Homeostasis Flashcards
What are Ectotherms?
Animals which gain heat from their surroundings
What are endotherms?
Animals like mammals and birds which generate their own heat
What is the control centre for thermoregulation?
The heat loss and heat gain centres in the hypothalamus
What centre activates when CORE temperature rises above the set point?
The heat loss centre
List thermoregulatory responses to core temp rising
Heat loss centre causes:
- Vasodilation so heat is lost by radiation through skin
- Sweat produced which evaporates. Carries lots of heat because water has a high latent heat of evaporation
- Behavioural Responses
List thermoregulatory responses to core temp decrease
Heat gain centre causes:
- Vasoconstriction causing blood to be redirected to shunt vessel, reducing heat loss by radiation
- Skeletal muscles contract and relax repeatedly generating heat from friction and metabolic reactions
- Non Shivering Thermogenesis occurs in Brown Adipose Tissue
- Behaviour
How do Ectotherms control temperature?
Only Behavioural responses, e.g. Sitting in sun or on hot surface to gain heat, going to shade to decrease temp, changing their angle in relation to the sun.
What are the three sources of glucose for the body?
- Digestion of dietary carbohydrates
- Gluconeogenesis
- Conversion of glycogen to glucose
What is the control centre for blood glucose homeostasis?
The Pancreas.
What are the two types of thermoregulators?
Endotherms and Exotherms
What are the receptors and effectors for blood glucose regulation?
The islets of Langerhans act as both
What are the two kinds of cells in the Islet of Langerhans and what do they do?
Alpha cells release glucagon when they detect low blood glucose levels.
Beta cells release insulin when they detect high blood glucose
What effect does insulin have on liver and muscle cells?
Increases the rate of Glycogenesis (Conversion of Glucose to Glycogen) in both muscle and liver. Increases rate of lipogenesis in liver
What effect does insulin have on cells?
Insulin increases uptake of glucose by cells by stimulating the recruitment of more glucose transporters to the cell membrane from the inner membrane pool
What effect does glucagon have in the liver?
Glucagon increases the rate of glycogenolysis and Gluconeogenesis in the liver. (The rate of breakdown of glycogen to glucose and the rate of synthesis of glucose from non carbs)
