MCAT FC3 CC3B

How many chromatids and chromosomes should one expect to find in a secondary spermatocyte in a human?

-46 chromatids, 23 chromosomes

What is an aponeurosis?

-A large, flat tendon that anchors muscle

Major histocompatibility complex (MHC) refers to a large group of genes that code for proteins that play an essential role in which of the following?

-Antigen representation to T lymphocytes

Which of the following correctly identifies muscle components in order from largest to smallest?

-Fasciculus, muscle fiber, myofibril

What path do bile salts take?

-Liver, gall bladder, duodenum, jejunum, ileum, liver

Bronchodilators are a class of drug often used in the treatment of asthma and COPD, which act on β-adrenergic receptors of the airways to induce smooth muscle relaxation. The anatomic distribution of these receptors is closely correlated to the function of each structural component of the lungs. What structural component(s) of the airway would be most affected by the use of a bronchodilator, and in what functional zone(s) are they found?

-Lobar Bronchi which are found in the conducting zone -because the site of action is on smooth muscle (alveoli are not smooth)

A second degree burn can result in a loss of sensation, but do not necessarily affect motor control of arrector pili muscles. Which of the following are damaged in a second degree burn?

-Meissners corpuscles

Why does eating peppers feel hot?

-Molecules in the pepper bind the same receptors responsible for thermoregulation

Which of the following statements best describes how parathyroid hormone (PTH) affects the serum concentration of calcium?

-PTH stimulates osteoclasts, increasing serum Ca2+

Which of the following is NOT a function of the human skeletal system?

-Primary glycogen storage

What is the role of acetylcholine in calcium release?

-Stimulates cellular contraction by opening voltage-gated ion channels

Which of the following is a major organic component of bone?

-collagen

The phenomenon known as "goosebumps" is often combined with shivering to reduce heat loss. What integumentary layer is most directly related to this reflex?

-reticular dermis

What is spermiogenesis?

-shedding of unnecesssary cytoplasm

The partial pressures of co2 and o2 in the atmosphere are .3 and 160. The partial pressures of these gases in blood leaving the lungs are 40 and 95. What factor most likely accounts for this difference?

-co2 is more soluble in blood than 02

Scientists are measuring mechanoreceptor reactions to a variety of stimuli. What stimuli would you expect to generate the following response? (high levels of merkel disks and hair follicle receptors)

-constantly changing light touch on hairy skin

Which of the following has a rate of urinary excretion (units of solute per unit time) that is almost always identical to its rate of glomerular filtration in a healthy adult?

-creatinine

Which of the following is NOT a feature of the stratum granulosum?

-cytokeratin is produced in this layer

Interstitial lung disease (ILD) refers to a set of conditions which affect the pulmonary interstitium-- the area of tissue and space which lies between the alveoli and alveolar capillaries. What factor in the setting of severe ILD, would NOT decrease the extent to which oxygen passes from the air sacs of the lungs into the blood?

-decreased interstitial thickness

Curare is a naturally-occurring compound that competitively binds to nicotinic acetylcholine receptors on muscle cells. Which of the following symptoms might be seen in a patient who has been exposed to curare?

-diaphragmatic paralysis

What is the respiratory zone of the respiratory system?

-directly participates with gas exchange -made up of only the alveoli and the respiratory bronchioles/alveolar ducts

What would be a direct result of an enzymatic deficiency on the acrosome?

-egg would not complete metaphase II

What produces the force which drives normal exhalation, and is the process active or passive?

-elastic force, passive

Which of the following will increase lymph flow?

-elevated cardiovascular capillary pressure

Which of the following best describes the immediate fate of high-molecular weights proteins that are removed from the interstitial spaces of the body and taken up by the lymphatic system?

-emptying into the circulatory system at the jugular vein

The pancreas arises from which embryonic germ layer?

-endoderm

Recognition of self vs. non-self by the adaptive immune system in humans is accomplished in which of the following ways?

-exposure of T cells to the body's own antigens in the thymus

Urine is formed in a three-step process: which of the following gives the correct order in which these steps take place in the nephron?

