Reflexes and Reactions

Question 1

what is a reflex?

Answer 1

Involuntary reactions to a stimulus and your spinal cord usually controls the reflexes. E.g blinking because its bright. Most reflexes don’t have to travel up to the brain to be processed (which is why they take place quickly). A reflex action often involves a very simple nervous pathway called a reflex arc.

Question 2

how does reflex arc work

Answer 2

1. Receptor is stimulated (action potentials fired). eg: touch something sharp
2. Impulse travels along sensory neuron to the spinal cord
3. Impulse is passed to interneuron/association neuron in the spinal cord. The message splits – one message sent to brain, one message sent to motor neuron
4. Impulse travels along motor neuron to effector
5. Response occurs in the effector (eg: muscle contracts)
6. Impulse from spinal cord reaches the brain after the response for interpretation, eg: ‘ouch!!’

Question 3

how does patellar or knee jerk reflex work

Answer 3

Also known as deep tendon reflex (DTR) because the doctor is tapping on the patellar tendon. The tap stretches the tendon and the muscle in the thigh that connects to it. A message is then quickly sent to the spinal cord that the muscle has been stretched, the spinal cord then sends a message quickly back to the muscle telling it to contract. The contraction of the muscle causes the lower leg to kick out, this type of reflex is important in keeping your balance.