Coordination and Response Flashcards
Stimulus => … => response
Receptor => coordination => effector
Homeostasis
The maintenance of a constant internal environment e.g. body water content or body temperature
Shoot Phototropism
Positive
Root Phototropism
Mostly none or some negative
Shoot Geotropism
Negative
Root Geotropism
Positive
What does auxin do?
Stimulates cells in the shoot to grow. As it diffuses downwards it moves away from light. The higher concentration of the hormone on the “dark” side of the shoot causes cells there to grow more, resulting in a bending of the shoot toward the light source
How are hormones transmitted?
They are secrete from a gland and travel in the bloodstream
How are nerve signals transmitted?
Electrical impulses and neurotransmitters at synapses
What makes up the Central Nervous System?
The brain and spinal cord
How does a synapse work?
- Impulse arrived down axon of first neurone
- Neurotransmitter diffuses across synapse
- Neurotransmitter attached to membrane of second neurone
- Impulse started in second neurone
- Neurotransmitter broken down by enzyme from second neurone
What is the effect of nerve impulses?
Fast, short-lived and localised
What is the effect of hormones?
Slower, longer-lasting and more widespread
What happens when the body is cold?
- Behaviour changes
- Vasoconstriction
- Faster metabolism due to adrenaline release
- Shivering
- Hair erection
What happens when the body is hot?
- Sweating
- Vasodilation
- Behaviour changes
- Hair erector muscle relaxes
