Chapter 23 - The Digestive System Flashcards
Alimentary canal (describe anatomy, physiology, and associated organs)
Anatomy: the alimentary canal is the continuous muscular tube that winds through the body from mouth to anus.
Physiology: The alimentary canal breaks down food and absorbs the fragments into the blood via active or passive transport through the mucosal cells.
Organs: mouth, pharynx, esophagus, stomach, small intestine, large intestine.
Alimentary canal (list organs)
Mouth, pharynx, esophagus, stomach, small intestine, large intestine.
How long is the alimentary canal in a cadaver?
~9m, or 30ft.
Is food material considered inside or outside the body when it is in the alimentary canal?
Food material in this tube is technically outside the body because the canal is open to the external environment at both ends.
“Aliment”
nourish
Accessory organs (describe anatomy, physiology, and list the organs)
Anatomy: the teeth and tongue are in the oral cavity, while digestive glands and the gallbladder lie outside the alimentary canal and connect via duct systems.
Physiology: teeth and tongue act in mechanical break down, while other organs and glands make diverse secretions that aid in food breakdown.
Organs: teeth, tongue, gallbladder, salivary glands, liver, and pancreas.
Accessory digestive organs (list)
Teeth, tongue, gallbladder, salivary glands, liver, and pancreas.
List all major processes involved in digestion.
- Ingestion
- Propulsion
- Mechanical breakdown
- Digestion
- Absorption
- Defecation
Ingestion
Ingestion is taking food into the digestive tract. (Basically, eating)
Propulsion
Propulsion moves food through the GI tract. This includes swallowing and peristalsis.
Peristalsis
Peristalsis is an involuntary process that moves food through the GI tract by alternating in squeezing and relaxing its lining before and after the food (bolus/chyme). Peristalsis also functions in mixing the food.
Mechanical breakdown
Mechanical breakdown increases the surface area of ingested food, physically preparing it for digestion by enzymes. Includes mastication, incorporation of saliva, churning in stomach, and segmentation.
Segmentation
Segmentation is where nonadjacent segments of the alimentary canal organs contract and relax. The food is move forward, then backward, and is mixed with digestive juices. Mixing and mechanical breakdown. V. little net forward movement is accomplished by segmentation.
Absorption
Absorption is where the end products plus vitamins, minerals, and water are moved from the lumen of the GI tract to the blood or lymph via mucosal cells by active or passive transport.
Defecation
Waste leaves the body via the anus in the form of feces.
Are major digestive processes the job of a single organ each?
No. The mouth and the large intestine have a singular job: to take food in and to move waste out, respectively, but most other organs work together as the food moves along the tube.
Abdominopelvic peritoneum
The most extensive serous membrane
Visceral peritoneum
Lines external surfaces of digestive organs
Parietal peritoneum
Lines body wall
Peritoneal cavity
Contains serous fluid to lubricate organs
A mesentery (describe the anatomy, physiology, and explain common locations and how they’re referred to)
Anatomy: a mesentery is a double layer of peritoneum — a sheet of two serous membranes fused back to back — that extends to the digestive organs from the body wall.
Physiology: a mesentery provides routes for blood vessels, lymphatics, and nerves to reach digestive viscera. A mesentery also functions in storing fat and holding organs in place.
Common locations: mesenteries are mostly found in the dorsal portions of the body. As is in the case of the liver, sometimes it is found in the central portion of the body.
How they are referred to: some mesenteries have names, and some are deceptively referred to as ligaments (v. different from bone ligaments)
Retroperitoneal digestive organs
Retroperitoneal organs lose their mesenteries during development and thus lie behind the abdominopelvic peritoneum. The mesenteries act as organ placeholders WITHIN the peritoneum. Without them, organs slip behind the membrane.
Intraperitoneal or peritoneal organs
These are organs which are suspended by mesenteries within the abdominopelvic peritoneum.
Peritonitis (describe what it is, what causes it, what happens during, how dangerous it is, and treatment options)
It is: inflammation of the peritoneum
What causes it: 1) piercing abdominal wound 2) perforating ulcer that leaks stomach juices into peritoneal cavity 3) poor sterile technique during abdominal surgery, but MOST commonly results from a 4) burst appendix that sprays feces all over the membrane.
What happens then: the peritoneal coverings stick together at the sites of bacterial infection, macrophages come and work.
How dangerous it is: widespread peritonitis can cause damage and may be lethal in many cases.
Treatment options: mechanical removal of infectious debris and mega doses of antibiotics.
Matthew 15:17-18
Do you not see that whatever goes into the mouth passed into the stomach and is expelled? But what comes out of the mouth proceeds from the heart, and this defiles a person.
