Responding To Change Flashcards
What is osmoregulation
Regulating water content in the body
What is homeostasis
Maintaining a stable internal environment
Eg water content
Temperature
Blood glucose regulation
What is thermoregualtion
Regulating the internal body temperature
What is negative feedback
Changes in the environment trigger a response that counteracts the change
This means the internal environment will stay normal
It only works within certain limits
How is body temperature controlled
In the hypothalamus there are receptors that are sensitive to blood temperature in the brain and it receives impulses from the skin about the skin temp
When the hypothalamus detects a change it sends a response to the dermis
What happens when we’re too hot
Erector muscles relax and hairs lie flat
Lots of sweat is produces so when it evaporates it transfers heat to the environment and cools us down
Blood vessels close to the surface dilate this is vasodilation and allows more more blood to go to the surface of the skin so more heat can be transferred to the surroundings this gives us a red face
What happens when we’re too cold
Erector muscles contract so hairs stand up trapping a layer of warm air keeping us warm
Very little sweat is produced
Blood vessels vasoconstrict so less blood flows near the surface so less heat is transferred to the surroundings and more blood goes to the internal organs to keep them warm
What are hormones
A slow chemical message that travels in the blood and acts for a long time in a general way
What is the structure of a Neurone
Lots of dendrons to connect with other neurones
The main part of the cell has a nucleus
The electrical impulse moves along the axon
Th myelin sheath insulates the axon which speeds up the impulse and stops it leaving the cell
The neurones are long to increase the speed the Impulse can travel
What is a synapse
The connection between two neurones
The impulse is transmitted by chemical neurotransmitters which diffuse across the gap to the next neurone
They set off a new electrical impulse in the next neurone
What is a nerve
A fast electrical message that acts for a short time on a precise area
What receptors do the five sense organs have
Eyes light Ears sound and balance Nose smell Tongue taste Skin touch pressure and temperature
How does the body respond to a stimulus
Stimulus Receptor Sensory neurones Central nervous system Brain and spinal chord Motor neurone Effector cell Response
What is the sensory neurone like
Long dendrons and short axon to carry the nerve impulse to the cns
What is the relay neurone like
Many short dendrons and axons surrounding the nucleus
What is the motor neurone like
Many short dendrons and one long axon
What is the effector
Muscles respond in different ways and contract in response to a nervous impulse
What are reflexes for
They are automatic responses to certain stimuli which reduce our chances of being injured
This is known as the reflex arc
They’re much quicker than normal responses because we have no time to think about it
What is the reflex arc
Stimulus eg bee sting Pain receptor Sensory neurones Relay neurone in the spine Motor neurone Effector Response eg move away
How is oxygen removed from the blood in s normal person
Metabolism of cells
Vigorous exercise
What happens when our blood glucose level is too high
Blood with too much glucose
Insulin secreted by pancreas
Too much glucose and insulin go in the blood to the liver
Glucose is removed by the liver
Insulin causes it to be changed to glycogen
Blood glucose levels are reduced so insulin stops being secreted
What happens when our blood glucose level is too low
Blood with too little glucose
Glucagon is secreted by pancreas
Blood with too little glucose and glucagon travel in the blood to the liver
Glucagon turns glycogen to glucose in the liver
Glucose is released back to the blood and the levels increase
What is type one diabetes
A condition where the pancreas produces little or no insulin so there is no way of the blood sugar levels being brought down
How is type one diabetes overcome
Limit the intake of foods rich in simple carbohydrates
Insulin is injected often at meal times to make sure the excess glucose is removed quickly after eating
The insulin is injected into subcutaneous fat
A healthy diet and regular exercise reduce the amount of insulin needed
What is type two diabetes
A condition where the pancreas doesn’t produce enough insulin or when the person becomes resistant to insulin so the blood sugar level rises
People with a BMI over 30 have an increased risk of developing type 2 diabetes
BMI=
Body mass/(height)2
Mass in kg
Height in m
How is type 2 diabetes controlled
Eating a healthy diet and regular exercise to lose weight and reduce BMI
Medication or insulin injections can be used
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 s plant in response to gravity
Roots are positively phototrophic and grow downwards
What is auxin
It is a plant growth hormone that promotes growth at the tips of roots and shoots
It stimulates the tips just behind the tips to elongate
If the tip of the shoot is removed then no auxin is available so the plant will stop growing
It promotes growth in the shoot but inhibits growth in the roots
How does auxin make a shoot phototrophic
When the shoot is exposed to light more auxin accumulates on the side in the shade so it promotes cell elongation in this side causing the plant to grow towards the light
This allows plants to absorb more light for photosynthesis
How does auxin make plant roots gravitrophic
Gravity causes more auxin to fall tot he bottom of the root
But the extra auxin inhibits growth so the cells on top elongate faster and the root bends down wards
This allows plants to anchor themselves into the soil so they can absorb more water and minerals
What is gibberilin
It is a plant growth hormone
It stimulates seed germination stem growth and flowering
allows plants to grow tall
Auxin and gibberilin can work together to have big impacts on plant growth
How are plant hormones used as selective weed killers
Most weeds are broad leafs and grasses and cereals are narrow leaved
Selective weedkillers only kill broadleaf plants
They disrupt the normal growth pattern and soon kills them whilst leaving the other crops untouched
How is rooting powder used to grow cuttings
A cutting is a part of a plant being cut off
If you put a cutting in a soil with rooting powder roots are produced quickly and start growing
This allows clones to be produced quickly
How are plant hormones used In the ripening of fruit
It can control the ripening of fruit while they’re still on the plant or in transport
This means the fruit can be picked while it’s still unripe so firmer and less easily damaged
Ripening hormone is then added and the fruit will ripen on the way to the supermarket
How are plant hormones used to produce seedless fruits
If a plant isn’t pollinated then fruit seeds won’t grow
If growth hormones are given to unpollinated flowers then the fruit will grow but the seeds won’t
Seedless grapes and citrus can be made in this way
