Podcast
Questions and Answers
What is a major risk associated with thermal injuries in terms of tissue health?
What is a major risk associated with thermal injuries in terms of tissue health?
Which condition is characterized by painful muscle spasms due to water and electrolyte loss?
Which condition is characterized by painful muscle spasms due to water and electrolyte loss?
What is defined as a life-threatening condition resulting from heat exposure and marked by the failure of heat regulation?
What is defined as a life-threatening condition resulting from heat exposure and marked by the failure of heat regulation?
What complication can arise from generalized edema in burn patients?
What complication can arise from generalized edema in burn patients?
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Which syndrome is most commonly characterized by weakness, headache, nausea, and vertigo?
Which syndrome is most commonly characterized by weakness, headache, nausea, and vertigo?
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In managing hypovolemia due to burn injuries, what is critical to prevent tissue necrosis?
In managing hypovolemia due to burn injuries, what is critical to prevent tissue necrosis?
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What can result from the high quantities of corticosteroids used in burn treatment?
What can result from the high quantities of corticosteroids used in burn treatment?
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What is one characteristic feature of heat stroke that differentiates it from other heat-related conditions?
What is one characteristic feature of heat stroke that differentiates it from other heat-related conditions?
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Which of the following best describes the management strategy for heat cramps?
Which of the following best describes the management strategy for heat cramps?
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The development of which condition can lead to a significant risk of infection after thermal injuries?
The development of which condition can lead to a significant risk of infection after thermal injuries?
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What is a significant consequence of the formation of eschar following a thermal injury?
What is a significant consequence of the formation of eschar following a thermal injury?
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What is a distinguishing factor of heat exhaustion compared to heat stroke?
What is a distinguishing factor of heat exhaustion compared to heat stroke?
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Which mechanism primarily contributes to the development of Curling's ulcers in burn patients?
Which mechanism primarily contributes to the development of Curling's ulcers in burn patients?
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What physiological response occurs in the body when encountering hyperthermia?
What physiological response occurs in the body when encountering hyperthermia?
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Which of the following accurately describes generalized edema in the context of thermal injuries?
Which of the following accurately describes generalized edema in the context of thermal injuries?
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What triggers the increased body temperature observed in fever, distinct from hyperthermia?
What triggers the increased body temperature observed in fever, distinct from hyperthermia?
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In the context of fluid loss, which statement is correct regarding the state of the patient during heat exhaustion?
In the context of fluid loss, which statement is correct regarding the state of the patient during heat exhaustion?
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What is the primary issue associated with hypovolemia in burn victims?
What is the primary issue associated with hypovolemia in burn victims?
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Which term describes the leathery and stiff necrotic tissue formed after a burn injury?
Which term describes the leathery and stiff necrotic tissue formed after a burn injury?
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Generalized edema in burn patients can lead to respiratory insufficiency.
Generalized edema in burn patients can lead to respiratory insufficiency.
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Heat cramps are characterized by increased body temperature over 40 C without sweat cessation.
Heat cramps are characterized by increased body temperature over 40 C without sweat cessation.
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Formation of eschar is a sign of necrotic tissue that can lead to compression complications.
Formation of eschar is a sign of necrotic tissue that can lead to compression complications.
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Heat exhaustion is more severe than heat stroke and often leads to mortality.
Heat exhaustion is more severe than heat stroke and often leads to mortality.
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Malignant hyperthermia is a condition resulting from exposure to certain drugs and is inherited.
Malignant hyperthermia is a condition resulting from exposure to certain drugs and is inherited.
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Match the following heat-related conditions with their characteristics:
Match the following heat-related conditions with their characteristics:
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Match the following complications of thermal injuries with their descriptions:
Match the following complications of thermal injuries with their descriptions:
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Match the following terms with their definitions:
Match the following terms with their definitions:
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Match the following heat-related conditions with their management strategies:
Match the following heat-related conditions with their management strategies:
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Match the following physiological responses with their characteristics:
Match the following physiological responses with their characteristics:
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What is a common effect of ionizing radiation on cells?
What is a common effect of ionizing radiation on cells?
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What is a factor that influences the severity of tissue damage from ionizing radiation?
What is a factor that influences the severity of tissue damage from ionizing radiation?
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What type of radiation is classified as potentially carcinogenic by the International Agency for Research on Cancer?
What type of radiation is classified as potentially carcinogenic by the International Agency for Research on Cancer?
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What is a common effect of nonionizing radiation on cells?
What is a common effect of nonionizing radiation on cells?
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What is a type of skin cancer associated with ultraviolet radiation exposure?
What is a type of skin cancer associated with ultraviolet radiation exposure?
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What is a sign that a mole may be turning into a malignant melanoma?
