Some organs have a secondary endocrine function. For example, the walls of the atria of the heart produce the hormone atrial natriuretic peptide (ANP), the gastrointestinal tract produces the hormones gastrin, secretin, and cholecystokinin, which aid in digestion, and the kidneys produce erythropoietin (EPO), which stimulates the formation of red blood cells. Even bone, adipose tissue, and the skin have secondary endocrine functions.
atrial natriuretic peptide (ANP)
peptide hormone produced by the walls of the atria in response to high blood pressure, blood volume, or blood sodium that reduces the reabsorption of sodium and water in the kidneys and promotes vasodilation
erythropoietin (EPO)
protein hormone secreted in response to low oxygen levels that triggers the bone marrow to produce red blood cells
leptin
protein hormone secreted by adipose tissues in response to food consumption that promotes satiety
thymosins
hormones produced and secreted by the thymus that play an important role in the development and differentiation of T cells
thymus
organ that is involved in the development and maturation of T-cells and is particularly active during infancy and childhood
1. The walls of the atria produce which hormone?
A) cholecystokinin
B) atrial natriuretic peptide
C) renin
D) calcitriol
B
2. The end result of the RAAS is to ________.
A) reduce blood volume
B) increase blood glucose
C) reduce blood pressure
D) increase blood pressure
D
3. Athletes may take synthetic EPO to boost their ________.
A) blood calcium levels
B) secretion of growth hormone
C) blood oxygen levels
D) muscle mass
C
4. Hormones produced by the thymus play a role in the ________.
A) development of T cells
B) preparation of the body for childbirth
C) regulation of appetite
D) release of hydrochloric acid in the stomach
A
1. Summarize the role of GI tract hormones following a meal.
The presence of food in the GI tract stimulates the release of hormones that aid in digestion. For example, gastrin is secreted in response to stomach distention and causes the release of hydrochloric acid in the stomach. Secretin is secreted when acidic chyme enters the small intestine, and stimulates the release of pancreatic bicarbonate. In the presence of fat and protein in the duodenum, CCK stimulates the release of pancreatic digestive enzymes and bile from the gallbladder. Other GI tract hormones aid in glucose metabolism and other functions.
2. Compare and contrast the thymus gland in infancy and adulthood.
The thymus gland is important for the development and maturation of T cells. During infancy and early childhood, the thymus gland is large and very active, as the immune system is still developing. During adulthood, the thymus gland atrophies because the immune system is already developed.