Test 4: Digestive & Reproductive System FINAL Flashcards

Question

The Mouth: Structure & Functions

Answer 1

The mouth is known as the oral, or buccal cavity Functions: * Ingestion (food intake) * Taste and other sensory responses to food * Chewing and chemical digestion * Swallowing, speech, and respiration Mouth enclosed by cheeks, lips, palate, and tongue

Answer 2

anterior opening between lips

Answer 3

posterior opening to the throat

Answer 4

Stratified squamous epithelium lines mouth * Keratinized in areas subject to food abrasion: gums and hard palate * Nonkeratinized in other areas: floor of mouth, soft palate, and insides of cheeks and lips

Answer 5

Structure: * Fleshiness due to subcutaneous fat, buccinator muscle of the cheek, and orbicularis oris of the lips * Labial frenulum: median fold that attaches each lip to the gum between the anterior incisors * Vestibule: space between cheeks or lips and the teeth Function: * Retain food and push it between the teeth * Essential for speech * Essential for sucking and blowing actions, including suckling by infants

Answer 6

Lingual glands: serous and mucous glands amid the extrinsic muscles •Secrete a portion of the saliva Lingual tonsils: contained in the root

Answer 7

•separates oral cavity from nasal cavity; makes it possible to breath while chewing food

Answer 8

•Hard (bony) palate—anterior portion that is supported by the palatine processes of the maxillae and the palatine bones

Answer 9

•posterior to hard palate with more spongy texture Structure/ Function: * Composed of skeletal muscle and glandular tissue * No bone * Uvula: conical medial projection visible at the rear of the mouth * Helps retain food in the mouth until one is ready to swallow

Answer 10

transverse ridges that help the tongue hold and manipulate food

Answer 11

* Palatoglossal arch: anterior arch * Palatopharyngeal arch: posterior arch * Palatine tonsils are located on the wall between the arches

Answer 12

**Structure:** 32 adult teeth 16 in mandible (lower jaw) 16 in maxilla (upper jaw) From midline to the rear of each jaw 2 incisors—chisel-like cutting teeth used to bite off a piece of food 1 canine—pointed and act to puncture and shred food 2 premolars—broad surface for crushing, shredding, and grinding 3 molars—even broader surface for crushing, shredding, and grinding **Function:** Masticate (chew) food into smaller pieces * Makes food easier to swallow * Exposes more surface area for action of digestive enzymes, speeding chemical digestion

Answer 13

tooth socket in bone •Gomphosis joint formed between tooth and bone

Answer 14

—modified periosteum whose collagen fibers penetrate into the bone on one side and into the tooth on the other * Anchors tooth firmly in alveolus * Allows slight movement under pressure of chewing

Answer 15

covers the alveolar bone

Answer 16

1. Crown: portion above the gum 2. Root: the portion below the gum, embedded in alveolar bone 3. Neck: the point where crown, root, and gum meet 4. Gingival sulcus: space between the tooth and the gum •Hygiene in the sulcus is important to dental health

Answer 17

hard yellowish tissue that makes up most of the tooth

Answer 18

covers crown and neck •A noncellular secretion that cannot regenerate

Answer 19

—covers root Cementum and dentin are living tissue and can regenerate

Answer 20

—space in a root leading to pulp cavity in the crown * Nerves and blood vessels * Apical foramen: pore at the basal end of each root canal

Answer 21

meeting of the teeth with the mouth closed

Answer 22

20 deciduous teeth (milk teeth or baby teeth) Teeth develop beneath gums and erupt in a predictable order * Erupt from 6 to 30 months * Beginning with incisors * Between 6 and 25 years of age, are replaced by 32 permanent teeth Third molars (wisdom teeth) erupt from age 17 to 25 years •May be impacted: crowded against neighboring teeth and bone so they cannot erupt

Answer 23

The human mouth is home to more than 700 species of microorganisms, especially bacteria 1.Plaque—sticky residue on the teeth made up of bacteria and sugars * Calculus: calcified plaque * Bacteria metabolize sugars and release acids that dissolve the minerals of enamel and dentin to form dental caries (cavities) 2. Root canal therapy is necessary if cavity reaches pulp 3. Calculus in the gingival sulcus wedges the tooth and gum apart * Allows bacterial invasion of the sulcus * Gingivitis: inflammation of the gums * Periodontal disease: destruction of the supporting bone around the teeth which may result in tooth loss

Answer 24

Saliva 1. Moistens mouth 2. Begins starch and fat digestion 3. Cleanses teeth 4. Inhibits bacterial growth 5. Dissolves molecules so they can stimulate the taste buds 6. Moistens food and binds it together into bolus to aid in swallowing

Answer 25

Saliva is a hypotonic solution of 97.0% to 99.5% water and the following solutes: 1. Salivary amylase: enzyme that begins starch digestion in the mouth 2. Lingual lipase: enzyme that is activated by stomach acid and digests fat after food is swallowed 3. Mucus: binds and lubricates a mass of food and aids in swallowing 4. Lysozyme: enzyme that kills bacteria 5. Immunoglobulin A (IgA): an antibody that inhibits bacterial growth 6. Electrolytes: Na^+, K^+, Cl^-, phosphate, and bicarbonate •pH: 6.8 to 7.0

Answer 26

•binds and lubricates a mass of food and aids in swallowing

Answer 27

•enzyme that begins starch digestion in the mouth

Answer 28

enzyme that is activated by stomach acid and digests fat after food is swallowed

Answer 29

enzyme that kills bacteria

Answer 30

•an antibody that inhibits bacterial growth

Answer 31

Na^+, K^+, Cl^-, phosphate, and bicarbonate

Answer 32

6.8 to 7.0

Answer 33

Compound tubuloacinar glands •Branched ducts ending in acini Mucous cells secrete mucus Serous cells secrete thin fluid rich in enzymes and electrolytes Mixed acinus has both mucous and serous cells

Answer 34

muscular funnel connecting oral cavity to esophagus and nasal cavity to larynx * Digestive and respiratory tracts intersect * Has deep layer of longitudinal skeletal muscle * Has superficial layer of circular skeletal muscles that form pharyngeal constrictors (superior, middle, and inferior) that force food downward during swallowing * When not swallowing, the inferior constrictor (upper esophageal sphincter) remains contracted to exclude air from the esophagus * Disappears at the time of death when the muscles relax, so it is a physiological sphincter, not an anatomical structure

Answer 35

Esophagus—straight muscular tube 25–30 cm long * Begins at level between C6 and the cricoid cartilage * Extends from pharynx to cardial orifice of stomach passing through esophageal hiatus in diaphragm * Lower esophageal sphincter: food pauses here because of constriction * Prevents stomach contents from regurgitating into the esophagus * Protects esophageal mucosa from erosive stomach acid * Heartburn—burning sensation produced by acid reflux into the esophagus

