Digestion Flashcards
Mechanical digestion
Muscles
Appetite vs hunger
Hunger- physiological drive for food stimulated by hypothalamus.
Appetite-psychological desire to consume specific foods.
Cephalon phase of digestion
Earliest phase of digestion in which the brain this about & prepares the digestive organs for food.
Function of mouth in digestive tract
Ingestion - food enters gi tract is mouth
Mechanical- mastication tears,shreds, and mixes food with saliva
Chemical-salivary amylase begins with carb breakdown
Esophagus function in digestive tract
Propulsion-swallowing & peristalsis move food from mouth to stomach. No digestion here.
Stomach functions in the digestive tract
Mechanical-mixes and churns food with gastric juice into chyme
Chemical digestion-pepsin begins digestion of proteins and gastric lipase breaks lipids
Absorption- a few fat soluble substances are absorbed through stomach wall.
3 parts of small intestine
Duodenum
Jejunum
Ileum
3 parts of large intestine
Ascending
Transverse
Descending
Salivary glands
Where: under jaw and behind tongue
Product:saliva
Pancreas
Where:Gland behind stomach Product: 3 digestive enzymes 1) pancreatic amylase- digests carbs 2)pancreatic lipase- digests fats 3)protease- digests proteins
Bicarbonate- secreted to neutralize chyme
Liver
Where: above stomach
Product: bile (600-1000mm/day)
Gallbladder
Where:right below liver
Job: stores bile
Bile
Mixes fat and water. Think of salad dressing. Separates unless they add emulsifier is added to keep it mixed
Hormones involved in digestion
Gastrin, secretin, cholecystokinin (cck), gastric inhibitory peptide
Gastric
Production site- stomach
Target organ- stomach- stimulates secretion of hcl and pepsinogen (inactive pepsin) and stimulates gastric motility
Secretin
Production site small intestine
Target organ
pancreas- stimulates secretion of Pancreatic bicarbonate
Stomach- decrease gastric motility
CCK
Production site small intestine (dudenum & jejunum)
Target organ
pancreas- stimulates secretion of pancreatic digestive enzymes
gallbladder- stimulates gallbladder contraction
Stomach- slows gastric emptying
Gastric inhibitory peptide
Production site: small intestine
Target organ:
Stomach- inhibits gastric acid secretion & slows gastric emptying
Pancreas- stimulates insulin release
Villi
Fold in the lining of the mucosal membrane that are in close contact with nutrient molecules
Enteroyte
Absorptive cells in the villi
Microvilli
Cells on the surface of the villi, enterocytes, end in hairlike projections called microvilli. Form brush border where nutrients are absorbed
Passive diffusion
Nutrients pass through the enterocytes and into the blood stream WITHOUT use of ATP or carrier protein.
Ex: fats,h2o, some vitamins and minerals
Facilitated diffusion
Requires a carrier protein to transport protein
Ex: simple sugars (fructose)
Active transportation
Requires ATP and carrier protein to transport nutrients
Ex: glucose, galactose, potassium, magnesium, vitamin c , calcium, some aminos, iron.
Endocytosis
Active transport in which small amount of intestinal contents is engulfed by the cell membrane.
Ex: some proteins, and other large particles ( breast milk)
Heart burn
Hydrochloride acid in the esophagus leads to excess HCL making it too acidic.
IBS
Associated with stress, caffeine, chocolates, etc.
Symptoms include abdominal cramping, bloating, constipation and diarrhea
Chemical digestion
Enzymes
