Digestive System Flashcards
Occurs when gastric juices regurgutate into esophagus
Cause?
Heartburn; caffeine, smoking or eating/drinking in excess
- Take in food
- Break down food
- Absorb digested materials
- Provide nutrients
- Eliminate waste
DIGESTIVE SYSTEM FUNCTIONS
Layer of smooth epithelial tissue
Peritoneum
Connective tissue of organs in
abdominal cavity
Mesenteries
Mesentery connecting lesser curvature of stomach to liver and diaphragm
Lesser Omentum
Mesentery connecting greater curvature of stomach to transverse colon and posterior body wall.
Greater Omentum
First part of the digestive system
Oral Cavity
Tissue type present in the oral cavity
Stratified squamous epithelia
Produce saliva
Salivary glands
Salivary Glands
- contains ____ to break down carbohydrates into ____
- ______ the mouth
- dissolves and _____ food
- enzymes; glucose
- cleanses
moistens
Salivary enzyme that breaks down carbohydrates
Amylase
Salivary enzymes that are active against bacteria
Lysozyme
House taste buds and mucus
Tongue
a normal adult has ____ teeth
32
types of teeth
Incisors, canine, premolars, molars, wisdom teeth
primary teeth consists of __ baby teeth
20
Tooth structure
Each tooth has a crown, cusp, neck, and root
The center of the tooth
Pulp cavity
Hard covering that protects against
abrasions
Enamel
Breakdown of enamel by acids from
bacteria
Cavities
Roof of oral cavity
Palate
hard palate vs soft palate
hard is anterior and soft is posterior
Includes submandibular,
sublingual, and parotid glands
Salivary Glands
Inflammation of the parotid gland
Mumps
Purely serous secretion
Parotid Gland
Mixed secretion, predominantly serous
Submandibular Gland
Mixed secretion, predominantly mucous
Sublingual Gland
pharynx is aka?
throat
Connects mouth to esophagus
pharynx
Tube that connects the pharynx to
the stomach
esophagus
Transports food to the stomach
esophagus
Joins the stomach at the cardiac opening
Esophagus Connection
Occurs when gastric juices regurgitate into the esophagus; caused by caffeine, smoking, or eating or drinking in excess
heartburn
Bolus (mass of food) formed in the mouth and pushed into the oropharynx
swallowing
Swallowing reflex initiated when the bolus stimulates receptors in the oropharynx
Pharyngeal phase
it refers to mass of food
bolus
Moves food from the pharynx to the stomach
Esophageal phase
Wave-like contractions that move food through the digestive tract (Myenteric plexus/Auerbach’s plexus)
Peristalsis
stomach is located in ____
abdomen
it is the Storage tank for food
stomach
Produces mucus, hydrochloric acid, and protein-digesting enzymes
stomach
stomach Contains a ______
that lubricates and protects epithelial cells on
the stomach wall from acidic pH (3)
thick mucus layer
capacity of stomach
can hold 2L of food
layer of stomach that produce churning action
thick muscular layer
Large folds that allow the stomach to stretch
rugae
Paste-like substance that forms when
food begins to be broken down
Chyme
Opening between the stomach and small intestine
Pyloric opening
Thick, ring of smooth
muscle around the pyloric opening
Pyloric sphincter
Stomach is stimulated to
contract by low blood glucose levels, usually
12-24 hours after a meal
hunger pangs
Stomach is stimulated to
______ by ________ levels, usually
12-24 hours after a meal
contract; low blood glucose
increases stomach secretions
Parasympathetic stimulation, gastrin,
histamine
- 1st phase of secretion regulation
- Stomach secretions are initiated by the sight, smell, taste, or thought of food
Cephalic phase
- 2nd phase of secretion regulation
- Partially digested proteins and distention of the stomach promote secretion
Gastric phase
- 3rd phase of secretion regulation
- Acidic chyme stimulates neuronal reflexes and secretion of hormones that inhibit gastric secretions by negative feedback loops
Intestinal phase
Cephalic Phase - The taste, smell, or thought
of food or tactile sensations of food in the
mouth stimulate the ______
medulla oblongata
Carry parasympathetic action
potentials to the stomach, where
enteric plexus neurons are activated.
Vagus Nerves
Stimulate secretion by parietal and chief cells and stimulate gastrin and histamine secretion by endocrine cells.
Postganglionic Neurons
Carried through the circulation back to the stomach, where, along with histamine, it stimulates secretion.
