Title: Physiology 2130 / Module 15: Digestive System

Q: The main function of the digestive system is to break down [...] so they can be [...] into the body.
A: organic nutrients; absorbed

Organic nutrients are: proteins, carbohydrates, fats, water, vitamins and minerals.

Header: Label the part of the digestive system:

Q: [...] involves the release of digestive fluids into the lumen of the digestive tract.
A: Secretion
Extra: Digestive fluids include: water, mucus, electrolytes, acid, enzymes, bile, salts and digestive enzymes.

Q: [...] is the process where food is broken into smaller molecules by digestive enzymes so they can be taken up (uptake) by the body.
A: Digestion

Q: [...] is the process where these small molecules are taken up by the circulatory system and distributed throughout the body.
A: Absorption

Q: [...] is the movement of 'food' through the digestive system by the contraction of smooth muscle that lines the walls of the tract.
A: Motility

Q: [...] is the removal of the unwanted waste products from the body after almost all of the wanted material is absorbed.
A: Excretion

Q: Salivary Glands:
1. [...] Gland
2. [...] Gland
3. [...] Gland
A: Parotid; Submandibular; Sublingual
Extra: These glands can produce up to 2L (0.5 gallons) of saliva each day.

Q: Saliva is [...]% water and [...]% protein & ions.
A: 99.5; 0.5

Q: The production and the secretion of saliva under control of the [...].
A: autonomic nervous system

Swallowing Reflex:
1.Uvula of the soft palate closes over the nasopharynx;
2. Larynx is lifted by the muscles in the neck;
3. Epiglottis bends back over the glottis, covering the larynx
4. Bolus moves down the esophagus;
5. Through the cardiac orifice into the stomach by a wave of smooth muscle contraction called peristalsis.
Extra: Occurs once the bolus is sufficiently lubricated.

Q: [...] are the folds which the stomach has when empty. They increase surface area and allow for the expansion of the stomach as it fills with food.
A: Rugae

Q: The liquefied mixture that the stomach holds is called [...]
A: chyme

Q: In the stomach, very little [...] occurs, the exceptions are [...] and [...].
A: absorption; alcohol; asprin

Q: The mixing of chyme is achieved by [...] of the stomach walls.
A: peristaltic contraction
Extra: The contractions start at the fundus and end at the antrum.

Q: Exocrine products of the pancreas are secreted into the long [...].
A: pancreatic duct

Q: The pancreatic duct merges with the [...] (from the liver and gallbladder) before entering the [...].
A: common bile duct; duodenum

The Pancreas Secretes:
1. Amylase;
2. Trypsin;
3. Chymotrypsin;
4. Proteases;
5. Lipase;
6. Sodium Bicarbonate.

Q: The small intestine is the longest section of the digestive tract, reaching [...] meters long.
A: 9

Q: The small intestine ends at the [...], which empties into the ascending colon of the large intestine.
A: ileocecal sphincter

Q: The inner wall of the small intestine is thrown into folds that contain finger-like projections called [...].
A: villi

Q: Villi contain a [...] and [...] to absorb digested material.
A: capillary network; lymphatic lacteal
Extra: Lymphatic lacteal absorb digested fats.

Q: There is a layer of [...] that secrete digestive enzymes covering the villi of the small intestine.
A: epithelial cells
Extra: The epithelial cells have microvilli that face out into the lumen of the intestine = brush border.

Q: Bile from the liver helps digest [...] even though it is not a digestive enzyme.
A: fat

Q: In the small inestine, absorbed material is sent to the [...] and [...] systems.
A: circulatory; lymphatic

Q: The process of absorption is enhanced by:
1. The large surface area produced by the [...];
2. The large [...] to the digestive tract;
3. The [...] of the food in the intestine.
A: villi lining; blood supply; motility

Q: Monosaccharides = [...], [...], and [...].
A: glucose; fructose; galactose
Extra: Made up of a single building block.

