Responding To Change Flashcards
What is homeostasis
It ins the maintaining of a stable internal environment
What things does your body maintain?
Water levels (osmoregulation) Blood glucose content Body temperature ( thermoregulation)
What mechanism does the body use to detect change
Negative feedback mechanism
In the Brain what detects temperature?
Hypothalamus
How does the body respond to different temps?
Too hot, erector muscles relax so hairs lie flat allowing air to circulate, blood vessels widen (vasodilation) this means blood runs closer to the surface giving off heat. Body sweats evaporation takes away heat.
Too cold, hairs stand on end to trap warm layer of air, very little sweat, blood vessels vaso-constrict.
Describe the function of a nerve cell
Dendrons to connect with other neurones, axon to transmit the electrical impulse, myelin sheath acts as an insulator and speeds up the impulse.
What occurs at the synapse?
Neurotransmitters diffuse across the gap and receptors cells absorb them this continues the electrical impulse, the neurotransmitters are chemical messengers.
What detects a stimulus?
Receptors
Why are sensory neurones long?
To carry the signal to the CNS
What is an effector?
They respond in different ways to an electrical impulse for example a muscle might contract
Why do we have reflexes.
To prevent injury
Describe the reflex arc.
Receptors detect a stimulus this then travels along the sensory neurone to the CNS where the message is passed to a relay neurone which passes to the correct motor neurone. The impulse goes to the effector and the effector does the right response for that stimuli.
Describe how the body regulates glucose if too high
Pancreas secretes insulin which travels in the blood stream to the liver, here’re insulin makes the liver turn glucose into glycogen. This reduces the levels.
Describe how the body gullets glucose when it’s too low
The pancreas secretes glucagon which travels in the blood stream to the liver and makes the liver turn stored glycogen back into glucose
What is type two diabetes and how can it be treated
Where the body becomes resistant to insulin. The cells don’t respond correctly to the hormone. To counter this you can have a healthy diet and use regular exercise and loose weight. Some people also have medication.
What is gravitropism?
The growth of a plant in response to gravity . Roots are positively gravitropic so they grow downwards.
What is phototropism .
The growth of w plant in response to light. Shoots are positively phototropic so they grow towards light
What hormone in a plant causes it to grow?
Auxin
How does auxin work in shoots.
It accumulates on the shaded shaded side of the plant and causes the cells to elongate, this makes the plant bend towards the light
How does auxin work in roots ?
It accumulates on the bottom of the root, here is inhibits growth therefore the other side grows faster moving the root towards the ground.
What are some commercial uses of plant hormones?
Selective weed killers, plant hormones that only affect broad leave plants, it disrupts there growth cycle killing them
Controlling the ripening of fruit
Producing seedless fruit
