Module 18 Flashcards

Question

Tongue

Answer 1

The tongue forms the floor of the oral cavity. It is skeletal muscle with a mucous membrane. It also functions as a taste organ. Individual taste buds cover the entire surface of the tongue,

Answer 2

Several gustatory receptor cells and supporting cells are clustered in each taste bud: 1. Fungiform papillae 2. Foliate papillae 3. Vallate papillae Also scattered taste buds on lips, palate, and oropharynx

Answer 3

Look like little threads (Latin filum: "thread"). They cover most of the tongue surface. These are non-taste structures that give the tongue a rough texture.

Answer 4

(Latin fungus: "mushroom") Look like little mushrooms

Answer 5

(Latin folium: "leaf") Are leaf-shaped papillae found along the lateral surface of the posterior tongue.

Answer 6

(Latin vallatus: "surrounded by a wall") Form a V-shaped row along the poterior tongue. There are usually 7-12 of these, and it's easier to see them on a friend's tongue than on your own.

Answer 7

Papillae - Filiform - Fungiform - Foliate - Vallate Muscle Taste buds (blue) Lingual Glands: tongue has a set of these. They secrete mucous plus an enzyme, lingual lipase, which helps break down patty foods in the mouth.

Answer 8

- Parotid gland: the largest gland, inferior and anterior to the ears, parotid duct - Sublingual gland: beneath the tongue, lesser sublingual ducts - Submandibular gland: floor of the mouth medial and inferior to the mandible, submandibular ducts Duct names copy the gland name.

Answer 9

- labial - buccal - palatal - lingual

Answer 10

Microscopically, there are 2 kinds of acini (cell groupings) found in salivary glands: - Mucous acini: make mucus - Serous acini: make enzymes in a watery fluid

Answer 11

Saliva is almost all water (99.5%). The remaining part is mucus and enzymes. Enzymes in the saliva include: - Lysozyme: breaks down invading microbes - Immunoglobulin A (IgA): Recall that IgA is the immunoglobin found in the body's secretions - Salivary amylase (Latin amylum: "starch") This enzyme begins the breakdown of starchy foods into sugars, which is why starchy foods (such as potatoes) taste sweet, even though they have little free sugar; the sugar is released by salivary amylase.

Answer 12

- The parotid gland has more serous acini, therefore makes water + enzymes - The submandibular gland has both serous and mucous acini, therefore makes water + mucous+ enzymes - The sublingual gland has mostly mucous acini, therefore, mucous with few enzymes

Answer 13

The pharynx is the point of transition between the oral cavity and the esophagus. It is divided into 3 parts: - nasopharynx: connects the paranasal sinuses to the pharynx, allowing air to pass from the nose to the trachea. - oropharynx: joins the nasal cavity and oral cavity to the gut tube and trachea - laryngopharynx: is adjacent to the larynx ("voicebox"). Here, the epiglottis covers the trachea when swallowing food and drink, and covers the esophagus when breathing.

Answer 14

Is simply a muscular tube that moves food from the pharynx to the stomach, it doesn't have an absorptive surface. - The epithelial sublayer of the mucosa is a nonkeratinized stratified squamous epithelium. The muscularis mucosae of the mucosa is relatively thick.

Answer 15

The 2 layers of the muscularis are: - circular layer: closes off the lumen when contracted - longitudinal layer: contracts in waves (peristalsis) to move things along.

Answer 16

Esophagus Borders - upper esophageal sphincter: between the pharynx and esophagus - lower esophageal sphincter: between esophagus and stomach Voluntary - upper esophageal sphincter and first third (5cm) is striated muscle Involuntary - lower 2/3 of esophagus and lower esophageal sphincter is smooth muscle

Answer 17

Deglutition is the process of swallowing. Swallowing has 3 phases: 1. Voluntary: the stage we control consiously 2. Pharyngeal: when the bolus of food is in the oro - and laryngopharynx. This is the stage where food and water are kept out of the trachea. 3. Esophageal: the upper esophageal sphincter opens, and the autonomic process of peristalsis begins.

