Chapters 12 + 13 - homeostasis Flashcards
What is homeostasis?
The maintenance of constant internal conditions.
What is vasoconstriction?
The narrowing of blood vessels, to prevent blood flow to the skin surface, therefore reducing heat loss.
What is vasodilation?
The dilation of blood vessels to increase blood flow to the skin surface, increasing heat loss.
Which area of the brain is the coordinator for temperature control?
The hypothalamus.
what is the autonomic nervous system?
The part of the nervous system which supplies the muscles and glands that aren’t under our conscious control.
What is a hormone?
A molecule which is transported in the blood and acts as a chemical messenger. They are produced by various cells and glands that make up the endocrine system. Most of hormones found in a mammal are either proteins that bind to receptors (insulin) or steroids that penetrate the plasma membrane and activate genes (oestrogen and progesterone).
What is a second messenger?
A molecule found inside a cell which responds to the presence of a hormone outside the cell by activating a particular enzyme.
What are islets of Langerhans?
Small groups of cells found in the pancreas which are responsible for the secretion of hormones involved in the control of blood glucose.
What do alpha cells secrete?
Glucagon.
What do beta cells secrete?
Insulin.
What is insulin?
A hormone that is stimulated by a rise in blood glucose concentration. It increases absorption of glucose into cells and increases glycogenesis.
What is glucagon?
A hormone stimulated by a fall in blood glucose concentration, it increases glycogenolysis and gluconeogenesis.
What is glycogenolysis?
The conversion of glycogen to glucose.
What is glycogenesis?
The conversion of glucose to glycogen, mostly in the muscles and liver.
What is gluconeogenesis?
A biochemical process in which glucose is made from non-carbohydrates (amino acids and glycerol).
