chapter 15- homoestasis

Question 1

What term is used to describe communication between adjacent cells or cells at a distance?

Answer 1

cell signalling

Question 2

What two systems are used in animals to coordinate responses to changes in the environment?

Answer 2

the hormonal and the nervous system

Question 3

What name is given to the type of homeostatic control in which the response to a stimulus restores a factor to its original set point?

Answer 3

negative feedback

Question 4

What name is given to the type of homeostatic control in which the response to a stimulus causes a factor to deviate further from its original set point?

Answer 4

positive feedback

Question 5

What is a receptor?

Answer 5

A cell or protein that detects one specific type of stimulus.

Question 6

what is steady or stable state

Answer 6

the reference point, the ideal

Question 7

what is dynamic equilibrium

Answer 7

changes and fluctuation about the norm/set point

Question 8

what is negative feedback

Answer 8

something is switched off, work is done to reverse the initial stimulus and restore whatever to the base level, switching off a mechanisms once the baseline level has been rectified

Question 9

what is positive feedback

Answer 9

once a change is detected, the effectors reinforce that change increasing the response (keep increasing)

Question 10

what is the normal level

Answer 10

the range around the optimum/set point

Question 11

examples of positive feedback

Answer 11

childbirth
lactation
blood clotting
opening of voltage gated Na+ channel proteins in the axolemma

Question 12

examples of negative feedback systems

Answer 12

thermoregulation
blood glucose regulation
water balance in the body

Question 13

homeostasis is dependent on variables eg ……
and they need to be regulated despite..

Answer 13

pH of extracellular fluid, body temp

despite changes in environment, diet, level of activity

Question 14

what is the difference between terrestrial and marine ectotherms

Answer 14

many marine ectotherms dont need to thermoregulate because water has a high specific heat capacity so temp of environment doesnt change much

for terrestrial ectotherms the temp of the air changes dramatically over short periods of time (days/hours/seasons) so have developed behavioural and physiological responses to thermoregulation

Question 15

why is thermoregulation important as a homeostatic process

Answer 15

for enzymes
activation energy
KE and the rate of chemical reactions
to maintain set point

Question 16

what is an ectotherm

Answer 16

they cannot maintain body temp by themselves so rely on using the surroundings to warm their bodies, core body temp is heavily dependent on the environment

metabolic processes not enough to maintain constant body temp

inc invertebrates, fish, amphibians and reptiles

used to be known as cold blooded

An animal which depends on the environment to regulate its internal body temperature.

Question 17

what can gains in heat come from

Answer 17

waste heat from cellular respiration.
conduction from the surroundings.(contact)
convection from the surroundings.(current)
radiation from the surroundings (emwaves)

Question 18

examples of losses of heat

Answer 18

latent heat of evaporation of water (as sweat from blood)

conduction
convection
radiation

Question 19

examples of behavioural responses for ectotherms for warming up (general)

Answer 19

basking in the sun, orientation of the body to maximise exposure to the sun (increase sa to the sun)

pressing their bodies against warm surface- conduction

increasing metabolic reaction eg movement, exercise

Question 20

examples of behavioural responses for ectotherms for warming up (specific)

Answer 20

lizards bask to get warm enough to move fast and hunt prey

butterflies orientate for max exposure to the sun spread their wings

moth and butterflies vibrating their wings

galapagos iguanas contract and vibrate their muscles increasing cellular metabolism

Question 21

examples of behavioural responses for ectotherms for cooling down (general)

Answer 21

sheltering in burrows
pressing body against cool surface- conduction
orientating body to expose the least sa to the sun.
minimising movement to reduce metabolic reactions

Question 22

examples of behavioural responses for ectotherms for cooling down (specific)

Answer 22

seek shade, hiding in cracks of rocks, digging burrows, move into water or mud, cold rocks, stay still

Question 23

advantages of ectotherms

Answer 23

need less food/feed on food of a lower calorific quality.
can have bigger population in a habitat.
allows sit and wait foraging strategy which uses less energy

Question 24

example of ectotherm: goldenrod crab spider

Answer 24

wait on flower for fly. fly is attracted to flower and so the spider gets the fly. waiting is a learnt response (behavioural)

Question 25

physiological responses warming/cooling for ectotherms plus egs

Answer 25

lizards in cooler climates have darker skin so the skin absorbs radiant heat more easily

alter heart rate to inc or decrease metabolic rate

Question 26

Sun basking and shade seeking are both examples of which type of response shown by ectotherms to help them control internal temperature?

Answer 26

behavioural response

Question 27

What is meant by the term “endotherm”?

Answer 27

An animal that maintains a constant/stable internal body temperature regardless of the
external temperature by generating heat through metabolic processes.

Question 28

In endotherms, temperature receptors are located in which two parts of the body?

Answer 28

skin and hypothalamus

Question 29

In endotherms, which part of the brain is involved in thermoregulation?

Answer 29

hypothalamus

Question 30

What is seen in endotherms in response to a rise in core body temperature?

Answer 30

vasodilation, sweating, loweing hair by relaxing erector muscles

Question 31

What is seen in endotherms in response to a fall in core body temperature?

Answer 31

vasoconstriction, shivering, raising hair by contracting hair erector muscles