Anatomy and Physiology Chap. 23, 24, 25
Which layer of the alimentary canal is responsible for segmentation and peristalsis?
Contractions of the circular and longitudinal layers of the muscularis externa produce the effects of peristalsis and segmentation. In the stomach, an additional muscle layer adds a twisting action.
Which layer of the alimentary canal contains not only glands and blood vessels but also a nerve plexus that helps regulate digestive activity?
The submucosa layer contains blood and lymphatic vessels, lymphoid follicles, and the submucosal plexus of nerve fibers.
The __________ circulation collects nutrient-rich venous blood draining from the digestive viscera.
The hepatic portal circulation drains all of the blood from the digestive organs and routes that blood through the liver for processing.
Which layer of the digestive tract contains the effectors for digestive propulsion?
The smooth muscles in the muscularis work to make the propulsive movements called peristalsis.
Which of the following structural elements is common to both cardiac and smooth muscle?
Which digestive process does NOT occur in the mouth?
Segmentation is the back-and-forth mixing movement of food in the small intestine. The process of chewing and mixing food with saliva in the mouth is known as mastication.
What event triggers the opening of the gastroesophageal sphincter?
peristalsis in the esophagus.
As the peristaltic wave triggered by deglutition reaches the stomach, the gastroesophageal sphincter relaxes and allows food into the stomach.
Which of the following constitute a portal triad?
a bile duct along with a portal venule and arteriole.
A bile duct along with a portal venule and arteriole constitute a portal triad. The blood vessels provide blood flow to the lobule and the bile duct drains bile.
Which of the following best describes the capillary wall structure found in the liver lobules?
The capillary walls have openings that allow large proteins and small cells to pass through.
The capillary walls in the lobules of the liver are sinusoidal and allow large proteins and even blood cells to pass, permitting the liver to perform its functions.
What is a major function of pancreatic juice?
neutralizing chyme entering the small intestine from.
Pancreatic juice contains bicarbonate (as baking soda does) that can neutralize the pH of acidic chyme coming from the stomach.
Bile is secreted by the __________ under hormonal influence of __________.
Secretion of bile from the liver is stimulated hormonally by secretin. Bile salts themselves provide the major stimulus for enhanced bile secretion. After a fatty meal, when the enterohepatic circulation is returning large amounts of bile salts to the liver, its output of bile rises dramatically.
Which of the following is not a secretion of the pancreas?
Bile is secreted by the liver.
Which cells in the small intestine's mucosa secrete mucus?
Goblet cells, which secrete mucus and are found in several areas of the digestive tract, are located on the villi of the small intestine.
Which of these best describes a lacteal?
a lymphatic vessel designed to help introduce fats to the blood.
Lacteals are lymphatic vessels located in the intestinal villi. Their ability to accept large materials makes them helpful in transporting large fat particles (called chylomicrons) into the lymph for eventual transport to the bloodstream.
Most absorption of nutrients occurs in the __________.
jejunum and ileum.
The majority of nutrients are absorbed as digesting foods make their way through the jejunum (~8 feet long) and ileum (~12 feet long) of the small intestine. Although absorption begins in the duodenum, it is too short (~12 inches long) to account for the majority of nutrient absorption.
Which of the following propels food residue over large areas of the colon three to four times a day?
Mass movement propels food residue over large areas of the colon three to four times a day. The defecation reflex occurs when the rectal wall stretches as mass movements force feces into it.
Which of the following is the primary physiological function of the large intestine?
water absorption and feces elimination.
Though most water is absorbed in the small intestine, the absorption of most remaining water and the elimination of feces are the primary physiological functions of the large intestine. The large intestine also provides a transport route and a surface for healthful bacteria.
What type of blood capillary located in this sublayer is uniquely suited for absorption of nutrient material?
Your patient has had a total gastrectomy (removal of the stomach). Which of these potential problems are you MOST concerned about?
The parietal cells of the stomach produce intrinsic factor, which permits the absorption of vitamin B12, a nutrient required for the maturation of red blood cells. Unless your patient receives vitamin B12 replacement therapy, he or she will develop pernicious anemia.
You are caring for a patient with late-stage cirrhosis that has led to a decrease in the number of functioning hepatocytes. Which of the following would NOT be typical for a patient with this condition?
Decreased half-life for drugs processed by the liver.
Hepatocytes break down and eliminate a variety of drugs. If the number of functional hepatocytes decreases, more of the drug remains in your patient's system, prolonging the half-life and possible reducing the amount of drug to be administered or increasing the dosage interval.
What protein (purine)-rich food should be limited to prevent a reoccurrence of uric acid kidney stones?
Protein malnutrition can result in a moderate anemia. Which of the below-listed vitamins would be most likely to be associated with this condition?
Select the correct sequence of steps as energy is extracted from glucose during cellular respiration.
glycolysis → acetyl CoA → citric acid cycle → electron transport chain.