Q: Disaccharides = [...], [...], and [...].
A: maltose; sucrose; lactose
Extra: Consist of 2 monosaccharides.

Q: Carbohydrates made up of more than 2 units are [...].
A: polysaccharides
Extra: Include starch & glycogen.

Q: Polysaccharides must be broken into [...] to be absorbed.
A: monosaccharides

Q: [...] breaks up polysaccharides into a smaller polysaccharide + maltose.
A: Amylase

Q: Salivary amylase is [...] in the stomach due to its acidic envrionment.
A: denatured

Q: The pancreas secretes bicarbonate ions which [...] the stomach. This neutralized environment permins the pancreatic amylase to perform its digestive function.
A: neutralizes

Q: Lactose = [...] + glucose
Maltose  = [...] + glucose
Sucrose = [...] + glucose
A: galactose; glucose; fructose

Q: [...] is caused by the inability to produce lactase, so you cannot digest lactose.
A: Lactose intolerance

Q: Serious cramps, bloating, gas and diarrhea are indicative of [...].
A: lactose intolerance

Q: People that suffer from lactose intolerance can take [...] before any meal that constains lactose.
A: synthetic lactase

Q: If carbohydrates are present in the large intestine, [...] feed on it and = gas, bloating and cramps.
A: bacteria

Q: There are 20 types of amino acids - [...] nonessential and [...] essential.
A: 11; 9
Extra: Essential means it must come from diet because the body doesn't make it.

Q: Proteins must be broken into [...] before they can be absorbed.
A: amino acids

Q: Inactive pepsinogen is turned into active [...] in the stomach by HCl.
A: pepsin

Q: [...] helps uncoil long strands of proteins, giving pepsin access to the chains to digets into small polypeptides.
A: HCl

Q: Pepsin becomes [...] in the small intestine because of the neutral pH environment.
A: inactivated

Q: [...] must have a neutal pH to work optimally.
A: Pancreatic enzymes

Q: To neutralize chyme from stomach, [...] is secreted from the pancreas.
A: bicarbonate

Q: Proteases are found along the [...] of epithelial cells and in the [...].
A: brush border; small intestine

Q: 2 Classes of Protease Enzyme:
1. [...] - break bonds between amino acids in the inner parts of the protein;
2. [...] - break bonds between amino acids at the ends of the proteins.
A: Endopeptidases; Exopeptidases

Q: Amino acids and very small [...] can be absorbed.
A: polypeptides (dipeptides and tripeptides)

Lipids = triglycerides, phospholipids, cholestrol, and long-chain fatty acids.

Q: Fats are [...] by the churing action of the stomach, makes it easier for enzymes to do their work.
A: emulsified

Q: [...] is the breakup of large drops of fat into smaller ones.
A: Emulsification

Bile = water, bile salts, cholestrol, fatty acids and many ions

Q: The [...] realeases bile into the duodenum of the small intestine during a meal.
A: gallbladder

Q: [...] keep lipid droplets emulsified, preventing them from forming back into large droplets.
A: Bile salts

Q: When lipids are coated in bile salts, [...] cannot reach and digest the lipids.
A: lipase

Q: [...] is not an enzyme, but it allows lipase to get access to the lipid interior of the fat droplet.
A: Colipase
Extra: Now the pancreatic lipase can digest the lipids.

Q: Fat droplets can contain either [...] or [...].
A: cholestrol; phospholipids

Q: Phosphilipid Breakdown by Lipase:
1. Lipase attacks and removes 2 fatty acid chains, leaves a [...] behind;
2. Lipase slowly digests interior of the fat droplet until a [...] is formed.
A: monoglyceride; micelle
Extra: Micelles consist of a single layer of bile salts surrounding a very small lipid droplet. These micelles help to ferry the lipid droplets to the intestinal epithelial cells where the lipids are absorbed.

