Endothermy

endothermy.md

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 # Endothermy
 
 - Present in [[Mammalia]] and [[Aves]]
+- [[Brown fat]] [[mitochondrion]]
+  - Puts food and oxygen towards generating heat instead of ATP
+- Maintaining body temperature is important for [[enzymes]] to operate
+- Metabolic rate _decreases_ when temperature increases, the direct opposite
+  of [[ectothermy]]
+- [[Fish]] swimming styles
+  - [[Tuna]]: [[Thunniform swimming]] with a narrow [[caudal peduncle]] and a
+    sickle-shaped tail, leaves less turbulence behind and uses less energy
+  - [[Trout]]: [[Subcaraigiform swimming]] leaves turbulence behind but allows
+    more mobility
+  - Most kinds of fish are [[ectothermy|ectothermic]]
+  - Thunniform swimmers have the muscles they use on their inside, so heat
+    is generated internally, where most fish have their swimming muscles on
+    the outside which get cooled by the water
+  - This elevated body temperature allows them to be fast thinkers and movers
+- Endothermy is costly
+  - We expect endotherms to reduce the costs via adaptations
+  - We expect endothermy to only evolve when the costs can be offset
+  - Minimizing heat loss
+    - [[Gigantothermy]]: The bigger you are, the less surface area there is to
+      lose body temperature to
+    - Allow temperature to drop purposefully during some times in some places
+      - [[Hibernation]]
+      - Reducing circulation
+    - [[Insulation]]: Hot-body radiation only occurs at the surface, so if
+      you can prevent heat from reaching the surface, you can prevent
+      hot-body radiation
+      - [[Feathers]]: When you pick up a bird it will be cold, although without
+        its feathers it would be warm
+    - [[Countercurrent Heat Exchange]]: If the blood on the way back from
+      an extremity would be cold, wrap the veins around the arteries so the
+      returning blood warms up while the leaving blood cools