Prelim | Intestines Flashcards
MEASUREMENT OF SMALL INTESTINE
2.5cm (1”) in diameter
3m (10ft) long
Length of the SI in a cadaver
6.5 m (21 ft)
The SI starts at the (1) until the (2)
- pyloric sphincter
- opening of large intestine
Parts of the SI and their meaurements
Duodenum: 25cm (10in)
Jejenum: 1m (3ft)
Ileum: 2m (6ft)
The ileum joins the large intestine at a smooth muscle sphincter called the —
ileocecal sphincter
Layers of the SI
A. Mucosa
a. Epithelium
b. Lamina Propria
c. Muscularis mucosae
B. Submucosa
C. Muscularis
D. Serosa
Epithelium of the epithelial layer of SI
Simple columnar epithelium
What are found in the SI’s epithelilum?
Absorptive cells
Goblet cells
Paneth cells
Enteroendocrine cells
Contain enzymes that digest food and possess microvilli that absorb nutrients in small intestinal chyme.
Absorptive cells
Cells that produces mucus
Goblet cells
Secrete lysozyme, a bactericidal enzyme, and are capable of phagocytosis.
Paneth cells
Have a role in regulating the microbial population in the small intestine
Paneth cells
Three types of enteroendocrine cells found in the intestinal glands of the small intestine and their functions
S Cells: Secretes secretin (regulates secretion of stomach, liver, and pancreas)
K Cells: Secretes glucose-dependent insulinotropic peptide (regulates glucose)
CCK Cells: Secretes cholecystokinin (stimulates GB)
The lamina propria of the small intestinal mucosa contains (1) and has an abundance of (2)
- areolar connective tissue
- mucosa-associated lymphoid tissue (MALT).
— are most numerous in the distal part of the ileum.
Solitary lymphatic nodules
Groups of lymphatic nodules present in the ileum
Peyer’s patches
The muscularis mucosae of the small intestinal mucosa consists of —
smooth muscle
The submucosa of the duodenum contain which gland? and what is its function?
Brunner’s glands: Secretes an alkaline mucus that helps neutralize gastric acid in the chyme.
What makes up the muscularis of the SI?
Inner circular m and outer longitudinal m
Special structural features of the small intestine which facilitate the process of digestion and absorption
Circular folds/ Plicae circulares
Villi
Microvilli
When viewed through a light microscope, the microvilli are too small to be seen individually; instead they form a fuzzy line, called —, extending into the lumen of the small intestine
brush border
About — of intestinal juice, a clear yellow fluid, is secreted each day
1–2 liters (1–2 qt)
Intestinal juice contains (1) and is slightly alkaline with pH of (2).
- water and mucus
- 7.6
Among the brush-border enzymes are:
4 Carbohydrate-digesting
enzymes
- α-dextrinase
- maltase
- sucrase
- lactase
Protein-digesting enzymes
- peptidases (aminopeptidase and dipeptidase)
2 Types of nucleotide digesting enzymes
- nucleosidases
- phosphatases
The two types of mechanical digestion movements of the small intestine
Segmentations
Migrating motility complex (MMC)
The two types of movements of the small intestine—segmentations
and a type of peristalsis called migrating motility complexes—are governed mainly by the —
myenteric plexus
Segmentations occur most rapidly in the duodenum, about (1), and progressively slow to about (2) in the ileum.
- 12 times per minute
- 8 times per minute
What happens during segmentatino?
Segmentations are alternate contractions that mix chyme with digestive juices and bring particles of food into contact with mucosa for absorption
After most of a meal has been absorbed, which lessens distension of the wall of the small intestine, (1) stops and peristalsis termed as (2) begins.
- segmentation
- migrating motility complex (MMC)
Where does the MMC begin?
Lower portion of the stomach
Altogether, chyme remains in the small intestine for —
3–5 hours
Waves of contraction and relaxation of circular and longitudinal smooth muscle fibers passing the length of the small intestine; moves chyme toward ileocecal sphincter.
Migrating motility complex (MMC)
The small intestine absorbs about — of the fluid
8.3 liters
The medical specialty that deals with the diagnosis and treatment of disorders of the rectum and anus
proctology
Measurement of the LI
1.5 m (5 ft ) long and 6.5 cm (2.5 in.) in diameter
LI extends from the (1) to the (2)
- ileum
- anus
4 major regions of the large intestine
Cecum
Colon
Rectum
Anal canal
The opening from the ileum into the large intestine is guarded by a fold of mucous membrane called the —
ileocecal sphincter
Hanging inferior to the ileocecal valve
Cecum
Attached to the cecum is a twisted, coiled tube called —
vermiform appendix
The open end of the cecum merges with a long tube called the —
colon
The terminal 2–3 cm (1 in.) of the large intestine
Anal canal
The opening of the anal canal to the exterior, called the anus, is guarded by an (1) of (a) (involuntary) and an (2) of (b)(voluntary). Normally these sphincters keep the anus closed except during the elimination of feces.
- internal anal sphincter
a. smooth muscle - external anal sphincter
b. skeletal muscle
The passage of chyme from the ileum into the cecum is regulated by the action of the —
ileocecal sphincter
Unlike other parts of the GI tract, portions of the longitudinal muscles are thickened, forming three conspicuous bands called the — that run most of the length of the large intestine
teniae coli
Tonic contractions of the bands gather the colon into a series of pouches called —
haustra
In this process, the haustra remain relaxed and become distended while they fill up. When the distension reaches a certain point, the walls contract and squeeze the contents into the next haustrum.
haustral churning
A final type of movement in the mechanical digestion of the LI which is a strong peristaltic wave that begins at about the middle of the transverse colon and quickly drives the contents of the colon into the rectum
mass peristalsis
Mass peristaltic movements push fecal material from the sigmoid colon into the rectum. The resulting distension of the rectal wall stimulates stretch receptors, which initiates a —
defecation reflex
The final stage of digestion occurs in the colon through the activity of — that inhabit the lumen.
bacteria
(1) is secreted by the glands of the large intestine, but no (2) are secreted.
- Mucus
- enzymes
Excessive flatus (gas) in the stomach
Flatulence
What does bacteria convert the remaining carbohydrates into?
hydrogen
CO2
methane gases
What does bacteria convert the remaining proteins into?
amino acids: further breaks down into indole, skatole, hydrogen sulfide, and fatty acids
What does bacteria convert the bilirubin into?
Simplker pigments such as stercobilin
Some of the (1)and (2) is eliminated in the feces and contributes to their odor
- indole
- skatole
By the time chyme has remained in the large intestine (1), it has become solid or semisolid because of (2) and is now called (3).
- 3–10 hours
- water absorption
- feces
Chemically, feces consist of what?
water
inorganic salts
sloughed-off epithelial cells
bacteria
products of bacterial decomposition
Consists of indigestible plant carbohydrates—such as cellulose, lignin, and pectin—found in fruits, vegetables, grains, and beans
Dietary fiber
Does not dissolve in water, includes the woody or structural parts of plants such as the skins of fruits and vegetables and the bran coating around wheat and corn kernels
Insoluble fiber
Does dissolve in water, forms a gel that slows the passage of material through the tract. It is found in abundance in beans, oats, barley, broccoli, prunes, apples, and citrus fruits.
Soluble fiber,
An increase in the frequency, volume, and fluid content of the feces caused by increased motility of and decreased absorption by the intestines
Diarrhea
Infrequent or diff icult defecation caused by decreased motility of the intestines. Because the feces remain in the colon for prolonged periods, excessive water absorption occurs, and the feces become dry and hard.
Constipation
