A & P Digestive exam 4

THE GI TRACT IS LONG TUBE THAT

IS OPEN AT BOTH ENDS FOR THE TRANSIT OF FOOD DURING PROCESSING

NAMED PORTIONS OF THE TUBE INCLUDE THE

ESOPHAGUS, STOMACH, SMALLINTESTINE, LARGE INTESTINE, AND RECTUM

ACCESSORY STRUCTURES ARE

NOT PART OF THE GI TRACT, BUT THEY DO CONTRIBUTE TO FOOD PROCESSING

Pancreas

Liver

Gall bladder

ACCESSORY STRUCTURES INCLUDE THE

TEETH, TONGUE, SALIVARY GLANDS,LIVER, GALL BLADDER, AND PANCREAS

organs of the digestive system 2 photos

THERE ARE 6 BASIC PROCESSES INVOLVED IN DIGESTION photo

1. Ingestion

2. Secretion

3. Motility

4. Digestion

5. Absorption

6. Defecation

Layer of GI Tract photo

LAYERS OF THE GI TRACT

ESOPHAGUS TO LARGE INTESTINES

1. MUCOSA (INNER)

•MOIST, FRICTION RESISTANT

•SECRETES MUCUS, ENZYMES, HORMONES

LAYERS OF THE GI TRACT

ESOPHAGUS TO LARGE INTESTINES

2.SUBMUCOSA

•BLOOD VESSELS, NERVES, LYMPHATICS

LAYERS OF THE GI TRACT

ESOPHAGUS TO LARGE INTESTINES

3. MUSCULARIS EXTERNA

•SMOOTH MUSCLE FOR PERISTALSIS AND SEGMENTATION

LAYERS OF THE GI TRACT

ESOPHAGUS TO LARGE INTESTINES

4. SEROSA (OUTER)

•PERITONEUM

THE PERITONEUM IS THE 2 photos

LARGEST SEROUS MEMBRANE IN THE BODY

THE MOUTH IS FORMED BY

THE CHEEKS, HARD AND SOFT PALATES, AND TONGUE

SALIVARY GLANDS LIE OUTSIDE THE

MOUTH AND EMPTY THEIR CONTENTS INTO DUCTS WHICH DELIVER SALIVA INTO THE ORAL CAVITY

• SALIVARY AMYLASE

SALIVARY GLANDS 3 PAIRS:

1.PAROTID

2.SUBMANDIBULAR

3.SUBLINGUAL

TONGUE

TOGETHER WITH ASSOCIATED MUSCLE, FORMS THE FLOOR OF THE ORAL CAVITY

•COMPOSED OF SKELETAL MUSCLE COVERED WITH MUCOUS MEMBRANE

•PARTICIPATES IN CHEWING, SWALLOWING, AND SPEECH

•THE UPPER AND LATERAL SURFACES OF THE TONGUE ARE COVERED WITH PAPILLAE, SOME OF WHICH CONTAIN TASTE BUDS

•DO YOU REMEMBER THE 5 TYPES FROM YOUR NERVOUS SYSTEM STUDY?

THE TEETH

PROJECT INTO THE MOUTH AND ARE ADAPTED FOR MECHANICAL DIGESTION

•PERFECTEXAMPLE OF THE PRINCIPLE OF COMPLEMENTARITY

•20 DECIDUOUS

•32 PERMANENT

Mechanical digestion

Chewing mixes food with saliva and forms a bolus which can be easily swallowed

Chemical digestion

•Salivary amylase converts polysaccharides to disaccharides

•Lingual lipase converts triglycerides & other fats into fatty acids and diglycerides

Cheeks and lips summary

Keep food between teeth.

Foods uniformly chewed during mastication.

Salivary glands summary

Secrete saliva.

Lining of mouth and pharynx moistened and lubricated. Saliva softens, moistens, and dissolves food and cleanses mouth and teeth. Salivary amylase splits starch into smaller fragments

Tongue muscles summary

Move tongue from side to side and in and out; alter shape of tongue

Food maneuvered for mastication, shaped into bolus, and maneuvered for swallowing; speech

Taste buds summary

Serve as receptors for gustation (taste) and presence of food in mouth.

Secretion of saliva stimulated by nerve impulses from taste buds to salivatory nuclei in brain stem to salivary glands.

Lingual glands summary

Secrete lingual lipase.

Triglycerides broken down into fatty acids and diglycerides.

Teeth summary

Cut, tear, and pulverize food.

Solid foods reduced to smaller particles for swallowing.