Answer 18

Food and liquid leaving the esophagus pass through the lower esophageal sphincter (cardiac sphincter) as they enter the stomach. The stomach has 5 regions and 2 curves: Regions: - Cardia - Fundus - Body - Pyloric antrum - Pyloric canal Curves: - Greater curvature - Lesser curvature

Answer 19

The lower esophageal sphincter sometimes fails to tightly close, causing a condition called gastro-esophageal reflux disease (GERD). GERD can be caused by increased abdominal pressure, as in obesity.

Answer 20

A region of the stomach The cardia is the point at which the esophagus crosses the diaphragm to become the stomach.

Answer 21

A region of the stomach The fundus comes from the same word as "foundation", and describes any structure that you can see like the bottom of a bottle viewed through the neck of the bottle.

Answer 22

A region of the stomach The bulk of the stomach is the body.

Answer 23

The narrower part nearest the small intestine is the pylorus. (Latin: "gatekeeper") The pyloric antrum (Latin: "cave") transitions into the pyloric canal. At the end of the pyloric canal is the pyloric sphincter, which represents the end of the stomach and outlet for stomach contents. The pyloric sphincter opens into the duodenum (Latin: "12 finger breadths") which is the inital segment of the small intestine.

Answer 24

The stomach is a curved bag, and the smaller of the two curves is called the lesser curvature, while the larger arc is the greater curvature.

Answer 25

- Mucosa Layer: is specialized for the digestion of food. The specialization takes the form of gastric pits. - Gastric Glands: each of these depressions in lined with simple columnar epithelium. The bottom half of each gastric pit has a higher concentration of glandular cells that collectively are called the gastric glands. - Along the stomach lumen, epithelial cells and surface mucous cells predominate. Mucus is an essential part of the stomach lining, and protects the cells on the surface from being damaged by the acid and enzymes secreted by teh stomach.

Answer 26

Mucous Secreting C ells - surface mucous cells: secrete protective mucous - mucous neck cells Specialized Cells - parietal cells - secrete HCI - secrete intrinsic factor (vitamin B12) Enzyme-Secreting Cells - chief cells - secrete pepsinogen, lipase Enteroendocrine Cells - G cells - secrete gastrin

Answer 27

A type of Specialized Cell Have two essential roles: - First, they have specialized protein pumps that dump H+ and Cl- ions into the lumen, make HCI - stomach acid - Second, they secrete intrinsic factor which is critical for absorbtion of vitamin B12 which is needed for red bood cell production. Decreased production of intrinsic factor leads to pernicious anemia - abnormal red blood cells.

Answer 28

An enzyme-secreting cell Chief cells secrete the enzymes pepsinogen and lipase.

Answer 29

A type of Enteroendocrine cell G cells are an examples of enteroendocrine cells, a kindof hormonal system in the GI tract. They secrete the hormone gastrin.

Answer 30

Another special feature of the stomach is the presence of an "extra" layer in thick muscularis: the oblique muscle layer with fibers running diagonally. This layer aids in the stomach's ability to "churn" substances and speed digestion.

Answer 31

Parietal cells of the stomach secrete hydrochloric acid (HCI) to aid in digestion and protect from invaders, Make H+ ions (protons) - water + CO2 makes carbonic acid (H2CO3) which then buffers to H+ and HCO3- (bicarbonate ion) - H+ pumped out, K+ pumped in by active transport (H+/K+ ATPase) Make Cl- ions - Cl- concentrated in cell by antiporter (dumps HCO3- into bloodstream) - Cl- concentration high in parietal cell, flows into stomach lumen through Cl- channel

Answer 32

Several neurotransmitters/hormones up-regulate HCI secretion: - acetylcholine from parasympathetic stimulation (vagus) - gastrin from G cells - histamine from mast cells in the lamina propria (via H2 receptors)

Answer 33

Disease can increase secretion of stomach acid, or more commonly, decrease the secretion of protective materials (such as mucous). When this happens, the stomach has an increased tendency to ulcerate. Bacterium Helicobacter pylori disrupts the secretion of protective mucus and predisposes patients to gastric ulcers. Failure of the pancreas to make bicarbonate can result in duodenal ulcers.