Answer 36

Nonkeratinized stratified squamous epithelium Esophageal glands in submucosa secrete mucus Deeply folded into longitudinal ridges when empty Skeletal muscle in upper one-third, mix of muscle types in middle one-third, and only smooth muscle in bottom one-third Meets stomach at level of T7 Covered with adventitia

Answer 37

Stomach—a muscular sac in upper left abdominal cavity immediately inferior to the diaphragm * Primarily functions as a food storage organ * volume of about 50 mL when empty * 1.0 to 1.5 L after a typical meal * Up to 4 L when extremely full—can extend nearly as far as the pelvis

Answer 38

Mechanically breaks up food, liquefies it, and begins chemical digestion of protein and fat •Chyme: soupy or pasty mixture of semidigested food in the stomach Most digestion occurs after the chyme passes on to the small intestine

Answer 39

•soupy or pasty mixture of semidigested food in the stomach

Answer 40

J-shaped; relatively vertical in tall people, horizontal in short people •Divided into four regions: 1. Cardial part (cardia)—small area within about 3 cm of the cardial orifice 2. Fundus—dome-shaped portion superior to esophageal attachment 3. Body—makes up the greatest part of stomach 4. Pyloric part—narrower pouch at the inferior end * Subdivided into the funnel-like antrum * Narrower pyloric canal that terminates at pylorus * Pylorus—narrow passage to duodenum * Pyloric sphincter—regulates the passage of chyme into the duodenum

Answer 41

Stomach has a simple columnar epithelium covered by mucous * Apical regions of its surface cells are filled with mucin * Mucin swells with water and becomes mucus after it is secreted Mucosa and submucosa are flat when stomach is full but form longitudinal wrinkles called gastric rugae when empty Muscularis externa has three layers (instead of the two seen elsewhere) •Outer longitudinal, middle circular, and inner oblique layers

Answer 42

Gastric pits—depressions in gastric mucosa * Lined with simple columnar epithelium * Two or three tubular glands open into the bottom of each gastric pit * Cardiac glands in cardial part * Pyloric glands in pyloric parts Gastric glands in the rest of the stomach

Answer 43

secrete mucus * Predominate in cardiac and pyloric glands * In gastric glands, called mucous neck cells since they are concentrated at the neck of the gland

Answer 44

found in base of pit and in neck of gland •Divide rapidly and produce continual supply of new cells to replace cells that die

Answer 45

found mostly in the upper half of the gland •Secrete hydrochloric acid (HCl), intrinsic factor, and a hunger hormone called ghrelin

Answer 46

HCl activates pepsin and lingual lipase Breaks up connective tissues and plant cell walls •Helps liquefy food to form chyme Converts ingested ferric ions (Fe^(3+) ) to ferrous ions (Fe^(2+) ) •Fe^(2+) absorbed and used for hemoglobin synthesis Contributes to nonspecific disease resistance by destroying most ingested pathogens Most ulcers are caused by acid-resistant bacteria Helicobacter pylori, which can be treated with antibiotics and Pepto-Bismol

Answer 47

most numerous * Secrete gastric lipase and pepsinogen * Dominate lower half of gastric glands * Absent from pyloric and cardiac glands

Answer 48

concentrated in lower end of gland •Secrete hormones and paracrine messengers that regulate digestion

Answer 49

Zymogens—digestive enzymes secreted as inactive proteins •Converted to active enzymes by removing some of their amino acids Pepsinogen—zymogen secreted by chief cells * Hydrochloric acid removes some of its amino acids and forms pepsin that digests proteins * Autocatalytic effect—as some pepsin is formed, it converts more pepsinogen into more pepsin Pepsin digests dietary proteins into shorter peptides Protein digestion is completed in the small intestine

Answer 50

produced by chief cells Gastric lipase and lingual lipase play a minor role in digesting dietary fats * Digests 10% to 15% of dietary fats in the stomach * Rest digested in the small intestine

Answer 51

a glycoprotein secreted by parietal cells Essential to absorption of vitamin B\_12 by the small intestine •Binds vitamin B\_12 and then intestinal cells absorb this complex by receptor-mediated endocytosis Vitamin B\_12 is needed to synthesize hemoglobin •Deficiency causes anemia Secretion of intrinsic factor is the only indispensable function of the stomach •Digestion can continue if stomach is removed (gastrectomy), but B\_12 supplements will be needed

Answer 52

Gastric and pyloric glands have a variety of cells that produce a variety of chemical messengers * Most are hormones that enter blood and stimulate distant cells * Some are paracrine secretions that stimulate neighboring cells * Several are peptides produced in both the digestive tract and the central nervous system: gut–brain peptides * Substance P, vasoactive intestinal peptide (VIP), secretin, gastric inhibitory peptide (GIP), cholecystokinin, and neuropeptide Y (NPY)

Answer 53

Swallowing center of medulla oblongata signals stomach to relax Vagus nerve relays message from medulla and activates a receptive-relaxation response in stomach •Resists stretching briefly, but relaxes to hold more food Soon stomach shows a rhythm of peristaltic contractions controlled by enteric pacemaker cells in longitudinal layer of muscularis externa * A ring of constriction every 20 seconds * Becomes stronger contraction at pyloric part Thick muscularis of antrum acts as a strong pump that breaks up semidigested food and prepares it for intestine Antral contractions come in waves that churn and break up the chyme into small particles Only about 3 mL of chyme is squirted into the duodenum at a time; this small amount allows duodenum to: * Neutralize the stomach acid * Digest nutrients little by little If duodenum is overfilled, it inhibits gastric motility Typical meal emptied from stomach in 4 hours •Less time if the meal is more liquid As long as 6 hours for a high-fat meal * After 30 minutes or so these contractions become quite strong * They churn the food, mix it with gastric juice, and promote its physical breakup and chemical digestion

Answer 54

forceful ejection of stomach and intestinal contents (chyme) from the mouth

Answer 55

Emetic center in the medulla oblongata integrates multiple muscle actions

Answer 56

* Overstretching of the stomach or duodenum * Chemical irritants such as alcohol and bacterial toxins * Visceral trauma * Intense pain or psychological and sensory stimuli

Answer 57

* Results in dangerous fluid, electrolyte, and acid–base imbalances * Bulimia: eating disorder; hydrochloric acid in vomit causes tooth enamel to erode

Answer 58

Stomach does not absorb any significant amount of nutrients •Does absorb aspirin and some lipid-soluble drugs Alcohol is absorbed mainly by small intestine •Intoxicating effects depend partly on how rapidly the stomach is emptied

Answer 59

1. Cephalic Phase: Vagus nerve stimulates gastric selection even before food is swallowed 2. Gastric Phase: Food stretches the stomach and activate myentric and vagovagal reflexes. These reflexes stimulate gastric secretion. Histamine and gastrin also stimualate acid and enzyme secretion. 3. Intestinal Phase: Intestinal gastrin briefly stimulates the stomach but then secretin, CCK, and the enterogastric reflex inhibit gastric secretion and motility where the duodenum processes the chume already in it. Symphathetic nerve fibers supress gastric activity, while vagal (parasymphatetic) stimulation of the stomach is now inhibited.

