Ch. 15 Digestive System Flashcards
The digestive system can be divided into 2 categories:
- (1) Alimentary canal/Digestive tract— Passage way for food
- Mouth
- Esophagus
- Stomach
- Small intestine
- Large intestine
- Rectum
- Anal canal
- Anus
- (2) Accessory organs— Secretion helps with the digestion of food
- Salivary gland (In the mouth)
- Liver
- Gallbladder
- Pancreas
The alimentary canal/digestive tract is a..
Passageway for food
The organs of the alimentary canal/digestive tract are the..
- Mouth
- Esophagus
- Stomach
- Small intestine
- Large intestine
- Rectum
- Anal canal
- Anus
[Alimentary canal/Digestive tract— Passageway for food]
Accessory organs: (Function)
Secretion helps with the digestion of food
The accessory organs are the..
- Salivary gland (In the mouth)
- Gallbladder
- Liver
- Pancreas
[Accessory organs— Secretion of these organs help with the digestion of food]
The digestive system carries..
Out the process of digestion
[Digestion: Mechanical and chemical breakdown of foods and absorption of nutrients]
Digestion:
Mechanical and chemical breakdown of foods and absorption of nutrients
2 Types of digestion:
- (1) Mechanical digestion: (Physically breaking down food) from large pieces of food into smaller ones
Chemical composition is not changed by this process - EX: Chewing
- (2) Chemical digestion: (Breaking down complex forms of nutrients into simpler forms) by breaking chemical bonds
- EX: Polysaccharides breaking down into monosaccharides
Mechanical digestion: (Function and example)
- (Physically breaking down food) from large pieces of food into smaller ones
- Chemical composition is not changed by this process
- EX: Chewing
Chemical digestion: (Function and example)
(Breaking down complex forms of nutrients into simpler forms) by breaking chemical bonds
- EX: Polysaccharides breaking down into monosaccharides
The alimentary canal is a muscular tube that passes through..
Thoracic and abdominopelvic cavities (through the diaphragm)
The alimentary canal is a food passageway between the..
Mouth and anus
How long is the alimentary canal?
~8 meters long
The wall of the alimentary canal consist of the same 4 layers throughout its length, these layers are:
- (1) Mucosa— Secrete mucus
- The inner layer of the wall
- A mucous membrane that surrounds the lumen of the tube
- Consist of epithelium, underlying connective tissue, a little smooth muscle
- Protects tissues of the canal
- Carries on secretion and absorption of dietary nutrients
- In some regions, the mucosa is modified into fold or projections, which increase surface area
- (2) Submucosa
- Lies under the mucosa
- Consists of loose connective tissue, housing blood and lymphatic vessels, nerves, and glands
- Nourishes the surrounding layers of the canal
- Vessels transport absorbed nutrients away from digestive organs
- (3) Muscularis— Smooth muscle (Contraction and relaxation)
- Consist of 2 layers of smooth muscle: Inner circular layer and outer longitudinal layer
- Propels food through the canal
- (4) Serosa— AKA visceral peritoneum
- Outer serous layer, or visceral peritoneum (covers the organs of the abdomen)
- Protects underlying tissues, and secretes serous fluid to reduce friction between organs
The mucosa, a layer of the alimentary canal..
- Is the inner layer which secretes mucus
- A mucous membrane that surrounds the lumen of the tube
- Consist of epithelium, underlying connective tissue, a little smooth muscle
- Protects tissues of the canal
- Carries on secretion and absorption of dietary nutrients
- In some regions, the mucosa is modified into fold or projections, which increase surface area
The submucosa, a layer of the alimentary canal..
- Lies under the mucosa
- Consists of loose connective tissue, housing blood and lymphatic vessels, nerves, and glands
- Nourishes the surrounding layers of the canal
- Vessels transport absorbed nutrients away from digestive organs
The muscularis, a layer of the alimentary canal..
