Dive Medicine and Physiology
Expert-defined terms from the Advanced Certificate in Dive Health Risk Perception course at UK School of Management. Free to read, free to share, paired with a globally recognised certification pathway.
Dive Medicine and Physiology #
Dive Medicine and Physiology
Dive Medicine and Physiology is a field of study that focuses on the medical and… #
It encompasses a wide range of topics related to the effects of pressure, gas mixtures, and environmental conditions on the human body while submerged in water.
Altitude Diving #
Altitude Diving
Altitude diving refers to diving in freshwater or saltwater at altitudes above 3… #
At higher altitudes, the atmospheric pressure decreases, which can affect the decompression calculations and gas absorption of divers. Altitude diving requires special training and consideration of the reduced atmospheric pressure.
Barotrauma #
Barotrauma
Barotrauma is a condition caused by changes in pressure, leading to injury or di… #
Examples of barotrauma in diving include ear barotrauma (pressure-related ear injuries) and pulmonary barotrauma (lung overexpansion injuries). Proper equalization techniques and descent/ascent rates can help prevent barotrauma.
Breath #
Hold Diving
Breath #
hold diving, also known as free diving, involves diving without the use of breathing apparatus. It relies on the diver's ability to hold their breath while descending and ascending in water. Breath-hold diving requires specific training to manage breath-holding techniques, equalization, and buoyancy control.
Bubble Formation #
Bubble Formation
Bubble formation refers to the creation of gas bubbles in body tissues or blood… #
The formation of bubbles can lead to decompression sickness (DCS) if the ascent is too rapid or the diver exceeds no-decompression limits. Monitoring dive profiles and adhering to decompression protocols can reduce the risk of bubble formation.
Decompression Illness #
Decompression Illness
Decompression illness (DCI) encompasses decompression sickness (DCS) and arteria… #
Symptoms of DCI may include joint pain, neurological issues, skin rash, or chest pain. Prompt recognition and treatment with hyperbaric oxygen therapy are essential for managing DCI.
Decompression Sickness #
Decompression Sickness
Decompression sickness (DCS) is a condition caused by the formation of gas bubbl… #
DCS symptoms can range from mild joint pain and skin itching to severe neurological impairment or cardiopulmonary collapse. Treatment involves recompression in a hyperbaric chamber to reduce bubble size and relieve symptoms.
Deep Diving #
Deep Diving
Deep diving involves descending to depths greater than 18 meters (60 feet), wher… #
Deep divers must consider gas narcosis, oxygen toxicity, and decompression requirements when planning and conducting dives. Specialized training and equipment, such as mixed gases and redundant systems, are essential for safe deep diving.
Dive Tables #
Dive Tables
Dive tables are tools used by divers to plan and monitor their dives based on de… #
Tables provide information on no-decompression limits, surface intervals, and maximum dive times at specific depths. Divers can use recreational dive tables or dive computers to track their dive profiles and prevent decompression illness.
Dive Computers #
Dive Computers
Dive computers are electronic devices that monitor and display real #
time diving data, such as depth, time, ascent rate, and decompression status. Dive computers calculate nitrogen uptake, remaining bottom time, and decompression stops based on the diver's profile. They provide more accurate and personalized dive information compared to traditional dive tables.
Diving Gas Mixtures #
Diving Gas Mixtures
Diving gas mixtures, such as compressed air, nitrox, trimix, and heliox, are use… #
Gas mixtures help reduce nitrogen narcosis, oxygen toxicity, and decompression risks during deep or repetitive dives. Proper gas blending and analysis are crucial for safe diving operations.
Diving Physics #
Diving Physics
Diving physics involves the study of physical laws and principles that govern th… #
Concepts such as Boyle's Law (pressure-volume relationship), Henry's Law (gas solubility), and Archimedes' Principle (buoyancy) are essential for understanding diving physiology, gas dynamics, and equipment design.
