Ernest Henry Starling and Sir William Maddock Bayliss were English physiologists in the early 20th century. In 1902, they discovered the hormone secretin, the first hormone to be identified, by showing that acid in the duodenum activates a substance that stimulates pancreatic secretions. In 1905, Starling introduced the term "hormone" to describe these chemical messengers that travel through the bloodstream to affect distant organs. Their discovery of secretin and definition of hormones established the field of endocrinology and marked a major advance in understanding the body's chemical signaling systems.

1. The Discovery of Hormone
Dr Pranab Kumar Sahana:MD,DM
(Associate Profofessor),
Department of Endocrinology,
NRS Medical College, Kolkata

2. Starling and Bayliss
Earnest Henry Starling
Died 2nd May
Sir William Maddock Bayliss
Born 2nd May

3. Starling- Biography
• Starling (17 April 1866 – 2 May 1927)
• English physiologist.
• His father, Matthew Henry Starling, was a barrister and
served for many years as a clerk of the crown at
Bombay
• Starling studied medicine at Guy's Hospital, London,
where he obtained his MB in 1889
• In 1899 he moved to University College, London, to
become Professor of Physiology, a position he held
until his death.
His main collaborator in London was his brother-in-law,
Sir William Maddock Bayliss.

4. Starling‘s discoveries
• Starling is most famous for developing the "Frank–Starling
law of the heart", presented in 1915, stating that the
energy of contraction of the heart is a function of the
length of the muscle fiber.
His other major contributions to physiology were:
• The discovery of peristalsis, with Bayliss (1899)
• The Starling equation, describing fluid shifts in the body
(1896)
• The discovery that the distal convoluted tubule of
the kidney reabsorbs water and various electrolytes
• The discovery of secretin, the first hormone, with Bayliss
(1902) and the introduction of the concept
of hormones (1905).

5. The famous Experiment (1902)
• They showed that dilute hydrochloric
acid, mixed with partially digested
food, activates a chemical substance
in the epithelial cells of the
duodenum. They found that this
activated substance, which they
called secretin, released into the
bloodstream, comes into contact with
the pancreas, where it stimulates
secretion of digestive juice into the
intestine through the pancreatic
duct.

6. Croonian lecture on “chemical correlation of the
functions of the body”at Royal College of Physicians in
London on 20th June, 1905
“These chemical messengers … or hormones (from [the
greek word,ormao] = I excite or arouse), as we may call them,
have to be carried from the organ where they are produced
to the organs which they affect, by means of the blood
stream, and the continually recurring physiological needs of
the organism must determine their repeated production and
circulation through the body.”-

7. Figure 2 The beginning of Starling’s lecture, and the important sentence which appears a page
later in the lecture.
Henderson J J Endocrinol 2005;184:5-10
© 2011 Society for Endocrinology

8. Henry Starling
• "Only . . . by way of experiment, can we hope
to attain to a comprehension of the “wisdom
of the body and the understanding of the
heart,” and thereby to the mastery of disease
and pain, which will enable us to relieve the
burden of mankind." Lancet, 1923, 2: 865.
• “. . . in matters of urgent necessity [such as
education], it is unprofitable to count the
cost.” - Starling

9. Sir William Maddock Bayliss
• 2 May 1860 – 27 August 1924
• was an English physiologist.
• He gained a B.Sc from London University. He graduated MA
and DSc in physiology from Wadham College, Oxford.
• Bayliss and Ernest Henry Starling discovered the peptide
hormone secretin and peristalsis of the intestines.
• He jointly delivered their Croonian lecture in 1904 and was
awarded Royal Medal in 1911 and Copley Medal in 1919.
• He was knighted for his contribution to medicine in 1922.
• Bayliss died in London in 1924.

11. Thank you