Hormonal Regulation of Carbohydrates

Hormones What are hormones? maintain homeostasis (jack) chemical messenger (jady) chemical produced at one part of the body in response to situation at another part of the body insulin & glucagon – from the pancreas to regulate blood glucose level (bgl)

Islet of Langerhans As blood goes through the pancreas, insulin or glucagon is released into the blood stream based on the b.g.l Alpha-cells – glucagon Beta-cells - insulin http://www.britannica.com/EBchecked/media/101913/The-islets-of-Langerhans-are-responsible-for-the-endocrine-function

Blood Glucose Level When B.G.L is high When B.G.L is low Insulin is released (β) body cells to take in glucose Muscles and liver takes in glucose (why?) muscle & liver cells use glucose to make glycogen for storage Excess glucose is turned into fat (why?) long-term storage of energy When B.G.L is low Glucagon is released (α) Epinephrine and cortisol are released Hydrolysis of glycogen Glycogen – storage form of carbohydrates in animals The release of insulin and glucagon is not an all-or-nothing situation. The relative concentrations of these two hormones in the blood determine the shift between energy storage and mobilization Impaired glucose regulation: hyperglycemia and hypoglycemia

Insulin-Responsive Glucose Transporter Glucose transporter – facilitated diffusion Insulin responsive glucose transporters – requires insulin Skeletal muscles temporarily take up glucose during exercise without insulin b/c muscle contraction “opens up” glucose transporter. Brain and liver cells have glucose transporters that do not require insulin for the uptake of glucose http://www.lifesci.utexas.edu/faculty/sjasper/bio301L/digestion.html http://www.40daydetox.com/blood-sugar-insulin-and-diabetes-day-29/insulin-cell-receptors/

a lot more complex… http://flipper.diff.org/app/items/info/3459

Insulin Promotes Energy Storage Uptake of glucose into some cells Glycogenesis: glucose  glycogen (reversible) Glucose  fatty acids (irreversible) Stimulate protein synthesis

Hypoglycemia – low glucose Feel nauseated, dizzy, irritable, sleepy, etc Too much insulin produced Prolonged exercise Reactive hypoglycemia Fasting hypoglycemia

Glucagon Promotes Mobilization of Stored Energy Glycogenolysis: glycogen  glucose glucagon – liver to break up glycogen to release glucose into the blood for energy epinephrine – muscle to break up glycogen to release glucose used by muscles Gluconeogenesis: amino acids  glucose liver glycogen lasts for about 24 hrs after that the body breaks down proteins for energy Ketogenesis: fatty acids  ketones (acidic/toxic) Liver glycogenolysis is stimulated by glucagon Muscle glycogenolysis is stimulated by epinephrine Gluconeogenesis is stimulated by both glucagon and epinephrine

Ketogenesis Fatty acids  ketones Occurs in the liver Stimulated by glucagon Energy usable by the brain, heart, muscles, and kidney Accumulation of ketones  ketosis Gluconeogenesis results in muscle loss and has its consequences (cardiac muscles).

Immediate Energy Source Cortisol released in response to a “fight or flight” situation Decrease glucose uptake (exept for the brain) Stimulate glycogenolysis & gluconeogenesis

Concept Map Groups of 2 or 3 Blood glucose level Scott & Tommy / Isabelle & Shirley Chemical reactions in b.g.l. regulation Joseph & jack / lily & Noelle Hormones involved in b.g.l. regulation Jady & Leo & George Theo & Emily & Maggie