Answer 34

One class of drugs acts by inhibiting the proton pump (H+/K+ ATPase). Examples of these proton-pump inhibitors include: - omeprazole (Prilosec) - lansoprazole (Prevacid) - esomeprazole (Nexium)

Answer 35

From stomach to large intestine: - duodenum (Latin: "12 finger breadths"), about 0.25 m in length - jejunum (Latin: "empty"), about 1 m long - ileum (Latin: "flank"), about 2 m long The lumen is wrinkly, with plicae circularis, the Latin name for "circular folds".

Answer 36

In the mucosa, the epithelial layer consists of a simple columnar epithelium. The shape of these cells allows them to absorb water and nutrients on their apical (luminal surfaces). For this reason, the lamina propria of the mucosa has a rich capillary bed, with numerous arterioles and venules. Also, a small lymph vessel called a lacteal carries lipids from the absorptive epithelium. These lymphatics evenutally gather into the thoracic duct which, in turn, releases into the bloodstream and left jugular/subclavian junction. the muscularis layer reverts to the "normal" two sublayers of smooth muscle fibers: a circular and a longitudinal layer. Between them lie clusters of neurons that control autonomic movements of the intestines: the myenteric plexi. These neurons generate the peristaltic waves that keep things moving in the GI tract.

Answer 37

Cells Lining the Villus: Mucus-Secreting Cells - goblet cells Specialized Cells - absorptive cells - absorb nutrients - microvilli increase surface area for absorption Enzyme-Secreting Cells - Paneth cells - secrete lysozyme - can phagocytose Enteroendocrine Cells - secrete secretin, CCK, GIP

Answer 38

The luminal surface of the small intestine appears velvety. This is because of the presence of villi (Latin: "shaggy"), These finger-like projections are about 1 mm long by 0.1 mm diameter. - Most of the villi's epithelial cells are specialized for absorption. These cells are coated with microvilli, a smaller version of the villi.

Answer 39

An enzyme-secreting cell They secrete many enzymes and are also capable of phagocytosis.

Answer 40

Enteroendocrine cells of the intestine secrete secretin from S cells, cholecystokinin (CCK) from CCK cells, and glucose-dependent insulinotropic peptide (GIP) from K cells.

Answer 41

At every level, the small intestine is specialized to increase surface area. - plicae circularis - villi - microvilli All these folds and shag carpets and microscopic fingers are aimed at increasing the surface area of the small intestine. Since the surface is covered with an epithelium of (mostly) absorptive cells, this increased surface area increases the area available for absorption of water and nutrients. The absorptive cells, on the other hand, are covered with protein channels that bring substances from the lumen into the absorptive cell by symport systems that carry Na+ and and glucose, or Na+ and amino acids, into the intestinal cell at the same time

Answer 42

Sugars: 1. Enzymes convert di and polysaccarides to glucose, galactose, and fructose 2. Glucose, galactose pumped into the intestinal cell cytoplasm; fructose moves into intestinal cell cytoplasm by facilitated diffusion 3. From intestinal cell to bloodstream by facilitated diffusion. The only moosaccarides absored by intestinal cells are glucose, galactose, or fructose.

Answer 43

Proteins: 1. Enzymes convert proteins to amino acids, di-, tripeptides 2. These pumped into intestinal cell cytoplasm by active transport 3. From intestinal cell to bloodstream by simple diffusion.

Answer 44

Fats (Lipids): 1. Short-chain fatty acids - simple diffusion from lumen to intestinal cell cytoplasm to bloodstream 2. Long-chain fatty acids and monoglycerides: - insoluble in water: carried in bloodstream in balls called micelles - move into intestinal cell cytoplasm by simple diffusion - intestinal cell forms these into triglycerides, which are packaged in chylomicrons and dumped into lacteals (lymph vessel in core of villus).

