thermoregulation

Question 1

what is metabolic rate?

Answer 1

= rate at which energy is released by the breakdown of food

Question 2

what factors affect the metabolic rate?

Answer 2

• stress
• exercise
• body temperature

Question 3

what happens to the rate of biochemical reactions for each 1 degree Celcius rise in body temp?

Answer 3

• 10% increase

= high fever = double normal metabolic rate

Question 4

what are peripheral receptors?

Answer 4

• found in skin + mucous

- detect temp changes in the external environment and send this information to the hypothalamus

Question 5

what are central thermoreceptors?

Answer 5

• found in the hypothalamus

- detect the temperature of the internal environment

Question 6

what are the two main types of thermoreceptors?

Answer 6

• peripheral

- central

Question 7

what are cold receptors?

Answer 7

• stimulated by lower temperatures

Question 8

what are heat receptors?

Answer 8

• detect temperatures higher than normal

Question 9

what happens when cold receptors are stimulated?

Answer 9

• hypothalamus receives information and initiates heat conservation and heat production mechanisms

Question 10

what happens when heat receptors are stimulated?

Answer 10

• mechanisms operate to reduce heat production and increase heat loss

Question 11

what are 4 ways the body can lose heat through the skin?

Answer 11

• conduction
• convection
• radiation
• evaporation

Question 12

what is conduction?

Answer 12

transfer of heat by direct contact between particles

Question 13

what is convection?

Answer 13

transfer of heat by the movement of liquid or gas

Question 14

what is radiation?

Answer 14

transfer of heat by infrared radiation being emitted by objects

Question 15

what is evaporation?

Answer 15

vaporization of sweat off the skin to create the cooling effect

Question 16

what is vasodilation?

Answer 16

• increase in diameter

- more blood is transported to the capillaries in the skin and the rate of heat loss increases

Question 17

what is vasoconstriction?

Answer 17

• decrease in diameter

- less blood is transported to the capillaries in the skin and the rate of heat loss decreases

Question 18

what is sweating?

Answer 18

• active secretion of fluid by the sweat glands and the periodic contraction of cells surrounding the ducts to pump the sweat to the skin surface
• stimulated by sympathetic nerves

Question 19

what is the cooling effect?

Answer 19

= evaporation of sweat from the skin

• heat is removed from the skin when sweat changes to vapor
• cooling of the skin results in cooling of the blood flowing through the skin

Question 20

what is a mechanism used to gain heat?

Answer 20

= shivering

• increase in skeletal muscle tone, producing muscle tremors
• heat produced by the muscles is released as heat

Question 21

describe the thermoregulatory feedback loop (vasoconstriction)

Answer 21

stimulus = low body temp
receptors = central thermoreceptors in the hypothalamus and peripheral thermoreceptors in the skin and mucous membranes detect drops in body temp and send a nerve impulse to the hypothalamus 
modulator = hypothalamus send nerve impulses via sympathetic nerves to blood vessels in the skin
effector = blood vessels in the skin
response = vasoconstriction of blood vessels in skin → reduces heat loss via radiation and convection

Question 22

describe the shivering feedback loop

Answer 22

stimulus = low body temp
receptors = thermoreceptors in hypothalamus and peripheral thermorecptors in skin and mucous membranes
modulator = the hypothalamus sends nerve impulse via sympathetic nerves to skeletal muscle
effector = skeletal muscles
response = contraction and relaxing of nerve skeletal muscle fibres to produce metabolic heat from shiverin