120 



KINETIC HORMONES — II 



for a hormone, secreted from the pyloric region of the stomach, 

 causing the secretion of acid from the fundus region has also been 

 supported by the use of purified gastrin, extracted from the 

 stomach wall and freed of histamine and secretin. Injection results 



pylorus of stomach 



oesophagus 

 fundus of stomach 



spleen 



pancreas 



stimulates 

 inhibits 



jejunum 

 ileum 



Fig. 4-1. Diagram to show the actions of hormones in the mam- 

 malian gut. Heavy arrows extend from the source of each hormone 

 to the effector which it controls, either by stimulation or inhibition. 

 Secretin stimulates the secretion of bicarbonate ; pancreozymin, 

 DUOCRININ and enterocrinin the secretion of enzymes. In addi- 

 tion to their effects upon the secretion of HCl, gastrin and 

 enterogastrone stimulate and inhibit respectively the muscles of 

 the stomach. Cholecystokinin only stimulates the muscles of the 

 gall bladder and relaxes its sphincter (amplified from Turner, 



1955). 



in an increased flow of acid, but in little change in the pepsin 

 content of the gastric juice. 



The secretion of gastrin is therefore stimulated either by food 

 or by mechanical distension ; it is secreted from the mucosa of the 