Answer 45

All these molecules enter hepatic portal circulation - Except lipids as chylomicrons in lymphatic drainage: lymph drains into thoracic duct, then enters bloodstream via left subclavian vein.

Answer 46

Vitamins work to speed up essential chemical reactions in cells by lowering the activation energy of chemical reactions. Vitamins are non-protein catalysts. Water-soluble vitamins (B, C, niacin, biotin, folic acid) absorbed directly by stomach and intestines. Fat-soluble vitamin K make by bacteria in large intestine, aids in blood clotting Water-soluble vitamin B12 absorbed with help of intrinsic factor secreted by parietal cells of stomach

Answer 47

Disruption of normal intrinsic factor production by diseases of the stomach results in pernicious anemia, a macrocytic anemia. In this disease, RBCs are too large and low in number.

Answer 48

- Cecum: vermiform appendix - ascending colon - transverse colon - descending colon - sigmoid colon - rectum - anal canal / anus

Answer 49

The large intestine begins where the ilium (final portion of the small intestine) has an outlet through the ileocecal sphincter into the cecum.

Answer 50

Latin: "blind [pouch]" The cecum is a classic example of bad design. Not only does it tend to catch objects that have passed into the large intestine, but it ends in the vermiform appendix (or just appendix)

Answer 51

Is a small, worm-like tube that often becomes inflamed and may even burst, dumping the bacteria-laden intestinal contents into the peritoneal cavity, a medical emergency.

Answer 52

Like the small intestine, the colon has a velvety appearance with numerous microvilli. There are openings for intestinal glands (crypts of Lieberkuhn).

Answer 53

Cells lining the intestinal glands (crypts of Lieberkuhn). The only 2 cell types present are goblet cells and absorptive cells. Mucus-Secreting Cells - goblet cels Specialized Cells - absorptive cells absorb water - microvillio increase surface area for absorption Enzyme Secreting Cells - None: digestions is carried out by bacteria - Some B vitamins and vitamin K made by cavteria

Answer 54

The rectum ends in anal canal and anus. There are 2 sphincters in the anus: - Internal anal sphincter: involuntary sphincter; autonomic motor, smooth muscle - External anal sphincter: voluntary sphincter; somatic motor, skeletal muscle

Answer 55

Elimination is the removal of wastes from the body by expelling material from the anus Defecation Reflex: Like swallowing, the defecation reflex is a mixture of autonomic and voluntary motor control. It is triggered by distension (enlargement) of the rectum. (e.g. enema to trigger defecation) Activation of stretch receptors in the wall of the rectum lead to internal anal sphincter relaxation (involuntary). This can be overridden by the external anal sphincter, which is controlled by the cortex of the brain (voluntary).

Answer 56

In the Valsalva Maneuver, the patient tries to exhale against a closed nose and mouth while bearing down (as in a bowel movement) - This increases abdominal pressure and results in characteristic changes in blood pressure and heart rate. - Can be used to diagnose heart disease - This can also correct atrial fibrillation in some cases

Answer 57

The liver is tied with the brain as the second-largest organ of the body. It is divided into 4 lobes: - Right Lobe - Left Lobe - Caudate Lobe ("tail shaped") - Quadrate Lobe ("square")

Answer 58

The liver is held in place by three strips of connective tissue called ligaments: - falciform ligament ("sickle-shaped"): Attach ed to the diaphragm, divides the left lobe from the right, caudate, and quadrate lobes. - coronary ligament: Superior to the liver, attached to the diaphragm to keep the liver in a position in the superior part of the abdominal cavity, and mostly to the right. - round ligament (ligamentum teres)

Answer 59

The liver receives blood from digestive organs for: - detoxification - adding essential proteins Has a Dual Blood Supply: - oxygenated blood from heart via hepatic artery - deoxygenated blood with absorbed nutrients from digestive organs via hepatic portal vein.

