Definition and process:
reflexes are involuntary and automatically occurring reactions of the body, which are coordinated via nerve cells and serve the protection of the body. In principle, we can distinguish between two types of reflexes: innate reflexes and acquired reflexes.
A reflex that everyone probably knows from their own experience is the knee-jerk reflex. In a light hit below the kneecap, the leg responds with a bobbing forward motion. But how do reflexes work?
A physical or chemical stimulus hits a sensory cell, the receptor, The receptor converts the stimulus into electrical signals (transduction). These pulses run over one afferent nerve fiber (afferent = to the central nervous system) into Rьckenmarkwhere the processing of the stimulus takes place. About one efferent nerve fiber (exiting) the signal finally reaches the effector (mostly muscle cells). The motor end plate Transfers electrical excitement from a nerve fiber to a muscle. As a result, it then comes to reaction, the contraction of the muscle.
This process is so fast and automatic that we do not realize it. Mostly the brain is not involved at all. A controlled control of the innate reflexes is therefore also not possible.
1.) Innate reflexes (unconditioned reflexes):
In the innate reflexes a distinction is made between intrinsic and external reflex. The most important difference is the number of synapses involved. Only one synapse is involved in a self-reflex; in a foreign reflex, several synapses are involved.
|reflex arc||Receptor and effector are in the same organ||Receptor and effector are in different organs|
|reaction||fast (short reflex time)||slow (long reflex time)|
|habituation||no habituation possible||Habituation possible|
|example reflexes||Patellar tendon reflex (knee flexion); all muscle reflexes||Eye closure reflex, pupillary reflex, swallowing reflex, cervical reflex|
2.) Acquired reflexes (conditioned reflexes):
In addition to innate reflexes, certain reactions can also be learned (via conditioning). The best example of a conditioned reflex is the increased salivary production of Pavlov's dogs, at the sounding of the bell tone.
The early childhood reflex
The innate reflexes also include the childish reflexes. Most of these reflexes are functional only in the first months of life. As the brain progresses, some reflexes are lost again. But the automatic reactions fulfill a vital function: they protect the baby from injury and facilitate food intake.
Babinski: If you stroke the baby centrally over the bottom of the foot, it pulls the big toe up.
grasp reflex: on contact with the palm of the hand, the baby attacks.
clip reflex: also known as Moro reflex. In the event of a sudden change in the position of the head, infants make a claw movement.
sucking reflex: is closely linked to the swallowing reflex. The baby begins to suck as soon as something touches the palate.
swimming reflex: often observed with baby swimming. Babies begin paddle-like forward movements when in contact with water.
rooting reflex: by touching the corners of his mouth, the baby turns his head in that direction. Helps the baby, even without visually recognizing something, to find the mother's breast.