Section 38.4 (Exam 3)

Question 1

What are the two classifications of animals based on constancy of body temperature?

Answer 1

Homeotherms and Poikilotherms

Question 2

What are homeotherms?

Answer 2

animals that maintain a constant body temperature

Question 3

What are poikilotherms?

Answer 3

animals with fluctuating body temperatures

Question 4

What are the three classifications of animals based on the source of heat that determines their body temperature?

Answer 4

Endotherms

Ectotherms

Heterotherms

Question 5

What are endotherms?

Answer 5

can vary metabolic heat production

(mammals and birds)

Question 6

What are ectotherms?

Answer 6

body temperature depends on external sources of heat

(non avian reptiles, fishes, amphibians, invertebrates)

Question 7

What are heterotherms?

Answer 7

can behave either as an endotherm or an ectotherm

(animals that undergo hibernation or daily torpor)

Question 8

What are the two major differences between ectotherms and endotherms?

Answer 8

Resting metabolic rate

Response to changes in environmental temperatures

Question 9

How does the resting metabolic rate of endotherms differ from ectotherms?

Answer 9

Endotherms have a higher resting metabolic rate

(they have to expend energy to gain or lose heat)

Question 10

How does body temperature of endotherms and ectotherms vary with environmental temperature?

Answer 10

Endotherm body temperature remains constant within the survivable range

Ectotherm body temperature fluctuates directly with the environment

Question 11

How does metabolic rate of endotherms and ectotherms vary with environmental temperature?

Answer 11

Endotherm metabolic rate decreases with increasing temperature because they have less need to generate heat

Ectotherm metabolic rate correlates directly with environmental temperature because higher temperature increases the rate of reaction

Question 12

How can ectotherms regulate body temperature?

Answer 12

behavioral mechanisms

Question 13

What are some behavioral mechanisms that animals can use to regulate temperature?

Answer 13

• Burrowing or basking in the sun
• Seeking shade
• Climb vegetation
• Changing body orientation

Question 14

What is a behavioral mechanism humans use to regulate body temperature?

Answer 14

wear clothes

Question 15

How can surface temperature of an organism be controlled?

Answer 15

By altering blood flow to the skin

Question 16

How does increased blood flow to the skin affect body temperature?

Answer 16

Increases heat loss and lowers body temperature, but increases surface temperature

Question 17

How does constriction of blood vessels to the skin affect body temperature?

Answer 17

Conserves heat and body temperature, but decreases surface temperature

Question 18

How do Galapagos marine iguanas regulate body temperature?

Answer 18

Maintain body heat while swimming, and warm up quickly while basking by changing the heart rate (and the blood flow to the skin) to match the environmental temperature

Question 19

What is the function of fur on mammals?

Answer 19

insulation that retains body heat

Question 20

What if animals with fur are active and generate too much heat?

Answer 20

They lose excess heat by using special blood vessels that carry heat to hairless skin surfaces

Question 21

How is heat loss tightly controlled in the hairless skin surfaces of furry mammals?

Answer 21

Opening and closing of the special blood vessels

Question 22

How do fish produce heat?

Answer 22

metabolically

Question 23

How do fish lose heat?

Answer 23

as blood travels over the gills

Question 24

How does blood travel in “cold” fish?

Answer 24

cool, oxygenated blood travels from the gills to the aorta and is distributed to organs and muscles

Question 25

How does blood travel in “hot” fish?

Answer 25

most of the cool, oxygenated blood to the body moves through large peripheral arteries rather than through a central aorta

Question 26

Why does moving cool, oxygenated blood through the large peripheral arteries conserve more heat than moving blood through the aorta?

Answer 26

The large peripheral arteries are connected to countercurrent heat exchangers near swimming muscles that warm up the blood

Question 27

What is the function of the countercurrent heat exchanger?

Answer 27

helps keep the heat within the muscle by returning heat back to the muscles before the blood returns to the gills and loses less heat