Q: [...] molecules must be transported into cell using specific active transport system.
A: Cholestrol

Q: Bile salts are left behind after lipid absorption, they are reabsorbed by a transport system in the cells in the [...] and returned to the liver to be reused.
A: ileum

Q: In the smooth ER, absorbed lipids combine with cholestrol and protein to form [...].
A: chylomicrons

Q: Chlyomicrons are packed up into secretory vesicles by the golgi and enter lacteals of [...].
A: lymphatic system

Q: Total amount of water absorbed by the intestine is [...]L a day.
A: 9

Q: [...] of water is reabsorbed from water contained in the saliva, digestive enzymes, pancreas, bile and secretions.
A: 80%

Q: [...] of water comes from drinking and food.
A: 20%

Q: The duodenum and jejunum absorb [...] of water, ileum [...], large intestine [...] and the last 100mL is excreted.
A: 44%; 38%; 1.5%

How water is absorbed in the small intestine:
1. Osmotic gradient builds up across intestinal epithelial cells;
2. Cells develop a higher solute concentration inside (low water conc);
3. Water flows into the cells due to osmosis;
4. As solutes move out of the cell into circulation, water continues to follow by osmosis into the blood .

Absorption of Ions in the Small Intestine:
Na+
1. Na+/K+ pump located on the basal lateral surface of intestinal cells, establishes a concentration gradient for Na+;
2. Na+ will move into the cell and down the concentration gradient;
3. Na+ will also facilitate absorption of carbs and amino acids.
K+
1.Intestinal contents slowly absorbed = increase in concentration of K+ in the lumen;
2. Concentration gradient that favours the passive diffusion of K+ into the cells.

Q: The large intestine is aka the [...].
A: colon

Q: The large intestine is [...]m in length.
A: 1

Q: The [...] of the large intestine is much larger than the small, but it lacks the folds and villi.
A: diameter

The colon begins after the ileocecal valve.
It consists of an ascending, longitudicanl/ transverse and descending limb, a curved sigmoid section, and the rectum that ends at the anus.

Q: In the large intestine, Na+ absorbed by [...] mechanism and water by [...].
A: active transport; osmosis

Q: Most absorption in the large intestine occurs in the [...].
A: first half

Q: Some [...] and [...] are secreted into the colon.
A: K+; bicarbonate

Q: Gas is aka [...].
A: flatus

Q: Vitamin K is for [...].
A: blood coagulation

Q: In the colon, undigested [...] are metabolized into free fatty acids by bacteria.
A: polysaccharides
Extra: Free fatty acids are absorbed by passive diffusion.
Bacteria produces gas and vitamin K.

Q: Digestion and absorption processes are [...].
A: unregulated

Q: [...] and [...] secretion are carefully regulated.
A: Motility; enzyme

Q: The PSYN [...] gastric motility and secretions, also production of watery saliva.
The SYN [...] gastrict motility and secretions.
A: increases; decreases
Extra: PSYN = Parasympathetic Nervous System
SYN = Sympathetic Nervous System

Q: [...] is the muscular contractions of the stomach and intestine that mix the food and propel it thru the digestive tract.
A: Motility

Q: [...] surround digestive tract.
A: Interstitial cells

Q: Interstital cells are specialized cells that alter membrane potentials spontaneously, producing [...].
A: basal electrical rhythms (BERs)
Extra: BERs do not cause muscle to contract because they do not reach threshold.

Q: BERs travel between smooth muscle cells through [...].
A: gap junctions

Q: In the stomach, BERs are [...] waves/min in the duodenum they are [...] waves/min.
A: 3; 12

Q: For a BER to reach threshold, additional [...] is needed.
A: stimulus
Extra: Mechanical, nervous or hormonal.

Q: Digestion of [...] can take longer than carbohydrates and proteins. Therefore, the release of fatty chyme from the stomach must be carefully regulated
A: fat

Q: Hormones release [...].
A: digestive enzymes

Q: HCl is secreted by [...] cells in the stomach.
A: parietal

Q: [...] helps to lubricate the bolus of food and begins digesting [...] because it contains the enzyme amylase.
A: Saliva; carbohydrates