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1. Homeostasis during scuba diving

2. Relationship of chemoreceptor and lung capacity with scuba diving

3. Relationship of cardiovascular and respiratory in normal and extreme

condition

1. The cardiovascular system of a person is most influenced by diving, as it has a

strong influence of the external pressure due to the water. The deeper one dives

into the water, the greater the external factors affect his body. This results in poor

circulation in the limbs, while in the central part the circulation is maintained at

normal levels, due to the physiological structure of the chest, which helps to cope

with the external pressure. The normal circulation in blood vessels is not only due

to the work of the main pump - the heart, but also because of gravitation, which

facilitates the work of the myocardium.

There is less gravity in water, so the heart has to work in full force. And

this moment the problems in the cardiovascular system may appear which areinvisible in normal. Particularly large burden falls on the left ventricle, which is

responsible for pushing blood into the systemic circulation. Under external

pressure vessels in the peripheral parts of the body are narrowed, and the heart has

to do more to push the blood on them. Due to such extreme factors invisible in

everyday life heart problems "climbs out".

In diving the organism is also affected by:

Change of temperature. The sharp drop in temperature can cause coronary artery

spasm and arrhythmia, which in turn can cause heart attack  or cardiac arrest.

Diving reflex. This results in stimulation of the vagus nerve, which slows the heart

rate. Blood vessels are constricted (excluding those feeding the brain and heart). This

reflex is necessary, especially marine mammals to reduce oxygen consumption.

However, in human being occurs all by the scheme but the normalization of pressure,

which is often increased due to emotional arousal, resulting in increased load on the

heart.

This complex adaptive mechanism is caused by simultaneous activation of the

sympathetic and parasympathetic parts of the nervous system. It consists of 

bradycardia; peripheral blood vessels narrowing, therefore causing a greater amount

of blood to move into the chest; and a hormonal reaction of the adrenal glands,

causing increased secretion of catecholamines and the splenetic effect

Carotid sinus syndrome. Our brain is supplied with blood by two carotid arteries

with sensory sinuses located in the larynx. In diving the external pressure affects these

information sites, signaling to the brain. In response, heart rate reflex inhibition

occurs, which leads to arrhythmias, weakness and even loss of consciousness.

Fear. This factor is often characteristic of novices, but occurs in pros who perceive

new unexplored depths. Fear causes the release of adrenaline in the blood, whichstimulates the heart resulting vasodilation. Adrenaline increases heart beating rate and

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with more force pushes blood into the vessels, also increases respiration. Increased

load on the heart leads to arrhythmias and myocardial infarction.

Besides underwater pressure and cold temperatures, these changes also include

breathing oxygen at the elevated pressure and increased resistance to breathing (5).Intensified physical activity and coldness can lead to the increased production of free

radicals. Additionally, hyperoxia as a result of the hyperbaric exposure during diving

and breathing oxygen at high pressure could induce oxidative stres

2. The first sensor, which has the strongest effect by far on ventilation (at sea level) is

the central chemoreceptor. The neurons responsible are located in the medulla.

These are close to, but separate, from the neurons that generate the rhythm of 

breathing. Small changes in the partial pressure of carbon dioxide (PaCO2) in the

systemic arterial blood flowing to the medulla produce pronouced changes inventilation.

The second sensor is the peripheral chemoreceptor, which consists of afferent

neurons monitoring the blood in the carotid and aortic bodies. These are close to the

baroreceptors, but entirely separate. By contrast with the central chemoreceptor, the

peripheral chemoreceptor has little effect on the breathing of a normal person at rest at

sea level. But in two important circumstances the peripheral chemoreceptor begins to

drive breathing.

• When the partial pressure of oxygen (PaO2) falls below about 60 mm Hg. Thiscan occur in various respiratory disorders and at high altitude.

• With an increase in the hydrogen ion concentration. This occurs when lactic

acid is released into the blood during strenuous exercise. This point, at which

ventilation increases markedly, is called the lactate threshold (anaerobic

threshold).

3. In normal condition The cardiovascular and the respiratory system both work 

toward the same goal: getting oxygen to tissues and getting carbon dioxide out. Therespiratory system is involved in supplying oxygen to the blood and removing carbon

dioxide. When the heart receives blood that is low in oxygen and high in carbon

dioxide, it pumps it to the lungs via the pulmonary arteries. When the lungs expand

and get fresh air from the environment, oxygen is transferred (via the alveoli) into the

low-oxygen blood, which also then sends some of its carbon dioxide back into the

lungs. Now that this blood has fresh oxygen in it, it returns to the heart and the heart

then pumps it throughout the body.