Renal and Digestive Systems MCAT Biology Diagnostic Exam 4A Flashcards
The exocrine functions of the pancreas include chemical digestion of each of the following EXCEPT:
A. polypeptides.
B. carbohydrates.
C. nucleotides.
D. triglycerides.
C. Proteins (polypeptides) are chemically digested by pancreatic proteases such as trypsin and chymotrypsin (choice A is digested by pancreatic enzymes and can be eliminated). Some carbohydrate chemical digestion starts in the mouth, but much of it is done in the duodenum by enzymes such as pancreatic amylase (choice B can be eliminated). Triglycerides (lipids) are not digested until they reach the small intestine; this is mediated by pancreatic lipases after bile from the liver/gallbladder has emulsified the fat molecules (choice D can be eliminated). However, pancreatic nucleases digest DNA and RNA, not nucleotides (choice C is not digested by pancreatic enzymes and is the correct answer choice).
Concepts tested
Digestive System: Accessory Organs
A drug is discovered that markedly increases hemoglobin’s affinity for oxygen. What physiological situation is this drug mimicking?
A. Hyperventilation
B. Rigorous exercise
C. Running a fever
D. Increased production of BPG at high elevation
A. Hyperventilation results in reduced blood carbon dioxide levels, which leads to an increase in blood pH and an increase in hemoglobin’s affinity for oxygen (choice A is correct). The other answer choices all result in a decrease in oxygen affinity (choices B, C and D are wrong).
Concepts tested
Respiratory System: Ventilation and pH Regulation
Osteoclasts are stimulated to destroy bone and increase circulating levels of calcium by which hormones?
A. Parathyroid hormone and calcitonin
B. Calcitonin and calcitriol
C. Parathyroid hormone and calcitriol
D. Calcitonin and cortisol
C. Parathyroid hormone and calcitriol (the active form of vitamin D) are involved in stimulating the osteoclasts to phagocytically destroy bone, thus freeing up calcium to be transported by the bloodstream to other parts of the body (note however that calcitriol’s effect on bone is minor). They also promote the absorption of calcium from the gut (choice C is correct). Calcitonin inhibits osteoclasts, decreasing bone resorption (choices A and B are wrong), and cortisol is involved in long-term stress responses (choice D is wrong).
Concepts tested
Endocrine System: Hormones and Hormone Functions Skeletal System: Bone Structure/Turnover
Which of the following is made up of pluripotent cells?
A. The mesoderm
B. The zygote
C. The morula
D. The inner cell mass
D. The cells of the inner cell mass differentiate into the three primary germ layers and have the ability to become any cell in the body; they are considered to be pluripotent cells (choice D is correct). The mesoderm is one of the three primary germ layers and can become many, but not all cell types in the body; it is considered to be multipotent (choice A is wrong). The zygote and morula are totipotent; they can become any of the cells in the body and can also form the trophoblast (choices B and C are wrong).
Concepts tested
Development: Embryology/Fetal Development
Cartilage can play roles in support, flexibility, or a combination of the two. The strongest cartilage is fibrous, the most flexible is elastic, and hyaline cartilage is in between, both strong and somewhat flexible. Which of the following structures is most likely made of elastic cartilage?
A. Articular (joint) cartilage
B. Intervertebral disks
C. Pubic symphysis
D. Epiglottis
D. The epiglottis is found in the respiratory tract, above the opening to the trachea. When swallowing, the epiglottis must fold downward to seal off the trachea thus preventing food and liquid from entering. This requirement for flexibility makes the epiglottis most likely to be made of elastic cartilage. Articular cartilage needs to be strong but somewhat flexible and is made of hyaline cartilage (choice A is wrong), and both the intervertebral disks and the pubic symphysis must be very strong and are made of fibrous cartilage (choices B and C are wrong).
Concepts tested
Skeletal System: Connective Tissue/Bone
Which of the following are involved in carrying blood to the kidneys?
A. Abdominal aorta and renal vein
B. Inferior vena cava and renal vein
C. Abdominal aorta and renal artery
D. Inferior vena cava and renal artery
C. The abdominal aorta carries blood away from the heart and into the trunk of the body. The renal artery branches off the aorta to supply the kidneys with blood (choice C is correct). The renal vein and inferior vena cava are both involved in returning blood back to the circulatory system after it has been filtered (choices A, B, and D are incorrect).