-filtration, reabsorption, secretion

In a situation where the respiratory bronchioles become inflamed and narrowed, such as is seen in asthma, which aspect of respiration would be most mechanically impaired?

-forced expiration

Which of the following is not a commonality shared by large lymph vessels and cardiovascular veins (veins of the cardiovascular system)?

-forms a closed system

Presence of which of the following in the urine, even in small amounts, is indicative of a possible problem in the renal system of a patient?

-glucose

Which of the following has a rate of urinary excretion (units of solute per unit time) that is always much lower than its rate of glomerular filtration in a healthy adult?

-glucose

Many respiratory diseases affect pulmonary function by altering the ability of alveoli to participate in gas exchange. What physical change would most greatly reduce the degree to which a particular alveolus is ventilated?

-increased alveolar elastic recoil

Septic shock is a serious condition resulting from the body's response to systemic bacterial infections, which may impair oxygen uptake and delivery. What physiological change may result from septic shock which would decrease the ability of hemoglobin in the alveolar capillaries to become fully saturated with oxygen?

-increased capillary blood flow

Hyperhidrosis is characterized by excessive sweating, especially at the palms of the hands and soles of the feet. Which of the following could cause this disorder?

-increased stimulation of merocrine glands

Increased stomach pH is the consequence of which of the following?

-inhibition of parietal cells because they secrete hydrochloric acid which increases the H+ of the stomach. Inhibiting these cells would increase the pH

Most avian skeletons include pneumatic bones, which contain pockets of air that make the bones less dense. A researcher suspects that this design weakens the tensile strength of bone and that the skeletal system of birds must compensate for this loss by adjusting the composition of the bone matrix. If this hypothesis is true, how would the bone matrix of birds differ from that of other vertebrates?

-it would contain a relatively high proportion of collagen

Which of the following is least likely to be present in the glomerular filtrate (the filtrate produced by the nephron before it enters the loop of Henle) of a healthy adult nephron?

-large molecular weight protein

Which connective tissue connects and stabilizes adjacent bones?

-ligaments

Lymph from which of the following parts of the body does not enter into the systemic circulation through the thoracic duct?

-lymph from the right arm

Mature T-lymphocytes accumulate at which of the following organs, where they play a central role in the adaptive immune response?

-lymph nodes

Monocytes move from the systemic circulatory system into general connective tissues, where they differentiate into what phagocytic cell type?

-macrophage

Which of the following is not a basic function of the lymphatic system?

-maintenance of blood pressure

The products of the liver and pancreas participate in what type of digestion?

-mechanical and chemical

SGLT1 is a symporter that can be found in the small intestine. Which macromolecule does it transport?

-monosaccharides

We would expect to find smooth muscle in all of the following EXCEPT:

-myocardial tissue

Which of the following is not one of the three main antigen-presenting cell types?

-natural killer cells

Which impairment in the male reproductive system will NOT necessarily lead to sterility?

-obstruction of bulbourethral glands

Which type of cell produces osteoid, a combination of proteins that become mineralized to produce new bone tissue?

-osteoblasts

Which structures contain connective tissue, blood vessels, and nerves?

-papillary and reticular dermis

Which of the following would most likely be found in the esophagus of a patient suffering from gastroesophageal reflux disease?

-pepsin

In humans, which meiotic phase has the longest duration?

-prophase 1 in females

Which of the following anatomical portions of a nephron connects the Bowman's capsule to the loop of Henle?

-proximal convoluted tubule

Which of the following would be least likely to be found in lymph fluid?

-red blood cells

What do Basophils do?

-release histamine used to respond to allergens

How many nephrons does the average adult human kidney contain (a nephron is the main functional unit of the kidney)?

-roughly 1 mil

The space between two Z lines constitutes the:

-sacromere

Which type of synovial joint is multiaxial, allowing motion in more than one plane of movement?

-saddle joint

What does Von Ebners gland do?

-secretes lingual lipase -damage to this gland could lead to decreased fat digestion and increased triglyceride concentration in the esophagus

A patient comes in with abdominal pain. Their lab results reveal normal levels of pancreatic enzymes, pepsinogen, and both stomach and gall bladder motility, but an acidic small intestine environment. Which hormone is not in balance?

