Responding To Change - Unit 2 Flashcards
What does homeostasis mean?
keeping the body’s internal environment consistant
What is osmoregulation?
Regulating water content
What is thermoregulation?
Regulating body temperature
What is blood glucose regulation?
Regulating blood glucose
What is negative feedback?
When something changes in the environment it trigger a response that counteracts the change - e.g a rise in body temp causes a response that lowers body temp.
When wont negative feedback work?
When the environment changes too much
What part of the body controls body temperature?
The Hypothalamus (part of your brain)
What happens when you are too hot
Erector hair muscles relax, so hairs lie flat Lots of sweat is produced because it cools you down when it evaporates Blood vessels close to the skin dilate (widen) (vasodilation) it allows more blood to flow near the surface so it can transfer more heat into the surroundings.
What happens when you are too cold
Erector muscles contract, hairs stand on end Very little sweat is produced Vasoconstriction. Blood vessels near the skin constrict so less heat is transferred to the surroundings
What is a hormone?
Chemical messages sent in the blood
What are the two ways signals can be sent in your body?
Using hormones or nerves
What do hormones travel in
Blood
What are the cells and organs called that hormones affect?
Target cells Target organs
What kind of effect does a hormone have
A long lasting effect
How do neutrons send signals
The transmit an electrical impulse
What is the branched ending of a nerve called
Dendron
Why do dendrites have branched endings
To connect with lots of other neurones
What part of the cell is the electrical impulse passed along
The axon
What does a myelin sheath do
It acts as an electrical insulator which stop the impulse getting lost
What is the connection between neurones called?
A synapse
What chemicals transmit the nerve impulse
Neurotransmitters
What are the differences between hormones and nerves?
Nerves: Very fast message Act for a very short time Act on a very precise area Electrical message Hormones: Slower message Act for a long time Act in a more general area Chemical message
What is a stimulus
A change in your environment
What are the 5 sense organs
Eyes Ears Nose Tongue Skin
What are receptors
A group of cells which are sensitive to a stimulus. They change stimulus energy into electrical impulses
What receptors does each of the sense organs have
Eyes - light receptors
Ears - sound and balance receptors
Nose - smell receptors
Tongue - taste receptors
Skin - pressure and heat receptors
What parts of the body are in the central nervous system
Brain spinal cord
What does the central nervous system do
Coordinates the response to the stimulus
What is an effector
A muscle or gland that responds to a nervous impulse or secretes a substance e.g hormones
name the parts of the motor neurone
a) dendron
b) axon
c) effector cells
name the parts of a relay neuron
what do motor neurones do
many short dendrons and one long axon carry nerve impulses from the CNS to the effectors.
what does a relay neuron do?
many short dendrons and axons carry nerve impulses from sensory neurones to motor neurones
what are the parts of a sensory neurone
what does a sensory neurone do
long dendrons and short axons carry nerve impulses from the receptors on the sense organs to the CNS
what order does the reflex arc go in?
stimulus
receptor cells
sensory neurone
nerve impulse
synapse
relay neurone
synapse
motor neurone
neurotransmitter
effector
response
which types of food put glucose into your blood?
carbohydrates
what activity removes glucose from the blood?
vigerous exxercise
what hormone is released if your blood glucose levels are too high?
Insulin
what part of your body releases insulin and glucagon?
pancreas
what does insulin do when it is released?
it gets transported to the liver by blood. then it makes the liver turn some glucose into glycogen
what hormone is released when your blood glucose levels are too low?
glucagon
what does glucagon do when it is released?
it gets transported to the liver by blood then it makes the liver turn glycogen into glucose
what causes type 1 diabetes?
your pancreas doesn’t produce enough insulin so your blood glucose level is too high.
how can type 1 diabetes be treated?
by avoiding carbohydrates or injecting insulin.
what factors determine how much insulin you inject?
your diet
how active you are
what causes type 2 diabetes?
your body becomes resistant to insulin so your blood glucose levels are too high
which type of people are more likely to get diabetes type 2?
obese people
how do you work out body mass index (BMI)?