Answer 60

- Blood from the heart arrives via the hepatic artery. The cells of the liver need this oxygen from the heart. - Blood from digestive organs arrives via the hepatic portal vein. The blood here goes through detoxification and energy from it is stored. This supply comes from a venous drainage of the stomach and intestines through a vessel called the hepatic portal vein. This brings glucose-rich but oxygen-poor blood from the abosorptive cells of the digestive organs to the liver for processing.

Answer 61

- Blood minus toxins plus proteins made by liver is dumped into the hepatic vein which goes to the heart via the inferior vena cava.

Answer 62

1. Oxygenated blood from hepatic artery OR Nutrient-rich deoxygenated-bood from hepatic portal vein 2. Liver sinusoids 3. Central vein 4. Hepatic vein 5. inferior vena cava 6. Right atrium of heart.

Answer 63

- Hepatocytes: inactivate toxins, produce bile, and also produce a variety of blood proteins. Also play a role in the metabolism of carbohydrates, lipids, and proteins. - Kupffer Cells: are just a special name for a type of macrophage found in the liver. They destroy aged red blood cells and any invaders that reach the liver from the intestinal drainage.

Answer 64

One of the jobs of hepatocytes is to produce bile, a greenish liquid substance that is stored in the gallbladder. - When bile is released into the GI tract, it helps to emulsify fats so they can be transported across the intestinal cell and dumped into the lymph vessel (lacteal) in the center of each villus. - Bile is produced and secreted by hepatocytes, and it travels in tiny vessels called bile canaliculi to join together as a bile duct.

Answer 65

The structures seen together at 3 of the 6 "corners" of the lobule are: 1. Branch of hepatic portal 2. Branch of hepatic artery 3. Bile duct. Together, these are called the portal triad (or hepatic triad).

Answer 66

1. Bile produced by hepatocytes 2. Bile Canliculi 3. Bile Duct (as part of Portal Triad) 4. Right and Left Hepatic Ducts 5. Common bile duct 6. Cystic duct (leads to gall bladder) 7. Storage in gall bladder or release to small intestine. If bile is stored, and GI tract signals presence of fats in a meal, the smooth muscle of gallbladder squeezes to release stored bile into cystic duct (again), and into the common bile duct which joins pancreatic duct at hepatopancreatic ampulla.

Answer 67

(Latin: "bottle") The ampulla is a mixing chamber for pancreatic juices and bile; the sphincter controls release of this mixture into the duodenum.

Answer 68

Recall that 85% of the body's heme is found in red blood cell hemoglobin. Heme is constantly being broken down. The spleen (and other cells) use the enzyme "heme oxygenase" to convert heme to biliverdin. Biliverdin spontaneously converts into bilirubin. Bilirubin made this way is referred to as "unconjugated"; it gloms into the blood protein and is carried to the liver.

Answer 69

Unconjugated Bilirubin is insoluble in blood. In the liver, it is conjugated to the small molecule glucuronic acic, making it water-soluble. In this form, it makes up a major portion of bile. Conjugated Bilirubin ends up in several places: - Converted to urobilinogen, it travels in the blood circulation. A small amount is processed by the kidneys and gives urine its characteristic yellow color. - Conjugated bilirubin in bile is released into the intestines where it is converted to stercobilin, which has a brown color ad gives its brown color to feces.

Answer 70

Problems arise when this well-oiled machine goes off the rails: 1. Bile Obstruction 2. Jaundice

Answer 71

If the bile is obstructed, then it can no longer release in normal quantities through the hepatopancreatic sphincter. In this case, little or no conjugated bilrubin is converted to stercobilin and the feces are pale in color. At the same time, urobilinogen accumulates in urine, which gives it a darker than normal color.

Answer 72

The liver may be incapacitated, for example by a virus (hepatitis), or by drug or alcohol abuse. In newborns, the liver has to switch over from its role of making red blood cells to its digestive roles, and sometimes this changeover does not occur smoothly. In any of these cases, bilirubin cannot be conjugated, and the skin and especially the "whites" of the eyes become noticeably yellow. This is called jaundice. The yellow color is from accumulation of unconjugated bilrubin.