-secretin

The lining of lymphatic vessels is composed of which of the following cell type?

-simple squamous epithelium

Steatorrhea is the presence of increased fat in feces. Which organ is least likely to be the cause of a patient's steatorrhea?

-stomach

People with albinism have a defect in tyrosinase, an oxidase that helps to control skin pigment production. In what epidermal layer is tyrosinase active?

-stratum basale

Which of the following is NOT innervated by the autonomic nervous system?

-striated skeletal muscle cell

Lymph from the right lymphatic duct enters the systemic circulation at what point?

-the junction of the right subclavian vein and the jugular vein

What is the pressure of gas within the alveoli at the peak of inspiration, just before expiration, relative to that of atmospheric air?

-the same

Osteoporosis is a disease caused by the imbalance of bone resorption and bone formation that causes weakening of the bones. The medication ibandronate treats osteoporosis by slowing bone loss. If ibandronate is transported through the blood, how will it most directly reach bone tissue?

-through haversian canals

Which portion of an antibody provides antigen-binding sites?

-variable portion

Damage to which gland of the oral cavity would lead to an increase in the concentration of triglycerides in the esophagus?

-von ebners

A hepatic lobule can be split into three zones radiating outward from each other. Which of the following statements about the three zones is true?

-zone

Which of the following cell types of the innate immune system does not perform phagocytosis?

-Basophils

The renal system does not play a direct role in regulating which of the following?

-Blood temperature

Which statement correctly identifies a similarity between cartilage and bone?

-Both are produced by specialized mesenchymal cells

Which of the following choices correctly traces the route of glomerular filtrate on its path to the collecting duct of a nephron?

-Bowman's capsule, proximal tubule, descending loop of Henle, ascending loop of Henle, distal tubule

How might central and peripheral chemoreceptors compare with regard to their role in the detection of respiratory gases resulting from a prolonged period of hypoventilation?

-Central chemoreceptors and peripheral chemoreceptors may both respond to the resultant increase in pCO2, but only peripheral chemoreceptors could respond to the decrease in pO2

Which penile tissues remain pliable during an erection? Which tissues become firm? What is the function of the pliable tissues?

-Corpus spongiosum; corpora cavernosa; maintain the urethra open

Central tolerance refers to which of the following processes?

-Destruction of lymphocytes that are specific for self-antigens

What is the correct trajectory of sperm during ejaculation?

-Epididymis, vas deferens, ampulla of vas deferens, ejaculatory duct, urethra

As glomerular filtrate moves through the ascending loop of Henle, the filtrate becomes more dilute: why?

-The ascending loop of Henle is permeable to ions but impermeable to water

Which of the following allows for an almost instantaneous response to painful stimuli?

-The extensive myelination of A-delta fibers, leading to increased conductance

Scientists isolate the lymph fluid from the right thoracic duct of a fasted ( ~24 hours) experimental animal 20 minutes after a meal. After chemical analysis, they find a high concentration of fatty acid ( ~2% of total volume) and no detectable amounts a free carbohydrates: what does such data indicate about the composition of the meal?

-The meal contained fats, but no conclusion about carbohydrates is warranted from the data

What is the role of tropomyosin in muscle contraction?

-To prevent myosin from continuing to slide up the actin filament

Which of the following is accurate regarding Type I and Type II muscle fibers?

-Type I fibers store much of their energy as triglycerides, whereas Type II fibers store energy as ATP or creatine phosphate

What is the conducting zone of the respiratory system?

-a series of tubes through which gases travel

If the mouth and nose are closed at the peak of a complete inspiration, but before expiration, and the breath is held, what is the pressure of gases within the alveoli relative to the pressure of atmospheric air?

-alveolar pressure is greater

Humoral immunity is a type of adaptive immunity that results in the circulation of which of the following throughout the blood?

-antibodies

Lactose intolerance is the inability to digest lactose, due to insufficient amounts of the enzyme lactase. Where is lactase usually found?

-brush border of duodenum