning & pushing food through GI tract
  • digestion: physically & chemically breaking down food
  • absorption: passing digested products from GI tract into blood & lymph
  • defecation: eliminating feces from GI tract
  • the digestive system has all the organs while the digestive tract is from the mouth to the anus

layers of the GI tract:

we have 32 teeth
3 major salivary glands:
salivary amylase: enzyme that begins digestion of starch
mucus: lubricates food
lysozyme: enzyme that kills bacteria
  • deglutition: swallowing
  • peristalsis: successive muscular contractions along the wall of a hollow muscular structure 
  • sphincters:
  1. (gastro)esophageal- controls the movement of material from esophagus to stomach
  2. pyloric- controls movement of material from stomach to duodenum
  3. ileocecal- separates the large & small intestines 
  • the fundus is on the left side of the body
small intestines:
  • ileum transports material into the cecum of the large intestine 
  • liver cells (hepatocytes) make bile
  • the liver fills most of the right hypochondriac & epigastric regions
  • gallbladder stores bile
digestion: mouth--> pharynx--> esophagus--> gastroesophageal sphincter--> stomach--> pyloric sphincter--> small intestine: duodenum-->jejunum-->ileum--> large intestine: cecum--> ileocecal valve--> colon: ascending--> transverse --> descending--> sigmoid--> rectum--> anal canal--> internal anal sphincter--> external anal sphincter

the large intestine: absorbs water & eliminates waste
  • right lumbar region- ascending colon; left lumbar region- descending colon
  • the small intestines is located almost entirely in the umbilical & hypogastric regions
  • the rectum is in the hypogastric region 
  • enzymes secreted by the pancreas:
-pancreatic amylase: breaks down starches
-trypsin, chymotrypsin, carboxypeptidase: break proteins into amino acids
-pancreatic lipase: breaks trigylcerides into fatty acids
-ribonuclease, deoxyribonuclease: breaks down nucleic acids 
-pancreatic juice flows into the duodenum through the pancreatic duct

  • diarrhea: frequent defecation of liquid feces, caused by increased motility of the intestines or absence of enzymes to process the food nutrients
  • constipation: infrequent or difficult defecation caused by decreased motility of the intestines 
  • metabolism: all the chemical reactions in the body
  • anabolic reactions (synthesis reactions): molecules combine 
  • catabolic reactions (decomposition reactions): molecules are broken down 
  • glycolysis: anaerobic process (requires no oxygen)
  • aerobic respiration: uses oxygen
  • type 1 diabetes: involves lack of insulin bc immune sys. has destroyed pancreatic B cells
  • type 2 diabetes: involves decreased sensitivity of target cells to insulin
  • obesity: an imbalance btwn energy intake & energy expenditure
  • carbs break down into sugars
  • proteins break down into amino acids
  • lipids break down into fatty acids
  • nucleic acids break down into nucleotides 

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