DIGESTIVE SYSTEM Flashcards
Functions of the digestive system
- Take in food
- Break down foods
- Absorb digested materials
- Provide nutrients
- Eliminate waste
Layer of smooth epithelial tissue
PERITONEUM
connective tissues of organs in abdominal cavity
Mesenteries
Mesentery connecting lesser curvature
Lesser Omentum
mesentery connecting greater curvature of stomach to transverse colon and posterior body wall.
Greater Omentum
: First part of digestive system
: Contains stratified squamous epithelia
ORAL CAVITY
: Produce saliva which contains enzyme to breakdown carbohydrates into glucose
: Cleanse mouth
: Dissolve and moisten food
SALIVARY GLANDS
Salivary enzyme that breaks down carbohydrates into glucose.
Amylase
Salivary enzymes that are active against bacteria.
Lysozyme
houses taste buds and mucus
TONGUE
Center of each tooth
PULP CAVITY
: 32 teeth in normal adult
: Incisors, canine, premolars, molars, wisdom tooth
: 20 primary teeth (baby teeth)
: Each tooth has crown, cusp, neck, & root
TEETH
of baby teeth
20
teeth in normal adult
32
Roof of the oral cavity
PALATE
2 palates
- Hard
2. Soft
anterior part (palate)
HARD PALATE
posterior part (palate)
SOFT PALATE
: Includes submandibular, sublingual, parotid
: Produce saliva that contains enzymes to breakdown food
SALIVARY GLANDS
is inflammation of parotid gland. Usually caused by a virus.
MUMPS
3 types of glands
- Parotid Gland
- Submandibular Gland
- Sublingual Gland
Secretion of parotid gland
Purely serous
Secretion of submandibular gland
Mixed, predominantly serous
Secretion of sublingual gland
Mixed, predominantly mucous
Largest salivary gland; outer of masseter muscles.
Parotid gland
Where secretion of parotid gland passes through.
Parotid duct
Below mandibular bone
Submandibular gland
Where secretion of submandibular gland passes through.
Submandibular duct
Gland located at the Inferior of the tongue.
Sublingual gland
Where secretion of sublingual gland passes through.
Sublingual ducts
: Throat
: Connects mouth to esophagus
PHARYNX
3 parts of the pharynx
- Nasopharynx
- Oropharynx
- Laryngopharnx
: Tube that connects pharynx to stomach
: Transport food to stomach
: Joins stomach at cardiac opening
ESOPHAGUS
: Occurs when gastric juices regurgitate into esophagus.
: Caused by caffeine, smoking, or eating or drinking in excess.
: Mimics heart attack.
: Hyperacidity
HEARTBURN
4 phases of swallowing
- VOLUNTARY PHASE
- PHARYNGEAL PHASE
- ESOPHAGEAL PHASE
- PERISTALSIS
Bolus (mass of food) formed in mouth and pushed into oropharynx.
VOLUNTARY PHASE
Swallowing reflex initiated when bolus stimulates receptors in oropharynx.
PHARYNGEAL PHASE
Moves food from pharynx to stomach.
ESOPHAGEAL PHASE
Wave-like contractions that moves food through digestive tract (Myenteric plexus / Auerbach’s plexus). Found on the muscular layer of the digestive tract wherein peristalsis occurs.
PERISTALSIS
- A wave of smooth muscle relaxation moves ahead of the bolus, allowing the digestive tract to expand.
- A wave of contraction of the smooth muscle behind the bolus propels it through the digestive tract.
PERISTALSIS
: Located in the abdomen
: Storage tank for food
: Produces mucus, hydrochloric acid, protein digesting enzymes
: Contains thick mucus layer that lubricates and protects epithelial cells on stomach wall from acidic pH (3)
: Can hold up to 2 liters of food.
STOMACH
How much can the stomach hold?
2 L
Parts of the stomach that functions to produce churning action.
Thick muscular layer
Large folds that allow stomach to stretch.
Rugae
Opening between the stomach and small intestine.
Pyloric opening
Thick, ring of smooth muscle around pyloric opening. Regulate the passage of food from the stomach to the small intestine.
Pyloric sphincter
paste-like substance that forms when food begins to be broken down. From small intestine and large intestine.
CHYME
stomach is stimulated to contract by low blood glucose levels usually 12-24 hours after a meal.
HUNGER PANGS
• Parasympathetic stimulation, gastrin, histamine increase stomach secretions
REGULATION OF THE STOMACH SECRETIONS
3 Phases of stomach secretion/ digestion
- Cephalic phase
- Gastric phase
- Intestinal phase
: 1st phase
: Stomach secretions are initiated by sight, smell, taste, or food thought
CEPHALIC PHASE
: Partially designed proteins and distention of stomach promote secretion
GASTRIC PHASE
: Acidic chime stimulates neuronal reflexes and secretions of hormones that inhibit gastric secretions by negative feedback loops.