Answer 60

* Stomach responds to sight, smell, taste, or thought of food * Sensory and mental inputs converge on hypothalamus * Hypothalamus relays signals to medulla oblongata * Vagus nerve fibers from medulla stimulate the enteric nervous system of stomach, stimulating gastric secretion * 40% of stomach’s acid secretion occurs in cephalic phase

Answer 61

* Period in which swallowed food and semidigested protein activate gastric activity * Two-thirds of gastric secretion and one-half of acid secretion occur in this phase * Ingested food stimulates gastric activity in two ways * By stretching the stomach * Activates short reflex mediated through myenteric plexus; activates long reflex mediated through the vagus nerves and the brainstem By increasing the pH of its contents

Answer 62

1. Acetylcholine (ACh)—secreted by parasympathetic nerve fibers of both reflexes 2. Histamine—a paracrine secretion from enteroendocrine cells in the gastric glands 3. Gastrin—a hormone produced by the enteroendocrine G cells in pyloric glands

Answer 63

* Duodenum responds to arriving chyme and moderates gastric activity through hormones and nervous reflexes * Duodenum initially enhances gastric secretion but soon inhibits it * Stretching of duodenum accentuates vagovagal reflex that stimulates stomach * Peptides and amino acids in chyme stimulate G cells of duodenum to secrete more gastrin, further stimulating stomach * Soon acids and fats trigger enterogastric reflex—duodenum sends inhibitory signals to stomach by way of enteric nervous system * Duodenum also signals medulla to inhibit vagal nuclei (reducing vagal stimulation of stomach) and stimulate sympathetic neurons (sending inhibitory signals to the stomach) * Chyme also stimulates duodenal enteroendocrine cells to release secretin and cholecystokinin * They stimulate the pancreas and gallbladder * Also suppress gastric secretion * Gastrin secretion declines and pyloric sphincter contracts tightly to limit chyme entering duodenum * Gives duodenum time to work on chyme * Enteroendocrine cells also secrete glucose-dependent insulinotropic peptide (GIP) originally called gastrin-inhibiting peptide * Stimulates insulin secretion in preparation for processing nutrients about to be absorbed by small intestine

Answer 64

Small intestine receives chyme from stomach and secretions from liver and pancreas * These secretions enter digestive tract near the junction of stomach and small intestine * These secretions are important to the digestive process of the small intestine

Answer 65

Liver—reddish brown gland located immediately inferior to the diaphragm The body’s largest gland •Weighs about 1.4 kg (3 lbs) Variety of functions Secretes bile which contributes to digestion Four lobes—right, left, quadrate, and caudate * Falciform ligament separates left and right lobes * Sheet of mesentery that suspends the liver from the diaphragm * Round ligament (ligamentum teres)—fibrous remnant of umbilical vein * Carries blood from umbilical cord to liver of the fetus Hilum—irregular opening between quadrate and caudate lobes * Point of entry for hepatic portal vein and proper hepatic artery * Point of exit for the bile passages * All travel in lesser omentum Gallbladder—adheres to a depression on the inferior surface of the liver, between right and quadrate lobes Bare area on superior surface where it attaches to diaphragm

Answer 66

Hepatic lobules—tiny cylinders that fill the interior of the liver * About 2 mm long and 1 mm in diameter * Central vein: passes down the core * Hepatocytes: cuboidal cells surrounding central vein in radiating sheets or plates Each plate of hepatocytes is an epithelium one or two cells thick Hepatic sinusoids: blood-filled channels that fill spaces between the plates * Lined by a fenestrated endothelium that separates hepatocytes from blood cells * Allows plasma into the space between the hepatocytes and endothelium * Hepatocytes have brush border of microvilli that project into this space * Blood filtered through the sinusoids comes directly from the stomach and intestines, enters through hepatic portal vein and leaves to drain into vena cava Stellate macrophages: phagocytic cells in the sinusoids that remove bacteria and debris from the blood

Answer 67

Hepatocytes * After a meal, hepatocytes absorb from the blood: glucose, amino acids, iron, vitamins, and other nutrients for metabolism or storage * Between meals, hepatocytes break down stored glycogen and release glucose into the blood * Remove and degrade: hormones, toxins, bile pigments, and drugs Secrete into the blood: albumin, lipoproteins, clotting factors, angiotensinogen, and other products

Answer 68

Bile canaliculi—narrow channels into which the liver secretes bile Bile passes into bile ductules of the triads Ultimately into the right and left hepatic ducts

Answer 69

formed from convergence of right and left hepatic ducts on inferior side of the liver.

Answer 70

Cystic duct coming from gallbladder joins common hepatic duct Bile duct: formed from union of cystic and common hepatic ducts •Descends through lesser omentum toward the duodenum

Answer 71

a pear-shaped sac on underside of liver •Serves to store and concentrate bile by absorbing water and electrolytes

Answer 72

Bile—yellow-green fluid containing minerals, cholesterol, neutral fats, phospholipids, bile pigments, and bile acids Bilirubin: principal pigment derived from the decomposition of hemoglobin Bacteria in large intestine metabolize bilirubin to urobilinogen Stercobilin responsible for the brown color of feces Urobilin responsible for yellow color of urine Bile acids (bile salts): steroids synthesized from cholesterol Bile acids and lecithin, a phospholipid, aid in fat digestion and absorption Gallstones may form if bile becomes excessively concentrated with wastes

Answer 73

hard masses in either the gallbladder or bile ducts •Composed of cholesterol, calcium carbonate, and bilirubin

Answer 74

presence of gallstones •Most common in obese women over 40—excess cholesterol

Answer 75

•Result in jaundice (yellowing of skin), poor fat digestion, and impaired absorption of fat-soluble vitamins

Answer 76

use of ultrasonic vibration to pulverize stones without surgery

Answer 77

spongy retroperitoneal gland posterior to greater curvature of stomach * Measures 12 to 15 cm long, and 2.5 cm thick * Has a head encircled by duodenum, a body (midportion), and a tail on the left

Answer 78

* Endocrine portion—pancreatic islets that secrete insulin and glucagon; concentrated in the tail of the gland * Exocrine portion—99% of pancreas that secretes 1,200 to 1,500 mL of pancreatic juice per day * Secretory acini release their secretion into small ducts that converge on the main pancreatic duct

Answer 79

1.Pancreatic duct runs lengthwise through middle of the gland * Joins the bile duct at the hepatopancreatic ampulla * Hepatopancreatic sphincter controls release of both bile and pancreatic juice into the duodenum 2.Accessory pancreatic duct: smaller duct that branches from the main pancreatic duct * Opens independently into the duodenum * Bypasses the sphincter and allows pancreatic juice (alkaline mixture of water, enzymes, zymogens, sodium bicarbonate, and other electrolytes ) to be released into duodenum even when bile is not

