Hormones Flashcards
what are hormones?
Hormones are a chemical substance produced by a gland, carried by the blood and alters the activity of one or more specific target organs and is then destroyed by the liver.
what is an endocrine gland?
it is ductless glands that secrete hormones directly into the bloodstream, which then transports the hormone around the body.
important endocrine gland
at the pancreas, blood glucose level is monitored by patches of cells known as the islets of Langerhans. These islets are hormone-secreting glands (endocrine glands)
how is blood glucose concentration regulated? (increase in concentration)
(memorise!)
An increase in blood glucose concentration above the norm is detected by receptors, which are the islets of Langerhans of pancreas.
Beta cells of islets of Langerhans of pancreas are stimulated to secrete the hormone insulin into the capillary network.
Insulin stimulates the uptake of glucose by cells, especially by liver and muscle cells. Insulin also triggers the conversion of glucose to glycogen and of glucose to fatty acids and fats in liver cells.
Once blood glucose concentration decreases back to normal, this is detected in the islets of Langerhans. The beta cells respond by reducing insulin secretion.
Insulin is destroyed in the liver and excreted through the kidneys. Blood insulin level falls.
how is blood glucose concentration regulated? (decrease in concentration)
(memorise!)
A decrease in blood glucose concentration above the norm is detected by receptors, which are the islets of Langerhans of pancreas.
Alpha cells of islets of Langerhans of pancreas are stimulated to secrete the hormone glucagon into the capillary network.
Glucagon activates the enzymes that convert glycogen and amino acids to glucose. Glucagon also reduces the rate of respiration of cells.
Once blood glucose concentration increases back to normal, this is detected in the islets of Langerhans. The alpha cells respond by reducing glucagon secretion.
Glucagon is destroyed in the liver, and excreted through the kidneys. Blood glucagon level falls.
signs of diabetes
a persistently high blood glucose level
presence of glucose in urine after meal
slow/difficult healing of wound
when is adrenaline secreted by the adrenal gland?
when you are afraid, angry, anxious, or stressed
what does adrenaline do?
prepares your body for ‘fight or flight’ or for states of emergency
effects of adrenaline secretion
stimulates the liver to convert glycogen to glucose so that more glucose is available for muscle contraction
increases the blood glucose level when more glucose is released from the liver into the bloodstream.