Diving Physiology #
Diving Physiology
Diving physiology explores how the human body responds to pressure, gas exposure… #
Topics include gas exchange in the lungs, blood, and tissues; gas transport in the circulatory system; and physiological adaptations to diving stress. Understanding diving physiology helps divers prevent injuries and optimize performance in challenging environments.
Equalization Techniques #
Equalization Techniques
Equalization techniques are methods used by divers to balance the pressure betwe… #
Common equalization methods include swallowing, yawning, and the Valsalva maneuver (pinching the nose and blowing gently). Proper equalization prevents ear barotrauma, improves comfort, and maintains diving safety.
Hyperbaric Medicine #
Hyperbaric Medicine
Hyperbaric medicine focuses on the use of high #
pressure oxygen environments (hyperbaric chambers) to treat various medical conditions, including decompression sickness, arterial gas embolism, and non-healing wounds. Hyperbaric oxygen therapy enhances tissue oxygenation, reduces inflammation, and promotes healing in divers and patients with diving-related injuries or medical disorders.
Nitrogen Narcosis #
Nitrogen Narcosis
Nitrogen narcosis, also known as "rapture of the deep," is a reversible alterati… #
Symptoms may include euphoria, impaired judgment, and slowed reaction times, resembling alcohol intoxication. Nitrogen narcosis can impair diver performance and decision-making, necessitating depth limits and gas switching strategies.
Oxygen Toxicity #
Oxygen Toxicity
Oxygen toxicity is a condition resulting from prolonged exposure to elevated oxy… #
Symptoms of oxygen toxicity may include visual disturbances, convulsions, and respiratory distress. Divers must adhere to oxygen exposure limits and use appropriate gas mixtures to mitigate the risk of oxygen toxicity.
Recompression Chamber #
Recompression Chamber
A recompression chamber, also known as a hyperbaric chamber, is a sealed pressur… #
The chamber simulates increased atmospheric pressure to reduce gas bubble size, alleviate symptoms, and promote gas elimination from the body. Recompression chambers are essential facilities for dive emergency management and medical care.
Saturation Diving #
Saturation Diving
Saturation diving involves prolonged exposure to elevated pressures in underwate… #
Saturation divers breathe a helium-oxygen mixture to reduce nitrogen uptake and avoid repetitive decompression. Saturation diving requires specialized training, equipment, and support personnel for safe operations.
Squeeze #
Squeeze
Squeeze refers to discomfort or pain experienced by divers due to pressure diffe… #
Common types of squeeze include mask squeeze (facial pressure), sinus squeeze (nasal congestion), and drysuit squeeze (compression-related injuries). Proper equalization, fit adjustments, and descent techniques can help prevent squeeze during dives.
Technical Diving #
Technical Diving
Technical diving involves advanced underwater activities beyond recreational lim… #
Technical divers use specialized equipment, gas mixtures, and procedures to manage complex dive profiles, decompression obligations, and emergency scenarios. Technical diving certification and experience are required to safely explore challenging environments.
Underwater Physiology #
Underwater Physiology
Underwater physiology examines how the body responds to immersion, hydrostatic p… #
Factors like cold water immersion, hydrostatic pressure effects on circulation, and gas exchange in breath-hold diving influence physiological responses in divers. Understanding underwater physiology helps optimize dive safety, performance, and adaptation to aquatic environments.
Ventilation #
Perfusion Mismatch
Ventilation #
perfusion mismatch refers to an imbalance between air ventilation (breathing) and blood perfusion (circulation) in the lungs, leading to impaired gas exchange and oxygenation. Divers may experience ventilation-perfusion inequalities at depth due to breathing gas density changes, pulmonary shunts, or lung compression effects. Proper breathing techniques and gas selection can help minimize mismatch and improve diving efficiency.
