Coordination and Response Flashcards
Define homeostasis
Maintaining a constant internal environment despite external change
State 3 conditions which need to be controlled by the body
- Temperature
- Water levels
- Blood glucose concentration
What are the 3 main parts to a coordinated response?
- A stimulus (e.g. temperature change)
- A receptor (to detect change)
- An effector (to carry out the response)
What does auxin trigger?
Auxin triggers growth of the main stem of the plant (and it inhibits the growth of side shoots)
What is phototropism and which part of a plant is positively phototropic?
Phototropism is the growth of a plant towards a light source. The shoots are positively phototropic (they grow towards the light source)
What is geo tropism and which part of the plant is positively geotropic?
Geotropism is the growth of a plant towards the pull of gravity. The roots are positively geotropic (they grow down in the same direction as the pull of gravity)
How does auxin cause shoots to grow towards the light source?
- Auxin collects on the shaded side
- Auxin promotes cell growth
- The shoot curves towards the light
Give 3 differences between nervous and hormonal communication
- Nervous communication uses nerve cells and impulses whereas hormones are secreted by glands and travel in the blood
- Nervous communication is generally much faster than hormonal communication
- Hormonal communication usually brings about longer lasting responses than nervous communication
What is the difference between the central nervous system and the peripheral nervous system?
The central nervous system is the brain and the spinal cord. The peripheral nervous system is every other part of the nervous system.
How is an impulse transmitted between two neurones?
- The impulse reaches the end of one neurone
- A neurotransmitter is released and it diffuses across the gap
- A new impulse is triggered in the next neurone
What is a stimulus?
A stimulus is a change in the environment
What type of neurone connects a receptor to the CNS?
A sensory neurone
What is an effector?
A part of the body that brings about the response to a stimulus like a muscle or a gland
What type of neurone connects the CNS to an effector?
A motor neurone
Describe the reflex arc
- Stimulus detected by a receptor
- Impulse passed along sensory neurone to CNS
- Impulse passed along motor neurone to effector
- Effector brings about the response
Describe the sequence of events involved in removing a hand away form a hot flame
- Thermoreceptors in the hand detect the heat of the flame
- An impulse is sent along the sensory neurone
- The impulse passes through relay neurones in the CNS
- The impulse then passes along a motor neurone and triggers the muscles in the arm to move the hand away
What is the cornea and what is its function?
The transparent layer in front of the eye that protects the eye from damage
What is the iris and what is its function?
The coloured ring around the pupil that controls its diameter
What is the pupil and what is its function?
The pupil is the hole in the middle of the iris that lets light into the eye
What is the optic nerve and what is its function?
The nerve coming out the back of the eye that sends signals to the brain
What is the function of the lens?
The lens focuses the light rays onto the retina
What is the retina and what is its function?
The retina is the back part of the eye and it converts visual stimuli into electrical impulses
What do the ciliary muscles and suspensory ligaments do?
They control the shape of the lens (accommodation)
How does the eye focus on near objects?
- Ciliary muscles contact and suspensory ligaments relax, causing the lens to thicken
- Thicker lens causes the light to refract more