Gastrin
Distention of the stomach stimulates mechanoreceptors (stretch receptors) and activates a parasympathetic reflex. Action potentials generated by the mechanoreceptors are carried by the vagus nerves to the medulla oblongata. What phase is this?
Gastric Phase
Increases action potentials in vagal and chief cells that
stimulate secretion by parietal cells and stimulate gastrin and histamine secretion by endocrine cells
Medulla Oblongata
Distention of the stomach also activates local reflexes that increase stomach secretions
Local Reflexes
Carried through the circulation back to the stomach, where, along with histamine, it stimulates secretion.
Gastrin
In the duodenum with a pH less than 2 or containing fat digestion products (lipids) inhibits gastric secretions by three mechanisms (2-4).
Chyme
In the duodenum are stimulated by H+ (low pH) or lipids. Action potentials generated by the ______ are carried by the vagus nerves to the medulla oblongata (green arrow), where they inhibit parasympathetic action potentials, thereby decreasing gastric secretions.
chemoreceptors
Activated by H+ or lipids also
inhibit gastric secretion. what reflex is this?
local reflexes
Produced by the duodenum (brown arrows) decrease gastric secretions in the stomach.
Secretin and Cholecystokinin
Secretin and Cholecystokinin - Produced by
the ______ and ______
gastric secretions in the stomach.
duodenum; decrease
Weak contractions that thoroughly mix food to form chyme.
Mixing waves
Mixing Waves - _____ contractions that thoroughly mix food to form _____
weak; chyme
Stronger contractions that force chyme toward and through the pyloric sphincter.
Peristaltic Waves
Peristaltic Waves - _____ contractions that force chyme toward and through the pyloric sphincter.
stronger
Hormonal and Neural Mechanisms -
Stimulate _________
stomach secretions.
stomach empties every ___ hours after a regular meal, and ___ hours after a high-fat meal.
4 ; 6-8
Initiated in the body of the stomach and progresses toward the pyloric sphincter. what wave is this?
mixing wave
More fluid part of the chyme is pushed toward the pyloric sphincter, while the more solid contents are squeezed back toward the body of the stomach through peristaltic constriction. what movement is this?
Chyme Movement
Move in the same direction and in an orderly way as mixing waves but are stronger
Peristaltic Waves
more fluid part of the chyme is pushed toward the pyloric region, while the more solid center of the chyme squeezes past the peristaltic constriction back toward the body of the stomach. what movement is this
Chyme Movement
Force a few milliliters of the most fluid chyme through the pyloric opening into the duodenum. Most of the chyme, including the more solid portion, is forced back toward the body of the stomach for further mixing. what contraction is this?
Peristaltic Contractions-
Mucin in an alkaline fluid
Surface mucous cells
Mucin in an acidic fluid
Mucous neck cells
Chief cells
Pepsinogen & lipase
A 6-meter-long major absorptive organ where chyme takes 3-5 hours to pass through, containing enzymes to further break down food and secretions to protect against chyme’s acidity.
Small Intestine
Parts of Small Intestine:
duodenum, jejunum, Ileum
25 cm long section containing absorptive cells, goblet cells, granular cells, endocrine cells, microvilli, and many folds. It also houses the bile and pancreatic ducts.
Duodenum
2.5-meter-long section responsible for nutrient absorption.
Jejunum
A 3.5-meter-long section of the small intestine.
Ileum
Its function is to absorb water from indigestible food and contains the cecum, colon, rectum, and anal canal.
large intestine
Joins the small intestine at the ileocecal junction and has the appendix attached.
cecum
9 cm structure that is often removed.
appendix
1.5-meter-long section with ascending, transverse, descending, and sigmoid regions.
colon
Straight tube that begins at the sigmoid and ends at the anal canal.
rectum
Last 2-3 cm of the digestive tract
anal canal
Food Passage – Takes ___ hours to pass
through the large intestine.
18-24
Feces Product is made up of?
water, indigestible food, and microbes.
Microbes in the large
intestine synthesize _____
vitamin K
Weighs about 3 lbs and is located in the ___ ____ quadrant of the abdomen under the _____. It has right, left, caudate, and quadrate lobes.
right upper; diaphragm
Gateway where blood vessels, ducts, and nerves enter and exit the liver
porta
liver Receives blood from the _____
hepatic artery.
what duct Transports bile out of liver
hepatic duct
Formed from left and right hepatic duct
common hepatic duct
Joins common hepatic duct and it is from gallbladder
cystic duct
Formed from common hepatic duct and cystic duct
common bile duct
(no answers!!)