Answer 80

1.Trypsinogen * Secreted into intestinal lumen * Converted to trypsin by enteropeptidase that is secreted by mucosa of small intestine Trypsin is autocatalytic—converts trypsinogen into still more trypsin 2. Chymotrypsinogen: converted to trypsinogen by trypsin 3. Procarboxypeptidase: converted to carboxypeptidase by trypsin

Answer 81

1. Panncreatic Amylase:digests starch 2. Pancreatic Lipase:digests fat 2. Ribonuclease and deoxyribonuclease: digest RNA and DNA, respectively

Answer 82

Three stimuli are chiefly responsible for the release of pancreatic juice and bile: acetylcholine, cholecystokinin, and secretin

Answer 83

* from vagus and enteric nerves * Stimulates acini to secrete enzymes during cephalic phase of gastric control even before food is swallowed * Enzymes remain in acini and ducts until chyme enters the duodenum

Answer 84

(CCK): secreted by mucosa of duodenum in response to arrival of fats in small intestine * Stimulates pancreatic acini to secrete enzymes * Strongly stimulates gallbladder * Induces contractions of gallbladder and relaxation of hepatopancreatic sphincter to discharge bile into duodenum Secretin: released from duodenum in response to acidic chyme arriving from the stomach •Stimulates ducts of both liver and pancreas to secrete more sodium bicarbonate Raises pH to the level required for activity of the pancreatic and intestinal digestive enzymes

Answer 85

Secretin: released from duodenum in response to acidic chyme arriving from the stomach •Stimulates ducts of both liver and pancreas to secrete more sodium bicarbonate Raises pH to the level required for activity of the pancreatic and intestinal digestive enzymes

Answer 86

**Function:** Nearly all chemical digestion and nutrient absorption occurs in the small intestine **Structure:** The longest part of the digestive tract * About 5 m long in a living person * Up to 8 m long in a cadaver—no muscle tone “Small” intestine refers to the diameter—not length •Diameter is about 2.5 cm (1 in.)

Answer 87

coiled tube filling most of the abdominal cavity inferior to stomach and liver

Answer 88

1. Duodenum: first 25 cm (10 in.) 2. Jejunum:first 40% of small intestine beyond duodenum 3. Ileum: forms last 60% of the postduodenal small intestine

Answer 89

**Structure:** * Begins at pyloric valve * Major and minor duodenal papillae distal to pyloric valve * Receives major and minor pancreatic ducts, respectively * Arches around head of the pancreas Ends at a sharp bend called the duodenojejunal flexure •Most is retroperitoneal **Function:** * Receives stomach contents, pancreatic juice, and bile * Stomach acid is neutralized here * Fats are physically broken up (emulsified) by bile acids * Pepsin is inactivated by increased pH * Pancreatic enzymes perform chemical digestion

Answer 90

**Structure:** first 40% of small intestine beyond duodenum * Roughly 1.0 to 1.7 m in a living person * Has large, tall, closely spaced circular folds * Its wall is relatively thick and muscular * Especially rich blood supply which gives it a red color **Function** •Most digestion and nutrient absorption occurs here

Answer 91

**Structure:** forms last 60% of the postduodenal small intestine * About 1.6 to 2.7 m, thinner, less muscular, less vascular, and paler pink color * Aggregated lymphoid nodules—prominent lymphatic nodules in clusters on the side opposite the mesenteric attachment; visible to naked eye; become larger near large intestine * Ileocecal junction—end of the small intestine; where the ileum joins the cecum of the large intestine * Ileal papilla—formed by the thickened muscularis of the ileum; protrudes into the cecum; regulates passage of food residue into the large intestine * Both jejunum and ileum are intraperitoneal and covered with serosa

Answer 92

The small intestine receives nearly all of its blood supply from the superior mesenteric artery Fans out through the mesentery to give rise to 12 to 15 jejunal and ileal arteries Superior mesenteric vein •This joins the splenic vein and then flows into the hepatic portal system, headed for the liver with its load of nutrients

Answer 93

Small intestine tissues designed for nutrient digestion and absorption 1. Lumen lined with simple columnar epithelium 2. Muscularis externa is noted for a thick inner circular layer and a thinner outer longitudinal layer 3. Large internal surface area—great length and three types of internal folds or projections * Circular folds (plicae circulares)—increase surface area by a factor of 2 to 3 * Villi—increase surface area by a factor of 10 * Microvilli—increase the surface area by a factor of 20

Answer 94

Circular folds (plicae circulares)—largest folds of intestinal wall * Up to 10 mm high * Involve only mucosa and submucosa * Occur from duodenum to middle of ileum * Relatively small and sparse in ileum; not found in distal half, as most nutrient absorption is completed by this point * Cause chyme flow in spiral path causing more contact with mucosa * Promote more thorough mixing and nutrient absorption

Answer 95

Villi—finger-like projections 0.5 to 1 mm tall * Make mucosa look fuzzy * Villus covered with two types of epithelial cells * Absorptive cells (enterocytes) * Goblet cells—secrete mucus * Epithelia joined by tight junctions that prevent digestive enzymes from seeping between them * Core of villus filled with areolar tissue of lamina propria * Contains arteriole, capillaries, venule, and lymphatic capillary called a lacteal

Answer 96

Microvilli: form a fuzzy brush border on apical surface of each absorptive cell * Brush border enzymes—contained in plasma membrane of microvilli * Carry out some of the final stages of enzymatic digestion * Not released into the lumen * Contact digestion: chyme must contact the brush border for digestion to occur * Intestinal churning of chyme ensures contact with the mucosa

Answer 97

Intestinal crypts—numerous pores that open into tubular glands on the floor of the small intestine between bases of the villi * Similar to gastric glands * In upper half, have enterocytes and goblet cells like the villi * In lower half, dominated by dividing stem cells * Life span of 3 to 6 days; new epithelial cells migrate up the crypt to the tip of the villus where they are sloughed off and digested * A few Paneth cells are clustered at the base of each crypt * Secrete lysozyme, phospholipase, and defensins—defensive proteins that resist bacterial invasion of the mucosa

Answer 98

in submucosa of duodenum * Secrete an abundance of bicarbonate-rich mucus * Neutralize stomach acid and shield the mucosa from its erosive effects

Answer 99

Large population of lymphocytes throughout lamina propria and submucosa of small intestine •Intercept pathogens before they can invade bloodstream Aggregated into lymphatic nodules in ileum

Answer 100

1.To mix chyme with intestinal juice, bile, and pancreatic juice * To neutralize acid * Digest nutrients more effectively 2. To churn chyme and bring it in contact with the mucosa for contact digestion and nutrient absorption 3. To move residue toward large intestine

