Factors affecting breathing - class-X

The troposphere varies in height, but 8km is a commonly cited average altitude for the poles, though it extends higher at the equator. Given the options, 8km is the standard textbook answer.

Compressive asphyxia (also called as chest compression) is mechanically limiting expansion of the lungs by compressing the torso, hence interfering with breathing. Compressive asphyxia occurs when the chest or abdomen is compressed posteriorly. In accidents, the term traumatic asphyxia or crush asphyxia usually refers to compressive asphyxia resulting from being crushed or pinned under a large weight or force. 

Arterial hypoxia (also known as hypoxiation or anoxemia) is a condition in which the body or a region of the body is deprived of adequate oxygen supply. Hypoxia may be classified as either generalized, affecting the whole body, or local, affecting a region of the body. Generalized hypoxia occurs in healthy people when they ascend to high altitude, where it causes altitude sickness or mountain sickness leading to potentially fatal complications: high altitude pulmonary edema (HAPE) and high altitude cerebral edema (HACE). Thus, option B is correct.

Ischemia, meaning insufficient blood flow to a tissue, can also result in hypoxia. This is called as 'ischemic hypoxia'. This can include an embolic event, a heart attack that decreases overall blood flow, or trauma to a tissue that results in damage. An example of insufficient blood flow causing local hypoxia is gangrene that occurs in diabetes. 

Perinatal asphyxia is the medical condition resulting from deprivation of oxygen (hypoxia) to a newborn infant long enough to cause apparent harm. It results most commonly from a drop in maternal blood pressure or interference during delivery with blood flow to the infant's brain. 

Asphyxia or asphyxiation is a condition of severely deficient supply of oxygen to the body that arises from abnormal breathing. 

Asphyxia is a condition of severely deficient supply of oxygen to the body that arises from being unable to breathe normally, often caused by an accumulation of carbon dioxide in the blood.

Tapeworms live in the human gut and can be up to 9 meters long. Parasites have specific features which enable them to survive in or on their host. They use anaerobic respiration, so that they can survive without oxygen.

The atmospheric pressure goes on decreasing as we go up above the sea level, and the amount of oxygen also decreases at higher altitude. 

At sea level, our blood is 98% saturated with oxygen and this decreases to 89% at 3000 metres and reaches as low as 40% on the summit of Everest. Red blood cell production increases, resulting in an increased haemoglobin concentration, which is required to pick up oxygen and transport it around the body. This mechanism enables the body to continue to deliver enough oxygen to each cell, despite the lower oxygen levels. 

Hypoxia refers to a state where there is an inadequate supply of oxygen to the tissues, which can be caused by various factors like low blood flow or low oxygen content in the blood.

 Altitude sickness (also known as mountain sickness), is caused by gaining altitude too rapidly, which does not allow the body enough time to adjust to reduced oxygen and changes in air pressure, and causes hypobaric hypoxia (a lack of oxygen reaching the tissues of the body).

Asphyxia is the physiological state resulting from the inability to breathe, leading to high CO2 and low O2 levels, which can cause loss of consciousness.

$pO _2$ of atmospheric air decreases with increasing altitude.

Hypoxia is a condition in which the body or a region of the body is deprived of oxygen due to the lack of oxygen supply at the tissue level. It is, therefore, the condition in which the body suffers from acute oxygen shortage. So, the correct option is 'True'.

Asphyxia is the extreme condition caused by lack of oxygen and excess of carbon dioxide in the blood, produced by interference with respiration or insufficient oxygen in the air; suffocation. Asphyxia is caused by an injury or obstruction of airway passages.
So, the correct answer is option B.

Hypoxia is the specific term for an inadequate supply of oxygen to the tissues. While related to asphyxia, hypoxia is the condition of the tissues themselves.

During asphyxiation, oxygen is depleted, meaning hemoglobin cannot bind to oxygen to form oxyhaemoglobin, leaving it in a deoxygenated state.

In a postmortem, a piece of lung from a child who breathed air will float because of the residual air in the alveoli. If the child never breathed, the lung tissue is dense and will sink.

Every living cell requires oxygen for performing cellular respiration. In unicellular organisms (e.g amoeba), the single cell is in direct contact with environment. Oxygen passes into it through diffusion. In simple multicellular organisms (e.g, hydra), every cell may take also oxygen through diffusion from environment. This is not possible in multicellular organisms like humans. The body is covered by dead cells. The living cells are not in contact with the external environment. Air containing intercellular spaces are absent. Therefore, quick diffusion cannot occur. Cell to cell diffusion is a very slow process. Passage of oxygen from lungs to toes through cell to cell diffusion will take about three years. Therefore, diffusion cannot meet the oxygen requirements of multicellular organisms like humans.

Asphyxia is a condition of severely deficient supply of oxygen to the body that arises from abnormal breathing. Asphyxia causes generalized hypoxia, which affects primarily the tissues and organs. There are many circumstances that can induce asphyxia, all of which are characterized by an inability of an individual to acquire sufficient oxygen through breathing for an extended period of time.

Multicellular organisms need oxygen to live. The multiple layer of cells in multicellular organism means that the surface area to volume ratio is low; so, diffusion happens slowly. If only diffusion would have been the source then only the outer layer of the body would get oxygen and the inner layers would be oxygen deprived.  So, the organism will die.