Answer 73

The pancreas is at least two organs in one, with 2 functions: 1. Endocrine Pancreas: Endocrine system = islets 2. Exocrine Pancreas: Digestive function = acini Pancreatic Islets house the endocrine pancreas. The 5 Islet cells are: - alpha cells (1/6): glucagon - beta cells (3/4): insulin - delta cells (1/12): somatostatin - F cells or PP cells (1/20): pancreatic polypeptide - epsilon cells (<1/100): ghrelin

Answer 74

An increase in ghrelin increases appetite. Mice that are genetically altered to interfere with the ghrelin system are not only skinny, but they live longer.

Answer 75

The pancreas is about 99% acini and 1% islets. Acini secrete pancreatic juices which neutralize stomach acids: Sodium bicarbonate: to buffer stomach acid (similar to baking soda) Amylase: a starch-digesting enzyme. Protein-Digesting Enzymes: - Trypsin, chymotrypsin, carboxypeptidase, and elastase Fat Digesting Enzymes: - Pacreatic Lipase RNA & DNA Digesting Enzymes: - Ribonuclease and deoxyribonuclease

Answer 76

1. Cephalic Phase 2. Gastric Phase 3. Intestinal Phase

Answer 77

Stimulus: smell, taste, sight, or thought of food. Action: brain prepares body for a meal Result: CN VII, CN IX stimulate salivation; CN X stiulates stomach acid secretion.

Answer 78

Stimulus: stomach wall stretches or pH increases Action: increase gastric motility and secretion of HCI Result: stomach empties into duodenum as food is digested Hormonal regulation: by gastrin secreted from G cells.

Answer 79

Stimulus: Chyme in duodenum Action: Activation of enterogastric reflex Result: - Stretch receptors in duodenal wall signal medulla - Medulla inhibits parasympathetic ACh release from vagus - Decreased gastric motility, Increased tone in pyloric sphincter. More chyme stays in stomach, less enter duodenum. (note: this is an example of a long reflex) Hormonal Regulation: cholecystokinin (CCK) and secretin from duodenum.

Answer 80

- Made by: G cells of stomach - Acts on: stomach - Action: promotes secretion of gastric juices

Answer 81

- Made by: enteroendocrine cells of small intestine - Acts on: gallbladder, pancreas, and brain - Action: ejection of bile; opening of sphincter of hepatopancreatic ampulla; more pancreatic juice, feel full

Answer 82

- Made by: enteroendocrine cells ("S cells") of duodenum - Acts on: pancreas - Action: more bicarb in pancreatic juice

Answer 83

- Made by: enteroendocrine cells ("K cells") of duodenum and jejunum - Acts on: beta cells of pancreatic islets - Action: increases insulin secretion

Answer 84

Made by: mast cells of lamina propria Acts on: parietal cells of stomach Action: increases acid secretion

Answer 85

Made by: hypothalamus Acts on: many digestive organs Action: decreases exocrine pancreas, decreases many hormones, and slows gastric emptying.

Answer 86

Made by: enteroendocrine cells ("M cells") of duodenum and jejunum. Action: Increases migrating myoelectric complex, increases pepsin, and increases bowel motility.

Answer 87

Peristalsis is a traveling wave of contraction. - A section of bowel contracts, pushing bolus out - At the same time, adjacent section relaxes and bolus squirts from area of high pressure to low pressure (like toothpaste) - This process is controlled by the autonomic nervous system that resides in the bowel wall (myenteric and submucosal plexi)

Answer 88

Peristalsis results in mass movement. - If pressure is recorded at a single location, peristalsis looks like waves of contraction and relaxation - If electrical activity is measured at a single point, see spikes with each contraction (a migrating myoelectric complex) - These waves of electrical activity lead to smooth muscle contraction. Pressures are created by the activity of the enteric nervous system.

Answer 89

The alternating contraction and relaxation of the mass movement.