Answer 101

movement in which stationary ring-like constrictions appear in several places along the intestine * They relax and new constrictions form elsewhere * Most common kind of intestinal contraction * Enteric pacemaker cells in muscularis externa set rhythm of segmentation * Contractions about 12 times per minute in the duodenum * 8 to 9 times per minute in the ileum * When most nutrients have been absorbed and little remains but undigested residue, segmentation declines and peristalsis begins Ileal papilla usually closed * Food in stomach triggers gastroileal reflex that enhances segmentation in the ileum and relaxes the valve * As cecum fills with residue, pressure pinches the valve shut Prevents reflux of cecal contents into the ileum

Answer 102

Starch—most digestible dietary carbohydrate * Cellulose is indigestible * Starch is first digested to oligosaccharides (up to eight glucose residues long) * Oligosaccharides then digested to the disaccharide maltose * Maltose finally digested to glucose which is absorbed by the small intestine

Answer 103

Process begins in the mouth * Salivary amylase hydrolyzes starch into oligosaccharides * Amylase works best at pH of 6.8 to 7.0 of oral cavity * Amylase quickly denatured on contact with stomach acid and digested by pepsin * About 50% of dietary starch is digested before it reaches small intestine * Pancreatic amylase resumes starch digestion in intestine

Answer 104

When reaching small intestine, pancreatic amylase quickly converts starch to oligosaccharides and maltose Brush border enzymes continue carbohydrate digestion: * Dextrinase and glucoamylase hydrolyze oligosaccharides * Maltase hydrolyzes maltose (a disaccharide) * Sucrase and lactase hydrolyze the disaccharides sucrose and lactose * In most people, lactase production stops in childhood * Monosaccharides produced by disaccharide hydrolysis (such as glucose) are immediately absorbed

Answer 105

Plasma membrane of absorptive cells has transport proteins that absorb monosaccharides as soon as brush border enzymes release them 80% of absorbed sugar is glucose * Taken up by sodium–glucose transport (SGLT) proteins * Glucose is transported out the base of absorptive cell into ECF by facilitated diffusion * Sugar entering ECF increases its osmolarity * Draws water osmotically from lumen of intestine, through leaky tight junctions between epithelial cells * Water carries more glucose and other nutrients with it by solvent drag

Answer 106

SGLT also absorbs galactose Fructose is absorbed by facilitated diffusion (by a different carrier protein) and converted to glucose Glucose, galactose, and any remaining fructose are transported out of the base of the cell by facilitated diffusion Absorbed by blood capillaries in the villus Hepatic portal system delivers them to the liver

Answer 107

In people without lactase, lactose passes undigested into large intestine * Increases osmolarity of intestinal contents * Causes water retention in the colon and diarrhea * Gas production by bacterial fermentation of the lactose Occurs in many people •15% of American Whites, 90% of American Blacks, 70% of Mediterraneans; and nearly all of Asian descent Can consume yogurt and cheese since bacteria have broken down the lactose

Answer 108

Amino acids absorbed by the small intestine come from three sources * Dietary proteins * Digestive enzymes digested by each other * Sloughed epithelial cells digested by enzymes Endogenous amino acids from last two sources total about 30 g/day Exogenous amino acids from our diet total about 44 to 60 g/day

Answer 109

Proteases (peptidases)—enzymes that digest proteins * Begin their work in stomach in optimum pH of 1.5 to 3.5 * Pepsin hydrolyzes any peptide bond between tyrosine and phenylalanine * Pepsin digests 10% to 15% of dietary protein into shorter peptides and some free amino acids

Answer 110

Protein digestion continues in small intestine * Pepsin inactivated when it passes into the duodenum and mixes with alkaline pancreatic juice (pH 8) * Pancreatic enzymes trypsin and chymotrypsin take over the process Hydrolyze polypeptides into even shorter oligopeptides

Answer 111

1.Carboxypeptidase—removes amino acids from –COOH end of the chain Carboxypeptidase is a pancreatic secretion 2. Aminopeptidase (Brush border enzyme)—removes amino acids from –NH2 end 3. Dipeptidase (brush border enzyme)—splits dipeptides in the middle and release two free amino acids

Answer 112

Brush border enzymes finish task, producing free amino acids that are absorbed into intestinal epithelial cells * Sodium-dependent amino acid cotransporters move amino acids into epithelial cells * Facilitated diffusion moves amino acids out into bloodstream Infants absorb proteins by pinocytosis (maternal IgA) and release them into the blood by exocytosis

Answer 113

Hydrophobicity of lipids makes their digestion and absorption complicated Lipases—fat-digesting enzymes * Lingual lipase secreted by intrinsic salivary glands of the tongue * Active in mouth, but more active in stomach along with gastric lipase * 10% to 15% of lipids digested before reaching duodenum * Before digestion in duodenum, vigorous pumping in stomach’s antrum emulsifies the fat (breaks up globs) Emulsification droplets are passed to small intestine

Answer 114

Emulsification droplets are broken down further by bile, lecithin, and agitation produced by intestinal segmentation •Exposes more fat surface to enzymatic action There is enough pancreatic lipase in the small intestine after a meal to digest the average daily fat intake in as little as 1 to 2 minutes Lipase acts on triglycerides •Removes first and third fatty acids from glycerol backbone, but leaves the middle one The product of lipase action are two free fatty acids (FFAs) and a monoglyceride

Answer 115

Absorption of free fatty acids, monoglycerides, and other lipids depends on minute droplets in the bile called micelles * Made in the liver * Consist of 20 to 40 bile acid molecules aggregated with their hydrophilic side groups facing outward and their hydrophobic steroid rings facing inward Bile phospholipids and cholesterol diffuse into the center of the micelle to form its core

Answer 116

Micelles pass down the bile duct into the duodenum •There they absorb fat-soluble vitamins, cholesterol, and the FFAs and monoglycerides produced by fat digestion They transport lipids to the surface of the intestinal absorptive cells Lipids leave the micelles and diffuse through the plasma membrane into the cells Micelles are reused, picking up another cargo of lipid, transporting them to the absorptive cells

Answer 117

Within the intestinal cell, free fatty acids and monoglycerides are transported to the smooth ER Resynthesized into triglycerides Golgi complex coats these with phospholipids and protein to form chylomicrons * Packaged into secretory vesicles that migrate to basal surface of cell * Release their contents into core of villus * Taken up by lacteal into lymph * White, fatty intestinal lymph (chyle) flows into larger and larger lymphatic vessels until it enters the bloodstream

Answer 118

Nucleic acid * Nucleases (deoxyribonuclease and ribonuclease) of pancreatic juice hydrolyze DNA and RNA to nucleotides * Nucleosidases and phosphatases of brush border split them into phosphate ions, ribose or deoxyribose sugar, and nitrogenous bases Membrane carriers allow absorption