Is smooth muscle (Contraction and relaxation)
- Consist of 2 layers of smooth muscle: Inner circular layer and outer longitudinal layer - Propels food through the canal
The serosa, a layer of the alimentary canal..
Is also known as the visceral peritoneum
- Outer serous layer, or visceral peritoneum (covers the organs of the abdomen)
- Protects underlying tissues, and secretes serous fluid to reduce friction between organs
Peristalsis:
Wavelike movement of food through the GI Tract
The salivary glands secrete saliva, which..
moistens and dissolves food particles, binds them together, aids in tasting, helps to cleanse the mouth and teeth, and begin carbohydrate digestion
1st stage of swallowing:
- The breakdown of carbohydrates starts in the mouth
- Food mixes with saliva which is being chewed mechanically to form the bolus (a soft ball of food)
[Bolus: Chewed food mixed with saliva forming a soft ball of food]
Bolus:
Chewed food mixed with saliva forming a soft ball of food
Salivary glands contain serous cells that produce a watery fluid containing..
Salivary amylase, and mucous cells that produce lubricating and binding mucus
- Amylase breaks down starch into disaccharides
- [Amylase— An enzyme that breaks down complex carbohydrates which is released from the salivary glands to be aka salivary amylase]
Salivary amylase—
An enzyme that begins breakdown of complex carbohydrates and is released from the salivary glands
Salivary glands receive parasympathetic stimulation that triggers the production of a large volume of..
Watery saliva at the thought, sight, or smell of food
There are 3 major pairs of salivary glands
- Parotid glands:
- Lie in the front of the ear
- Largest of the major salivary glands
- Secrete a clear, watery (serous) fluid rich in amylase - Submandibular glands:
- Located in the floor of the mouth
- Secrete a more viscous fluid (serous and mucous) than parotid glands - Sublingual glands:
- Inferior to the tongue
- Smallest of the major salivary glands
- Secrete a saliva that is thick and stringy (mucous)
Pharynx (throat):
Cavity lying posterior to the mouth (Connects mouth to esophagus)
Esophagus:
Muscular tube leading from pharynx to stomach (Connects pharynx to stomach)
Structure of the pharynx:
Connects the nasal and oral cavities with the larynx/voice-box and esophagus
The 3 portions of the pharynx:
- (1) Nasopharynx: Top portions, air passage behind nasal cavity (Behind the nose)
- (2) Oropharynx: Middle portion, passageway for food and air (Behind the oral cavity)
- (3) Laryngopharynx: Bottom portion, passageway to esophagus (Larynx— Voice-box)
Nasopharynx:
Top portions, air passage behind nasal cavity (Behind the nose)
Oropharynx:
Middle portion, passageway for food and air (Behind the oral cavity)
Laryngopharynx:
Bottom portion, passageway to esophagus (Larynx— Voice-box)
Swallowing can be divided into 3 stages:
- 1st Stage:
- Voluntary stage
- Food is chewed and mixed with saliva, forming a bolus
- Bolus is is forced into the oropharynx with the tongue - 2nd Stage:
- Sensory receptors in the oropharynx sense food, which triggers swallowing reflex
- Soft palate and uvula elevate to block the nasal cavity
- Hyoid bone and larynx elevate, and the epiglottis closes off the larynx
- Tongue presses against the soft palate to seal off the oral cavity from the nasopharynx
- Pharyngeal muscles contract, pulling the pharynx upward
- Muscles of the laryngopharynx relax, opening the esophagus
- Peristaltic wave begins in the pharynx, and proceeds toward the esophagus
- Breathing is inhibited briefly - 3rd Stage:
- Peristalsis transports food from the esophagus to stomach
2nd stage of swallowing:
- Sensory receptors in the oropharynx sense food, which triggers swallowing reflex
- Soft palate and uvula elevate to block the nasal cavity
- Hyoid bone and larynx elevate, and the epiglottis closes off the larynx
- Tongue presses against the soft palate to seal off the oral cavity from the nasopharynx