Water Immersion #
Water Immersion
Water immersion involves the full or partial submersion of the body in water dur… #
Immersion in water affects body temperature regulation, hydrostatic pressure distribution, and cardiovascular responses. Divers must acclimatize to water immersion conditions, use appropriate exposure protection, and monitor physiological changes to ensure comfort and safety underwater.
Wet vs #
Dry Diving Suits
Wet and dry diving suits are protective garments worn by divers to maintain body… #
Wet suits are made of neoprene material that traps a thin layer of water against the skin for insulation. Dry suits are waterproof suits that keep divers dry by sealing out water and maintaining thermal protection. Choosing the right suit depends on water temperature, dive duration, and personal preference.
**Decompression Sickness (DCS)** #
**Decompression Sickness (DCS)**
Decompression sickness, commonly known as DCS or "the bends," is a condition tha… #
This happens when a diver ascends too quickly without allowing these gases to be properly expelled from the body.
**Hyperbaric Chamber** #
**Hyperbaric Chamber**
A hyperbaric chamber is a sealed chamber that allows a person to breathe oxygen… #
This is commonly used in the treatment of decompression sickness, carbon monoxide poisoning, and other conditions that benefit from increased oxygen levels.
**Nitrogen Narcosis** #
**Nitrogen Narcosis**
Nitrogen narcosis, also known as "rapture of the deep," is a reversible alterati… #
It is caused by the increased partial pressure of nitrogen in the bloodstream, leading to symptoms such as euphoria, impaired judgment, and slowed reaction times.
**Oxygen Toxicity** #
**Oxygen Toxicity**
Oxygen toxicity is a condition that occurs when a person is exposed to high leve… #
Divers are particularly at risk of oxygen toxicity when breathing high concentrations of oxygen during decompression stops or in hyperbaric chambers.
**Pulmonary Barotrauma** #
**Pulmonary Barotrauma**
Pulmonary barotrauma is a condition that occurs when there is a sudden increase… #
This can result in a variety of symptoms, including chest pain, coughing up blood, and difficulty breathing. Pulmonary barotrauma is a serious condition that requires immediate medical attention.
**Recompression Chamber** #
**Recompression Chamber**
A recompression chamber, also known as a hyperbaric chamber, is a device used to… #
A recompression chamber, also known as a hyperbaric chamber, is a device used to treat decompression sickness and other diving-related injuries by recompressing the diver to high pressures and then gradually reducing the pressure to allow the gases to be safely eliminated from the body.
**Squeeze** #
**Squeeze**
A squeeze is a condition that occurs when a diver's mask, wetsuit, or other equi… #
This can lead to pain, bruising, and even injury if not addressed promptly.
**Venous Gas Embolism (VGE)** #
**Venous Gas Embolism (VGE)**
Venous gas embolism is a condition that occurs when bubbles of gas enter the blo… #
VGE is a common cause of decompression sickness and requires immediate medical attention.
**Wet Lung Syndrome** #
**Wet Lung Syndrome**
Wet lung syndrome, also known as immersion pulmonary edema, is a condition that… #
This can lead to symptoms such as coughing, shortness of breath, and chest pain, and may require medical treatment to resolve.
**Xenon Gas** #
**Xenon Gas**
Xenon gas is a rare noble gas that has been proposed as an alternative to nitrog… #
Xenon is currently being researched for its potential applications in dive medicine and physiology.
**Yawning** #
**Yawning**
Yawning is a reflex action that involves the simultaneous inhalation of air and… #
Yawning is a common technique used by divers to prevent barotrauma and discomfort in the ears.
**Zooplankton** #
**Zooplankton**
Zooplankton are small, drifting organisms that form an essential part of the mar… #
Zooplankton play a crucial role in the ocean ecosystem and are an important indicator of water quality and environmental health.
This glossary provides a comprehensive overview of key terms and concepts relate… #
By familiarizing themselves with these terms, learners can enhance their understanding of the risks and challenges associated with diving, as well as the strategies and techniques used to mitigate these risks and ensure safe and enjoyable diving experiences.