This illustration by AlbrechtGFX is of the molecular sequence that occurs every day in dairy milking parlors-milk let-down.
(1)Teat suckling (by calf or milking machine) sends nerve impulses to the brain’s hypothalamus(2) and on to the pituitary (3). The pituitary gland secretes oxytocin into the bloodstream, which carries it to udder alveoli(4). Udder alveoli contract to let down milk.
The yellow arrows show the nervous system pathway, while the green arrows show the circulatory system pathway.
Learn more about the process of creating this image on the AlbrechtGFX blog.