- Pharyngeal muscles contract, pulling the pharynx upward
- Muscles of the laryngopharynx relax, opening the esophagus
- Peristaltic wave begins in the pharynx, and proceeds toward the esophagus
- Breathing is inhibited briefly
3rd stage of swallowing:
- Peristalsis transports food from the esophagus to stomach
[Peristalsis: Wavelike movement of food through the GI Tract]
Esophagus: (Function)
Acts as a passageway
Esophagus: (Structure)
- Straight, collapsible food passageway leading to the stomach
- Extends downward through an opening in the diaphragm, the esophageal hiatus (Opening in the diaphragm so the esophagus can go from the thoracic cavity to the abdominopelvic cavity)
- Mucuous glands scattered throughout submucosa produce mucus to moisten and lubricate the inner lining of the tube
- Lower esophageal (cardiac) sphincter (Gastroesophageal Junction): helps to prevent regurgitation of the stomach contents into the esophagus
- [Regurgitate— To come back]
- Act as a valve so food does not go back into the esophagus
- Eating spicy food (”Heartburn”) — Relax the lower esophageal sphincter as well as delay stomach emptying and therefore cause acid reflux
Gastroesophageal Junction:
Helps to prevent regurgitation of the stomach contents into the esophagus
Stomach: (Location)
Upper left abdominal quadrant
J-shaped muscular organ:
The stomach
When the stomach is empty, mucus membrane goes into holes which are called:
Rugae
Rugae, or gastric folds, of the mucosa and submucosa, allow for..
Distention
Stomach: (Function)
- Receives food from esophagus
- Mixes food with digestive juices
- Begins digestion of proteins
- Limited absorption of nutrients occurs in stomach
- Propels food to the small intestine
Parts of the stomach: Cardia
A small region near opening to the esophagus
Parts of the Stomach: Fundus
A small rounded region superior to the cardia
Parts of the stomach: Body region
Main portion of the stomach, between fundus and pylorus
Parts of the stomach: Pylorus
A distal portion, near small intestine
- Pyloric canal is a narrowed area close to small intestine
- Pyloric sphincter, at end of pyloric canal, is a muscular ring that controls release of food from stomach into small intestine
Parts of the stomach:
- The stomach is divided into the following regions:
- Cardia: A small region near opening to the esophagus
- Fundus: A small rounded region superior to the cardia
- Body region: Main portion of the stomach, between fundus and pylorus
- Pylorus: A distal portion, near small intestine
- Pyloric canal is a narrowed area close to small intestine
- Pyloric sphincter, at end of pyloric canal, is a muscular ring that controls release of food from stomach into small intestine
Major Components of Gastric Juice:
- Mucus
- Pepsin
- Hydrochloric acid
Mucus: (Source and Function)
- Source: Mucous cells
- Function: Provides a viscous, alkaline protective layer on the stomach’s inner surface
Pepsin: (Source and Function)
- Source: Formed from pepsinogen in the presence of hydrochloric acid
- Function: A protein— Splitting enzyme that digests nearly all types of dietary protein into polypeptides
Hydrochloric acid: (Source and Function)
- Source: Parietal cells of the gastric glands
- Function: Provides the acid environment needed for the production and action of pepsin
Regulation of gastric secretions:
- Gastric juice production occurs continuously, but rate can be modified neurally and hormonally
- Gastric secretions are enhanced by parasympathetic impulses, via release of acetylcholine (ACh), and the hormone gastrin, which is released from gastric glands
- As food enters the small intestine, the presence of acid stimulates sympathetic impulses, which inhibit further secretion of gastric juice
- Presence of fats and proteins in the upper small
intestine causes the release of the hormone cholecystokinin from the intestinal wall, which decreases gastric motility
The stomach absorbs only small quantities of the following substances:
- Water
- Certain salts
- Alcohol
