Reproductive and digestive system Flashcards
When chyme enters duodenum, CCK is released what happens?
- Hepatopancreatic sphincter relaxes.
- Gallbladder contracts
Full gallbladder contains how much bile?
- 40-70 mL.
Enolecysittis
- Gallstones are so large, blockage occurs.
Small intestine is described how?
- Long, muscular tube
Where is chemical digestion completed?
- Small intestine
True or False:
90% of nutrients absorption occurs in the stomach.
- False, Small intestine
What are the 3 segments of the small intestine?
- Duodenum
- Jejunum
- Ilium
Duodenum is located where?
-Segment of small intestine closest to stomach.
How long is the duodenum?
- 25 cm.
Why is the duodenum is referred to as the mixing bowl?
- Receives chyme from stomach and digestive secretions from pancreas and liver.
Where is the Jejunum located?
Middle segment of small intestine
How long is the Jejunum?
2.5 meters long
What is area is the site of most chemical digestion and nutrient absorption?
Jejunum
What is the final segment of small intestine?
Ileum
What are circular folds?
- Transverse folds in intestinal lining.
- Permanent features that do not disappear when small intestine fills.
What are intestinal villi?
Finger like projections in mucous of small intestine.
What type of tissue covers intestinal villi?
Simple columnar epithelium and carpeted with microvilli that form brush border.
What are lacteals?
Lymphatic vessel in each villus.
What is the function of a lacteal?
Transports chylomicron that are too large to enter blood capillaries.
Duodenal submucosal glands produce what?
Copious qualtities of mucus.
When chyme arrives from stomach what happens?
Mucus protects epithelium from acidity of chyme.
Mucus contains what?
Bicarbonate ions that raise pH.
How much intestinal juice enters intestinal lumen each day?
1.8 liters
What are functions of intestinal juice?
- Moistens chyme
- Assists in buffering acids
- Keeps digestive enzymes and products of digestion in solution
Mucosa of _______ _______ produces few enzymes involved in chemical digestion.
small intestine
What are functions of the brush border enzymes?
- Intergral membrane proteins on intestinal microvilli.
- Break down materials in contact with brush border.
Enterropeptidase
Activates pancreatic trypsinogen.
After chyme arrives in duodenum what happens?
Weak peristaltic contractions move it slowly toward jejunum.
True or False:
Under control of the CNS control.
- False, not under control of CNS.
____________ stimulation accelerates local peristalsis and segmentation.
Parasympathetic
Gastroenteric reflex does what?
Stimulates motility and secretion along entire small intestine.
Gastroileal reflex triggers what?
Opening of ileocecal valve.
What does the gastroileal reflex allow materials to pass from?
Small intestine into large intestine.
What are 1 function of hormonal mechanisms?
-Coordinates activities of digestive glands
Where are acids neutralized and enzymes are added?
Centered on duodenum
Neural mechanisms involving the CNS prepare the ________ _______ for activity, through ____________ innervation.
- Digestive system
2. parasympathetic
Inhibit ____________ activity through sympathetic innervation.
gastrointestinal
How are movements of materials along the digestive tract coordinated?
Reflexes
Motor neuron synapses in digestive tract release ___________.
Neurotransmitters
What kind of hormones does the intestinal tract secrete?
peptide hormones
What are 6 hormones of the duodenum?
- Gastrin
- Secretion
- gastric inhibitory peptide
- cholecystokinin
- vasoactive intestinal peptide
- enterocrinin
What is gastrin secreted by?
G cells
What happens when G cells are exposed to incompletely digested proteins? ( 2 activities)
- Promotes increased stomach motility
- Stimulates production of acids and enzymes.
Secretin is released when?
-When chyme arrives in duodenum.
What are the 2 functions of secretin when activated?
- Increases secretion of buffers by pancreas and bile by liver
- reduces gastric motility and secretory rates.
When is gastric inhibitory peptide secreted?
When fats and carbohydrates enter small intestine.
When is cholecystokinin?
Secreted when chyme arrives in duodenum.
what affect cholecytokinin have on the body? (2 functions)
- Accelerates pancreatic production and secretion of digestive enzymes.
- Relaxes hepatopancreatic sphinter and contracts gallbladder.