Answer 119

* Absorbed unchanged * Fat-soluble vitamins: A, D, E, and K absorbed with other lipids * If ingested without fat-containing food, they are not absorbed at all but are passed in the feces and wasted * Water-soluble vitamins, B complex and C, absorbed by simple diffusion and B\_12 if bound to intrinsic factor from the stomach

Answer 120

Minerals (electrolytes) * Absorbed all along small intestine * Na+ cotransported with sugars and amino acids * Cl− exchanged for bicarbonate reversing chloride–bicarbonate exchange that occurs in the stomach * K+ absorbed by simple diffusion

Answer 121

Iron and calcium absorbed as needed * Iron absorption is inhibited by liver hormone hepcidin to prevent overload * Absorptive cells bind ferrous ions (Fe2+) and internalize them by active transport * Unable to absorb ferric ions (Fe3+) but stomach acid reduces ferric ions to absorbable ferrous ions * Transferrin (extracellular protein) transports iron in blood to bone marrow, muscle, and liver

Answer 122

1.Transcellular absorption in the duodenum * Enters through calcium channels in apical cell membrane * Binds to calbindin protein so concentration gradient will continue to favor calcium influx * Actively transported out of base of cell into bloodstream by calcium–ATPase and Na+–Ca2+ antiport 2.Diffusion between epithelial cells in jejunum and ileum * Most absorbed calcium is from meat and dairy * Dietary fat retards calcium absorption

Answer 123

Parathyroid hormone—secreted in response to a drop in blood calcium levels * Stimulates kidney to synthesize vitamin D from precursors made by epidermis and liver * Vitamin D affects absorptive cells of the duodenum in three ways * Increases number of calcium channels in apical membrane * Increases the amount of calbindin in cytoplasm * Increases the number of calcium–ATPase pumps at basal membrane * Parathyroid hormone increases the level of calcium in the blood

Answer 124

Digestive system is one of several systems involved in fluid balance Digestive tract receives about 9 L of water/day * 0.7 L in food, 1.6 L in drink, 6.7 L in gastrointestinal secretions * 8 L is absorbed by small intestine and 0.8 L by large intestine 0.2 L voided in daily fecal output

Answer 125

Water is absorbed by osmosis following the absorption of salts and organic nutrients Diarrhea—occurs when large intestine absorbs too little water * Feces pass through too quickly if intestine is irritated * Feces contain high concentrations of a solute (such as lactose) Constipation—occurs when fecal movement is slow, too much water gets reabsorbed, and feces become hardened

Answer 126

Large intestine * Measures 1.5 m (5 ft.) long and 6.5 cm (2.5 in.) in diameter in cadaver * Begins as cecum inferior to ileal papilla * Appendix attached to lower end of cecum * Densely populated with lymphocytes—a significant source of immune cells * Ascending colon, right colic (hepatic) flexure, transverse colon, left colic (splenic) flexure, and descending colon frame the small intestine * Sigmoid colon is S-shaped portion leading down into pelvic cavity

Answer 127

Rectum: portion ending at anal canal •Has three curves and three infoldings, called the transverse rectal folds (rectal valves)

Answer 128

Anal canal: final 3 cm of the large intestine * Passes through levator ani muscle and pelvic floor, terminates at the anus * Anal columns and sinuses—exude mucus and lubricant into anal canal during defecation * Large hemorrhoidal veins for superficial plexus in anal columns and around orifice * Hemorrhoids—permanently distended veins that protrude into anal canal or bulge outside the anus * Obesity and pregnancy

Answer 129

* Taenia coli—longitudinal fibers concentrated in three thickened, ribbon-like strips * Haustra—pouches in the colon caused by the muscle tone of the taeniae coli * Internal anal sphincter—smooth muscle of muscularis externa * External anal sphincter—skeletal muscle of pelvic diaphragm

Answer 130

club-like, fatty pouches of peritoneum adhering to the colon; unknown function

Answer 131

Supplied by mesenteric arteries. The superior and inferior mesenteric veins drain the same parts of the large intestine as the correspondingly named arteries and drain into the hepatic portal system

Answer 132

simple columnar epithelium •Anal canal has nonkeratinized stratified squamous epithelium in its lower half for abrasion resistance

Answer 133

Intestinal crypts—glands sunken deep into lamina propria with a high density of mucus-secreting goblet cells

Answer 134

Lamina propria and submucosal have a lot of lymphatic tissue •Provides protection from large population of bacteria in large intestine

Answer 135

Gut microbiome—about 800 species of bacteria that populate the large intestine * Bacteria digest cellulose, pectin, and other carbohydrates for which our cells lack enzymes * Help in synthesis of vitamins B and K

Answer 136

Flatus—intestinal gas * Average person produces 500 mL of flatus per day * Most gas in large intestine is reabsorbed instead * Much of flatus is swallowed air, but bacteria add to it * Hydrogen sulfide, indole, and skatole produce odor * Hydrogen gas may explode during electrical cauterization used in surgery

Answer 137

Large intestine takes about 36 to 48 hours to reduce residue of a meal to feces * Most time in transverse colon * Does not chemically change the residue * Reabsorbs water and electrolytes Feces consist of about 75% water and 25% solids •Solids: 30% bacteria, 30% undigested fiber, 10% to 20% fat, small amount of mucus, proteins, salts, digestive secretions, and sloughed epithelial cells

Answer 138

Haustral contractions occur every 30 minutes * Distension of a haustrum stimulates it to contract * Churns and mixes residue promoting water and salt absorption Mass movements—stronger contractions that occur one to three times a day * Triggered by gastrocolic and duodenocolic reflexes * Filling of the stomach and duodenum stimulates motility of the colon * Move residue several centimeters

Answer 139

1. Feces stretch the rectum and stimulate stretch receptors, which transit signal to the spinal cord. 2. A spinal reflex stimulates a contraction of the rectum 3. The spinal reflex also relaxes the internal anal sphincter 4. Impulses from the brain prevent untimely defecation by keeping the extermal anal sphinchter contracted \*\*\*Defecation only occurs only if this sphincter also relaxes

Answer 140

•Sex of child determined by type of sperm that fertilizes mother’s egg AND stimulation of specific hormones during development –X-carrying sperm fertilizes the egg: female –Y-carrying sperm fertilizes the egg: male * Initially, a fetus is sexually undifferentiated * Gonads begin to develop at 5 or 6 weeks as gonadal ridges * Two sets of ducts adjacent to each gonadal ridge –In males, mesonephric ducts develop into reproductive tract; paramesonephric ducts degenerate –In females, paramesonephric ducts develop into reproductive tract; mesonephric ducts degenerate •The two sexes indistinguishable for first 8 to 10 weeks of development 1.Female reproductive tract develops from the paramesonephric ducts **–Not due to the positive action of any hormone** but because of the absence of testosterone and müllerian-inhibiting factor (MIF) -Estrogen levels are always high in pregnancy but if estrogen was the –If estrogen was the hormone that directed female development, all fetuses would be feminized from mothers hormone •Female development of a fetus occurs whenever there is an absence of androgen hormones –Not because estrogen is present 2.SRY Gene (sex determining region on Y chromosome) found only in males codes for a portein TDF (testes determining factor)-TDF that initiates development of testes –Testes begin to secrete testosterone at 8 to 9 weeks •Stimulates mesonephric ducts to develop into male tracts –At same time, the testes secrete müllerian-inhibiting factor causing degeneration of the paramesonephric ducts