Glycolysis produces pyruvic acid, which enters the mitochondrion. There, it is converted to acetyl CoA, which enters the citric acid cycle. Electron carriers bring electrons from the first three steps to the electron transport chain, and ATP is made.
What is the correct general equation for cellular respiration?
C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + ATP energy.
Cellular respiration extracts energy from glucose (C6H12O6) to produce smaller energy packets (ATP).
Which of the following processes takes place in the cytosol of a eukaryotic cell?
Glycolysis, the breakdown of glucose into two molecules of pyruvic acid, takes place in the cytosol, outside the mitochondria.
In what organelle would you find acetyl CoA formation, the citric acid cycle, and the electron transport chain?
All of the steps of cellular respiration except glycolysis take place in the mitochondrion.
Which statement describes glycolysis?
This process splits glucose in half and produces 2 ATPs for each glucose.
In glycolysis, glucose is split into two molecules of pyruvic acid. The released energy is stored in ATP and the electron carrier NADH.
Which statement describes the citric acid cycle?
This process produces some ATP and carbon dioxide in the mitochondrion.
The citric acid cycle breaks down carbon molecules, releasing carbon dioxide and forming some ATP.
Which statement describes the electron transport chain?
This process uses energy captured from electrons flowing to oxygen to produce most of the ATPs in cellular respiration.
In the electron transport chain, electrons move from one electron carrier to another, eventually reaching oxygen. The released energy is used to make ATPs.
Which of the following is NOT a fat-soluble vitamin?
Vitamin B is a water-soluble vitamin.
__________ are considered "bad" cholesterol; high blood levels are correlated with increased risk of cardiovascular disease.
LDLs are considered "bad" cholesterol because high levels are correlated with an increased risk of cardiovascular disease. The job of cholesterol-rich LDLs is to transport cholesterol to peripheral tissues, making it available to tissue cells to synthesize membranes or hormones, and to store it for later use.
Which of the following is not an essential role of the liver?
Though the liver is involved in creating urea from ammonia released during amino acid deamination, it is up to the kidney to eliminate the urea thus formed.
__________ reflects the energy the body uses (kilocalories consumed) to perform only its most essential activities.
The basal metabolic rate.
The basal metabolic rate (BMR) reflects the energy (kilocalories consumed) that the body uses to perform only its most essential activities, such as breathing and maintaining resting levels of organ function, not all ongoing activities.
Which of the following would decrease body temperature?
dilation of cutaneous blood vessels.
Dilation of cutaneous blood vessels increases blood flow, which carries heat, to the skin. Bringing warm blood closer to the surface of the body increases the rate of heat loss (via radiation, conduction, and convection) to the external environment, cooling the body.
Which brain region is the main integrating center for thermoregulation?
The hypothalamus is the main homeostatic integration center for thermoregulation.
__________ is the primary hormonal regulator of the postabsorptive state.
Glucagon is the key hormone regulating nutrient metabolism during the postabsorptive state. It promotes the breakdown of stored nutrients in order to maintain normal blood glucose levels.
Which of these processes is associated with the postabsorptive state?
gluconeogenesis in the liver.
In order to maintain a normal blood glucose level, nutrients that were stored during the absorptive state and now being broken down during the postabsorptive state. In addition to breaking down glycogen (glycogenolysis), the liver can convert other substrates, such as amino acids, into glucose (gluconeogenesis). Both processes allow the liver to release glucose into the blood for other cells to use.
Which hormone promotes protein catabolism?
As one of the “stress” hormones, cortisol is involved in helping cope with turning to protein and fat breakdown in order to spare limited glucose available if one is injured and unable to eat (postabsorptive state).
Ammonia, which is a byproduct of protein metabolism, is converted to __________ primarily in the __________.
Ammonia produced during protein metabolism is converted into urea in the liver.
Your emergency department has just received several victims of smoke inhalation resulting from a fire in an apartment complex. You recall that cyanide poisoning is often a result of smoke inhalation. Why is cyanide so dangerous?
Cyanide disrupts oxidative phosphorylation at the electron transport chain.
Cyanide is an "uncoupler" poison that binds to cytochrome oxidase, blocking the flow of electrons from complex IV to oxygen and abolishing the production of ATP.
You are reviewing a postdischarge plan of a newly diagnosed patient with Type I diabetes mellitus. Why is the presence of ketones in his urine a significant finding?
Urinary ketones indicate that the body is using fat rather than carbohydrate as an energy source.
During lipolysis, or fat-burning, acetyl CoA enters the citric acid cycle. However, if inadequate carbohydrate precursors are available, acetyl CoA accumulates and is converted to ketone bodies in the liver.
Which of the following best describes glomerular filtration rate (GFR)?
the volume of filtrate created by the kidneys per minute.
