MDS PREP
What is the effect of fluorescent lighting on detecting scleral icterus?
1) It enhances the visibility of scleral icterus.
2) It does not affect the visibility of scleral icterus.
3) It makes it more difficult to detect scleral icterus.
4) It causes a false-positive result for scleral icterus.
Fluorescent lighting enhances the visibility of scleral icterus, making it easier to detect jaundice.
What is the role of troponin in skeletal muscle contraction?
1) It initiates contraction by binding to calcium ions
2) It is essential for the sliding of actin and myosin filaments
3) It is involved in the excitation-contraction coupling process
4) It is not present in skeletal muscles and plays no direct role in their contraction
Troponin is a protein complex found in cardiac and smooth muscles, not in skeletal muscles. In skeletal muscles, it is the regulatory proteins tropomyosin and the troponin complex that are crucial for excitation-contraction coupling.
What is the main difference between endopeptidases and exopeptidases?
1) Endopeptidases cleave internal peptide bonds, while exopeptidases act on the terminal peptide bonds.
2) Endopeptidases are inactive in the stomach, whereas exopeptidases are active in the stomach.
3) Endopeptidases are exclusively found in the pancreas, whereas exopeptidases are exclusively found in the intestinal mucosa.
4) Endopeptidases are exclusively activated by enterokinase, whereas exopeptidases are activated by other enzymes.
E) Endopeptidases are inhibited by acidic pH, while exopeptidases function best at acidic pH.
Endopeptidases, also known as endoproteinases, are enzymes that hydrolyze peptide bonds within the polypeptide chain, breaking down proteins into smaller peptides. Examples include pepsin, trypsin, and chymotrypsin. In contrast, exopeptidases, or exoproteinases, cleave peptide bonds at the ends of the polypeptide chain, either at the N-terminal (aminopeptidases) or C-terminal (carboxypeptidases). These enzymes are involved in the final steps of protein digestion and the degradation of small peptides into individual amino acids.
How does the cerebellum contribute to motor coordination?
1) By timing and comparing the duration of agonist muscle activity and latency of antagonist activity
2) By directly controlling the force of muscle contraction
3 ) By regulating the rate of nerve impulse conduction in motor neurons
4) By initiating voluntary movement
The cerebellum is crucial for the coordination of movement. It receives signals from the motor cortex about the intended movement and the actual position of the limb through climbing fibers. By timing these signals, it helps to stop the movement at the correct point by inhibiting the agonist muscles and stimulating the antagonist muscles.
What is the function of the middle piece in a sperm cell?
1) It produces the enzymes needed for sperm maturation
2) It contains the mitochondria for energy production
3) It is responsible for the sperm's ability to penetrate the egg
4) It is involved in the process of fertilization
Physiology
Answer: 2
The middle piece of the sperm cell is where the fibrous sheath is surrounded by spirally arranged mitochondria, which are the cell's powerhouses. They provide the energy required for the flagellum's movement during sperm motility.
What is the normal ratio of glycine to taurine conjugates of bile acids in the bile?
1) 1:1
2) 2:1
3) 3:1
4) 4:1
The normal ratio of glycine to taurine conjugates of bile acids in the bile is approximately 3:1, reflecting the different conjugation patterns of bile acids.
The increased venous return to the heart causes:
1. End diastolic volume increase
2. End systolic volume decrease
3. Decrease stroke volume
4. Decreased isovolumetric ventricular contraction.
Physiology
Answer: 1
The increased venous return to the heart causes End diastolic volume increase
What is the primary effect of norepinephrine on the pupillary muscles during the fight-or-flight response?
1) Dilatation (mydriasis)
2) Constriction (miosis)
3) No effect on pupil size
4) It depends on the presence of other neurotransmitters
Answer: 1) Dilatation (mydriasis)Explanation: Norepinephrine acts on alpha-adrenergic receptors in the pupillary dilator muscles, leading to pupil dilation. This is a component of the sympathetic nervous system's response to stress, which also includes pupil dilatation mediated by epinephrine.