Question: Does The Knee Jerk Reflex Involve The Brain?

What happens if you don’t have reflexes in your knee?

Patellar tendon reflex.

In a normal test, your knee will extend and lift your foot a little.

A decreased or absent reflex may mean that there is compression in the L2, L3, or L4 region..

What is the doctor testing when he hits your knee?

The knee jerk reflex is one that you may have had tested at a check up at the doctor’s office. In this test, the doctor hits your knee at a spot just below your knee cap and your leg kicks out. Try it! Have a partner sit with his or her legs crossed so that his leg can swing freely.

Is brain involved in reflex action?

The path taken by the nerve impulses in a reflex is called a reflex arc. In higher animals, most sensory neurons do not pass directly into the brain, but synapse in the spinal cord. … Reflexes do not require involvement of the brain, although in some cases the brain can prevent reflex action.

What happens during a knee jerk reflex?

Knee-jerk reflex, also called patellar reflex, sudden kicking movement of the lower leg in response to a sharp tap on the patellar tendon, which lies just below the kneecap. … In reaction these muscles contract, and the contraction tends to straighten the leg in a kicking motion.

What is an example of a Polysynaptic reflex?

For example, stimulation of pain receptors in the skin initiates a withdrawal reflex, which involves several synapses with several motor neurons and results in the removal of the organism or part from the stimulus. …

Why does your knee jerk when you hit it?

The hit to the knee causes the thigh muscle to stretch. This stretch sends a signal along a sensory neuron to the spinal cord where it interacts directly with a motor neuron which goes to the thigh muscle. … More importantly, the knee-jerk reflex is what’s known as a mono-synaptic response.

Can you control reflex actions?

Reflexes are actions we can’t control. Most reflexes protect the body. They are coordinated by nerves that go to and from the spinal cord without the brain’s direct involvement.

How do reflexes protect the body?

Reflexes protect your body from things that can harm it. For example, if you put your hand on a hot stove, a reflex causes you to immediately remove your hand before a “Hey, this is hot!” message even gets to your brain.

Does mental distraction affect patellar reflex?

Mental distraction plays no part on the reflex. Is the patellar reflex more or less vigorous after exercise?

What parts of the body are involved in the knee jerk reflex?

Striking of the patellar tendon with a reflex hammer just below the patella stretches the muscle spindle in the quadriceps muscle. This produces a signal which travels back to the spinal cord and synapses (without interneurons) at the level of L3 or L4 in the spinal cord, completely independent of higher centres.

Is it possible for humans to override reflex actions?

Reflexes need to be fast in order to protect the body. If you pick up a hot plate, the reflex action will make you drop it almost immediately. … However, we can consciously override reflexes. If the hot plate had your dinner on it, you might try to resist the reflex to drop it so that you can put it down safely.

What are some examples of reflex actions?

A few examples of reflex action are:When light acts as a stimulus, the pupil of the eye changes in size.Sudden jerky withdrawal of hand or leg when pricked by a pin.Coughing or sneezing, because of irritants in the nasal passages.Knees jerk in response to a blow or someone stamping the leg.More items…