Answer 141

8-10 weeks into development when reproductive tract forms

Answer 142

* *Male:** 1. TDF (from SRY Gene) - fetal development: initiatives development of testes 2. Mullerian Inihibiting Factor - fetal development: causes degeneration of the paramesonephric ducts 3. Testosterone: - fetal development (at 8-9 weeks): stimulates mesenphreic duct to develop into male tract; levels are as about as high as they are in mid-puberty and then they become dormant until puberty; from puberty to adulthood, reproductive function is regulated by hormonal links btw. hypothalamus, pituitary gland, and gonads - puberty: secondary sexual characterisitcs; secretion peaks at 20 and then declines with age 4. GnRH: released as hypothalamus is matured later in life\> GnRH stimulates anterior pituitary to release: a. FSH (helps stimulate spermatogenesis) b. LH (stimulates production of testosterone) Female: - female fetal development occus when there is a lack or absence of androgen hormones (not because estrogen is present) 1. GnRH: stimulates anterior pituitary to secrete FSH (stimulats ovarian follicles to stimulate estrogen, progerstone, inhibin, and some androgen) and LH 2. Estrogen: feminizing hormones with widespread effects on body-Estradiol, Estriol, Estrone. - Functions; vaginal metalplasia, growth of ovaries & sexual seconary sex organs, stimulates growth hormone secretion, stimulates fat deposition, thickens skin,etc. 3. Progestrone: primarly acts on the utererus preparing it for possible pregnancy in the second half of the menstrual cycle; breast development; 4. Prolactin- breast development in puberty 5. Androgen: secondary sexual characteristics ie. pubic, axillary hair, sebaceous glands, axillary glands 6. Leptin:stimulates gonadotropin secretion important in menstruation

Answer 143

Rising levels of GnRH stimulates anterior pituitary to secrete FSH and LH in both male and females

Answer 144

stimulates ovarian follicles and they begin to secrete estrogen, progesterone, inhibin, and a small amount of androgen

Answer 145

•feminizing hormones with widespread effects on the body Estradiol (most abundant), estriol, and estrone •Estradiol stimulates many changes in puberty –Stimulates vaginal metaplasia –Stimulates growth of ovaries and secondary sex organs –Stimulates growth hormone secretion •Increase in height and widening of pelvis –Stimulates fat deposition (breast, hips, etc…) –Thickens skin •But girls’ skin is still thinner, softer, and warmer than boys -

Answer 146

–Primarily acts on the uterus preparing it for possible pregnancy in the second half of the menstrual cycle

Answer 147

* Estrogens and progesterone suppress FSH and LH secretion through negative feedback * Inhibin selectively suppresses FSH secretion * Hormone secretion is distinctly cyclic and the hormones are secreted in sequence

Answer 148

egg production

Answer 149

–Produces haploid gametes by means of meiosis –Distinctly cyclic event that normally releases one egg each month –Accompanied by cyclic changes in hormone secretion –Cyclic changes in histological structure of the ovaries and uterus * Uterine changes result in monthly menstrual flow * Embryonic development of ovary –Female germ cells arise from yolk sac –Colonize gonadal ridges the first 5 to 6 weeks of development –Differentiate into oogonia and multiply until the fifth month •6 to 7 million in number –Transform into primary oocytes: early meiosis I –Most degenerate (atresia) by the time the girl is born –Egg, or ovum: any stage from the primary oocyte to the time of fertilization –By puberty, 200,000 oocytes remain Lifetime supply—probably will ovulate only 480 times •Egg development resumes in adolescence –FSH stimulates monthly cohorts of about 24 oocytes to complete meiosis I –Each oocyte divides into two haploid daughter cells of unequal size and different destinies * Important to produce an egg with as much cytoplasm as possible * If fertilized, it must divide repeatedly and produce numerous daughter cells –Secondary oocyte: large daughter cell that is the product of meiosis I –First polar body: smaller one that ultimately disintegrates A means of discarding the extra set of haploid chromosomes –Secondary oocyte proceeds as far as metaphase II * Arrests until after ovulation * If not fertilized, it dies and never finishes meiosis * If fertilized, it completes meiosis II and casts off a second polar body –Chromosomes of the large remaining egg unite with those of the sperm

Answer 150

process of sperm production in seminiferous tubules

Answer 151

•Involves three principal events: 1. Division and remodeling of large germ cells into small, mobile sperm cells with flagella 2. Reduction of chromosome number by one-half 3. Shuffling of genes so each chromosome contains new gene combinations that did not exist in parent •Ensures genetic variation in the offspring

Answer 152

Meiosis is important to produce haploid cells so that the sperm and egg can fuse and combin genetic material to form a full set. **Females:** starts at fetal development and resumes at adolescence –FSH stimulates monthly cohorts of about 24 oocytes to complete meiosis I –Each oocyte divides into two haploid daughter cells of unequal size and different destinies * Important to produce an egg with as much cytoplasm as possible * If fertilized, it must divide repeatedly and produce numerous daughter cells –Secondary oocyte: large daughter cell that is the product of meiosis I –First polar body: smaller one that ultimately disintegrates A means of discarding the extra set of haploid chromosomes –Secondary oocyte proceeds as far as metaphase II * Arrests until after ovulation * If not fertilized, it dies and never finishes meiosis * If fertilized, it completes meiosis II and casts off a second polar body **Males:** * Primary spermatocyte undergoes meiosis I which gives rise to two equal-size, haploid, genetically unique secondary spermatocytes * Each secondary spermatocyte undergoes meiosis II dividing into two spermatids—a total of four for each spermatogonium * Spermiogenesis—four spermatids undergo transformations in which they differentiate into a spermatozoa

Answer 153

combined endocrine and exocrine glands that produce sex hormones and sperm

Answer 154

white fibrous capsule on testes

Answer 155

•ducts where sperm are produced –One to three in each lobule –Each tubule lined with a thick germinal epithelium of germ cells (becoming sperm) and nurse cells –Nurse cells in between germ cells * Protect the germ cells, and promote their development * Germ cells depend on them for nutrients, waste removal, growth factors, and other needs

Answer 156

•a network on the posterior side of the testis that collects sperm from seminiferous tubules –Sperm flow with fluid secreted by nurse cells –Sperm do not swim while in the male reproductive tract

Answer 157

•A testicular artery supplies each testis –Low BP of testicular artery results in poor O\_2 supply to the testes –Sperm develop large mitochondria to cope with poor oxygen supply and to help them survive hypoxic environment of female reproductive tract