- Some lipid-soluble drugs
Mixing and emptying actions:
- After a meal, mixing actions of the stomach turn the food into a pasty (thick) mixture of food and gastric juice, called chyme
- Chyme is passed toward the pyloric region using peristaltic waves
- Chyme enters the duodenum of the small intestine in small amounts, through the pyloric sphincter
The rate at which the stomach empties depends on the fluidity of the chyme and the type of food:
- Proteins, lipids, carbohydrates pass through quickly
- Fats may be in the stomach for 3 to 6 hours
As chyme fills the duodenum, accessory organs— salivary glands, liver, gallbladder, pancreas—
Add secretions to the mixture
Vomiting:
- Contents of stomach and intestines are emptied in reverse direction, through the mouth
- Causes: Emotional upset, pain, stretching of the stomach, irritants, sensory overload
- Vomiting center in medulla oblongata controls reflex
- Motor response results in squeezing stomach from all sides, forcing contents through esophagus, pharynx, and out of the body through the mouth
Pancreas is both endocrine and exocrine gland:
- Exocrine function is to produce pancreatic juice that aids in digestion
- Exocrine glands— Called acini, secrete the following enzymes: (Together are called: Pancreatic juice)
- Amylase— Digestion of carbohydrates
- Lipase— Digestion of fat
- [Fatty acid— Building block of fat]
- Trypsin— Digestion of protein
- [Amino acid— Building block of protein]
- Endocrine glands— Called islets of langerhans, secrete the following hormones:
- Beta Insulin
- Alpha Glucagon
- Delta Somatostatin
(Pancreas) Exocrine glands— Called acini, secrete the following enzymes: (Together are called: Pancreatic juice)
- Amylase— Digestion of carbohydrates
- Lipase— Digestion of fat
- [Fatty acid— Building block of fat] - Trypsin— Digestion of protein
- [Amino acid— Building block of protein]
(Pancreas) Endocrine glands— Called islets of langerhans, release the following hormones:
- Insulin
- Glucagon
- Somatostatin
Structure of the pancreas:
- The pancreas is closely associated with the small intestine
- Pancreatic acinar cells make up most of the pancreas; these cells produce pancreatic juice
- Acinar cells cluster around tiny tubes that merge to form larger ones, and then give rise to the pancreatic duct
- The pancreatic and bile ducts join, and empty into the duodenum of the small intestine together
- The hepatopancreatic sphincter (sphincter of ODDI) regulates passage of pancreatic juice and bile into the duodenum
Pancreatic juice contains enzymes that digest carbohydrates, fats, proteins, and nucleic acids:
- Pancreatic amylase: Breaks down starch into disaccharides
- Pancreatic lipase: Breaks down triglycerides to glycerol and fatty acids
- Two nucleases break down nucleic acids to nucleotides
- Proteolytic enzymes, trypsin, chymotrypsin, and carboxypeptidase, each split certain bones between amino acid, to break down proteins to dipeptides
Pancreatic amylase:
Breaks down starch into disaccharides
Pancreatic lipase:
Breaks down triglycerides to glycerol and fatty acids
Location of pancreas:
- The pancreas is retroperitoneum
- [Retro: Behind] - Lies horizontally in epigastric region and extends to the left hypochondriac region
- Lies between duodenum and spleen
- Anterior to aorta and inferior vena cava (which are also retroperitoneum)
- Aorta and IVC is posterior to the pancreas
Liver: (Location)
Located in the upper right quadrant of the abdominal cavity
- Right hypochodriac region and extends into the epigastric region
The body’s largest internal organ:
Liver
- Largest organ within intraperitoneum
Perenchyma:
Functional tissue (Which perform the function of a organ)
Stroma:
Connective tissue (Which are in between perenchyma)
Liver structure:
- Hepatocytes perform the function of the liver (Parenchyma)
- Divided into large right and left lobes (by the falciform ligament), and is enclosed by a fibrous capsule called the glisson capsule
- Also contains minor quadrate and caudate lobes