_body mass _
height2
what BMI do obese people have?
over 30
how can type 2 diabetes be treated?
healthy diet
regular exercise
losing weight
medication/inslulin injections
what is the name of a plant growth response?
tropism
what is the differnece between a positive and negative tropsim?
positive grows towards the stumulus
negetive grows away from the stimulus
what is phototropism?
the growth of a plant in response to light. shoots are positively phototrophic - they grow towards the light.
what is gravitropism?
the growth of a plant in response to gravity. roots are positively graitropic - they grow downwards.
what are the two plant growth hormones?
auxin
gibberellin
what does auxin do?
auxin controls growth at the tips of shoots and roots
where is auxin produced?
in the tips of plants
what happens if the tip of a plant is removed?
no auxin will be available so the shoot stops growing
what happens when a shoot tip is exposed to light?
more auxin accumulates on the side that’s in the shade than the side that’s in the light. this makes the cells grow (elongate) faster on the shaded side, so the shoot bends towards the light. this response enables plants to absorb more light for photosynthesis.
what happens if a root grows sideways?
gravity produces an unequal distribution of auxin, with more auxin on the lower side. but in a root the extra auxin inhibits growth. this means the cells on the top elongate faster, and the root bends downwards. this response enables plants to extend their root deep into the soil, so that they’re well anchored. the plants can absorb more water and minerals, which are needed for photosynthesis.
what does giberellin stimulate?
plant stems to grow by stem elongation - this helps the plant grow tall.
explain what this diagram shows
this diagram shows that auxin must be found in the tip of the shoot. this is because the plant c and b doesn’t bend towards the light.
what are the 4 uses of plant hormones?
- selective weedkiller
- growing cuttings with rooting powder
- controlling the ripening of fruit
- producing seedless fruit
how are hormones used as selective weedkillers?
most weeds growing in fields of crops or in a lawn are broad leaved, in contrast to grasses and cereasl which have very narrow leaves. selective weedkillers have been developed from plant growth hormones which only affect the broad leaved plants. they totally disrupt their normal growth patterns, which sooon kills them, whilstleaving the grass and crops untouched.
how are hormones used to grow cutting with rooting powder?
a cutting is a part of the plant that has been cut off it, like the end of a branch with a few leaves on it. normally, if you stick it in the soil they won’t grow, but if you add rooting power, which contains a plant growth hormone, they will produce roots rapidly and start growing as new plants. this enables growers to produce lots of clones of a really good plant very quickly.
how are hormones used to control the ripening of fruit?
the ripening of fruits can be controlled either while they are still on the plant, or during the transport to the shops. This allows the fruit to be picked while it’s still unripe (and therefore firmer and less easily damaged). Ripening hormone is then added and the fruit will ripen on the way to the supermarket and be perfect just as it reaches the shelves.
how are hormones used to produce seedless fruit?
fruit (with seeds in the middle) normally only grows on plants which have been pollinated by insects. if the plant doesn’t get pollinated, the fruit and seeds don’t grow. if the growth hormones are applied to the unpollinated flowers of some types of plant, the fruit will grow but the seeds won’t. some seedless cirtus fruits can be grown this way. hormones are also used in the porduction of seedless grapes (although these are usually fertilised first).
Describe an experiment that can be done to ivestigate plant growth responses
Put 10 cress seeds into three different petri dishes each lined with moist filter paper. Label each of the dishes
Shine a light onto one of the dishes from above and two of the dishes from different directions.
Leave the cress seeds one week until you observe their responses.
Describe an experiment to investigate external stimuli
In pairs one person wears a blindfold.
The other person uses a hairpin with the two points a fixed distance apart and touch an area of the blindfolded persons skin.
If the blindfolded person only feels one point the experiment is repeated withthe points further apart until they feel two points. The distance at which they feel two points is recorded.
On really sensative places such as the fingers or lips the blindfolded person will feels the two points when the points are a short distance apart.
What is a reflex
An automatic response to certain stimuli
