homeostasis

Question 1

what is an effector

Answer 1

cell tissue or organ bringing a response to reverse a change or contribute to a change internally

Question 2

what is homeostasis

Answer 2

maintaining a constant internal environment, withing a narrow range despite changes in the external or internal factors

Question 3

what is negative feedback

Answer 3

mechanism which reverses a change, bringing the system back to optimum

Question 4

what is positive feedback

Answer 4

mechanism which increases a change bringing system farther away from optimum, usually harmful

Question 5

what is more common- negative or positive feedback

Answer 5

negative

Question 6

what are sensory receptors

Answer 6

cell nerve endings that respond to a stimulus in internal/ external environment and create action potentials

Question 7

name factors that homeostasis controls

Answer 7

body temperature
blood glucose concentration
blood pressure
co2 conc
water potential of blood

Question 8

what is the standard response pathway

Answer 8

stimulus
receptors
communication pathway/ cell signalling
effector
response

Question 9

give an example of a sensory receptor

Answer 9

temperature receptors/ thermoreceptors on skin surface which monitor the conditions externally

Question 10

give an example of an interal sensory receptors

Answer 10

temperature receptors in the brain- when it detects a stimulus, it sends an output messenger to the effector

Question 11

what is an input

Answer 11

messages sent from receptor to the coordination centre

Question 12

what organ is the coordination centre

Answer 12

brain

Question 13

what are the two communication system

Answer 13

neuronal

hormonal

Question 14

what does a communication system enable

Answer 14

a form of cell signalling

allows transmission of messages from receptors to effectors

Question 15

what is an output

Answer 15

messages sent to effectors from coordination centre

Question 16

describe negative feed back

-what happens

• reduction in further activity

Answer 16

stimulus- change in conditions
receptors detect stimulus and sends an input to the coordination centre.
coordination centre recieves input and sends output to the effectors
effectors bring change to reverse initial change
system is closer to optimum

stimulus then reduces, input and out put reduces, effectors reduce activity

Question 17

what are the processes that take place to make negative feedback successful

Answer 17

stimulus must be detected

stimulus must be signalled to cells

there must be an effective response which reverses conditions

Question 18

are conditions always perfect?

Answer 18

no they are constantly fluctuating

Question 19

give an example of positive positive feedback

Answer 19

during birth
when cervix dilates, the pituitary gland produces oxytocin (hormone to dilate cervix more)
the more the cervix dilates, the more oxytocin produced.
increasing the change

birth ends production of oxytocin

Question 20

name two types of effector

Answer 20

muscle cell or cells in glands

Question 21

what is an ectotherm and endotherm

Answer 21

ectotherm- cold blooded animal

endotherm- warm blooded animal

Question 22

how do ectotherm control body temp

Answer 22

expose there bodies to the sun
take shelter to prevent overheating
burrow to prevent overheating
press bodies against ground to gain warmth
Generate metabolic heat- respiration provides small amount of heat.

Question 23

when endotherms are too hot, what are their physiological abilities to cool themselves down

Answer 23

vasodilation- arteriole diameter largens therefore more blood passes skin surface and heat is lost by radiation

panting- air evaporates water in mouth and cools them

sweating- heat from skin provides energy for evaporation

Question 24

when endotherms are too cold, what are their physiological abilities.

Answer 24

vasoconstriction- arteriole diameter near skin is reduced so more blood is insulated inside body, no heat lost by radiation

shivering- involuntary muscle contractions to generate metabolic heat caused by production of adrenaline or thyroxine

piloerection- hairs stand to trap layer of air near skin and insulate it

Question 25

what area of the brain control body temperature

Answer 25

Hypothalamus- by monitoring the temperature of blood passing through it

Question 26

name four structures on the skin involved in mammal thermoregulation

Answer 26

Fat tissue
hair erector muscles
arterioles
sweat gland

Question 27

can ectotherms thermoregulate

Answer 27

No

Question 28

what are the advantages of ectotherms

Answer 28

respire less, therefore the food they eat is used for growth not energy- therefore they need less food.

Question 29

what are the disadvantages of ectotherms

Answer 29

less active in cool temp and not capable of activity in winter as they hibernate

Question 30

what are the advantages of endotherms-

Answer 30

they can maintain a constant temperature
active in cold temperature

Question 31

what are the disadvantages of endotherms-

Answer 31

more food is needed and energy goes to metabolism and not growth.
will need more food
may overheat in hot weather

Question 32

what actions does the liver do if it is too hot or cold

Answer 32

less respiration so less heat is released, if too hot

more respiration in hepatocytes so more energy from food is converted to heat.

Question 33

name sensory cell in skin that detects change in environmental temperature change

Answer 33

thermoreceptor

Question 34

if blood glucose concentration is low- what does the effector produce

Answer 34

glucagon

Question 35

if blood glucose concentration is high, what does the effector produce

Answer 35

insulin.

Question 36

why does shivering not conserve heat

Answer 36

shivering doesnt conserve heat it generates it.