Homeostasis

Question 1

What is homeostasis?

Answer 1

Keeping the internal environment constant despite changes to the external environment

Question 2

What are the 6 conditions which are to be kept constant?

Answer 2

-Body temperature
-Blood glucose concentration
-Blood salt concentration
-Water potential of blood
-Blood pressure
-CO2 concentration

Question 3

What is the feedback loop of homeostasis?

Answer 3

Conditions in body change (stimulus) -> Change detected -> Corrective mechanism activated (response) ->Conditions returned to set point -> Corrective mechanism switched off

Question 4

What are the two types of feedback loops?

Answer 4

Negative and Positive

Question 5

Which type of feedback loop is used by most systems?

Answer 5

Negative

Question 6

What is a negative feedback loop?

Answer 6

Deviation from the set point that causes changes that bring the level back towards set point

Question 7

Examples of a negative feedback loop.

Answer 7

-Temperature
-Water Potential
-Blood Glucose

Question 8

What is a positive feedback loop?

Answer 8

Deviation from the set point that causes changes that result in an even greater deviation from the normal.

Question 9

Examples of a positive feedback loop.

Answer 9

-Excitation of Neurons
-Onset of Uterine Contraction at Birth

Question 10

What are Endothermic animals?

Answer 10

Animals which are able to maintain their body temperature within very tight limits (humans)

Question 11

What are Ectothermic animals?

Answer 11

Animals that have a core body temperature that fluctuates with ambient and are reliant on external sources to heat to keep warm

Question 12

What are advantages of endotherms?

Answer 12

-Constant body temperature
-Activity possible in cold environments
-Ability to inhabit colder areas of the planet

Question 13

What are disadvantages of endotherms?

Answer 13

-High proportion of food energy used in thermoregulation
-Need to eat more food
-Less energy for growth

Question 14

How do endotherms regulate their temperatures?

Answer 14

-Sweat glands in skin
-Mouth/Nose/Lungs
-Hairs on skin
-Arteriole vasodilation/vasoconstriction
-Liver cell metabolism
-Skeletal muscles
-Behavioural methods

Question 15

What are advantages of ectotherms?

Answer 15

-Use less food for respiration
-Can survive long periods without eating
-More energy from food can be used for growth

Question 16

What are disadvantages of ectotherms?

Answer 16

-Less active in colder areas/times so at risk of predation
-May not be active all winter so need sufficient stores of energy

Question 17

How do ectotherms regulate their temperatures?

Answer 17

-Use behavioural methods to adjust heat exchange with the environment
-Some are more specifically adapted to help

Question 18

What happens if there is a rise in core temperature in order to create the temperature to fall back to optimum?

Answer 18

-Thermoregulatory centre in hypothalamus detects change -> Nervous system and hormonal system carry signals to skin, liver and muscles -> Less heat generated and more heat lost

Question 19

What happens if there is a fall in core temperature in order to create the temperature to fall back to optimum?

Answer 19

-Thermoregulatory centre in hypothalamus detects change -> Nervous system and hormonal system carry signals to skin, liver and muscles -> More heat generated and less heat lost