Communication and homeostasis

Question 1

Explain why it is important for multicellular organisms, such as humans, to have communication systems?

Answer 1

. humans need to respond to changes in their environment
. information will be passed on from a receptor to an effector in order to bring a response about
. an example of this is homeostasis where internal and external conditions in the body are kept constant to promote optimum conditions for enzyme and cell function

Question 2

what does a receptor do?

Answer 2

detects a change in the stimuli (environment)

Question 3

what does an effector do?

Answer 3

responds to the change detected by receptors

Question 4

two examples of effectors?

Answer 4

muscles and glands

Question 5

what are two communication systems?

Answer 5

1. nervous system
2. endocrine system

Question 6

define homeostasis?

Answer 6

a process which keeps the internal and external body conditions constant within restricted limits so conditions are at their optimum for enzyme action and cell function

Question 7

examples of homeostasis that keeps body conditions constant and regulated?

Answer 7

blood glucose concentration
water levels in the body
blood ph
body temperature

Question 8

what is cell signalling?

Answer 8

when cells in a multicellular organism communicate with each other by secreting chemicals

Question 9

name the the chemicals found in the 1. nervous system and the 1. endocrine system which are secreted during cell signalling?
what chemical in nervous
what chemical in endocrine

Answer 9

nervous : neurotransmitters
endocrine : hormones

Question 10

what is autocrine cell signalling?

Answer 10

cell signalling to itself and receives its own signal

Question 11

what is endocrine signalling?

Answer 11

signalling between distant cells via the bloodstream

Question 12

what is paracrine signalling?

Answer 12

signalling between adjacent cells

Question 13

what molecule is always secreted by the endocrine signalling system and where are they transported between?

Answer 13

molecule always a hormone
transported between circulatory systems

Question 14

explain each step of the negative feedback loop?
6 stages

Answer 14

1. optimum conditions
2. changes away from optimum conditions
3. receptor detects change
4. communication system informs effector
5. effector responds and reacts to reverse the change
6. return to optimum conditions

Question 15

explain the steps of the positive feedback loop?
5 stages

Answer 15

1. optimum condition
2. changes away from optimum condition
3. receptor detects change
4. communication system informs effector
5. Effexor reacts increasing change

then goes BACK to stage 2!

Question 16

what is a feedback loop? definition?

Answer 16

informs receptor of changes the system brought about by effectors

Question 17

how to endotherms control their body temperature?

Answer 17

within restricted limits
control body temp independently from external temperatures

Question 18

how to exotherms control their body temperature?

Answer 18

rely on external sources of heat, like a heat lamp
may use behavioural mechanisms to control body temp

Question 19

name the 4 ways an endotherm may use to warm up?

Answer 19

1. exergonic actions like respiration that releases energy
2. vasocronstriction
3. shivering
4. piloerection = goosebumps

Question 20

what is vasoconstriction and how does it warm an endotherm up?

Answer 20

. when arterioles constrict
. blood shunted away from the skin so less heat is lost

Question 21

how does shivering warm an endotherm up?

Answer 21

1. multiple rapid contractions of skeletal muscle
2. more respiration in muscle cells
3. more heat energy released

Question 22

how does piloerection warm an endotherm up?

Answer 22

hairs stand on the end which creates a warm layer of air trapped around skin for insulation

Question 23

name the two ways in which an endotherm will cool down?

Answer 23

. vasodilation
. sweating

Question 24

how does vasodilation cool down an endotherm?

Answer 24

1. arterioles dilate
2. blood shunted towards the skin
3. more heat lost

Question 25

how does sweating cool down an endotherm?

Answer 25

1. the sweat water molecules absorb the heat energy from the skin 2. causes sweat / water from skin to evaporate 3. causes skin to lose heat energy

Question 26

describe two ways ectotherms warm up?

Answer 26

. absorb heat energy from solar radiation . condition to absorb heat energy from rocks and other surfaces

Question 27

what are two ways ectotherms cool down?

Answer 27

seeking shade drinking water

Question 28

strengths of endotherms? name three?

Answer 28

1. stable internal temperature allows to remain active with wide range of environments 2. can be active at any time and season 3. sustain high levels of activity because enzymes constantly at optimum temperatures

Question 29

weaknesses of endotherms? name 3

Answer 29

1. high energy demand , need to eat more food for thermoregulation 2. more energy from food goes into maintaining body temperature rather than growth or reproduction 3. may struggle to survive with scarce food environments

Question 30

name 3 strengths of ectotherms?

Answer 30

1. use less energy for thermoregulation , can survive with less food 2. more energy from food goes into growth and reproduction 3. survive in environments of limited food

Question 31

name 3 weaknesses of ectotherms?

Answer 31

1. Activity levels are temperature-dependent 2. Limited to warmer environments 3. Less control over internal temperature so may be more vulnerable