Answer 90

Controls motor neurons innervating the longitudinal and circular muscle layers of the muscularis. Receives sensory information from the GI tract

Answer 91

The myenteric plexus also sends axons to the submucosal plexus, where motor neurons innervate the small, weak muscles that give the mucosal epithelium its wrinkles. Receives sensory information from the GI tract

Answer 92

Intestines are responsible for absorbing water. Accounting for liquids in the GI tract: - Ingestion = 2.3L - Secretion = 6.0L - Total daily input = 9.3L - Small Intestine absorbs 8.3L - Large Intestine absorbs 0.9L - Feces (about 0.15L/day) contains about 0.1 L water

Answer 93

Laxatives act by increasing GI motility. Increased motility means faster transit time from mouth to anus and therefore, less absorption of water and nutrients. Factors that increase bowel motility include: 1. Chyme volume: an increase in chyme volume increases motility. 2. Chemical composition: chemicals that increase electrical activity, for example by activating sensory nerves of the GI epithelium, increase motility 3. Osmolarity: if non-absorbable chemicals (such as those found in sugar-free candies or some laxitives) are higher than 300 mOsm/kg (blood tonicity), water is "drawn" into the lumen.

Answer 94

- Mechanical Digestion: mixing and tearing forces - Chemical Digestion: chemicals and enzymes acting on food Each organ participates in both types of digestion.

Answer 95

- Stomach: rugae (Latin ruga: "a wrinkle on the face:) - Small Intestine: plicae circulares - Large Intestine: haustra (Latin haurere: "to draw up")

Answer 96

Oral Cavity: - chew food, tongue and cheeks move food - swallowing mixes food Esophagus: - peristalsis mixes food Stomach: - contractions of stomach mix food - rugae help in mixing Small Intestine: - peristalsis mixes food - plicae circulares aid in mixing Large Intestine: - peristalsis mixes food - haustra aid in mixing

Answer 97

Oral Cavity: - salivary glands secrete enzymes that break down starches and fats Stomach: - hydrochloric acid breaks down foods - pepsin breaks down proteins - gastric lipase breaks down fats Small Intestine: - pancreas releases bicarbonate to neutralize acid + enzymes to break down food - bile salts from liver emulsify fats Large Intestine: - beneficial bacteria make vitamin K, digest cellulose (fiber), and make methane.

Answer 98

In the small intestine, enzymes which carry out chemical digestion are found along the brush border. Look brushy because microvilli are coated with proteins (enzymes), giving them a fuzzy appearance. The 9 enzymes of the brush border are: - alpha-dextrinase - maltase - sucrase - lactase - enterokinase - aminopeptidase - dipeptidase - nucleosidases - phosphatases

Answer 99

Salivary amylase: found in starches

Answer 100

- Pepsin: found in proteins | - Lipase: found in triglycerides (fats and oils)

Answer 101

- Amylase: found in starches - Trypsin, Chymotrypsin, & Elastase: found in proteins - Carboxypeptidase: found in amino acid at carboxyl end of proteins

Answer 102

- Maltase, Sucrase, Lactase: found in maltose, sucrose, lactose - Amino peptidase: amino acid at amino end of proteins - Nucleosidases & Phosphateses: found in nucleotides

Answer 103

In a colloid, dispersed solid particles are larger than in a solution - large enough to scatter light Particles in a colloid stay dispersed over time

Answer 104

A suspension has even larger particles than a colloid, and these settle to the bottom of a container given time - like muddy water. - Blood is a suspension, a colloid, and a solution. Red blood cells are suspended in plasma, plasma is a colloid of large proteins dispersed in a solution of sodium chloride and other salts.

Answer 105

An emulsion is a colloid where all components are liquid. - Milk is an emulsion and a solution: large proteins and fat droplets are in a liquid colloidal suspension (emulsion); sugars are dissolved in solution.

Answer 106

The mixture of nutrients and GI secretions called chyme is an emulsion, so chyme is an example of an emulsion. - In order for enzymes to act on chemicals in food, the digestive system must emulsify chyme with digestive juices. (e.g. fats are insoluble in water; bile salts emulsify fats so that lipases can act on them) When lipid is emulsified in a water-based solution, the particles are called micelles.