Concepts tested
Renal System: Kidney Functions
Anatomical dead space is classified as that area of the respiratory pathway where no gas exchange occurs with the blood. Which of the following is part of the anatomical dead space?
A. Alveolar duct
B. Alveolus
C. Terminal bronchioles
D. Respiratory bronchioles
C. Anatomical dead space is the portion of the respiratory tree where gas exchange does not take place, also known as the conduction zone. The conduction zone includes the nose, pharynx, larynx, trachea, bronchi, bronchioles, and terminal bronchioles (choice C is correct). The respiratory zone includes the respiratory bronchioles, alveolar ducts, and alveoli (choices A, B and D are wrong).
Concepts tested
Respiratory System: Conduction and Respiratory Zones
A student becomes anxious during his final exam and begins hyperventilating. Which of the following is/are true?
Blood pH increases Blood CO2 levels decrease O2 saturation of hemoglobin increases A. I only B. I and II only C. II and III only D. I, II, and III
D. Items I and II are true: hyperventilation causes the loss of excess carbon dioxide, which shifts the equilibrium of the respiratory equation (CO2 + H2OEquilibrium arrow.H2CO3Equilibrium arrow.H+ + HCO3–) to the left. As H+ and HCO3– combine to form H2CO3, blood pH increases (choices A and C can be eliminated). Item III is true: as blood pH increases, the oxygen saturation curve of hemoglobin shifts to the left. A left-shifted curve means that hemoglobin’s affinity for oxygen is increased, and it will be more saturated (choice B can be eliminated and choice D is correct).
Concepts tested
Respiratory System: Ventilation and pH Regulation
Fully mature bone is composed of all of the following EXCEPT:
A. cartilage.
B. collagen.
C. calcium.
D. phosphate
A. Mature bone is made rigid by the inclusion of hydroxyapatite, a calcium-phosphate crystalline solid (choices C and D are found in bone and can be eliminated). Collagen forms the framework for mature bone and this framework is then hardened by the crystalline solid (choice B is found in bone and can be eliminated). Cartilage is deposited in growing bone, but is replaced with solid bone matrix as bone matures (choice A is not found in fully mature bone and is the correct answer choice).
Concepts tested
Skeletal System: Bone Structure/Turnover
A patient is diagnosed with a connective tissue disorder that results in severe shedding of the skin. Which normal function of skin would be disrupted?
A. Maintaining blood pH
B. Preventing dehydration
C. Excreting excess water and salt
D. Hormone regulation
B. The skin provides a substantial barrier to water loss; patients with large quantities of skin that have been damaged or removed are at risk for dehydration (choice B is correct). The remaining answer choices list processes that are not significantly influenced by the skin. Note that sweating is a process designed to cool the body, not eliminate excess water and salt.
Concepts tested
Skin: Layers Skin: Thermoregulation
Which of the following is NOT an accurate statement concerning the hydrochloric acid produced in the stomach?
A. HCl is produced by the parietal cells.
B. HCl converts the zymogen pepsinogen into the active enzyme pepsin.
C. HCl engages in acid hydrolysis of proteins, aiding in their elementary digestion.
D. HCl is part of the innate immune mechanisms present in the duodenum.
D. Hydrochloric acid is made by parietal cells in the stomach (choice A is an accurate statement and can be eliminated), causes zymogen conversion (choice B is an accurate statement and can be eliminated), and facilitates non-specific acid hydrolysis of proteins (choice C is an accurate statement and can be eliminated). However, while it plays a role in innate immune function of the stomach, HCl is neutralized by aqueous bicarbonate upon entry into the duodenum (choice D is not an accurate statement and is the correct answer choice).
Concepts tested
Digestive System: Alimentary Canal
Labor and delivery depends on each of the following EXCEPT:
A. uterine smooth muscle excitability.
B. oxytocin release from the posterior pituitary.
C. uterine contractions and cervical pressure.
D. prolactin release from the anterior pituitary.
D. Choices A, B, and C all describe physiological components of the birthing process and can be eliminated. Prolactin is required for lactation, which occurs postpartum (labor does not depend on choice D so it is the correct answer choice).