HOMEOSTATIC IMBALANCE

•MUMPS

•DENTAL CARIES

•PERIODONTAL DISEASE

•CANKER SORES

•ORAL HERPES

•HALITOSIS

PHARYNX

A FUNNEL SHAPED TUBE THAT EXTENDS FROM THE INTERNAL NARES TO THE ESOPHAGUS POSTERIORLY AND TO THE LARYNX ANTERIORLY

COMPOSED OF SKELETAL MUSCLE AND LINED WITH MUCOUS MEMBRANE

ESOPHAGUS

IS A COLLAPSIBLE, MUSCULAR TUBE THAT LIES POSTERIOR TO THE TRACHEA AND CONNECTS THE PHARYNX TO THE STOMACH

DEGLUTITION is 2 photos

Swallowing

Pharynx summary

Pharyngeal stage of deglutition.

Moves bolus from oropharynx to laryngopharynx and into esophagus: closes air passageways.

Esophagus summaRY

Relaxation of upper esophageal sphincter. Esophageal stage of deglutition (peristalsis). Relaxation of lower esophageal sphincter. Secretion of mucus.

Permits entry of bolus from laryngopharynx into esophagus. Pushes bolus down esophagus. Permits entry of bolus into stomach. Lubricates esophagus for smooth passage of bolus.

GASTROESOPHAGEAL REFLEX

•HEARTBURN FIRST SYMPTOM

•ACIDIC REFLUX ERODES ESOPHAGUS

•STOMACH CONTENTS FORCED SUPERIORLY

•PREGNANCY, OBESITY, EATING/DRINKING IN EXCESS

HOMEOSTATIC IMBALANCEs 2

•GASTROESOPHAGEAL REFLEX

•HIATAL HERNIA

THE STOMACH IS A

J SHAPED ENLARGEMENT OF THE GI TRACT

Stomach Layers:

•Muscularis

•Mucosa

Stomach Regions:

•Cardiac

•Fundus

•Body

•Pylorus

FUNCTIONS OF THE STOMACH

Mixes saliva, food, and gastric juice to form chyme

Serves as a reservoir for food before release into the small intestine

Secretes gastric juice, which contains HCl, pepsin, rennin, intrinsic factor, and gastric lipase

Secretes gastrin into the blood

GASTRIC GLANDS AND CELLS IN THE STOMACH

Mucus, HCl, Intrinsic Factor, Pepsinogen, Gastric Lipase, Gastrin

Surface mucous cells and mucous neck cells summary

Secrete mucus.

Forms protective barrier that prevents digestion of stomach wall.

Absorption.

Small quantity of water, ions, short-chain fatty acids, and some drugs enter bloodstream.

Parietal cells summary

Secrete intrinsic factor.

Needed for absorption of vitamin B12 (used in red blood cell formation, or erythropoiesis).

Secrete hydrochloric acid.

Kills microbes in food; denatures proteins; converts pepsinogen into pepsin.

Chief cells summary

Secrete pepsinogen.

Pepsin (activated form) breaks down proteins into peptides.

Secrete gastric lipase.

Splits triglycerides (lipid) into fatty acids and monoglycerides.

G cells summary

Secrete gastrin.

Stimulates parietal cells to secrete HCI and chief cells to secrete, pepsinogen; contracts lower esophageal sphincter, increases motility of stomach, and relaxes pyloric sphincter.

Muscularis summary

Mixing waves (gentle peristaltic movements).

Churns and physically breaks down food and mixes it with gastric juice, forming chyme. Forces chyme through pyloric sphincter.

Pyloric sphincter

Opens to permit passage of chyme into duodenum.

Regulates passage of chyme from stomach to duodenum; prevents backflow of chyme from duodenum to stomach.

HOMEOSTATIC IMBALANCE 3

GASTRITIS (inflammation)

GASTRIC ULCER (erosion)

