The 'Hormone Secretin' was the first hormone to be discovered. It was discovered by:
A. William Bayliss and Ernest Starling
B. Andrew Schally and Roger Guillemin
C. Edward Kendall
D. Otto Loewi
Answer: Option A
Solution (By JKExamLibrary)
Secretin was the first hormone ever to be identified, marking the birth of endocrinology as a distinct field. It was discovered in 1902 by British physiologists William Bayliss and Ernest Starling. They observed that when acidic chyme entered the duodenum, it stimulated the pancreas to secrete bicarbonate-rich juice, even if all nerves to the pancreas were cut. They concluded that a chemical messenger (which Starling coined the term 'hormone' for in 1905) was released from the intestinal mucosa into the blood to stimulate the pancreas. They named this messenger secretin.
Explanation:
Alveoli are tiny air sacs surrounded by capillaries where gas exchange (O₂ and CO₂) occurs. Nephrons are kidney units, neurons nerve cells, villi intestinal projections. The lungs contain millions of alveoli to maximize surface area.
Explanation:
Metastasis is the process by which malignant cancer cells detach from the primary tumor, travel through the blood or lymph, and establish secondary tumors in other organs. Benign tumors do not metastasize. Apoptosis is programmed cell death.
Explanation:
Geotropism (gravitropism) is directional growth in response to gravity; roots show positive geotropism (downward), shoots negative (upward). Phototropism is light-directed, thigmotropism touch, hydrotropism water.
No comments yet. Be the first to start the discussion!