Fluid and small solutes that leave the glomerulus are collectively termed filtrate. Glomerular filtration is driven by glomerular hydrostatic pressure (HPg) and produces ~125 ml of filtrate per minute.
GFR regulation mechanisms primarily affect which of the following?
glomerular hydrostatic pressure (HPg).
Much like other capillaries in the body, hydrostatic pressure within the glomerular capillaries produces net outward movement of fluid. Unique to glomerular capillaries, HPg is consistently higher than other capillaries (~55 mm Hg), which ensures the one-way movement of fluid and solutes out of the glomerulus under normal conditions.
Which of the following are mechanisms of intrinsic control of glomerular filtration (renal autoregulation)?
myogenic mechanism and tubuloglomerular feedback.
Both of these mechanisms occur strictly within kidney (i.e., intrinsic controls). The myogenic mechanism is mediated by smooth muscle within the afferent arteriole. In contrast, tubuloglomerular feedback is mediated by macula densa cells of the juxtaglomerular apparatus (JGA).
Macula densa cells of the juxtaglomerular apparatus (JGA) regulate GFR through which intrinsic mechanism?
The JGA is a region of the nephron where the afferent arteriole and its associated tubule are closely apposed. This anatomical arrangement allows macula densa cells to adjust GFR according to the NaCl concentration in filtrate. This is called tubuloglomerular feedback because it allows the contents of the tubules (tubulo-) to affect the glomerular filtration rate.
The myogenic mechanism of renal autoregulation primarily involves smooth muscle in which blood vessels?
By regulating afferent arteriole diameter, the myogenic mechanism affects HPg and therefore GFR. Under normal physiological conditions, this intrinsic control works to maintain GFR despite moderate changes in systemic blood pressure.
What does a high concentration of NaCl in the renal tubule at the juxtaglomerular apparatus (JGA) most likely indicate?
insufficient NaCl reabsorption due to high GFR.
After glomerular filtration, NaCl is actively reabsorbed at many locations along the renal tubule. If the filtrate is moving through the tubule quickly, less reabsorption is possible, so more NaCl gets left behind. This means that at the JGA, the NaCl concentration within the filtrate will be high.
Through the tubuloglomerular feedback mechanism, how would an increase in filtrate NaCl concentration affect afferent arteriole diameter?
Afferent arteriole diameter would decrease.
High NaCl concentration in the filtrate at the JGA indicates that GFR is too high. By decreasing the diameter of the arteriole delivering blood to the glomerulus, HPg is decreased, resulting in lower GFR.
Granular cells of the juxtaglomerular apparatus (JGA) regulate GFR indirectly through which mechanism?
When systemic blood pressure decreases, granular cells release renin which ultimately causes the formation of angiotensin II. Angiotensin II causes widespread vasoconstriction of systemic arterioles and the increase of blood volume due to aldosterone release.
What area of the nephron is responsible for the reabsorption of most of the water from the filtrate as well as most nutrients?
proximal convoluted tubule.
Most of the water from the filtrate as well as most nutrients are reabsorbed in the proximal convoluted tubule.
In what part of the renal tubule does parathyroid hormone (PTH) promote the reabsorption of calcium ions?
distal convoluted tubule (DCT).
Parathyroid hormone (PTH) promotes the reabsorption of calcium ions in the distal convoluted tubule (DCT).
Approximately 80% of the energy used for active transport is devoted to the reabsorption of __________.
About 80% of the energy used for active transport is devoted to reabsorbing sodium. Na+ is actively transported out of the tubule cells by primary active transport—a Na+-K+ ATPase pump in the basolateral membranes.
Upon reaching what point in the nephron is reabsorption (1) dependent upon the body's needs at the time and (2) regulated by hormones?
distal convoluted tubule.
Distal convoluted tubule (DCT) reabsorption only occurs under the influence of hormonal regulation.
Which of the following processes would be considered as a secretory rather than an excretory activity?
Aldosterone release by the adrenal glands.
Your patient's urinalysis shows a large amount of protein in the urine. This suggests a problem in the ____________.
If the glomerular capillary is damaged, large molecules such as proteins can pass through the filtration membrane and appear in the urine.
The lab results of a newly admitted patient indicate renal impairment. How might this affect the dosing regimen of drugs that are excreted by the kidney?
The dosage or the dosage interval may need to be reduced.
If the renal clearance of the drug is reduced by kidney disease, then drugs eliminated by the kidney may need to be given less often, in smaller amounts, or both. This appropriate regimen is often found in information provided by the drug manufacturer.
Why do you have to carefully monitor certain patients who are on "loop diuretics" to lower their blood pressure?
Certain diuretics are not specific and in addition to getting rid of excess water, additional ions like potassium will be secreted.
If the diuretic is not potassium sparing, you must be careful to instruct patients that they may need to adjust their diet or take a potassium supplement while on this medicine.