VOMITING

GASTRITIS

INFLAMMATION OF STOMACH WALL

GASTRIC ULCER

•EROSION OF THE STOMACH WALL

•BACK PAIN FELT 1-3 HOURS AFTER EATING

•FACTORS THAT INCREASE HCL AND DECREASE MUCOUS

•IBUPROFEN, SMOKING, SPICY FOOD, ALCOHOL, COFFEE, STRESS

•HELICOBACTER PYLORI BACTERIA CAN DAMAGE MUCOSA

•TREAT WITH BISMUTH, ANTIBIOTICS (IF BACTERIA PRESENT), TAGAMENT, ZANTAC

DIGESTIVE PHASES

1.CEPHALIC REFLEX

2.GASTRIC

3.INTESTINAL

DIGESTIVE PHASES

1. CEPHALIC REFLEX

•VAGUSNERVE-SIGHT, SMELL, TASTE OF FOOD

•PREPARES STOMACH BEFORE FOOD ENTERS mouth

DIGESTIVE PHASES

2. GASTRIC:

SECRETION AND MOTILITY

•STIMULUS-DISTENSION, PEPTIDES, AND LOW ACIDITY

•GASTRIN SECRETED

comes from g cells,

DIGESTIVE PHASES

3.INTESTINAL

•FOOD ENTERING DUODENUM INHIBITS VAGUS, ACTIVATES SYMPATHETIC NERVES

•SMALL INTESTINES RELEASE GASTRIN INHIBITING HORMONES, SECRETIN AND CHOLECYSTOKININ (CCK)

THE PANCREAS IS A GLAND THAT:

LIES POSTERIOR TO THE STOMACH

PRODUCES ENZYMES THAT DIGEST CARBOHYDRATES, PROTEINS, FATS, AND NUCLEIC ACIDS

EXOCRINE SECRETIONS INCLUDE AMYLASE, LIPASES, NUCLEASES, PROTEASES

(ENDOCRINE: ISLETS PRODUCE HORMONES!)

PRODUCES SODIUM BICARBONATE WHICH BUFFERS STOMACH ACID

NEUTRALIZES ACIDIC CHYME

WHY IS THIS IMPORTANT????

EMPTIES ITS CONTENTS INTO THE DUODENUM

PANCREATIC ENZYMES

Pancreatic amylase carbs

Pancreatic acinar cells.

Starches (polysaccharides).

Disaccharides andtrisaccharides

PANCREATIC ENZYMES

Trypsin

Chymotrypsin

Pancreatic acinar cells.

Proteins.

Peptides.

PANCREATIC ENZYMES

Carboxypeptidase

Pancreatic acinar cells.

Amino acid at end of peptides.

Amino acids and peptides.

PANCREATIC ENZYMES

Pancreatic lipase

Pancreatic acinar cells.

Triglycerides (fats and oils) that have been emulsified by bile salts.

Fatty acids and monoglycerides.

PANCREATIC ENZYMES

Ribonuclease rna

Pancreatic acinar cells.

Ribonucleic acid.

Nucleotides.

PANCREATIC ENZYMES

Deoxyribonuclease dna

Pancreatic acinar cells.

Deoxyribonucleic acid.

Nucleotides.

HOMEOSTATIC IMBALANCE 2 pancreas

•PANCREATITIS

•PANCREATIC CANCER

•SIGNS AND SYMPTOMS MAY INCLUDE:

•PAIN IN THE UPPER ABDOMEN THAT RADIATES TO YOUR BACK

•LOSS OF APPETITE OR UNINTENDED WEIGHT LOSS

•DEPRESSION

•NEW-ONSET DIABETES

•BLOOD CLOTS

•FATIGUE

•YELLOWING OF YOUR SKIN AND THE WHITES OF YOUR EYES (JAUNDICE)

PANCREAS, LIVER, AND GALLBLADDER photo

THE LIVER MAKES

BILE, WHICH IS IMPORTANT IN THE EMULSIFICATION OF FATS

THE GALLBLADDER STORES

BILE UNTIL IT IS NEEDED

photo includes how direction bile goes into small intestine

LIVER LOBULES - FUNCTIONAL UNIT

•KUPFFER CELLS - MACROPHAGES of liver, REMOVE DEBRIS, BACTERIA, OLD BLOOD CELLS

•HEPATOCYTES (liver cells)