- Each lobe is separated into hepatic lobules consisting of hepatic cells radiating from a central vein
- Hepatic sinusoids, channels filled with blood, separate groups of hepatic cells
- [Hepatic sinusoids: Larger capillaries in the liver]
- Blood from the hepatic portal vein carries blood rich in nutrients to the liver
- Blood passes from the sinusoids into the central vein of a lobule and exits the liver via the hepatic veins
- Kupffer cells carry on phagocytosis in the liver
- [Phagocytosis: Engulfing by projection of cell membrane called pseudopods; The trapped particle can either be destroyed or get digested by an enzyme present in the cell]
- Bile and secretions from hepatic cells are collected in bile canaliculi, which empty into bile ductules, that converge to become hepatic ducts and finally form common hepatic duct
- The common hepatic duct transports bile out of the liver
Liver functions:
- Metabolism of carbohydrates, lipids, and proteins because all nutrients is transported to the liver by the portal vein
- Breaks down into smaller forms
- What remains (extra) is stored in the liver - Maintains glucose levels and stores extra sugar in the form of glycogen (also stores vitamins and nutrients)
- Synthesizes plasma proteins all produced by the hepatocytes
- 3 groups of plasma proteins: albumin, globulins, fibrinogen
- (1) Albumin— Keeps plasma inside blood vessels (Produced in liver)
- Excessive filtration of albumin in the urine will cause plasma to go out of the tissues, causing edema
- (2) Globulins
- (3) Fibrinogen— (One of the factors) to help to form clots - Kupffer cells filters the blood, removing viruses, bacteria, and toxins
- Secrete bile
Bile:
- A yellowish-green liquid that hepatic cells secrete continuously
- Composed of water, bile salts, bile pigments, cholesterol, and electrolytes
- Bile pigments (bilirubin and biliverdin) are breakdown products of hemoglobin from worn out red blood cells
- Only the bile salts have a digestive function
Gallbladder: (Function)
- (1) Stores bile produced by the liver
- (2) Absorbs excess water from the bile
A pear-shaped sac on the inferior surface of the liver
The gallbladder
Gallbladder:
- The gallbladder is a pear-shaped sac on the inferior surface of the liver
- Stores bile between meals and reabsorbs water to concentrate the bile
- Contraction of its muscular wall releases bile into the duodenum
- It is connected to the cystic duct, which joins the common hepatic duct to form the common bile duct
- The common bile duct leads to the duodenum, where it joins the pancreatic duct
- The hepatopancreatic sphincter (sphincter of ODDI) controls the release of bile from the common bile duct (and pancreatic juice from the pancreatic duct)
- In certain conditions, cholesterol may precipitate in the gallbladder to form gallstones (Choleithiasis), which often have to be surgically removed
Regulation of bile release by the gallbladder:
- Chyme with fat enters the duodenum
- Cells of the intestinal mucosa secrete the hormone cholecystokinin (CCK) into the bloodstream
- Functions of cholecystokinin (CCK)
- Contract gallbladder to produce bile
- Stimulate the hepatocytes to produce more bile
- Release sphincter of ODDI
- Stimulate acini to produce pancreatic enzymes - CCK Stimulates muscular layer of gallbladder wall to contract
- Bile passes down the cystic duct and bile duct to the duodenum
- Hepatopancreatic sphincter (sphincter of ODDI) relaxes and bile enter duodenum
Functions of cholecystokinin (CCK):
- Contract gallbladder to produce bile
- Stimulate the hepatocytes to produce more bile
- Release sphincter of ODDI
- Stimulate acini to produce pancreatic enzymes
Hormones of the digestive tract:
- Gastrin
- Cholecystokinin (CCK)
- Secretin
Function of bile salts:
- Bile salts help cartain digestive enzymes break down fat molecules/complex food
- Bile salts accomplish emulsification:
- [Emulsification: Breakdown of fat]
- Involves breaking down large fat globules into smaller droplets; this increases their solubility in water
