Digestive System Flashcards
What are the six main functions of the digestive system?
- Ingestion
- Motility
- Secretion
- Digestion
- Absorption
- Elimination
These functions work together to process food and expel waste.
Differentiate between gastrointestinal tract organs and accessory digestive organs.
Gastrointestinal tract organs form a continuous tube; accessory organs assist in digestion.
Gastrointestinal organs include the oral cavity, pharynx, esophagus, stomach, small intestine, large intestine, and anus. Accessory organs include salivary glands, liver, pancreas, teeth, tongue, and gallbladder.
What are the four tunics of the gastrointestinal wall?
- Mucosa
- Submucosa
- Muscularis
- Adventitia (serosa)
Each tunic has specific structures and functions that contribute to digestion.
Define the term retroperitoneal.
Located behind the peritoneum.
What is mesentery?
A fold of tissue that attaches the intestines to the abdominal wall.
Mesenteries are located in the abdominal cavity and support blood vessels and nerves.
What is peritonitis?
Inflammation of the peritoneum.
It can have serious implications, including infection and abdominal pain.
Identify the organs of the upper gastrointestinal tract.
- Oral cavity
- Salivary glands
- Pharynx
- Esophagus
- Stomach
- Duodenum
These organs are involved in the initial stages of digestion.
Define mastication.
The process of chewing food.
What is a bolus?
A small rounded mass of chewed food ready to be swallowed.
Describe the gross anatomy of the oral cavity.
- Uvula
- Lingual frenulum
- Labial frenulum
- Hard palate
- Soft palate
- Fauces
These structures play roles in digestion and swallowing.
Where are the different salivary glands located?
- Parotid glands: near the ear
- Submandibular glands: under the jaw
- Sublingual glands: under the tongue
Each gland produces saliva that aids in digestion.
What is the chemical composition of saliva?
- Water
- Electrolytes
- Mucus
- Enzymes (e.g., salivary amylase)
Saliva helps in the digestion of carbohydrates.
What types of teeth are there and their functions?
- Incisors: cutting
- Canines: tearing
- Premolars: grinding
- Molars: crushing
Deciduous teeth are temporary, while permanent teeth replace them.
What are the anatomical structures of the stomach?
- Cardia
- Fundus
- Body
- Pylorus
- Pyloric sphincter
- Greater curvature
- Lesser curvature
These structures aid in food storage and digestion.
What are the three layers of muscles in the muscularis of the stomach?
- Inner oblique layer
- Middle circular layer
- Outer longitudinal layer
These layers facilitate the mixing and propulsion of gastric contents.
What are the three phases of gastric function?
- Cephalic phase
- Gastric phase
- Intestinal phase
Each phase involves specific reflexes and hormonal responses.
What is peptic ulcer disease?
A condition where sores develop on the lining of the stomach or intestines.
What is the function of the gallbladder?
To store bile.
What stimulates the contraction of the gallbladder?
Cholecystokinin (CCK).
What are the three segments of the small intestine?
- Duodenum
- Jejunum
- Ileum
Each segment has unique functions in digestion and absorption.
What is the function of bile?
To emulsify fats.
What is the role of pancreatic juice?
To aid in digestion by providing digestive enzymes.
What are the main classes of digestive enzymes produced by the pancreas?
- Carbohydrases
- Lipases
- Proteases
- Nucleases
These enzymes break down carbohydrates, fats, proteins, and nucleic acids.
What is the normal flora in the large intestine?
The beneficial bacteria that reside in the gut.
What is the function of the rectum?
To store feces before elimination.
What is the defecation reflex?
The process of expelling feces from the rectum.
What is celiac disease?
An autoimmune disorder where ingestion of gluten damages the small intestine.
What is emulsification?
The process by which bile breaks down fats into smaller droplets.
How are water, electrolytes, and vitamins absorbed from the digestive tract?
Through the intestinal walls into the bloodstream.
What hormone is released from the duodenum and targets the stomach, gallbladder, pancreas, hepatopancreatic sphincter, and ileocecal valve?
Cholecystokinin (CCK)
CCK plays a role in digestion and is involved in the regulation of digestive enzymes and bile secretion.
Which hormone is released from the small intestine and targets the pancreas?
GIP
GIP stands for Glucose-dependent Insulinotropic Peptide, influencing insulin secretion.
What is the function of baroreceptors in the GI tract?
