MDS PREP
What is the primary mechanism responsible for the reclamation of bile acids in the enterohepatic circulation?
1) Active transport in the ileum
2) Facilitated diffusion in the colon
3) Passive diffusion in the small intestine
4) Bacterial synthesis in the liver
Physiology
Answer: 1
Bile acids are actively reabsorbed in the ileum, primarily by the sodium-dependent bile acid transporter (ASBT), and returned to the liver.
What is the effect of Secretin on the contraction of the pyloric sphincter?
1) It relaxes the pyloric sphincter.
2) It contracts the pyloric sphincter.
3) It has no effect on the pyloric sphincter.
4) It depends on the presence of gastrin.
Secretin has no effect on the contraction of the pyloric sphincter, which is primarily regulated by other hormones.
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 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.
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 transport maximum for glucose reabsorption in the kidneys?
1) 125 mg/min
2) 250 mg/min
3) 375 mg/min
4) 500 mg/min
The transport maximum for glucose reabsorption in the kidneys is about 375 mg/min, which indicates the maximum amount of glucose that can be reabsorbed before it appears in the urine.
What is the mechanism of action of umami taste substances?
1) Activation of sodium-dependent glucose transporters
2) Stimulation of bitter G-protein coupled receptors
3) Activation of amiloride-sensitive sodium channels
4) Activation of glutamate taste sensors (glutamate receptors)
Umami taste is triggered by the activation of glutamate receptors present in taste cells, which leads to the perception of savoriness.
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.