The hormone responsible for stimulating uterine contractions and milk ejection is_____________?
Show answer Hide answer
Answer: D. Oxytocin
Explanation
Oxytocin directly stimulates the contraction of uterine myometrium smooth muscle fibers during the active process of childbirth. The hormone also causes contraction of myoepithelial cells surrounding mammary alveoli to facilitate milk ejection during lactation. These physiological target actions make oxytocin the primary neurohypophysial hormone responsible for reproductive and nursing contractions. Oxytocin is synthesized in the hypothalamus and subsequently stored and released into the bloodstream by the posterior pituitary gland. Its release operates through a classic positive feedback neuroendocrine loop during parturition and infant suckling episodes. Receptor sensitivity for this powerful hormone increases dramatically in uterine tissue toward the end of human gestation.
Progesterone maintains the uterine lining during pregnancy and suppresses uterine contractions rather than stimulating active labor. Prolactin is primarily responsible for milk production within the glandular tissue rather than milk ejection or uterine contractions. Prostaglandins are local tissue lipid compounds that also influence labor, but oxytocin remains the specific primary neurohormone.
Related questions
Q1. Hemoglobin levels in a healthy newborn average______________?
Show answer Hide answer
Answer: D. 30
Hemoglobin concentration is significantly elevated at birth, with typical newborn values averaging around 17 to 20 g/dL.
Q2. The largest compartment of total body water is_______________?
Show answer Hide answer
Answer: B. Intracellular fluid
Intracellular fluid constitutes approximately two-thirds of total body water volume. This vast fluid compartment resides inside the trillions of cells in the body. Potassium and magnesium serve as the primary cations wit...
Q3. Renal medullary hyperosmolarity stems from elevated levels of_____________?
Show answer Hide answer
Answer: B. Na+
High concentrations of sodium chloride and urea in the medullary interstitium establish necessary hyperosmolarity. Active transport mechanisms in the loop of Henle continuously move sodium ions into the surrounding medul...
Q4. The intrinsic factor essential for vitamin B12 absorption is synthesized in the______________?
Show answer Hide answer
Answer: B. Stomach
Intrinsic factor is successfully produced and secreted by parietal cells located in the stomach lining. This crucial glycoprotein binds tightly to ingested vitamin B12 to protect it from early degradation. Without stomac...
Q5. The primary functional distinction between DNA and RNA lies in_____________?
Show answer Hide answer
Answer: B. DNA carries the information in all organizations
Deoxyribonucleic acid serves as the universal hereditary storage molecule in cellular life. Genetic instructions encoded in DNA direct protein synthesis across all known organisms. This primary functional role distinguis...
Q6. The physiological albumin-to-globulin ratio in blood is______________?
Show answer Hide answer
Answer: B. 2:1
The normal physiological ratio of albumin to globulin in human blood plasma is approximately two to one. Healthy individuals typically maintain a higher concentration of albumin compared to the total pool of globulin pro...