- Increases surface area of fats; this makes chemical digestion by enzymes called lipases more effective
- Bile salts aid in the absorption of fatty acids, cholesterol, and fat-soluble vitamins
Small intestine: (Structure)
- A long tubular organ which runs from the stomach to the beginning of the large intestine
- Fills a large part of the abdominal cavity
Functions of the small intestine:
- Receives chyme from the stomach
- Receives pancreatic juices from pancreas and bile from liver and gallbladder
- Finishes digestion of nutrients that arrive in the chyme
- Absorbs digestive end products
- Transports the remaining residue to the large intestine
Parts of the small intestine: (Proximal to distal)
- Duodenum, jejunum, and ileum
- The jejunum and ileum are suspended from the posterior abdominal wall by a double-layered fold of peritoneum called mesentery
- [Mesentery: A double layer of visceral peritoneum which covers the small intestine and attached to the posterior abdominal wall
- The mesentery contains blood vessels, nerves, and lymphatic vessels that service the intestinal wall
- Greater omentum drapes over the intestine; it is a double fold of peritoneal membrane
Duodenum:
The shortest and most fixed portion of the small intestine; the stomach empties chyme directly into the duodenum
- The duodenum is divided into 4 parts (2 horizontal, 2 vertical)
- The ampulla of VATER opens into the 2nd part of the duodenum
Jejunum:
Makes up the proximal 2/5th of the small intestine, has a slightly larger diameter than the ileum, and is more active in the digestion process
Ileum:
Most distal portion
- Opens into the large intestine
Structure of the small intestinal wall:
- The inner wall of the small intestine is lined with finger-like intestinal villi, which greatly increase the surface area available for absorption and aid in mixing actions
- Each villus consists of simple columnar epithelium with a core of connective tissue, housing blood capillaries and a lymphatic capillary called a lacteal
- Blood capillaries and lacteals transport absorbed dietary nutrients out of the alimentary canal
- Between the bases of adjacent villi are tubular intestinal glands
- Epithelial cells lining the small intestine are replaced every 3 – 6 days
Secretions of the small intestine:
- Mucus: secreted in the small intestine by goblet cells, which are abundant throughout the mucosa, and mucus-secreting glands located in the submucosa of the duodenum
- Watery fluid: carries digestive products into the villi, secreted by intestinal glands at the bases of the villi
- Enzymes: secreted by epithelial cells of the mucosa, and embedded in their microvilli
Mucus:
Secreted in the small intestine by goblet cells, which are abundant throughout the mucosa, and mucus-secreting glands located in the submucosa of the duodenum
Watery fluid
Carries digestive products into the villi, secreted by intestinal glands at the bases of the villi
Enzymes:
Secreted by epithelial cells of the mucosa, and embedded in their microvilli
Movements of the small intestine:
- Segmentation— Mixing movements
- In segmentation, contractile rings break up chyme and move it back and forth, mixing it and slowing its movement down the intestine
- Peristalsis— Propelling movements
- Weak
- Push chyme forward
- A strong peristaltic rush, resulting from over distension or irritation moves the chyme too quickly, causing diarrhea
- The ilieocecal sphincter at the junction of the small is large intestine usually remains closed (Unless a gastroileal reflex)
- The ileocecal sphincter is between the small (ileum) and large intestine (the first part called the cecum)
Large Intestine: (Function)
- Function: Absorb extra fluid
- Defecation— Stimulated by defecation reflex, that forces feces into the rectum where they can be expelled
Large intestine is named “large” because its..
Diameter is larger
than that of the small intestine
The large intestine is.. (How long?)
