MDS PREP
In the proximal convoluted tubule (PCT), which of the following substances is NOT reabsorbed?
1) Sodium
2) Chloride
3) Glucose
4) Water
In the proximal convoluted tubule (PCT), water is reabsorbed along with sodium, chloride, and glucose; however, not all substances are reabsorbed equally.
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.
The rate of gastric emptying is influenced by:
1) The quantity and type of food ingested
2) Distension of the duodenum
3) Gastric hormones like gastrin
4) All of the above
The rate of gastric emptying is influenced by the presence of food in the stomach, the type of food (carbohydrates, proteins, and fats), the distension of the duodenum, and the hormone gastrin, which can increase the rate of emptying.
What is the primary mechanism of vibration detection in the musculoskeletal system?
1) Meissner's corpuscles
2) Pacinian corpuscles
3) Merkel's discs
4) Ruffini's endings
Pacinian corpuscles are rapidly adapting mechanoreceptors that are highly sensitive to high-frequency vibrations and are responsible for detecting rapid changes in pressure.
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
Physiology
Answer: 1
The transport maximum for phosphate is 0.10 mM/min, indicating the maximum rate at which it can be reabsorbed by the renal tubules.
What is the function of the hypothalamus in the regulation of spermatogenesis?
1) It produces gonadotropin-releasing hormone (GnRH) which stimulates the release of LH and FSH from the pituitary
2) It produces androgens such as testosterone
3) It directly controls the maturation of spermatids
4) It has no role in spermatogenesis
Physiology
Answer: 1
The hypothalamus produces GnRH, which stimulates the anterior pituitary to release follicle-stimulating hormone (FSH) and luteinizing hormone (LH). FSH is essential for the maturation of spermatogonia into primary spermatocytes, while LH acts on Leydig cells to produce testosterone, which is critical for the later stages of spermatogenesis and sperm maturation.
What is the primary role of estrogen during the follicular phase of the menstrual cycle?
1) Suppression of FSH secretion
2) Stimulation of follicular development
3) Preparation of the endometrium for implantation
4) Induction of the LH surge
During the follicular phase of the menstrual cycle, estrogen stimulates follicular development, promoting the maturation of ovarian follicles.
What is the primary function of chymotrypsin in the digestive process?
1) Converting chymotrypsinogen into chymotrypsin
2) Breaking down proteins into peptides
3) Catalyzing the hydrolysis of disulfide bonds in proteins
4) Activating pepsinogen into pepsin
E) Releasing gastrin from gastric mucosa
Chymotrypsin is an endopeptidase enzyme that plays a crucial role in the digestive system by breaking down proteins into smaller peptides. It is activated from its precursor chymotrypsinogen by the enzyme trypsin. Once active, chymotrypsin hydrolyzes the peptide bonds at the carboxyl side of aromatic and bulky amino acids, such as phenylalanine, tryptophan, and tyrosine. This process is essential for the further digestion and absorption of dietary proteins.