Answer 158

•female gonads that produce egg cells (ova) and sex hormones

Answer 159

where germ cells develop

Answer 160

occupied by major arteries and veins

Answer 161

–Attached to uterus by ovarian ligament –Attached to pelvic wall by suspensory ligament •Contains ovarian artery, vein, and nerves –Anchored to broad ligament by mesovarium

Answer 162

•Ovary receives blood from two arteries –Ovarian branch of the uterine artery –Ovarian artery Equivalent to testicular artery in male

Answer 163

•formed by tight junctions between nurse cells –Separates sperm from immune system –Prevents antibodies and other large molecules in the blood from getting to germ cells –Germ cells are immunologically different from body cells and would be attacked by the immune system

Answer 164

•midlife change in hormone secretion –Accompanied by menopause: cessation of menstruation

Answer 165

cessation of menstruation ## Footnote –Usually occurs between ages of 45 and 55 –Age of menopause has increased in last century –Menopouse considered complete when there has been no menstruation for a year

Answer 166

Symptoms: –Follicles less responsive to gonadotropins – secrete less estrogen and progesterone –Uterus, vagina, and breast atrophy –Intercourse may become uncomfortable –Vaginal infections more common –Skin becomes thinner –Cholesterol levels rise, increasing risk of cardiovascular disease –Bone mass declines, increasing risk of osteoporosis –Blood vessels constrict and dilate in response to shifting hormone balances •Dilations may produce hot flashes: spreading sense of heat from abdomen to thorax, neck, and face

Answer 167

•male climacteric –A period of declining reproductive function that may be first seen in early 50s –Although sperm counts decline, men can still father children throughout old age

Answer 168

•mound of tissue overlying pectoralis major –Enlarges at puberty and remains so for life –Most of the time it contains very little mammary gland

Answer 169

•Mammary gland—develops within the breast during pregnancy –Remains active in the lactating breast –Atrophies when a woman ceases to nurse

Answer 170

–conical to pendulous, with nipple at its apex

Answer 171

–extension toward armpit •Lymphatics in axillary tail are important as a route for breast cancer metastasis

Answer 172

•surrounded by circular colored zone, called the areola –Capillaries and nerves close to skin surface: more sensitive –Sensory nerve fibers of areola trigger a milk ejection reflex when an infant nurses

Answer 173

–intermediate between sweat glands and mammary glands •Secretions protect the nipple from chapping and cracking during nursing –Smooth muscle fibers in dermis of areola that contract in response to cold, touch, and sexual arousal, wrinkling the skin and erecting the nipple

Answer 174

attach breast to dermis of overlying skin and fascia of the pectoralis major

Answer 175

•The nonlactating breast consists mostly of adipose and collagenous tissue –Breast size determined by amount of adipose tissue

Answer 176

•branch through fibrous stroma and converge on the nipple –Mammary gland develops during pregnancy –15 to 20 lobes around the nipple –Lactiferous duct drains each lobe •Dilates to form lactiferous sinus which opens into nipple –Ducts ends in acini (sacs) Acini are surrounded by myoepithelial cells

Answer 177

•Breast cancer occurs in 1 out of 8 or 9 American women –A leading cause of female mortality •Tumors begin with cells from mammary ducts –May metastasize by mammary and axillary lymphatics * Signs may include lump, skin puckering, changes in skin texture, and drainage from nipple * Contibuting causes –BRCA1 and BRCA2: two breast cancer genes •But most breast cancer is nonhereditary –Some breast cancers are stimulated by estrogen •Risk factors –Aging, exposure to ionizing radiation, carcinogenic chemicals, excessive alcohol and fat intake, and smoking –Over 70% of cases lack identifiable risk factors * Tumor discovery usually during breast self-examination (BSE)—monthly for all women * Mammograms (breast X-rays) –Late 30s: baseline mammogram –Ages 40 to 49: every 2 years –Over age 50: yearly

Answer 178

1. Lumpectomy: removal of tumor only 2. Simple mastectomy: removal of breast tissue only or breast tissue and some axillary lymph nodes 3. Radical mastectomy: removal of breast, underlying muscle, fascia, and lymph nodes •Rarely done as it generally does not improve outcome 4. Surgery is followed by radiation or chemotherapy 5. Breast reconstruction from skin, fat, and muscle from other parts of the body

Answer 179

–Second most common cancer in men after lung cancer –Tumors tend to be near the periphery of the gland where they do not obstruct urine flow •Go unnoticed until they cause pain –Metastasize to nearby lymph nodes and then to lungs and other organs –Digital rectal exam (DRE): palpated through rectal wall to check for tumors –Diagnosed from elevated levels of serine protease (PSA) and acid phosphatase in the blood

Answer 180

•noncancerous enlargement of the prostate –Compresses urethra and obstructs flow of urine –Promotes bladder and kidney infections

Answer 181

•Many STDs have an incubation period in which the pathogen multiplies with no symptoms and a communicable period in which the disease can be transmitted to others –Symptomless carriers do exist

Answer 182

1. Chlamydia 2. Gonorrhea 3. Syphilis

Answer 183

Bacterial STD ## Footnote may cause urethral discharge and testicular pain

Answer 184

Bacterial STD ## Footnote –pain and pus discharge; may result in sterility from pelvic inflammatory disease

Answer 185

Bacterial STD ## Footnote –hard lesions (chancres) at site of infection * Disappearance of chancres ends first stage * Second stage is widespread pink rash * Neurosyphilis is third stage with cardiovascular damage and brain lesions

Answer 186

1. Genital herpes: 2. Genital warts: 3. Hepatitis B and C:

Answer 187

Viral STD –most common STD in United States •Blisters and pain

Answer 188

Viral STDs ## Footnote –warts on perineal region, cervix, anus * Caused by human papillomavirus (HPV) * Vaccine available

Answer 189

Viral STD inflammatory liver disease

Answer 190

first menstrual period ## Footnote –Requires at least 17% body fat in teenager * Improved nutrition has lowered age of onset to age 12 * **Leptin** stimulates gonadotropin secretion * If body fat and leptin levels drop too low, gonadotropin secretion declines and menstrual cycle might cease –Menstruation ceases when body fat drops below 22% in adult woman * First few menstrual cycles are anovulatory (no egg ovulated) * Girls begin ovulating regularly about a year after they begin menstruating

Answer 191

Males: Testosterone Females: estrogen= widespread effects - vaginal metaplasa - growth of ovaries and secondary sex organs - growth hormone secretion (height and widening of pelvis) - fat deposition (breasts, hips, etc) - thickens skins progestone= breast development; utereus preparation for pregnancy prolactic= breast development androgens= pubarche (pubic and axillary hair, sebacaceous glands,& axillary glands)

Test 4: Digestive & Reproductive System FINAL Flashcards

(223 cards)