Detect stretch or pressure of a specific region of the GI tract
Baroreceptors help regulate digestive processes by monitoring changes in the GI tract.
What is the serous membrane associated with the abdominopelvic cavity called?
Peritoneum
The peritoneum consists of two layers: parietal and visceral.
What are intraperitoneal organs?
Organs completely surrounded by visceral peritoneum
Examples include the stomach, most of the small intestine, and parts of the large intestine.
What do retroperitoneal organs lie against?
The posterior abdominal wall
Retroperitoneal organs include the pancreas and parts of the large intestine.
What is the mesentery?
A double layer of peritoneum that supports, suspends, and stabilizes the intraperitoneal GI tract organs
It contains blood vessels, lymph vessels, and nerves between its layers.
What is peritonitis?
An inflammation of the peritoneum
Commonly caused by perforation of the GI tract, it can lead to severe complications.
What initiates mechanical digestion in the oral cavity?
Mastication
This process involves breaking food into smaller pieces to facilitate swallowing.
What is the primary enzyme in saliva that initiates the chemical digestion of starch?
Salivary amylase
Salivary amylase begins the breakdown of carbohydrates.
What is the function of the pharynx?
Accomplishes swallowing
The pharynx serves as a passageway for both air and food.
What are the three pairs of extrinsic salivary glands?
- Parotid
- Submandibular
- Sublingual
These glands produce the majority of saliva in the oral cavity.
What is the primary mass of a tooth called?
Dentin
Dentin forms the bulk of the tooth structure beneath the enamel.
What is the role of the gingivae?
Cover the alveolar processes of the upper and lower jaws and surround the neck of the teeth
Gingivitis is the inflammation of the gingivae.
What is the difference between deciduous and permanent teeth?
- Deciduous teeth: 20 teeth that erupt between 6 and 30 months after birth
- Permanent teeth: 32 teeth that replace deciduous teeth as an individual ages
Deciduous teeth are also known as baby teeth.
What does the inferior esophageal sphincter help prevent?
Reflux of materials from the stomach
This sphincter is also known as the gastroesophageal sphincter.
What is reflux esophagitis?
Inflammation of the esophagus due to acidic chyme reflux
It can cause burning pain and irritation in the esophagus.
What is the primary component of saliva?
99.5% water
Saliva also contains electrolytes, salivary amylase, and mucin.
What are the two types of secretory cells in salivary glands?
- Mucous cells
- Serous cells
Mucous cells secrete mucin, while serous cells secrete a watery fluid with enzymes.
What type of epithelium lines the oral cavity?
Stratified squamous epithelium
This epithelium provides protection against abrasion.
What is reflux esophagitis?
Reflux esophagitis occurs when acidic contents reflux into the esophagus, causing burning pain and irritation.
Which individuals are most commonly affected by reflux esophagitis?
Overweight individuals, smokers, and people with hiatal hernias.
What lifestyle changes can alleviate symptoms of reflux esophagitis?
- Losing weight
- Quitting smoking
- Limiting meal size
- Sleeping with the head elevated
- Not lying down after eating
What is gastroesophageal reflux disease (GERD)?
GERD is a buildup of scar tissue in the esophageal tissue, which can result from chronic reflux esophagitis.
What histological feature characterizes the mucosa of the esophagus?
Nonkeratinized stratified squamous epithelium.
What are the three phases of swallowing?
- Voluntary phase
- Pharyngeal phase
- Esophageal phase
What initiates the pharyngeal phase of swallowing?
The arrival of the bolus at the entryway to the oropharynx.
What is the primary function of the stomach?
The stomach is a holding sac where mechanical and chemical digestion continues on the bolus.
What substance is absorbed in the stomach?
- Alcohol
- Aspirin
What is the importance of intrinsic factor released by the stomach?
Intrinsic factor is required for the absorption of vitamin B12 in the small intestine.
What are the four regions of the stomach?
- Cardia
- Fundus
- Body
- Pylorus
What type of epithelium lines the stomach mucosa?
Simple columnar epithelium.
What do chief cells in the stomach secrete?
- Pepsinogen
- Gastric lipase
What is the role of hydrochloric acid in the stomach?
- Facilitates chemical digestion
- Protein denaturation
- Pepsin activation
- Enhances enzymatic activity
- Kills most microorganisms
What is retropulsion in gastric motility?
