PHED-2507EL Study Guide - Midterm Guide: Hyponatremia, Cortisol, Myogenic Mechanism
25 Jun 2018
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PHED2507 1
Physiology 2 Exam #3 Essay Questions
I. Chapter 23 Questions
A. Describe the steps how a polysaccharide can make its way under the form of glucose in
the blood
When carbohydrates are first ingested, they are in their polysaccharide
form. In the mouth, salivary amylase at neural or at a weakly alkaline pH, begins the di-
gestion of polysaccharides. From there, the polysaccharides travel down the esophagus
to the stomach and the small intestine, where further digestion occurs.
In the small intestine, salivary amylase continues to breakdown the
polysaccharide with the help of the enzyme called pancreatic amylase. Both of these en-
zymes are secreted by the lumen of the GI tract and continue to work until they are inac-
tivated by an acidic pH. Now, the polysaccharide has been broken down into disaccha-
rides and oligosaccharides. The surface intestinal enzymes (aka brush border enzymes)
maltose, lactose, sucrase and isomaltase further break these disaccharides and
oligosaccharides into monosaccharides such as galactose, glucose and fructose. From
here, the monosaccharides can now be transported across the apical membrane of the
microvilli in the small intestine via facilitated diffusion and/or secondary active transport.
Then, the monosaccharides travel to the blood through the basal membrane via facilitate
diffusion.
Finally, monosaccharides in the blood are converted to glycogen to be
stored in the muscles for later use after passing through the hepatic portal vein.
B. Describe the steps how a large fat droplet can travel in the blood and result in a triglyc-
eride storage molecule in white adipocytes
Bile salts in the duodenum emulsify large fat globules (aka they physically
break them up into smaller fat droplets). From here, the smaller fat droplets are further
digested by the pancreatic enzyme lipase into free fatty acids and monoglycerides.
These then associate with bile salts to form micelles which “ferry” them to the intestinal
mucosa.
The micelles release the contained fatty acids and monoglycerides to dif-
fuse into epithelial cells of the microvilli in the small intestine. The fatty acids and mono-
glycerides are then recombined with other lipids and proteins within the cells. The result-
ing chylomicrons are extruded from the epithelial cells by exocytosis. The chylomicrons
enter the lacteals of the villi and are transported to the systemic circulation via the lymph
in the thoracic duct. Next, some short-chain fatty acids are absorbed and move into the
capillary blood in the villi by diffusion and are transported to the liver via the hepatic por-
tal vein. While in the bloodstream, the triglycerides in the chylomicrons are hydrolyzed to
free fatty acids and glycerol by the enzyme lipoprotein lipase. These fatty acids and glyc-
erol can then pass through the capillary walls to be used by tissue cells for energy or
stored as fats in adipose tissue.
II. Chapter 24 Question
A. Describe how oxidative phosphorylation works at the mitochondrial level and result in
the production of ATP
Oxidative phosphorylation has 2 phases, the first is when the electron
transport chain creates a proton (H+) gradient across the inner mitochondrial membrane
using high-energy electrons removed from food fuels. This occurs by reduced coen-
zymes (NADH+H+ and FADH2) delivering electrons picked up during the oxidation of
food fuels to respiratory enzyme complexes I and II. Next, the electrons are transferred
from one complex to another in the membrane. Each complex is reduced and then oxi-
dized, releasing energy that is used up to pump H+ into the inter-membrane space. This
creates an electrochemical gradient between the matrix and the inter-membrane space.
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