Do Now: Page 22.
Do Now: Page 22
Speaking of frogs - this is what a red eyed tree frog looks like with its eyes closed. They actually have three eyelids. The third is called the nictitating membrane, and it allows the frog to protect their eye from danger and to keep it moist while still allowing some visibility.This membrane is found in many different groups of animals, but most of them it simply looks like an opaque membrane. The tree frog's is a bit more striking!
The Reflex Arc
1. A stimulus
2. The stimulus causes a sensory neuron to send a signal to the CNS
3. The sensory neuron stimulates an interneuron.
4. The interneuron stimulates a motor neuron.
5. The motor neuron sends a signal back to the muscle or organ “telling” it what to do.
The knee jerk reflex is called a monosynaptic reflex because there is only one synapse in the circuit needed to complete the reflex. It only takes about 50 milliseconds between the tap and the start of the leg kick. That is fast! The tap below the knee causes the thigh muscle to stretch. Information is then sent to the spinal cord. After one synapse in the ventral horn of the spinal cord, the information is sent back out to the thigh muscle that then contracts.
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