MDS PREP
Which of the following is the correct statement regarding mammalian nerve fibers?
1) A-alpha fibers have the lowest conduction velocity and are responsible for pain and temperature sensation.
2) A-beta fibers have the highest conduction velocity and are responsible for motor supply to skeletal muscles.
3) A-gamma fibers are heavily myelinated and have the fastest conduction velocity.
4) C fibers have a large diameter and are responsible for fine motor control.
Answer: 2) A-beta fibers have the second highest conduction velocity after A-alpha fibers and are responsible for touch, kinesthetic sense, and pressure sensation, not motor supply to skeletal muscles. A-alpha fibers have the highest conduction velocity and are indeed responsible for motor supply to skeletal muscles.
What are the main stimuli that increase the secretion of growth hormone (GH)?
1) High blood glucose levels and physical inactivity
2) Hypoglycemia, exercise, protein meals, and stress
3) REM sleep and increased IGF-1 levels
4) High cortisol and fatty acid levels
Answer: 2) Main stimuli that increase GH secretion include hypoglycemia, exercise, protein meals, and stress.
What is the role of the acrosome in sperm?
1) Provides energy for sperm motility
2) Contains enzymes that help in the penetration of the ovum
3) Protects the sperm DNA
4) Involved in the fertilization process by fusing with the egg membrane
Physiology
Answer: 2
The acrosome is a cap-like structure located on the head of a spermatozoon. It contains lysosome-like organelles rich in enzymes that are essential for penetrating the egg's outer layers during fertilization.
In which part of the nephron does the majority of bicarbonate reabsorption occur?
1) Glomerulus
2) Proximal Convoluted Tubule (PCT)
3) Loop of Henle
4) Collecting Duct
The majority of bicarbonate reabsorption occurs in the Proximal Convoluted Tubule (PCT), which is essential for maintaining acid-base balance.
What is the primary function of the vestibulospinal tract?
1) Control of posture and balance
2) Control of fine motor skills
3) Control of respiration
4) Control of pupillary response
The vestibulospinal tract is a medial pathway that plays a critical role in maintaining posture and balance by coordinating the contraction of antigravity muscles in response to information from the vestibular system.
What is the transport maximum for phosphate reabsorption in the kidneys?
1) 0.10 mM/min
2) 0.50 mM/min
3) 1.00 mM/min
4) 2.00 mM/min
The transport maximum for phosphate reabsorption in the kidneys is approximately 0.50 mM/min, indicating the maximum amount that can be reabsorbed before excretion occurs.
What is the primary mechanism by which acid secretion is regulated in the stomach?
1) By the pH of the stomach content
2) By the amount of food present
3) By the time of day
4) By the type of food consumed
The primary mechanism by which acid secretion is regulated in the stomach is by the pH of the stomach content, which influences gastric secretions.
Which hormone is primarily responsible for the conversion of 7-dehydrocholesterol to cholecalciferol in the skin?
1) Parathyroid hormone (PTH)
2) Vitamin D
3) Ultraviolet B (UV2) light
4) 25-hydroxyvitamin D3
Ultraviolet B (UVB) light is primarily responsible for the conversion of 7-dehydrocholesterol to cholecalciferol (vitamin D3) in the skin.