week 4 Flashcards
what is the difference between mechanical and chemical digestion
Mechanical: the chewing of food by the teeth before it is swallowed / the churning of food by the smooth muscles of the stomach and small intestine so that it is thoroughly mixed with digestive enzymes
Chemical: a series of catabolic reactions in which enzymes break down large food molecules (eg: carbohyrates, lipids, protein, nucleic acids) into smaller molecules that may be absorbed and used by body cells.
what are the four major layers that exist along the GI tract from the esophagaus to the anal canal (from innermost to outermost)
- mucosa 2. submucosa 3. muscularis 4. serosa
Understand the 3 MUCOSA layers of the GI tract
- what type of cells the inner layer is composed of
- what makes up the middle layer
- what is important about the outer layer
INNER LINING OF EPITHELIUM:
- nonkeratinized stratified squamous epithelium in the mouth, pharynx, esophagus, and anal canal.
- Simple columnar epithelium throughout the rest of the GI tract to assist in secretion and absorbtion
MIDDLE LAYER OF AREOLAR CONNECTIVE TISSUE (LAMINA PROPRIA)
- contains blood vessels, lymphatic vessels, and scattered lymphatic nodules
- contains most components of the mucosa-associated lymphoid tissue (MALT)
OUTER LAYER OF SMOOTH MUSCLE TISSUE (MUSCULARIS MUCOSAE)
- creates small folds in the stomach and small intestinal mucosa that increase the surface of areolar area for digestion and absorption
the mucosa is a _____ membrane that surrounds the _____.
mucus, lumen
the submucosa consists of _____ _____ tissue
areolar connective
which layer of the GI tract is highly vascular
the submucosa
what is the job of the submucosal plexus
innervates the mucosa and submucosa and plays an important role in regulating:
a. movements of the mucosa and vasoconstriction of blood vessels
b. secretions by the GI tract
the muscularis consists of _____ tissue
muscle
skeletal muscle tissue can be found in what structures and allows for ?
in the mouth, pharynx, upper and middle parts of the esophagus, and the external anal sphincter.
It produces voluntary swallowing and voluntary control of defecation
the parts of the GI tract that do not consist of skeletal muscle tissue, are composed of what kind of tissue and are divided into what two types of fibers
smooth muscle tissue
a.inner sheet of circular fibers
b.outer sheet of longitudinal fibers
what is the largest peritoneal fold
the greater omentum
what plexus primarily controls GI tract motility
myenteric plexus (plexus of Auerbach)
what kind of cells make up the serosa layer of the GI tract
simple squamous epithelium
what is the largest serous membrane of the body
the peritoneum
what is the space between the parietal and visceral peritoneum
peritoneal cavity, which contains serous fluid
ascites
a disease which is brought on by an accumulation of serous fluids
what does it mean if an organ is considered retroperitoneal
some abdominal organs, such as the kidneys and pancreas, are located on the posterior abdominal wall and are covered by peritoneum on their anterior surfaces only. These organs are said to be retroperitoneal
what are the functions of the folds of the peritoneum
a. binds organs to each other and to the walls of the abdominal cavity
b. contains blood vessels, lymphatic vessels, and nerves that supply the abdominal organs
what structure is considered a “fatty apron” and hangs in front of the abdominal viscera, extending from the stomach and duodenum downward over the small intestine, then turning upward and attaching itself to the transverse colon?
the greater omentum
what is the structure that attaches the liver to the anterior abdominal wall and diphragm
the falciform ligament
what structure suspends the stomach and duodenum from the liver and contains some lymph nodes
the lesser omentum
what structure extends from the posterior abdominal wall to wrap around the small intestine and then returns to its origin
mesentery
what structure is an outward fold of the parietal peritoneum, attaches the large intestine to the posterior abdominal wall, and carries blood and lymphatic vessels to the intestines
the mesocolon
internally, the cheeks contain what type of cells
nonkeratinized stratified squamous epithelium