INTESTINAL PHASE
2 Movements in the stomach
- Mixing waves
2. Peristaltic waves
: Weak contraction
: Thoroughly mix food to form chime
Mixing waves
: Stronger contraction
: Force chime toward and through pyloric sphincter
Peristaltic waves
TRUE OR FALSE
Stomach empties every 6-8 hrs. after regular meal, and 4 hrs. after high fatty meal.
FALSE
Stomach empties every 4 hrs. after regular meal, and 6-8 hrs. after high fatty meal.
cells of the gastric gland that secretes Gastrin
G cells / enteroendo-crine cells
cells of the gastric gland that secretes Mucin in an alkaline fluid
Surface mucous cells
cells of the gastric gland that secretes Mucin in an acidic fluid
Mucus neck cells
cells of the gastric gland that secretes HCl & intrinsic factor
Parietal cells
cells of the gastric gland that secretes Pepsinogen & lipase
Chief cells
mixed to the food to become acidic chime
HCl
involved in the reabsorption of vitamin B12.
Intrinsic factor
: Measures 6 meters in length
: Major absorptive organ
: Chyme takes 3-5 hrs. to pass through
: Contains enzymes to further breakdown food
: Contains secretions for protection against chyme’s acidity.
SMALL INTESTINE
3 PARTS OF THE SMALL INTESTINE
- DUODENUM
- JEJUNUM
- ILEUM
\: Largest diameter \: 25 cm long, smallest part \: Contains absorptive cells, goblet cells, granular cells, endocrine cells \: Contains microvilli and many folds \: Contains bile and pancreatic ducts
DUODENUM
: 2.5 meters long and absorbs nutrients
JEJUNUM
: 3.5 meters long, longest part
ILEUM
: Function is to absorb water from indigestible food
: 10% of absorption
: Contains cecum, colon, rectum, anal canal
LARGE INTESTINE
: Joins small intestine at ileocecal junction
: Has appendix attached
: most proximal to appendix
CECUM
: 1.5 meters long
: Contains ascending, transverse, descending, sigmoid regions
COLON
: Straight tube that begins at sigmoid and ends at anal canal.
RECTUM
: Last 2-3 cm of digestive tract
: Food takes 18-24 hours to pass through
: Feces is product of water, indigestible food, and microbes
: Microbes synthesize vitamin K
ANAL CANAL
: 9 cm structure that is often removed
Appendix
characterized by right lower quadrant pain.
APPENDICITIS
removal of appendix
APPENDECTOMY
: Bands of smooth muscle along the length of the colon
Teniae Coli
Accessory organs of digestion
- Liver
- Spleen
- Pancreas
- Gallbladder
: Weighs about 3 lbs.
: In right upper quadrant of abdomen under diaphragm
: Right, left, caudate, quadrate lobes
LIVER
: Gate where blood vessels, ducts, nerves enter and exit.
: Receives blood from hepatic artery that carries oxygenated blood from the heart to the liver.
Porta
4 LIVER DUCTS:
- Hepatic duct
- Common hepatic duct
- Cystic duct
- Common bile duct
Transport bile out of liver. (R&L)
Hepatic duct
Formed from left and right hepatic ducts.
Common hepatic duct
Joins common hepatic duct; from gall bladder.
Cystic duct
Formed from common hepatic duct and cystic duct.
Common bile duct
Most important part of the duodenum
Second part of the duodenum
The tail of the pancreas is
___ to the spleen
adjacent
FUNCTIONS OF THE LIVER
- Digestive and excretory functions
- Stores and processes nutrients
- Detoxifies harmful chemicals
- Synthesizes new molecules
- Secretes 700 mL of bile each day.
dilutes and neutralizes stomach acid and breaks down fats.
BILE
: Small sac on inferior surface of liver
: Stores and concentrates bile.
GALLBLADDER
causes the gallbladder to contract, thereby releasing bile into the duodenum.
Vagus nerve stimulation
produced by the duodenum (purple arrows) and carried through the circulation to the liver, stimulates bile secretion by the liver
Secretin
produced by the duodenum (pink arrows) and carried through the circulation to the gallbladder, stimulates the gallbladder to contract, thereby releasing bile into the duodenum
Cholecystokinin
also stimulate bile secretion
Bile salts
: Located posterior to stomach in inferior part of left upper quadrant.
: Head near midline of body.