About 1.5 meters long
The large intestine.. (Location)
Begins in lower right portion of abdominal cavity at the cecum, ascends on right, crosses to left side, and descends on left side
Opens to outside of body as the anus–
The large intestine
Parts of the large intestine:
- Cecum: a pouch at the beginning of the large intestine, with the appendix projecting downward from it
- Colon: consists of the ascending (reaches the liver), transverse, (reaches the spleen) descending, and sigmoid regions
- Rectum: a straight section of the large intestine, which lies next to the sacrum
- Anal canal: opens to the outside as the anus; guarded by an involuntary internal anal sphincter and a voluntary external anal sphincter
- Anus
Cecum:
A pouch at the beginning of the large intestine, with the appendix projecting downward from it
Colon:
Consists of the ascending (reaches the liver), transverse, (reaches the spleen) descending, and sigmoid regions
Rectum:
A straight section of the large intestine, which lies next to the sacrum
Anal canal:
Opens to the outside as the anus; guarded by an involuntary internal anal sphincter and a voluntary external anal sphincter
Describe Biliary Tree (With Image)
- There are 4 anatomical lobes (right and left lobe which are divided by the falciform liver in the superior aspect and the quadrate and caudate on the inferior aspect)
- The liver is covered by a fibrous capsule called the glisson capsule
- From the hepatocytes, the small bile ductule from the right side form the right hepatic duct, and the small bile ductules from the left side form the left hepatic duct
- The right and left hepatic ducts join to form the common hepatic duct
- The common hepatic duct descends down and joins the duct from the gallbladder, called the cystic duct
- The cystic duct joins the common hepatic duct and forms the common bile duct
- The common bile duct descends down and joins the pancreatic duct from the pancreas
- When they both join, there is a slight dilation which is called ampulla of VATER
- The ampulla of VATER opens into the first part of the small intestine, called duodenum by a sphincter/door, called the sphincter of ODDI
Describe Supply and Drainage of the Liver (With Image)
- The liver is highly vascular structure
- The portal vein is bringing the nutrients from the digestive tract and enters the liver
- inferior mesenteric vein, [splenic vein + superior mesenteric vein] → [portal conference] → portal vein
- The common hepatic artery (branch of celiac trunk) becomes the proper hepatic artery which takes oxygenated blood to enter the liver to supply oxygen
- The celiac trunk (an unpaired branch of the abdominal aorta) → Common hepatic artery → Proper hepatic artery → Liver
- O2 is needed because the liver does 24hr work because of eating
- The hilum of the liver called the: Porta hepatis
- [Hilum/hilus: Door in which vessels move in and out]
- Bile is then produced by the hepatocytes in liver and is transported out by the common hepatic duct
- Right and left hepatic ducts → Common hepatic duct (Then descends down and joins gallbladder) → [Cystic duct + Common hepatic duct] → [Common bile duct] (Then descends down and joins the pancreas) → Pancreatic duct → (Forms a slight dilation called) Ampulla of VATER → (Opens into the duodenum by the) Sphincter of ODDI
- Hepatic vein drains into the IVC → Right atrium
Describe Movement From End of Small Intestine to Large Intestine (With Image)
Ileum →
Cecum (Pouch like structure) →
(Ascends upward) Ascending color →
(Reaches where the liver is, turns towards the left side) Right colic (hepatic) flexure →
(Moves transversely) Transverse colon →
(Reaches the spleen) →
Left colic (splenic) colon →
(Goes downward) Descending colon →
(Forms an S shape) Sigmoid colon →
Rectum → Anal canal → Anus
The mesentery of the large intestine is called the:
- Mesocolon
- [Mesentery: A double layer of visceral peritoneum which covers the small intestine and attached to the posterior abdominal wall
- The mesentery contains blood vessels, nerves, and lymphatic vessels that service the intestinal wall
What are the hormones of the digestive tract?
Gastrin, cholecystokinin, and secretin
Gastrin (Source and Function)
- Source: Gastric cells, in response to food
- Function: Increases secretory activity of gastric glands
Cholecystokinin (Source and Function)
- Source: Intestinal wall cells, in response to proteins and fats in the small intestine
- Function: Decreases secretory activity of gastric glands and inhibits gastric motility; stimulates pancreas to secrete fluid with a high digestive enzyme concentration; stimulates gallbladder to contract and release bile
Secretin: (Source and Function)
- Source: Cells in the duodenal wall, in response to acidic chyme entering the small intestine
- Function: Stimulates pancreas to secrete fluid with a high bicarbonate ion concentration