Retropulsion is the reverse flow of chyme back into the stomach body as the pyloric sphincter closes.
What initiates the cephalic phase of digestion?
The thought, smell, sight, or taste of food.
What is a peptic ulcer?
A chronic, solitary erosion of the lining of the stomach or the duodenum.
What bacterium is commonly associated with peptic ulcers?
Helicobacter pylori.
What is the primary treatment for peptic ulcers?
- Antibiotics
- Antacids
- Proton pump inhibitors
- Histamine blockers
What is vomiting?
The rapid expulsion of gastric contents through the oral cavity.
What can trigger vomiting?
- Head injury
- Inner ear motion sickness
- Infection
- Toxicity
- Food irritation
What is the primary function of the small intestine?
To chemically digest chyme and absorb nutrients, water, and electrolytes.
What are the three parts of the small intestine?
- Duodenum
- Jejunum
- Ileum
What is the function of accessory organs in digestion?
- Liver produces bile
- Gallbladder stores and releases bile
- Pancreas produces bicarbonate and digestive enzymes
What is the function of the ileocecal valve?
It controls the entry of materials into the large intestine.
What is the role of pacemaker cells in the stomach?
They initiate smooth muscle contraction which spontaneously depolarizes less than four times per minute.
What is the primary region for nutrient absorption in the small intestine?
Jejunum
The jejunum is typically about 7.5 ft long.
What occurs in the ileum of the small intestine?
Absorption of bile salts and vitamin B12
The ileocecal valve controls the entry of materials into the large intestine.
What type of anatomical support do the jejunum and ileum have?
Intraperitoneal supported by the mesentery proper
The duodenum is mostly retroperitoneal.
What are plicae circulares?
Circular folds in the mucosal and submucosal tunics of the small intestine
They increase surface area and slow the movement of chyme.
What are villi?
Small fingerlike projections of the simple columnar epithelium in the small intestine
They are largest and most numerous in the jejunum.
What is a lacteal?
A lymphatic capillary within the villus
It is responsible for absorbing lipids and lipid-soluble vitamins.
What are brush border enzymes?
Enzymes embedded in the brush border that complete chemical digestion
They are crucial for nutrient absorption.
What do Goblet cells produce?
Mucus
This lubricates and protects the intestinal lining.
What is the role of enteroendocrine cells in the small intestine?
Release hormones such as CCK and secretin into the blood
These hormones help regulate digestion.
What is segmentation in the context of small intestine motility?
A back-and-forward motion that mixes chyme with accessory gland secretions
It is more prevalent when chyme enters the duodenum.
What initiates peristalsis in the small intestine?
Motilin hormone
Released from the duodenum in progressively greater amounts late in the intestinal phase.
What is the gastroileal reflex?
Moves contents from the ileum into the cecum
It is triggered by food entering the stomach.
What is the hepatopancreatic ampulla?
A swelling on the posterior duodenal wall where the main pancreatic duct joins the common bile duct
It is where bile and pancreatic juice enter the duodenum.
What is the liver’s primary function?
Produces bile
It is the largest internal organ and is located in the upper right quadrant of the abdominal cavity.
What are portal triads in the liver?
Composed of a hepatic duct, a bile ductule, and branches of the hepatic portal vein and artery
They are located at the periphery of each hepatic lobule.
What does bile contain?
Water, bicarbonate, bile salts, bile pigments, cholesterol, lecithin, and mucin
It does NOT contain digestive enzymes.
What is cirrhosis of the liver?
A condition where hepatocytes are destroyed and replaced by scar tissue
It can result from chronic alcoholism or diseases such as hepatitis B and C.
What is the gallbladder’s function?
Stores, concentrates, and releases bile
It has three tunics: mucosa, muscularis, and serosa.
What are gallstones?
Condensations of cholesterol or calcium and bile salts
They can cause severe pain and inflammation in the gallbladder.
What is the primary function of the pancreas?
Has both endocrine and exocrine functions
It produces hormones like insulin and digestive enzymes.
What is pancreatic juice?
An alkaline mixture of water, bicarbonate, and digestive enzymes
It assists in chemical digestion.
What regulates the release of pancreatic juice?
Vagal stimulation and hormones like CCK and secretin
CCK stimulates smooth muscle contraction in the gallbladder.
What is a major symptom of pancreatic cancer?
