Ch. 24 Flashcards
Digestive tract
Aka?
a tube extending from the mouth to anus
gastrointestinal tract
What are the accessory organs of the digestive tract?
Salivary glands, liver, gallbladder, and pancreas
*primary organs that secrete fluid into the digestive tract
What are the organs of digestive tract?
Oral cavity, pharynx, esophagus, stomach, small intestine, large intestine
What are the 6 functions of the digestive system?
- Ingestion and mastication
- Propulsion and mixing
- Secretion
- Digestion
- Absorption
- Elimination
What are ingestion and mastication?
- *Ingestion** - the intake of solid or liquid food into the stomach
- *Mastication** - the process by which the teeth chew food in the mouth to begin the process of digestion
What are propulsion and mixing?
What are the 3 propulsive movements?
What are the 2 mixing contractions?
Propulsion is the movement of food from one end of the digestive tract to the other
Mixing is the movement of food back and forth in the digestive tract, without forwarding movement
Propulsive movements:
Swallowing - moves food or liquid from oral cavity to esophagus
Peristalsis - Propels material through most of the digestive tract
Mass movements - contractions that move material in the distal parts of the large intestine to the anus
- Mixing contractions*
- *Mixing waves** - gentle contractions that churn the food with gastric secretions
- *Segmental Contractions** - mix food particles with digestive secretions in the small intestine
What is secretion?
What are the 3 main secretions?
added to lubricate, liquefy, buffer, and digest food as it moves through the digestive tract
- *Mucous** - lubricates food and lining of the tract/lubricates epithelial cells from damage
- *Water** - liquefies food making it easier to digest
- *Enzymes** - breakdown large food molecules into smaller molecules
What is digestion?
What are the 2 processes of digestion?
The breakdown of large organic molecules into their component parts
- *Mechanical** - mastication and mixing of food
- *Chemical** - digestive enzymes secreted along the digestive tract
What is absorption?
movement of molecules out of the digestive tract and into the blood or lymphatic system
What is elimination?
the process by which the waste products of digestion are removed from the body
What are the 4 tunics of the digestive tract?
- Mucosa
- Submucousa
- Muscularis
Serosa or adventia
What are the 3 types of glands associated with the digestive tract?
- unicellular mucous glands in mucosa
- multicellular glands in mucosa and submucosa
- Multicellular glands outside of digestive tract
What 3 layers does the mucosa consist of
and what specialized cells are there?
- inner mucous epithelium - stratified squamous in mouth, oropharynx, esophagus, and anal canal. Simple squamous in rest of digestive tract
- Loose connective tissue called lamina propria
- Thin outer layer of smooth muscle called muscularis mucosa
Specialized cells: mechanoreceptors and chemoreceptors
What is the submucosa?
What is the submucosal plexus?
What 2 organs of digestive system lack submucosal plexus?
Deep to the mucosa - a thick connective tissue layer that contains nerves, blood vessels, lymphatic vessels and small glands
Submucosal plexus - network of nerve cells consisting of axons, neuron cells bodies and glial cells. Main function is to regulate secretions
Esophagus and stomach lack submucosal plexus
What is the muscularis layer?
What is the myenteric plexus and its function?
Specialized interstitial cells?
A muscular layer deep to the mucosa and submucosa, consisting of a inner layer of circular smooth muscle and an outer layer of longitudinal smooth muscle
Myenteric plexus is between the 2 muscle layers and controls the motility of the intestinal tract. Consisting of axons, neuron cell bodies and glial cells.
Within the myenteric plexus, are specialized interstitial cells which form a network of pacemakers, which promote rhythmic contractions of smooth muscle along the digestive tract
What makes up the Enteric nervous system or enteric plexus?
submucosal and myenteric plexuses together - which controls secretion and movement
What is the 4th layer of the digestive tract?
part located in the peritoneal cavity have a SEROSA - called VISCERAL PERITONEUM- thin layer of connective tissue and simple squamous
when digestive tract is derived from adjacent connective tissue it is called ADVENTITIA - esophagus and retroperitoneal organs
What are the 3 major types of enteric neurons?
- enteric sensory neurons - detect changes in the chemical composition of digestive tract or mechanical changes such as stretch
- enteric motor neurons - stimulate or inhibit smooth muscle contraction and glandular secretion
- enteric interneurons - connect sensory and motor neurons
What are the serous membranes of the abdominal cavity called?
What is the serous membrane that covers the organ called?
What is the serous membrane that covers the interior surface of the abdominal wall called?
What is peritonitis?
what is an accumulation of excess serous fluid in peritoneal cavity called?
peritoneum
Visceral peritoneum
parietal peritoneum
potentially life-threatening inflammation of the peritoneal membranes
ascites
What are mesenteries?
what is the mesentery associated with small intestine?
What is the mesentery associated with colon?
What mesentery is associated with the appendix?
connective tissue sheets that hold organs in place
Mesentery proper - small intestine
transverse mesocolon - transverse colon to posterior body wall & sigmoid mesocolon
Mesoappendix
The oral cavity is divided into what 2 regions?
Vestibule - space between lips or cheeks and teeth
Oral cavity proper - medial to the teeth
