14. Coordination and control (mammals) Flashcards
Which organ produces a hormone?
OVARY
Which part of the human eye is sensitive to light?
RETINA
What happens when a person looks at an object far away from their eye?
- Suspensory ligaments tighten
- Lens becomes thinner
What happens when a ciliary muscle relaxes
- The lens will decrease its curvature
How do the muscles make the pupil smaller?
- Circular muscles contract
- Radial muscles relax
What would be the pupil size and lens shape of a person reading a mobile phone text message in a brightly lit room?
- The pupil size would be small and the lens shape would be fat
What happens when a ciliary muscle contracts?
- Reduces the pull on the lens, increasing its curvature
State two ways in which a voluntary action differs from an involuntary action.
- Takes more time
- No automatic
Explain how the parts of the reflex respond to the detection of heat.
- When a person touches a hot object. Electrical impulses are generated and transferred(by receptor) to the sensory neuron.
- Sensory neuron carries the impulses along itself to the central nervous system
- Electrical impulses are then transferred along the synapse to relay neuron
- Impulses travel along the relay neuron to the motor neuron again through a synapse
- Motor neuron then carries the impulses to the effector(muscle) and contracts.
What is meant by the term involuntary action
- It is a response without the use of the brain and is an automatic response
Describe the advantages of simple reflexes
- Fast
- Automatic
Describe 3 ways this adrenaline increase prepares the body for action.
- Heart beats faster
- Increased rate of breathing
- Heightened sensitivity
Describe a simple reflex arc
- Stimulus detected by receptor
- Receptor sends electrical impulses to the sensory neuron
- Sensory neuron passes impulses to relay
- Relay passes impulses to the motor
- Motor passes to the effector
Describe how impulses pass from one neuron to another across a synapse
- Neurotransmitters released from vesicles into the synaptic gap
- Neurotransmitters move by diffusion
- The neurotransmitter binds with the receptor which is on the other side of the synapse causing the impulse to continue
Outline the pathway in a reflex arc in response to shining a bright light into the eye
- The stimulus (light) is detected by the retina (receptor) and electrical impulses are generated by the receptor.
- Sensory neuron -> Relay neuron -> Motor neurone
- There are synapses between the neurons
- Circular muscles contract / Respond
Describe and explain how drug X affects the function of the relay neuron.
- Drug X blocks D (receptor molecules)
- Neurotransmitters are not able to bind to D (receptor molecules)
- Drug X’s shape is complimentary to the shape of the receptor
Name the part of the eye that alters the direction of light rays
Cornea
Name part of the eye where the light rays form an image
Retina