: Tail extends to left and touches spleen.
: Endocrine tissues have pancreatic islet that produce insulin and glucagon (hormones that control glucose production in the body).
: Exocrine tissues produce digestive enzymes.
PANCREAS
inflammation of the pancreas. Epigastric pain that radiates at the back.
ACUTE PANCREATITIS
Tests for acute pancreatitis. Pancreatic Lipase is more specific.
AMYLASE AND LIPASE
most common location of pancreatic cancer
HEAD OF PANCREAS
Digestive part of the pancreas
Pancreatic acinus/acini cells
Endocrine part of the pancreas
Islets of Langerhans
Increases glucose in the blood
Glucagon
Decreases glucose in blood
Insulin
from the vagus nerve (red arrow) causes the pancreas to release a secretion rich in digestive enzymes.
Parasympathetic stimulation
released from the duodenum, stimulates the pancreas to release a watery secretion rich in bicarbonate ions.
Secretin
released from the duodenum, causes the pancreas to release a secretion rich in digestive enzymes.
Cholecystokinin
Breakdown of food occurs in stomach and mouth.
DIGESTION
Moves food through digestive tract.
Includes swallowing and peristalsis.
PROPULSION
Primarily in duodenum and jejunum of small intestine.
ABSORTION
Elimination of waste in the form of feces
DEFECATION
Enzyme in the mouth that converts carbohydrates to polysaccharides
Salivary amylase
Enzyme in the duodenum that converts carbohydrates to disaccharides
Pancreatic amylase
Enzyme in the epithelium of the small intestine that converts carbohydrates to monosaccharides
disaccharidases
Enzymes in the duodenum that converts lipids into fatty acids / monoglycerides
- Bile salts (liver)
2. Lipase (pancreas)
Enzymes in the stomach that converts proteins into polypeptides
pepsin
Enzymes in the duodenum that converts proteins into peptides
Trypsin, chymotrypsin, carboxypeptidase (pancreas)
Enzymes in the epithelium of the small intestine that converts proteins into amino acids
peptidases
- Glucose is absorbed by symport with Na+ into intestinal epithelial cells.
- Symport is driven by a sodium gradient established by a Na+ - K+ pump.
- Glucose moves out of the intestinal epithelial cells by facilitated diffusion.
- Glucose enters the capillaries of the intestinal villi and is carried through the hepatic portal vein to the liver.
MONOSACCHARIDE GLUCOSE TRANSPORT
: Bile salts emulsify lipids
: Lipase breaks down lipids which form micelles
: Micelles are in contact with intestinal epithelial cells and diffuse with cells where they are packaged and released into lacteals.
: Lipids are stored in adipose tissue and liver.
LIPID DIGESTION
- Bile salts surround fatty acids and monoglycerides to form micelles.
- Micelles attach to the cell membranes of intestinal epithelial cells, and the fatty acids and monoglycerides pass by simple diffusion into the intestinal epithelial cells.
- Within the intestinal epithelial cell, the fatty acids and monoglycerides are converted to triglycerides; proteins coat the triglycerides to form chylomicrons, which move out of the intestinal epithelial cells by exocytosis.
- The chylomicrons enter the lacteals of the intestinal villi and are carried through the lymphatic system to the general circulation.
LIPID TRANSPORT
: Proteins are spilt into polypeptides by enzymes secreted by stomach and pancreas
: Peptides and amino acids are absorbed into intestinal epithelial cells.
: Amino acids are actively transported into cells (help from GH and insulin)
: Amino acids used to build new proteins.
PROTEIN DIGESTION
- Acidic and mot neutral amino acids are absorbed by symport into intestinal epithelial cells.
- Symport is driven by a sodium gradient established by a Na+ - K+ pump
- Amino acids move out of the intestinal epithelial cells.
- Amino acids enter the capillaries of the intestinal villi and are carries through the hepatic portal vein to the liver.
AMINO ACID TRANSPORT
: Water can move across intestinal wall in either direction.
: Depends on osmotic conditions.
: 99% of water entering intestine is absorbed.
: Minerals are actively transported across wall of small intestine.
WATER AND MINERALS
Fluid volume during ingestion
2 L
Fluid volume in salivary gland secretion
1 L
Fluid volume in gastric secretion
2 L
Fluid volume in pancreatic secretion
1.2 L
Fluid volume in bile secretion
0.7 L
Fluid volume in small intestine secretions
2 L
Fluid volume absorbed in the small intestine
92%
Fluid volume absorbed in the large intestine
6% - 7%
Fluid volume in feces
1%
Formula for water in feces
Water in feces = ingested + secreted - absorbed
