3/18-3/25 Endotherms and Ectotherms Flashcards
On average only birds and mammals use homeothermy, why don’t most animals use this method of temperature regulation?
It is very expensive.
To be an endotherms should you have a large or small body size?
large decent body size
from burning one gram of carbs does endothermic animals gain any more energy/heat than ectothermic animals?
No
What role does insulation play into the maintainment of a constant body temperature?
Very minimal. Birds have very poor insulation aka feathers. Over time they have decreased their weight and increased their power for flight and the birds that do have a very strong insulation cannot fly aka penguins. Humans also have very poor insulation we have coarse hair and no fur. It does not require good insulation to be an endotherm.
If you are small aka have a small mass to surface area ratio will you gain or lose heat?
You will lose heat more readily
Why are endotherms able to keep a stable warm body temperature?
Across the membranes, endotherms have anywhere from 5-10 times the number of sodium/potassium molecular pumps and the cycles in between the movement of sodium and potassium are much shorter so 5-10 times more ions are moved overall. Since ATP is hydrolyzed each action of the pump heat is also produced and thus the metabolic rate is 5-10 times greater than ectotherms.
For the membranes of endotherms to work 5-10 times harder what characteristic must the pumps have?
They must be extremely leaky. They leak potassium quickly and sodium is even leaked easier across endothermic membranes than ectothermic membranes.
What is the futile cycle?
Expenditure of energy with no net work being done no net outcome
What is the main difference between the ecothermic and endothermic animals?
Endothermic animals have an increase in the number of molecular pumps and number of ions moved that leads to a higher metabolic rate and thus a relatively constant internal temp.
What is the specific control mechanism in endotherms that has the ability to sense the heat generated and ensures enough to keep a stable body temperature?
hypothalamus
WHat happens when lesions are introduced into the hypothalamus of endothermic animals such as dogs?
They lose the ability maintain a stable body temperature. They still have a futile cycle going on but they over heat then cool down too much and cannot regulate their own body temperature.
What can be considered the thermostat of the human body?
The hypothalamus
What was the experiment done on Beagles to provide evidence that the hypothalamus is the specific control center for body temperature?
Into the hypothalamus a thermocouple was inserted. The thermocouple temperature can be increased or decreased. Dogs have a body temp of 37.8 degrees. When researchers reduced the temperature in the hypothalamus, when the temperature reached 36 degrees the dog began to shiver regardless of the temperature outside. When the temp was increased to 39 degrees the dog began to pant. The set point exhibited were precise.
What role does the outside temperature play in the hypothalamus maintenance of the internal body temp?
It is a form of physiological anticipation That when combined with a change in the hypothalamus temperature, a faster reaction is seen to regulate body temperature.
True or false the hypothalamus is sensitive to its own temperature?
True
The set point is constant in the hypothalamus, however changes in the ambient temperature will cause what?
changes in the set points for shivering and panting.
Heat production and heat loss mechanisms are plastic. What does this mean?
They are graded responses they can be moved.
What is shivering thermogenesis?
Skeletal muscles that spontaneously contract involuntary that produces heat but very little to no physical work is being done.
What type of ectotherm uses shivering thermogenesis?
Female indian pythons
Through shivering thermogenesis the female indian python could keep her eggs how many degrees water than the ambient temperature?
7-9 degrees centigrade
How do honey bee swarms use thermogenesis?
They shiver as a group. A ball of bees that constantly move, they vibrate their wings and the bees in the middle migrate towards the outside and the bees on the outside migrate towards the middle. The inside of the ball of bees is 25-30 degrees warmers than the ambient temperature.
Hoe do large flighted insects such as dragonflies generate heat? And by how much can they increase their body temperature?
They shiver they vibrate the wings and it generates heat. They can increase their body temperature up 20 degrees.
What is nonshivering thermogenesis?
Method to produce heat through some homeostatic control without shivering. Rats when paralyzed placed in cold weather still maintained warm temperatures.
What is BAT?
Brown adipose tissue
What is the significance of BAT?
Produces heat for animals. Only found in three specific types of mammals. It is only about 1-3 percent of the total body weight.
What three types of mammals does BAT show up in?
- newborn mammals
- cold acclimatized adults
- hibernate and torpid animals
What is the difference between acclimation and acclimatization?
Acclimation occurs in the lab and only one factor is changed. Acclimatization occurs in nature
Where is the location of BAT on animals?
between the shoulder blades and up onto the neck, also in the axilla, and the under sternum…aka wraps around the heart