Hypoxia

The body needs a specific amount of Oxygen to function normally and when this amount is lowered the body experiences hypoxia. Hypoxia literally means lack of oxygen for effective ventilation.

Hypoxemia refers to a state of abnormally low level of Oxygen in the blood.
Anoxia refers to the condition of absence of Oxygen supply to an organ or tissue
Anoxemia refers to the condition where the blood stream contains below normal amount of Oxygen.

Hypoxia is primarily classified into:

Generalized hypoxia: affects the entire body, may occur in normal healthy people when they scale high altitudes.
Local hypoxia: affects one particular region of the body.

When the level of oxygen in the blood reduces, it leads to the condition. People suffering from conditions like ischemia or blockage/constriction of blood vessels may suffer from hypoxia. In general when people travel from low to high altitudes, they may face this problem as the oxygen level depletes with altitude.

Hypoxia causes

Any condition wherein the body is deprived of oxygen can lead to hypoxia. Major causes that lead to the condition include:

• Severe head trauma
  
• Ischemia
  
• Asthma Severe Asthma can result in hypoxia and in Hypercarbia or Hypercapnia (elevated levels of Carbon dioxide CO₂ in blood)
  
• Pulmonary embolism
  
• Carbon monoxide poisoning
  
• Chronic alveolar hypo ventilation
  
• Shock can result in cellular hypoxia in the extremities
  
• Suffocation
  
• Choking
  
• High altitude climbing
  
• Inadequate ventilation

Types of hypoxia

Hypemic hypoxia: Obstruction in the ability of the blood to deliver oxygen, caused by carbon monoxide poisoning.

Anemic Anoxia: Occurs due to a decrease in the hemoglobin or RBC making it too little for the blood to carry oxygen. Anemia may be the result of iron deficiency, hemorrhage or shortened life span of RBC owing to an autoimmune disease.

Histotoxic: When the required amount of oxygen reaches the body part, however it does not utilize it because of its reduced ability, it is called as histotoxic hypoxia. Cyanide poisoning, for example, incapacitates a cellular enzyme essential for oxygen utilization. Other causes include: Alcohol, narcotics, acetone, formaldehyde and some anesthetic agents.

Hypoxic: Also called as Hypoxemic Anoxia: When the body does not receive the required amount of oxygen it leads to low partial pressure of oxygen in the blood thus leading to hypoxic hypoxia. The oxygen pressure of the blood which gets supplied to other body tissues is too low to push and flood the hemoglobin with oxygen. High altitude has lower density of air and lower pressure of oxygen than at sea level. Altitude Sickness occurs because the partial pressure of oxygen decreases with altitude. Hypoxemia is the direct result of lower oxygen in the high altitude which translates to lower level oxygen in the blood.

Stagnant: Obstruction of blood that carries oxygen. It can be due to exposure to cold, diseases which stifle blood circulation to the extremities or ergot poisoning.

Pulse Oximetry, a non invasive test is useful to diagnose Hypoxia. A blood test like serum lactate test can show elevated levels of lactic acid - the result of starvation of oxygen in tissues. The normal level of lactic acid is less than 2 mmol/L. However an increase in lactic acid alone does not indicate hypoxia and some form of Anoxia does not increase the lactic acid concentration. Symptoms may be dangerous on the onset and may include the following:

Generalized hypoxia

• Tachypnea or rapid breathing
  
• Severe headache
  
• Dizziness
  
• Nausea
  
• Tingling sensation
  
• Visual impairment
  
• Shortness of breath
  
• Bluish tint on the lips or on finger tips
  
• Coma
  
• Seizures
  
• Euphoria
  
• Mental fatigue
  
• Muscle fatigue

• Hot and cold flashes
  
• Discoloration of skin
  
• Pain in the area of hypoxia
  
• Severe hypoxia may cause gangrene

Hypoxia Treatment

Some types of Hypoxia cannot be prevented. Treatment depends on the severity of the condition and the appearance of the clinical symptoms. Treatment may include the following:

• Restoration of the tissue oxygen by supplementing the air supply with 100 % oxygen.
  
• Blood pressure and heart rate should be brought back to normal.
  
• In case of high altitudes, the person should be given sufficient rest and should not climb any further.
  
• Hypoxemic hypoxia patients can be put on blood transfusion.
  
• Proper medication and timely treatment can help save the life.

Amygdala

Amygdala is an almond shaped limbic structure placed within the brain's temporal lobe. It is involved in the processing of emotions, fears, motivation, anger etc. The amygdala plays a major role in processing our memories, in particular those that have emotional impact. In fact, our response to a particular event is triggered by the neurons in the amygdala. All the social stimuli we get are assimilated by the amygdala thereby making us responsive to a gaze, face or voice. It is involved in some of our cognitive functions like perception and attention. For all this, the amygdala is closely associated with the hippocampus and the hypothalamus.

Since amygdala is the structure associated with the limbic system, its functions are predominantly associated with emotions pertaining to the survival of the individual. These emotions can be categorized into types such as anger, fear, pleasure, hormonal secretion etc. The amygdala is also responsible for the storage of information as memory. It also helps in organizing the type of memory stored and where it has to be stored.

Amygdala is associated with the fear factor that is generated in a person. This is because the amygdala provides an autonomic response when associated with fear. This condition is also called as operant conditioning. Amygdala is generally associated with panic attack response, a subconscious response. It enables a person to be anxious or worried or escape a particular type situation. Although there is an element of anxiousness in every person, the level of anxiety varies. The memory of the anxious event is retained in the brain and the neural synapses store the information of the anxious condition in which fear was the response created by the amygdala. This facilitates the release of stress hormones which in turn yield to the symptoms associated with anxiety disorders.

Symptoms of overactive amygdala

The Amygdala in an over-activated condition responds to the physiological, environmental and chemical stress caused to an individual. The response may vary from small to big depending upon the situation and other physiological factors. The response of the amygdala facilitates into a condition called conditioned stress response, in which various conditions such as muscle fatigue, neurotransmitter and stress hormone release, sympathetic arousal, sleep deprivation, immune reactivation etc occurs. Along with these responses, sexual responses such as erection, copulation, ejaculation, ovulation, preterm labor etc. also occur.

The treatment includes medication which affects the amygdala. There is no proven result of the medication which influences the amygdala in response to anxiety. Most treatment methodologies include cognitive behavioral therapy.