Thermoregulation Summary

University:
Virtual High School
Course:
SBI4U | Biology
Academic year:

2023
Views:

0

Pages:

2
Author:

Emaan Zakaria

Date: Name: SBI4U Homeostasis Thermoregulation  Involves the regulation of body temperature.  Average human body temperature is 37˚ C (Note: temperatures will vary among individuals).  External temperature fluctuations often exceed the range in which our cells can efficiently function.  Recall: Enzymes have optimal temperatures and high temperatures can denature proteins  Thermoregulation is controlled by a region of the brain called the hypothalamus  The hypothalamus triggers heat loss or heat generating mechanisms  Fever is the result of a change to the set point for a biological “thermostat” How do animals regulate body temperature?  Control of body temperature occurs through balancing heat production and heat loss.  Scientists classify animals according to their major source of body warmth. o Endotherms (e.g. mammals and birds) are animals that generate most of their heat through metabolism; they are able to regulate their own body temperature regardless of external conditions. o Ectotherms (e.g. invertebrates, most fish, and reptiles) gain heat from external sources.  Both endotherms and ectotherms use behavioral responses to control body temperature.  e.g. reptiles sunning themselves on a rock, human putting on a coat, etc. Physiological response to excessive heating:  e.g. exercise, high external temperature  Sensors in brain detect increase in body temperature.  Message is sent to sweat glands to secrete sweat (evaporative cooling).  Another message is sent to blood vessels in skin; the skin blood vessels dilate, increasing blood flow to skin (promoting heat loss).  Cooler body temperature turns off mechanism. Campbell, N. A., & Reece, J. B. (2011). Campbell Biology. San Francisco, California: Benjamin Cummings. SBI4U ~ 1 of 2 ~ e-Summer School 2014 Date: Name: Physiological response to excessive cooling:  Temperature receptors in skin detect drop in temperature  message is sent to brain  Message is sent to organs and tissues; blood vessels in skin constrict limiting blood flow to skin minimizing heat loss.  Message is sent to skeletal muscles; series of rapid contractions (shivering) generates heat by increasing metabolism.  Muscles around hair follicles contract causing the hair to stand up (air is trapped within the animal’s fur to help insulate the body). o Note: this occurs in humans as well, but since we have no fur it causes “goosebumps”.  Warmer body temperature turns off mechanism. Campbell, N. A., & Reece, J. B. (2011). Campbell Biology. San Francisco, California: Benjamin Cummings. Physiological Response to Heat and Cold Raven, P., Johnson, G., Mason, K., Losos, J., & Singer, S. (2014). Biology. Canada: McGraw-Hill Ryerson Limited. Hypothermia: An Extreme Example  The state in which an individual’s body temperature is reduced below normal range.  A drop in temperature of only a few degrees can lead to a coma and possibly death. SBI4U ~ 2 of 2 ~ e-Summer School 2014