Difficulties in digestion and nutrient absorption
Early detection is crucial for a better prognosis.
What type of cells does pancreatic cancer typically originate from?
Exocrine cells of the pancreas
Approximately 95% of pancreatic cancer cases originate from these cells.
What improves the prognosis for pancreatic cancer?
Early detection
Early detection is crucial before the cancer metastasizes to lymph nodes.
What are two challenges in the early detection of pancreatic cancer?
- Lack of a screening test
- Absence of early signs and symptoms
What symptoms might indicate advanced pancreatic cancer?
- Abdominal pain
- Jaundice
- Loss of appetite
- Weight loss
Why is pancreatic cancer often fatal?
Late detection
It is often detected in advanced stages when complete surgical removal is not possible.
What is the primary function of the large intestine?
Absorbs water, electrolytes, and vitamins B and K
It compacts remaining digested material into feces.
What are the three regions of the large intestine?
- Cecum
- Colon
- Rectum
What is appendicitis?
Inflammation of the appendix
Usually due to obstruction by fecal matter.
What are common symptoms of appendicitis?
- Nausea or vomiting
- Abdominal tenderness in the right lower quadrant
- Elevated leukocyte count
How is appendicitis treated?
Appendectomy
Surgical removal of the appendix.
What are the four parts of the colon?
- Ascending colon
- Transverse colon
- Descending colon
- Sigmoid colon
What is the function of the rectum?
Stores fecal material prior to defecation
What are rectal valves?
Folds of the rectum that retain fecal material during gas passage
What characterizes colorectal cancer?
Malignant growth along the large intestine or rectum
What are common risk factors for colorectal cancer?
- Low-fiber diets
- Family history of colorectal cancer
- Personal history of ulcerative colitis
- Increased age
What are early symptoms of colorectal cancer?
- Rectal bleeding
- Persistent changes in bowel habits
- Abdominal pain
- Fatigue
- Unexplained weight loss
- Anemia
What is the role of intestinal microbiota?
Chemically breaks down complex carbohydrates, proteins, and lipids in the large intestine
What do feces consist of?
- Water
- Salts
- Epithelial cells
- Bacteria
- Undigested material
What is a fecal transplant?
Procedure involving the transfer of fecal matter from a healthy donor to a patient
What does the gastrocolic reflex do?
Causes mass movement in the colon initiated by stomach distension
What is diverticulosis?
Presence of diverticula in the intestinal lining
What is constipation?
Temporary impaired ability to defecate, resulting in compacted feces
What can cause diarrhea?
- Failure of the large intestine to absorb water
- Excessive osmotically active solutes
What enzyme initiates carbohydrate digestion in the mouth?
Salivary amylase
What is lactose intolerance?
Reduced amount or lack of lactase
What role does hydrochloric acid play in protein digestion?
Denatures proteins and activates pepsinogen to pepsin
What is celiac disease?
Autoimmune disorder triggered by gluten that damages intestinal villi
What is the function of pancreatic lipase?
Digests triglycerides in the small intestine
What is the primary absorption site for water and electrolytes?
Small intestine
What hormone regulates iron absorption?
Hepcidin
What hormone is released from the liver in response to iron levels?
Hepcidin
Hepcidin regulates iron absorption.
What does hepcidin inhibit in the gastrointestinal tract?
Ferroportin
Ferroportin is a transport protein located in the epithelial (basolateral) membrane.
What happens to hepcidin release when iron levels are low?
It decreases
This decrease allows for greater iron absorption.
Which vitamins are absorbed from the small intestine lumen with lipids within micelles?
Fat-soluble vitamins (A, D, E, K)
These vitamins require lipids for their absorption.
How are water-soluble vitamins (B and C) absorbed?
Through various membrane transport mechanisms
Mechanisms include simple diffusion and active transport.
What transport method is required for Vitamin B12 absorption?
Receptor-mediated endocytosis
This process requires intrinsic factor released from parietal cells.
Fill in the blank: Hepcidin inhibits the transport protein _______ located in the gastrointestinal tract.
ferroportin
True or False: Water-soluble vitamins are absorbed in the same way as fat-soluble vitamins.
False
Water-soluble vitamins use different transport mechanisms.
What is the role of intrinsic factor in Vitamin B12 absorption?
It is required for receptor-mediated endocytosis
Intrinsic factor is released from parietal cells in the stomach.