What affects does vasoactive intestinal peptide on the digestive system? (3 affects)
- Stimulates secretion of intestinal glands
- dilates regional capillaries
- Inhibits acid production in stomach
What 2 effects does enterocrinin have on the body?
- Released when chyme enters the duodenum
- stimulates alkaline mucus production by submucosal glands.
Movements of mucosa increase _________ ________ in the small intestines.
- Absorptive effectiveness
What is the large intestine shaped like?
Horseshoe shaped
Large intestine extends from end of ilieum to where?
Anus
Where is the large intestine in relation to the liver and stomach?
Lies inferior to both body structures.
How long is the large intestine?
1.5 meters
How wide is the large intestines?
7.5 cm.
What are the 3 portions of the large intestine?
- cecum
- colon
- rectum
What is the cecum?
- Expanded pouch
- Receives and stores materials arriving from ileum
- Begins compaction
Appendix
- Slender, hollow structure about 9 cm. long
- attached to posteromedial surface of cecum
- dominated by lymphoid nodules
- Meso-appendix (smaller mesentery) connects appendix to ileum and cecum.
Colon
Larger diameter and thinner wall than small intestine.
Haustra
- Pouches in wall of colon
- Permit expansion and elongation
Teniae coli
- Three longitudinal bands of smooth muscle
- Run along outer surfaces of colon, deep to serosa
- Similiar to out layer of muscular layer
- Muscle tone in teniae coli creates haustra
Omental appendices
Numerous teardrop shaped sacs of fat in serosa of colon
Name the 4 regions of the colon
- Ascending colon
- Transverse colon
- Descending colon
- Sigmoid colon
Where does the ascending colon begin?
Superior border of cecum
Ascending colon ascending along right lateral and _______ _____ of peritoneal cavity. To the inferior surface the ________.
Bends sharply to the left at ________ ________ _______ (hepatic flexure).
- posterior wall
- Liver
- right colic flexure
_________ ______ crosses abdomen from right to left. Turns at left ______ ________ (splenic flexure).
Supported by the ___________ mesocolon. Separated from anterior abdominal wall by greater ________.
- Transverse colon
- colic flexure
- transverse
- omentum
Descending colon proceeds _______ along left side to iliac fossa.
________, firmly attached to abdominal wall.
- inferiorly
2. Retroperitoneal
How long is the sigmoid colon?
15 cm.
Where is the sigmoid colon in relation to the urinary bladder?
Posterior to it
Sigmoid colon empties into what area in the body?
rectum
How long is the rectum?
15 cm.
What is the function of the rectum?
Expandable organ for temporary storage of feces.
Anal canal
- Last portion of rectum
- Contains small longitudinal folds (anal columns).
Anus
- exit of anal canal
- Keratinized epidermis like skin
Internal and sphincter
- Circular muscle layer
- Smooth muscle cells
- Not under voluntary control
External anal sphincter
- Encircles distal portion of anal canal.
- Skeletal muscle fibers
- Under voluntary control.
What does the large intestine lack?
villi
What type of cell does the large intestine have a abundance of?
Goblet cells
What are the functions of the large intestines?
- Absorption or reabsorption of water, nutrients, bile salts, organic wastes, and vitamins and toxins produced by bacteria.
- Compaction of intestinal content into feces
- Storage of fecal material prior to defecation.
Microbiome
- Microbes (bacteria, fungi, and viruses)that live in and on human body.
- Including those that inhabit large intestine.
Vitamins
- Organic molecules
- Important as cofactor or coenzymes in metabolism.
- Normal bacteria in colon make three vitamins that supplement diet.
Vitamin K (fat soluble)
Required by liver for synthesizing four clotting factors, including prothrombin.
Biotin (water soluble)
Important in glucose metabolism.
Vitamin B3 ( pantothenic acid; water soluble)
Required in manufacture of steroid hormones and some neurotransmitters.
Organic wastes
Bacteria convert bilirubin to urobilinogens and stercobilingens.
What are sometimes absorbed into bloodstream and excreted in urine?
Urobilinogens
If urobilinogens and stercobilinogens that remain in the colon are converted into what?
- urobilins
- stercobilins
Bacteria break down peptides into what 2 things?
- feces
- generate