Flow of Bile and Pancreatic Secretions through Duct System of Liver, Gallbladder, and Pancreas
- Hepatic ducts – From liver lobes combine to form the common hepatic duct.
- Common hepatic duct - Combines with the cystic duct from the gallbladder to form the common bile duct.
- Common bile duct - Joins the pancreatic duct
- Combined duct - Empties into the duodenum at the duodenal papilla
- Pancreatic Secretions - Pancreatic secretions also enter the duodenum through pancreatic duct, which empties into duodenum.
Small sac located on the inferior surface of the liver that stores and concentrates bile.
gallbladder
Responsible for digestive and excretory functions, storing and processing nutrients, detoxifying harmful chemicals, and synthesizing new molecules. It secretes 700ml of bile each day.
liver
Dilutes and neutralizes stomach acid and breaks down fats.
bile
this stimulation Causes the gallbladder to contract, releasing bile into the duodenum
vagus and nerve stimulation
Produced by the duodenum and carried through the circulation to the liver, stimulates bile secretion by the liver.
secretin
Produced by the duodenum and carried through the circulation to the gallbladder, stimulates the gallbladder to contract, releasing bile into the duodenum.
Cholecystokinin
Stimulate bile secretion; over 90% are reabsorbed in the ileum and returned to the liver, where they stimulate additional secretion of bile salts.
bile salts
Located posterior to the stomach in the inferior part of the left upper quadrant, with its head near the midline of the body and its tail extending to the left, touching the spleen.
pancreas
this tissues contain pancreatic islets that produce insulin and glucagon
Endocrine Tissues
this tissues Produce digestive enzymes
exocrine tissues
Causes the pancreas to release a
secretion rich in digestive enzymes.
Parasympathetic stimulation from the vagus
nerve
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 ____ and ____
stomach; mouth
Moves food through digestive tract includes swallowing and peristalsis.
propulsion
Elimination of waste in the form of feces
defecation
______ split into disaccharides by
salivary and pancreatic amylases.
Polysaccharides
are Broken down into monosaccharides by disaccharidases on surface of intestinal epithelium.
disaccharides
Absorbed by cotransport with Na+
into intestinal epithelium
glucose
____ is carried by hepatic portal vein to
liver and enters most cells by facilitated
______
glucose; diffusion
(no answer)
Monosaccharide (glucose) Transport
- 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 hepatic
portal vein and is carried through the liver.
Bile salts _____ lipids
emulsify
Lipase breaks down lipids, forming ____
micelles
Micelles come into contact with the intestinal epithelium and diffuse into the cells, where they are packaged and released into _____.
lacteals
Lipids are stored in ____ and ____
adipose tissue; liver.
Attach to the cell membranes of
intestinal epithelial cells, allowing fatty acids
and monoglycerides to pass by simple
diffusion into the intestinal epithelial cells.
micelles
Within the intestinal epithelial cells - ____
acids and _____ are converted to
triglycerides; proteins coat the triglycerides to
form chylomicrons, which move out of the
intestinal epithelial cells by _____.
Fatty; monoglycerides; exocytosis
Enter the lacteals of the intestinal villi and are carried through the lymphatic system to the general circulation.
Chylomicrons
____ are split into ____ by enzymes secreted by the stomach and pancreas.
Proteins; polypeptides
Peptides and amino acids are absorbed into ____
intestinal epithelial cells.
____ are actively transported into cells with help from growth hormone (GH) and insulin.
Amino acids
Amino acids are used to build
new ___.
proteins
(no answer)
Amino Acid Transport
1. Acidic and most neutral amino acids -
Absorbed by symport into intestinal epithelial
cells.
2. Symport - Driven by a sodium gradient
established by a Na+—K+ pump.
3. Amino acids - Move out of intestinal epithelial
cells.
4. Amino acids - Enter the capillaries of the
intestinal villi and are carried through the
hepatic portal vein to the liver.
___ can move across the intestinal wall in either direction, depending on osmotic conditions.
water
99% of the water entering the
intestine is ____.
absorbed
are actively transported across the wall of the small intestine.
minerals
(no answers)
Fluid Volumes in Digestive Tract
1. Ingestion - 2 L
2. Salivary gland secretions - 1.5 L
3. Gastric secretions - 2 L
4. Pancreatic secretions - 1.2 L
5. Bile - 0.7 L
6. Small intestine secretions - 2 L
7. Absorption in the small intestine - 92%
8. Absorption in the large intestine - 6%-7%
9. Water in feces - 0.1 L
