BIO 132 – Anatomy and Physiology
Study Outline
6.1.
Compositions of Pancreatic Secretions:
a. Each day the pancreas secretes on the order of _________________________ of fluid
b. This fluid contains a combination of _____________________________ and __________________________, of which the main electrolyte is ______________________________.
c. The __________________________ cell secretes the enzymes whereas the _____________________________cells are responsible for the bicarbonate.
d. _______________________ enzymes are secreted in inactive form to prevent ________________________. Once in the lumen of the small intestine trypsinogen is activated by _______________________________. In turn, __________________________ activates the other proteolytic enzymes.
e. Inflammation of the pancreas is called _____________________________ and may involve the release of ____________________________ in the active form resulting in self-digestion.
6.2. Regulation of
Pancreatic Secretion:
a. During the ________________________ phase and _________________________________ phase of gastric secretion, ______________________ stimulation also stimulates the pancreas to secrete.
b. CCK release from enteroendocrine cells of the _______________________ is stimulated in response to the presence of ________________________ and _________________________________ whereas secretin release from enteroendocrine cells of the ___________________________ is stimulated in response to __________________________.
c. Secretin stimulates the secretion of ________________________ while CCK stimulates the secretion of pancreatic ______________________________.
6.3. Composition of
Bile:
a. Each day _______________________ secrete about 800-1000 mL of bile. Bile plays a role in the ______________________ of fats in which they are broken down from large lipid globules to a ____________________________.
b. The principle bile pigment is __________________________ which is eventually broken down by bacterial action in the ______________________, giving ______________________ its characteristic color.
c. Most bile salts are _____________________________ by active transport in the ileum.
6.4. Regulation of Bile
Secretion:
a. Hepatocytes ___________________________ bile production in response to increased amounts of bile returning from the gut in blood of the portal vein.
b. Normally, between meals, bile is ________________________ in the gallbladder because the sphincter of _______________________ is closed.
c. After a meal, _______________________ stimulation to the liver acts to _______________________ bile production.
d. Fatty acids and amino acids entering the small intestine stimulate ___________________________ secretion which causes the gallbladder to ____________________________ and the sphincter of Oddi to _________________________________. ______________________ stimulates bicarbonate production by hepatocytes into bile.
e. Too much cholesterol or too few bile salts can lead to the crystallization of cholesterol to form ___________________________.
f. Blockage of the bile duct prevents both bile salts and bile pigments from entering the intestine. As a result, yellow bile pigments accumulate in _____________________ and are deposited in skin leading to a condition known as _____________________________.
6.5. Regulation of
Intestinal Motility:
a. The two types of motility in the small intestine are called __________________________ and __________________________________.
b. Following the bulk of absorption, segmentation stops and ____________________________ push the chyme forward.
c. In general the ____________________________ system increases motility and the _____________________________system decreases motility.
d. Typically the ieocecal valve is closed, but two mechanisms cause it to open. The first, called the _______________________ reflex is initiated by gastric activity. The second involves _______________________ which causes the sphincter to relax.
e. In the large intestine, the type of motility that involves movement of chyme forward is called ______________________.
f. Within the defecation reflex, filling of the rectum with feces stimulates _________________________ receptors which send their impulses to the sacral cord where they stimulate parsympathetic neurons which cause the ______________________ sphincter to relax. By contrast, the muscle in the ______________________ and ______________________ contracts. Finally, a voluntary command causing the _____________________ to relax is required for defecation to occur.
g. During defecation, the _____________________ pressure increases.
6.6. Chemical Digestion
in the Small Intestine:
a. Carbohydrates are broken down through the enzymatic action of _____________________ within the mouth, and _____________________ released from the pancreas. Eventually, carbohydrates are in the form of _______________________ which are now broken down by enzymes located in the brush border of columnar absorptive cells called __________________________, _________________________, and _________________________.
b. Lactose intolerance involves not enough _________________________ .
c. Protein digestion begins in the _________________________. The final step involves two brush border enzymes called _________________________ and ___________________________.
d. Lipids are broken down by enzymes called ______________________ which are released in the __________________________, _____________________________, and by the ________________________.
6.7. Absorption in the
Small and Large Intestines:
a. All nutrients pass to blood capillaries except ____________________________.
b. Insufficient bile salts can result in vitamin deficiencies involving ______________________ vitamins such as vitamins _________________, _______________________, ___________________, and __________________.
c. Chylomicrons are composed of _________________ and _______________________ coated with ____________________________. Chylomicrons are eventually broken down by an enzyme that lines blood vessels called ____________________________.
d. Most water absorption takes place in the _____________________________.
e. Among the breakdown products of bacterial action that are absorbed in the large intestine include the vitamins _____________________ and ______________________.
f. Diarrhea occurs when there is increased __________________________ and/or incomplete __________________ and therefore ___________________ absorption.
g. Constipation typically occurs because of excessive __________________ absorption, and can be corrected by including dietary _______________________.