Diving physiology studies how the human body responds to the underwater environment, including the effects of increased pressure, changes in breathing gases, and temperature variations. Understanding these physiological changes is crucial for safe diving practices and managing potential diving-related illnesses.
Physiological Responses to Diving
- Increased Pressure:
- Pressure increases by 1 atmosphere (atm) for every 10 meters (33 feet) of depth.
- Leads to compression of gases in the body, affecting lungs, sinuses, and other air-filled spaces.
- Breathing Gases:
- Air Composition: Typically, air is composed of 21% oxygen and 78% nitrogen.
- Partial Pressures: Increased pressure increases the partial pressures of gases, affecting their solubility and physiological effects.
- Temperature Changes:
- Water conducts heat away from the body faster than air, leading to hypothermia if adequate thermal protection is not used.
Diving Reflex
- Bradycardia:
- Slowing of the heart rate to conserve oxygen.
- Peripheral Vasoconstriction:
- Constriction of blood vessels in the extremities to redirect blood flow to vital organs.
- Blood Shift:
- Blood is shunted to the thoracic cavity to protect the lungs from collapse under pressure.
Diving-Related Illnesses
- Decompression Sickness (DCS):
- Also known as "the bends," caused by the formation of nitrogen bubbles in tissues and blood during rapid ascent.
- Symptoms: Joint pain, dizziness, headache, and in severe cases, paralysis or death.
- Prevention: Slow ascent and adherence to dive tables or dive computers.
- Treatment: Administration of 100% oxygen and hyperbaric oxygen therapy.
- Barotrauma:
- Injury caused by pressure changes affecting air-filled spaces in the body (e.g., ears, sinuses, lungs).
- Symptoms: Pain, hearing loss, dizziness, and in severe cases, lung rupture.
- Prevention: Equalizing pressure during descent and ascent.
- Nitrogen Narcosis:
- A state of altered consciousness caused by high partial pressures of nitrogen at depth.
- Symptoms: Euphoria, impaired judgment, and motor function.
- Prevention: Limiting depth and using mixed gases such as nitrox or trimix.
- Oxygen Toxicity:
- Caused by breathing high partial pressures of oxygen, leading to central nervous system or pulmonary toxicity.
- Symptoms: Visual disturbances, seizures, coughing, and chest pain.
- Prevention: Monitoring oxygen exposure and using appropriate gas mixtures.
- Hypothermia:
- Occurs when body heat is lost faster than it can be produced, leading to a drop in core temperature.
- Symptoms: Shivering, confusion, and loss of coordination.
- Prevention: Using appropriate thermal protection like wetsuits or drysuits.
Breathing Gas Mixtures
- Nitrox:
- Mixture of nitrogen and oxygen with a higher percentage of oxygen than air.
- Reduces nitrogen absorption, decreasing the risk of DCS.
- Trimix:
- Mixture of nitrogen, oxygen, and helium.
- Used for deep dives to reduce nitrogen narcosis and oxygen toxicity.
- Heliox:
- Mixture of helium and oxygen.
- Used for deep commercial diving to minimize nitrogen narcosis and oxygen toxicity.
Dive Planning and Safety
- Dive Tables and Computers:
- Tools to plan dives and monitor depth and time to avoid exceeding safe limits and to manage decompression stops.
- Buddy System:
- Diving with a partner for mutual assistance and safety.
- Emergency Procedures:
- Training in emergency ascent techniques, rescue procedures, and first aid for diving injuries.
Research and Future Directions
- Ongoing studies aim to better understand the long-term effects of diving on the body and to improve safety measures.
- Development of advanced dive computers and decompression algorithms to enhance safety.
Summary
Diving physiology explores the body's adaptations to underwater environments, focusing on the effects of increased pressure, changes in breathing gases, and temperature. Key responses include the diving reflex and physiological changes to manage hypoxia and hypercapnia. Understanding and mitigating risks such as decompression sickness, barotrauma, nitrogen narcosis, and oxygen toxicity are crucial for safe diving practices. Proper dive planning, use of appropriate gas mixtures, and adherence to safety protocols ensure the well-being of divers.