5.1 communication and homeostasis

Question 1

define cell signalling

Answer 1

the way in which cell communicate with each other

Question 2

what will a good communication system be able to do

Answer 2

cover the whole body
enable cells to communicate with each other
enable specific communication
enable rapid communication
enable both short and long-term responses

Question 3

define homeostasis

Answer 3

maintaining a constant internal environment despite changes in external and internal facots

Question 4

define negative feedback

Answer 4

the mechanism that reverses a change bringing the system back to the optimum

Question 5

define positive feedback

Answer 5

the mechanism that increases a change taking the system further away from the optimum

Question 6

define ectotherm

Answer 6

an organism that relies on external sources of heat to maintain body temperature

Question 7

define endotherm

Answer 7

an organism that uses heat from metabolic reactions to maintain body temperature

Question 8

what do ectotherms do if they aren’t warm enough

Answer 8

move into a sunny area
lie on a warm surface
expose a larger surface area to the sun

Question 9

what do ectotherms do if they are too hot

Answer 9

move out of the sun
move underground
reduce body surface exposed to the sun

Question 10

what are some examples of ectotherms and what are their behavioural adaptations

Answer 10

snakes bask in the sun

lizards use burrows and crevices

horned lizards can change their shape by contracting and expanding their ribcage

Question 11

What are some advantages of ectotherms

Answer 11

less of their food is used in respiration

more of the energy from food can be converted into growth

they can survive long periods without food

Question 12

what are some disadvantage’s of ectotherms

Answer 12

they are less active in cooler temperatures so this makes them more vulnerable to predators

Question 13

define exergonic

Answer 13

release of energy in the form of heat

Question 14

what are some organs that contain physiological adaptations to maintain body temperature in endotherms

Answer 14

skin
gaseous exchange system
liver
skeletal muscles
blood vessels

Question 15

What is the skins response if it is too hot

Answer 15

sweat glands secrete fluid to be evaporated of the skin by using blood as the latent heat of vaporisation

hairs and feathers lie flat to reduce insulation

vasodilation of arterioles and precapillary sphincters directs blood to the skin surface so more heat can be radiated from the body

Question 16

What is the response of the gaseous exchange system if it is too hot

Answer 16

panting to evaporate water from the surface of the lungs and airways and uses blood as the latent heat of vaporisation

Question 17

What is the response of the liver if it is too hot

Answer 17

less respiration takes place so less energy from food is converted to heat

Question 18

What is the response of the skeletal muscles if it is too hot

Answer 18

less contractions means less heat is released

Question 19

What is the response of the blood vessels if it is too hot

Answer 19

vasodilation to direct blood to the extremities so that more heat can be lost

Question 20

what are the advantages of endothermy

Answer 20

maintains a fairly constant body temperature

remain active even when temperatures are low

inhabitance of colder habitats

Question 21

what are the disadvantages of endothermy

Answer 21

may overheat in hot weather

need more food

use a significant part of their energy intake on maintaining body temperature

Question 22

What part of the brain regulates homeostatic responses

Answer 22

the hypothalamus

Question 23

what is the role of the periphery receptors

Answer 23

the thermoregulatory centre in the hypothalamus monitors blood temperature

However if the extremities begin to be too hot or too cold they send signals to the brain for behavioural adaptations such as going in the shade to occur

Question 24

What is the role of the hypothalamus in control of temperature regulation

Answer 24

Temperature receptors in the hypothalamus detect changes in the temperature and then send impulses
the neuronal system transmits impulses for rapid responses and the hormonal system is used for a long-term response