•PRODUCE BILE

•PROCESS NUTRIENTS-CONVERT GLUCOSE TO GLYCOGEN

•STORE VITAMINS

•DETOXIFY BLOOD from drugs -CONVERT AMMONIA TO UREA

BILE RELEASE

HEPATOPANCREATIC SPHINCTER IS

CLOSED WHEN NOT DIGESTING

BILE RELEASE

CHOLECYSTOKININ (CCK) -INTESTINAL HORMONE

•RELAXES HEPATOPANCREATIC SPHINCTER

•STIMULATES GALLBLADDER TO CONTRACT FORCING BILE INTO DUODENUM

•STIMULATES SECRETION OF PANCREATIC JUICES

BILE RELEASE

VAGUS NERVE CAN

STIMULATE CONTRACTIONS OF GALLBLADDER

FUNCTIONS OF THE LIVER AND GALLBLADDER

Carbohydrate, lipid, and protein metabolism

Processing detoxifying of drugs and hormones

Bilirubin excretion

Bile salt synthesis

Storage for bile

Phagocytosis

Vitamin D activation

HOMEOSTATIC IMBALANCE 4 LIVER

LIVER CIRRHOSIS

HEPATITIS

GALLSTONES

JAUNDICE

LIVER CIRRHOSIS

•CHRONIC INFLAMMATION DAMAGES HEPATOCYTES, SCAR TISSUE TO FORMS, ACTIVITY DEPRESSED

•CAUSED BY ALCOHOLISM, CHRONIC HEPATITIS (inflammation) irreversible

HEPATITIS

LIVER INFLAMMATION

VIRAL INFECTION

•HVA AND HVE-TRANSMITTED IN FOOD AND WATER

•HVB AND HVC-TRANSMITTED BY BLOOD

NON-VIRAL CAUSES INCLUDE DRUG TOXICITY AND WILD MUSHROOM POISONING

GALLSTONES

•CRYSTALLIZED BILE FROM TOO MUCH CHOLESTEROL OR TOO LITTLE BILE SALTS

•CONTRACTING ON SHARP CRYSTALS CAUSES PAIN

•OBESITY, ESTROGEN, DIABETES, CHOLESTEROL DRUGS…

•TREATMENTS-LASERS, ULTRASOUND, SURGICAL REMOVAL (BILE DUCT ENLARGES TO STORE BILE)

JAUNDICE

•YELLOWING OF SKIN DUE TO BILE DUCT BLOCKAGE OR LIVER DISEASE

buildup of bilirubin

•HEPATITIS, MALARIA, GALLSTONES, CANCER, PARASITES…

•YELLOW BILE PIGMENTS ACCUMULATE IN BLOOD

THE MAJORITY OF DIGESTION AND ABSORPTION OCCUR

IN THE SMALL INTESTINE

Parts of small intestine

Duodenum

jejunum

ileum

HISTOLOGY OF THE SMALL INTESTINE

•Circular folds increase the surface area for digestion and absorption in the small intestine

•Villi and Microvilli

INTESTINAL JUICE

provides a vehicle for absorption of substances from chymeas they come in contact with the villi

BRUSH BORDER ENZYMES

found on the surfaces of the microvilli of absorptive cells, break down food products; aids in digestion

FUNCTIONS OF THE SMALL INTESTINE

Segmentations (localized contractions) mix chyme with digestive juices and bring food into contact with mucosa for absorption; peristalsis (propulsive contractions) propels chyme through small intestine

Completes digestion of carbohydrates, proteins, lipids; begins and completes digestion of nucleic acids

Absorbs about 90% of nutrients and water that pass through digestive SYSTEM

ABSORPTION IN THE SMALL INTESTINE PHOTO

ABSORPTION ALCOHOL

•BEGINS IN STOMACH

•ABSORBS MORE RAPIDLY IN SMALL INTESTINE

ABSORPTION MALABSORPTION

•MAY BE DUE TO

•INADEQUATE CHEMICAL DIGESTION

•DAMAGE TO THE LINING OF THE SMALL INTESTINE

•IMPAIRMENT OF MOTILITY

ANATOMY OF THE LARGE INTESTINE (COLON) photos

internal and external anal sphincter photo

FUNCTIONS OF THE COLON

Haustral churning, peristalsis, and mass peristalsis drive contents of colon into rectum

Bacteria in colon convert proteins into amino acids, break down amino acids, and produce some B and k vitamins

Absorption of some water, ions, and vitamins

Formation of feces

Defecation

DEFECATION REFLEX

Motor impulses travel back to the descending colon, sigmoid colon, rectum, and anus

Rectal wall distends and stretch receptors send sensory nerve

Longitudinal rectal muscles contract and the internal anal sphincter opens

HOMEOSTATIC IMBALANCES 5

Appendicitis sharp abdominal pain

Polyps

•Colorectal cancer

Diarrhea

Constipation

Diverticula

AGING AND THE DIGESTIVE SYSTEM

AGING RESULTS IN:

•DECREASED SECRETORY MECHANISMS AND MOTILITY

•LOSS OF STRENGTH AND TONE OF DIGESTIVE MUSCULAR TISSUE

•CHANGES IN NEUROSECRETORY FEEDBACK

•DIMINISHED RESPONSE TO PAIN AND INTERNAL SENSATIONS

FOCUS ON HOMEOSTASIS PHOTO

DIGESTIVE SYSTEM DISORDERS 3

LACTOSE INTOLERANCE

INFLAMMATORY BOWEL DISEASE

IRRITABLE BOWEL SYNDROME