Concepts tested
Endocrine System: Hormones and Hormone Functions Reproductive Systems: Female Reproductive System
Spermatogenesis occurs:
A. throughout the male adult life, due to the ability of spermatogonia to perform binary fission.
B. in the seminiferous tubules, starting near the basement membrane and finishing near the lumen.
C. via two rounds of meiosis, and generates four reproductively mature spermatids.
D. in a testosterone and GnRH-dependent manner, during some phases of male adulthood.
B. Spermatogenesis occurs throughout male adulthood (choice D is wrong) because spermatogonia can undergo mitosis (to regenerate) and meiosis (to make primary spermatocytes). Note that only bacterial cells perform binary fission (choice A is wrong). Spermatogenesis involves two rounds of division during meiosis, not two rounds of meiosis, and generates four spermatids, but these cells are not mature (choice C is wrong). Choice B is true and the correct answer choice.
Concepts tested
Reproductive Systems: Spermatogenesis
All of the following are components or types of loose connective tissue EXCEPT:
A. adipose tissue.
B. collagen.
C. ligaments.
D. the extracellular matrix.
C. Connective tissues are classified as “loose” or “dense” based on the amount of collagen they contain; those with a lot of collagen are dense tissues, and tend to play more supportive roles. Ligaments connect bones to bones and are made primarily of collagen, thus they are a type of dense connective tissue (choice C is not loose connective tissue and is the correct answer choice). Adipose tissue, or fat, contains virtually no collagen and is a type of loose connective tissue (choice A can be eliminated). Collagen is found in both loose and dense connective tissue; the difference between the two is the amount of collagen (choice B is a component of loose connective tissue and can be eliminated). The extracellular matrix is the mix of proteoglycans and glycosaminoglycans that exists as the tissue between cells, It is responsible for holding on to water (among other functions); it is a component of loose connective tissue and many other tissues (choice D can be eliminated).
Concepts tested
Skeletal System: Connective Tissue/Bone
Which of the following is a true statement?
A. The release of secretin, triggered by high duodenal pH, causes the release of bicarbonate and enzymes from the pancreas.
B. The release of secretin, triggered by low duodenal pH, causes the release of bicarbonate and enzymes from the pancreas.
C. The release of secretin, triggered by low gastric pH, causes the release of bicarbonate and enzymes from the pancreas.
D. The release of secretin, triggered by high gastric pH, causes the release of bicarbonate and enzymes from the pancreas.
B. Secretin is released from duodenal cells when acidic chyme enters the duodenum from the stomach and duodenal pH drops (choice A is wrong). This causes the release of bicarbonate (and enzymes) from the pancreas to help neutralize that acid, bringing duodenal pH into a more neutral range. This provides a more optimal environment for the pancreatic enzyme to function in, as they do not work well at low (acidic) pH (choice B is true). Since the hormone is released by duodenal cells, and since the pH change must occur in the duodenum, it should not be affected by gastric pH (choices C and D are wrong).
Concepts tested
Digestive System: Accessory Organs
All of the following are functions of the liver EXCEPT:
A. storage of glycogen.
B. synthesis of blood proteins.
C. bile production.
D. secretion of digestive enzymes.
D. The liver has a number of functions in the body, including synthesis of bile (choice C can be eliminated), glycogen storage and metabolism (choice A can be eliminated), synthesis of blood proteins (such as albumin, fibrinogen, angiotensinogen, lipoproteins, etc., choice B can be eliminated), amino acid metabolism, production of urea, vitamin storage, detoxification, etc. However, the liver does not secrete digestive enzymes (choice D is not a function of the liver and is the correct answer choice).
Concepts tested
Digestive System: Accessory Organs
Which of the following does NOT refer to a region of the kidney?
A. Renal ductus
B. Renal cortex
C. Renal medulla
D. Renal pelvis
A. The renal cortex is the outermost layer of the kidney and the medulla is the inner region (choices B and C can be eliminated). The renal pelvis is a large space into which urine drains from the collecting ducts (choice D is part of the kidney and can be eliminated). There is no renal ductus (choice A is not a part of the kidney and is the correct answer choice).
Concepts tested
Renal System: Kidney Functions
How does pulmonary surfactant function?
A. By increasing alveolar elasticity
B. By increasing the cohesive force of water
C. By increasing the surface tension of water
D. By decreasing the surface tension of
D. Pulmonary surfactant decreases water’s surface tension (decreasing the cohesive forces of water) to help prevent collapse of the small airways in the lung (choice D is correct, and choices B and C are wrong). Pulmonary surfactant does not have a direct impact on alveolar elasticity although the decrease in cohesive force effectively reduces alveolar collapsing forces (i.e., a decrease in alveolar elasticity; choice A is wrong).
Concepts tested
Respiratory System: Conduction and Respiratory Zones