4.5 - hormone control

HORMONE ACTION

hormones are chemicals released into the blood. they’re generally produced by one organ or tissue but act on another organ or tissue. hormones control the release of digestive juices and enzymes in our digestive system


WHAT STIMULATES SECRETION?

digestive juices are released in response to the following stimuli:

  1. sensory (taste/smell)

  2. mechanical stimuli of swallowing

  3. hormones


GASTRIN

released in the presence of protein. stimulates gastric glands in the stomach to produce gastrin. goes via the blood to other gastric glands to stimulate the release of pepsinogen and HCl


SECRETIN

released by the duodenum in the presence of HCl - tells the pancreas to release its bicarbonate


CCK

chloecytoskin (CCK) released by the duodenum in the presence of protein or fat. tells the gall bladder to release bile and the pancreas to release enzymes


ENTEROGASTRIN

released by the small intestine when fat is present. slows peristalsis down and the emptying of the stomach


BLOOD GLUCOSE CONTROL

LIVER FUNCTIONS

  • destroys old RBCs and converts hemoglobin to bilirubin to produce bile

  • stores glucose as glycogen

  • produces urea from co2 + amine groups from amino acid breakdown

  • makes blood proteins

  • detoxifies blood


PANCREAS FUNCTIONS

  • has endocrine functions in producing insulin and glucagon

  • produced by beta cells primarily in the islets of langerhans


INSULIN

  • increases permeability of cell membranes to glucose

  • lowers blood glucose levels by telling the liver to produce glycogen from excess glucose

  • secreted when blood glucose levels are high - after meals


GLUCAGON

  • when blood glucose levels are low, glycogen is secreted from the pancreas alpha cells

  • causes glycogen in the liver to be broken down into glucose - increasing blood glucose levels


HOMEOSTASIS

liver and pancreas work together to keep blood glucose levels balanced


DIABETES

TYPE 1

  • do not produce insulin

  • need to take insulin to keep blood glucose levels normal

  • from birth/genetics


TYPE 2

  • occurs as adults

  • often to people that eat high sugar loads or are obese

  • insulin is produced but the body stops reacting to it