5.1.1 Flashcards
Why do plant need to respond to their external env?
avoid herbivory
grow towards sunlight / water
Why do animals need to respond to their environment?
eat/catch prey
avoid predation
What are abiotic and biotic factors?
abiotic is non-living
biotic is living
What needs to be regulated in the internal environment?
blood glucose concentration
internal temperature
water potential
cell pH
What needs to be regulated in the external environment?
humidity
external temperature
light intensity
new or sudden sound
What is a transducer?
a receptor that will convert one form of energy into another form of energyW
What is an example of a transducer?
receptors
What is a feature of receptors?
specific to 1 particular stimulus
What is an effector?
brings about a response to a stimulus
What secretes hormones?
glands
What are the 2 types of hormones?
Lipid-based
Non-lipid based
What can lipid-soluble hormones do?
diffuse straight through the phospholipid bilayer and act upon DNA
Why can peptide hormones not diffuse through the phospholipid bilayer?
too large
How do peptide hormones enter the phospholipid bilayer?
1st messenger and 2nd messenger response
What is the 1st messenger?
hormone
What does the hormone do?
binds to receptor on the cell surface membrane
How does the hormone bind to the receptor?
complimentary and specific in shape
What happens when the hormone binds to the receptor in the 1st msg 2nd msg response?
activates enzyme
adenyl cyclase
What does adenyl cyclase do?
activates 2nd messenger
What is the 2nd mesenger?
cAMP
What does cAMP do?
trigger a response inside the cell
Outline the entire 1st messenger 2nd messenger response?
First messenger = hormone
hormone binds to receptor
on c.s.m
as they are complimentary and specific in shape
activates adenyl cyclase enzyme
adenyl cyclase activates cAMP
cAMP triggers a response inside the cell
What is cell signalling?
communication between cells
cell recognition / identification
cells working together
to trigger a response
What is homeostasis?
maintaining a relatively stable internal environment / state
within narrow limits
even though the env is changing
Why does core body temp need maintaining?
enzymes and other proteins like channel proteins are sensitive to changes in temp
optimum temp
low temp - no efficient
Why does blood glucose concetration need to be maintained?
Glucose is used as a repsiratory substrate by cells so they need a constant supply
keeping it constant, ensures a constant water potential
What is ATP used for?
muscle contraction and active transport
What is glucose used for?
to generate ATP
Why does the W.P of blood need to be maintained?
W.P
changes in the water potential of blood may cause cells to shrink or expand as water leaves/ enters by osmosis
if not kept constant cells cannot function properly
What is negative feedback?
effector causes a change to bring internal env back to normal conditions
What is positive feedback?
situation is amplified until a change is brought about
What are endotherms?
Warm blooded animals that regulate their own internal temperature
What are ectotherms?
cold-blooded animal that does not regulate its own internal temperature using behaviourial responses
Why do ectotherms bask in the sun?
aerobic respiration
to generate ATP
for muscle contraction
What does hypothalamus do?
sends messages to parts of body by ANS
contains thermoreceptors
What happens in vasoconstriction?
less blood flow near surface of skin
What happens to blood flow in vasodilation?
more blood flows clsoer to skin surface
What do hair erector muscles do?
contracts
relaxes
hairs standing on end trap insulating layer of air
What happens when temp inc?
temp receptors on skin detect inc temp
sensory neurone passes this to thermoreceptors
motor neurones pass this to
skeletal muscles to prevent shivering
vasodilation
relaxation of hair erector muscles
shivering
dec production of thyroxine and adrenaline
dec in metabolsim
dec in heat production as by product of aerobic repsiration
normal temp
What initally detects the inc in temp?
temp receptors in skin
What passes impulses from temp receptors in skin to thermoreceptors?
sensory neurone
What passes impulses form thermoreceptors to effectors?
motor neurones
What do effectors do when temp inc?
skeletal muscle prevent shivering
vasodilation
relaxation of hair erector muscles
sweating
dec production of adrenaline and thyroxine
What happens when the temp dec compared to normal?
temp receptors in skin detect dec
sesnory neurone sends impulses to thermoreceptors in hypothalamus
motor neurones send impulses to effectors
skeletal muscles shivering
vasoconstirction
contractipon of hair erector myscle
hairs stand on end
trapping insulating layer of air
no/little sweating
inc prod of adrenaline and thyrioxine
inc in metabolism
inc heat prod
as by product of areobic resp
What sends impulses from receptors in skin to hypothalamus?
sensory
What sends impulses from the thermoregulatory centre to the effector?
motor neurones
What does the effector do when temp dec?
skeletal muscles shivering
vasoconstirction
contractipon of hair erector myscle
hairs stand on end
trapping insulating layer of air
no/little sweating
inc prod of adrenaline and thyrioxine
inc in metabolism
inc heat prod
as by product of areobic resp
Why do smaller organisms struggle to maintain their body temperature compared to mammals and birds?
(insects are smaller and) have a , large(r) / AW , surface
area to volume ratio
(insects have) greater rate of heat loss
mammals and birds have , more effective / thicker ,
insulation
ref to a method of more precise control of body
temperature in birds and mammals
Why are moths and bumblees described as endothermic?
scales and hair help to reduce heat loss
generate heat from , respiration / metabolism
