Thermoreception Flashcards
What is thermoregulation?
Maintenance of body temperature
What sort of processes happen under thermoregulation?
Homeostasis, constriction of capillary network to skin, which causes less blood flow to skin and reduces heat loss, evaporation (sweat)
List the factors contributing to heat death.
- Denaturation of proteins
- Thermal inactivation of enzymes exceeding rates of formation
- Oxygen limitation
- Effects on membrane structure
- Different processes in metastatic neurons have different temperatures
What is Q10?
When there is an increase in rate caused by a 10 degree increase in temperature
What is the Q10 equation?
Q10 = (R2/R1)10/(T2-T1)
Where R2 (higher temp) and R1 (lower temp) are rate values of the process measured at temperature T2 & T1
What does the Q10 value have to be for processes to be considered thermosensitive?
Processes with Q10 < 4 not v thermosensitive Processes with Q10 > 7 are thermosensitive
How does thermoregulation come into play when the body has a fever?😒
Body temperature increases with a fever - this increase is challenged with cooling metabolic rate which will increase to maintain the higher temperature - suggests thermostat reset
What happens when you apply heat locally to the hypothalamus?
Reduces a fever
What is the heat balance equation
Htot = Hc + Hr + He + Hs
What do the different components of the heat balance equation stand for?
Htot - rate of metabolic production Hc - rate of conductive and convective heat exchange Hr - rate of net radiation exchange He - rate of evaporative heat loss Hs - rate of heat storage in the body
What did early experiments with theromdes show?
Put thermode in preoptic are in anterior hypothalamus, can change temperature of the body.
Why is it harder for haemoglobin to carry oxygen at warmer temperatures?
Oxygen dissolves quite well in higher temperatures.
Where do thermal signals come from in the body and where do they project?
Cold and warm sensitive receptors in skin and viscera that project to the pre-optic area and act on neurons in the dorsomedial hypothalamus
What are some of the effects that happen in the body under thermoregulation to increase the temperature?
Brown adipose tissue formation, cutaneous vasoconstriction and shivering
What are the 3 pathways that thermostimulus coming in from the skin can go?
- Goes by the hypothalamus for perception of temperature and then to the somatosensory cortex
- Has a motor pathway
- Can go to the preoptic area of the anterior hypothalamus where thermoregulation takes place
