Digestion Flashcards
Describe the four basic digestive processes performed by the digestive system (motility)
-Muscular contractions–> mixing and moving
What type of muscle tissue does the mixing and moving with muscular contractions?
Smooth muscle, in the esophagus it has some skeletal muscles
Describe the four basic digestive processes performed by the digestive system (secretion)
-Digestive enzymes, bile salts, mucus, hormones, buffers, etc.
Describe the four basic digestive processes performed by the digestive system (digestion)
Chemical breakdown of large food molecules into smaller subunits for absorption
Describe the four basic digestive processes performed by the digestive system (absorption)
Small particles transported from digestive tract –> into body fluids (blood or lymph)
Describe why we need to break food molecules down into smaller particles.
- So they are small enough and easier to cross the membrane
- increase surface area to allow enzymes to move
Describe the digestion of proteins
Not much protein in mouth, mainly in the stomach
1) Pepsin(from the stomach): protein-> peptides(in stomach)
2) More proteases( from the pancreas): Proteins and peptides-> peptides (in small intestine)
3) Peptidases & dipeptidases( from the small intestine) peptides-> amino acids (in small intestine)
Describe the digestion of carbohydrates
1) Salivary amylase (from the salivary glands) stops being active when in the stomach. It breaks down starch->disaccharides (in the mouth)
2) Pancreatic amylase (from the pancreas) starch->disaccharides (in the small intestine)
3) Disaccharidases ( from the small intestine) Disaccharides -> monosaccharides( in the small intestine)
Describe the digestion of lipids
Must be physically broken into small enough droplets in order for digestion to be efficient (insufficient without bile in body)
1) By bile (used as an emulsifier) produced in the liver, occurs in the small intestine
2) Lingual lipase (make small amounts in the oral cavity) Lipids-> fatty acids and monoglycerides (in the oral cavity&stomach) small amount of digestion
3) Gastric lipase(from the stomach) Lipids-> fatty acids and monoglycerides (in the stomach) (infants only-milk diet)
4) Pancreatic lipase(from the pancreas) lipids-> fatty acids and monoglycerides(in the small intestine) digestion of fat is less efficient without gallbladder
5) Other lipases (from the pancreas and small intestine) lipids-> fatty acids and monoglycerides( in the small intestine)
Briefly describe the mechanisms used in the absorption of carbohydrates, proteins, and lipids.
carbohydrates:
-have to get broken down to monosaccharides, they absorb monosaccharides and are put into capillary of villus(get through cells by secondary active transport and facilitated diffusion)
Proteins:
-have to get broken down by amino acids, they absorb amino acids and are put into capillary of villus (get through cells by secondary and tertiary active transport and facilitated diffusion)
Lipids:
-Packaged as chylomicrons go into lacteal of villus
-Use diffusion into intestinal cell, and exocytosis out
-different because lipids are hydrophobic
In general, compare and contrast digestion, absorption, and transport of water-soluble nutrients (proteins and carbs, plus water-soluble vitamins) with lipid-soluble nutrients (fats, oils, and fat-soluble vitamins).
come back to this
Describe the function of other secretions of the digestive system: lysozyme
Anti-bacterial enzyme
Describe the function of other secretions of the digestive system: IgA (antibodies)
Antibodies in saliva and tears
Describe the function of other secretions of the digestive system: hydrochloric acid
Decreases pH, activates pepsinogen, produced by parietal cells (most effective in acidic environment or neutral just not basic
Describe the function of other secretions of the digestive system: intrinsic factor
produced by parietal cells; helps us absorb vitamin B12 (needed for cell division to make RBC)
Describe the function of other secretions of the digestive system: bile
used as an emulsifier, produced in the liver
Describe the function of other secretions of the digestive system: bicarbonate ions
they neutralize the pH in the small intestine, highly acidic
Describe the function of other secretions of the digestive system: mucus.
Mucins-> mucus; lubricates food and helps protects the digestive tract
Describe how different aspects of digestive function are regulated by the following hormones: Gastrin
Produced in part by cells of the stomach (also by cells of the duodenum) and will increase activity in the stomach to help facilitate digestion (from stomach and duodenum)
Stimulated by:
-the arrival of food and stretching of the stomach, also by nervous stimulation (vagus nerve)
-or by the signals in the stomach or small intestine(duodenum) with large amounts of undigested protein
-Causes more gastric secretion(acids and enzymes), increased gastric motility (the only 1/6 hormone that increases activity in the stomach)
Describe how different aspects of digestive function are regulated by the following hormones: Secretin
From duodenum
- Stimulated by the release of acidic chyme into the small intestine
- causes the pancreas to release bicarbonate ions(to neutralize the acidic chyme) and liver to secrete bile
- Inhibits gastric secretion, decreases gastric motility
- Slows down activity in the stomach
- Increase secretion from the pancreas and liver
Describe how different aspects of digestive function are regulated by the following hormones: Gastric Inhibitory Peptide (GIP)
AKA “Glucose-dependent insulinotropic Hormone”
- From duodenum
- respond to fatty acids and glucose in chyme
- Inhibits acid production and peristalsis in stomach(slows rate of chyme being dumped into small intestine)
- Stimulates release of insulin from pancreas
- Stimulates lipid synthesis and glucose use
- This hormone will get the pancreas to secrete insulin in anticipation of a rise in blood glucose levels before the levels actually have the chance to rise.
Describe how different aspects of digestive function are regulated by the following hormones: Cholecystokinin (CCK)
- From the duodenum
- In response to the arrival of chyme, especially with fatty acids and partially digested proteins
- Stimulates gall bladder to contract(release bile) and pancreas to release digestive enzymes
- Causes relaxation of hepatopancreatic sphincter; inhibits gastric secretion; may reduce hunger (CNS target)
Describe how different aspects of digestive function are regulated by the following hormones: Vasoactive intestinal peptide (VIP)
From duodenum
- Respond to the arrival of chyme
- Stimulates secretions of small intestine inhibits acid production in the stomach, dilates intest. capillaries( to aid in the removal of absorbed nutrients)
Describe how different aspects of digestive function are regulated by the following hormones: Enterocrinin
- has to do with mucus
- Released when chyme enters the duodenum
- Stimulates mucin production by submucosal glands
