First, the process of general anesthesia There are two kinds of general anesthetics. The first is inhalation anesthetics, such as ether; The second is intravenous anesthetics, such as ketamine.
Inhalation anesthetic is a volatile liquid or gas, which can enter respiratory tract and be absorbed by human body through alveoli. Intravenous anesthetics are general anesthetics administered by intravenous injection or drip.
Although the two drugs are administered in different ways, they all go through the same process in the body: they enter the blood, then enter the brain tissue, and then play a role.
General anesthesia is divided into four stages:
The first stage is analgesia, at which time there is anesthesia state of analgesia and forgetfulness.
The second stage is the exciting period, in which patients are agitated, breathing irregularly and blood pressure is unstable.
These two periods are called anesthesia induction period, and the patient's condition is dangerous, so it is not suitable for any operation and surgical examination.
The third stage was surgical anesthesia, and the patient recovered smoothly and underwent surgery.
The fourth stage is medullary anesthesia, which is excessive anesthesia and should be rescued in time.
The above four stages are typical stages of early pure ether anesthesia, and now induction anesthesia (multi-drug compound anesthesia) is commonly used in clinic to avoid the first and second stages and quickly enter the third stage.
Second, how does general anesthesia make people lose consciousness? The original explanation of general anesthesia mechanism is lipid theory:
General anesthetics with different chemical structures have high fat solubility, and the higher the fat solubility, the stronger the anesthetic effect. Therefore, general anesthetics with high fat solubility are easy to dissolve into the lipid layer of nerve cell membrane, causing physical and chemical changes of cell membrane, changing the conformation and function of membrane receptor protein and sodium and potassium channels, affecting the depolarization or transmitter release in nerve cells, thus widely inhibiting the transmission of nerve impulses and causing the effect of general anesthesia.
Later, after development, protein's theory appeared:
General anesthetics can bind to many targets in the central nervous system, which are mainly ligand-gated ion channels. General anesthesia can play a role by inhibiting excitatory synapses and enhancing the transmission function of inhibitory synapses.
3. How does local anesthesia make people unconscious? There are many theories about its mechanism. At present, it is recognized that local anesthetics block voltage-gated sodium channels on nerve cell membrane, so that sodium ions cannot enter the cell during its action, inhibit membrane excitability, increase the excitation threshold potential of nerve impulses, slow down the conduction speed, reduce the amplitude of action potential, and even lose excitability and conductivity.
To sum up, anesthesia makes people lose consciousness, which is mainly caused by affecting the function of ion channels on cell membranes and reducing their excitability.