What is a sign that a mole may be turning into a malignant melanoma?
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What is a effect of ionizing radiation on blood vessels?
What is a effect of ionizing radiation on blood vessels?
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What is a neurological effect of ionizing radiation?
What is a neurological effect of ionizing radiation?
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What is a effect of ionizing radiation on cells?
What is a effect of ionizing radiation on cells?
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Which of the following is a characteristic feature of nonionizing radiation?
Which of the following is a characteristic feature of nonionizing radiation?
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What is a common effect of ionizing radiation on cells?
What is a common effect of ionizing radiation on cells?
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Which of the following factors influences the severity of tissue damage from ionizing radiation?
Which of the following factors influences the severity of tissue damage from ionizing radiation?
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What is a type of skin cancer associated with ultraviolet radiation exposure?
What is a type of skin cancer associated with ultraviolet radiation exposure?
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What is a sign that a mole may be turning into a malignant melanoma?
What is a sign that a mole may be turning into a malignant melanoma?
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What is a effect of ionizing radiation on blood vessels?
What is a effect of ionizing radiation on blood vessels?
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What is a neurological effect of ionizing radiation?
What is a neurological effect of ionizing radiation?
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What is a characteristic feature of chromosomal and nuclear changes caused by ionizing radiation?
What is a characteristic feature of chromosomal and nuclear changes caused by ionizing radiation?
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What is a type of radiation classified as potentially carcinogenic by the International Agency for Research on Cancer?
What is a type of radiation classified as potentially carcinogenic by the International Agency for Research on Cancer?
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What is a common effect of nonionizing radiation on cells?
What is a common effect of nonionizing radiation on cells?
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Nonionizing radiation has sufficient energy to displace bound electrons from atoms.
Nonionizing radiation has sufficient energy to displace bound electrons from atoms.
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Total body irradiation can have long-term effects such as the production of cancer.
Total body irradiation can have long-term effects such as the production of cancer.
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Vascular anomalies caused by tissue damage from ionizing radiation may include thickening of the intima.
Vascular anomalies caused by tissue damage from ionizing radiation may include thickening of the intima.
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One of the factors that influence the severity of tissue damage from radiation is the duration of exposure.
One of the factors that influence the severity of tissue damage from radiation is the duration of exposure.
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Skin cancer caused by ultraviolet radiation only includes malignant melanoma.
Skin cancer caused by ultraviolet radiation only includes malignant melanoma.
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Match the following types of radiation with their characteristics:
Match the following types of radiation with their characteristics:
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Match the following types of skin cancer with their descriptions:
Match the following types of skin cancer with their descriptions:
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Match the following factors influencing tissue damage with their descriptions:
Match the following factors influencing tissue damage with their descriptions:
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Match the following possible effects of ionizing radiation with their outcomes:
Match the following possible effects of ionizing radiation with their outcomes:
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Match the following signs indicating a mole turning malignant with their descriptions:
Match the following signs indicating a mole turning malignant with their descriptions:
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Match the type of burn to its description.
Match the type of burn to its description.
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Match the type of mechanism of radiation injury to its description.
Match the type of mechanism of radiation injury to its description.
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Study Notes
Injury Due to Physical Agents
- Physical injuries arise from mechanical, thermal, electrical, and nuclear energy sources.
Temperature Injuries
-
Cold Injuries
- Localized: Includes frostnip (cold sensation without freezing) and frostbite (frozen tissue).
- Generalized: Hypothermia occurs when body temperature drops below 35°C (95°F).
-
Localized Cold Injury
- Frostnip: Skin appears cold, but no freezing damage.
- Trench foot/Immersion foot: Occurs from prolonged exposure to cold water.
- Frostbite: Superficial types may recover in weeks; deep types can cause necrosis and risk of reperfusion injury.
-
Generalized Cold Injury
- Hypothermia is especially risky for children and the elderly.
- Mild hypothermia (36-35°C): Peripheral vasoconstriction and shivering occur.
- Moderate hypothermia (<32°C): Symptoms include drowsiness and confusion.
- Severe hypothermia (<28°C): Can lead to coma and death.
-
Heat Injuries
- Localized heat injuries primarily manifest as burns.
-
Incidence of Burns
- About 450,000 burn cases treated yearly in medical facilities, with 40,000 hospitalizations and 3,500 fatalities.
- Roughly 30% of burns occur in children, commonly from scalds.
-
Causes of Burns
- Fire/flame (43%), scalds (34%), contact with hot objects (9%), electricity (4%), chemicals (3%).
Burn Classification
- First Degree: Involves only the epidermis; appears pink, dry, heals in 5-10 days without scarring.
-
Second Degree:
- Superficial partial-thickness: Red, blistered, wet, and painful; heals in approximately 3 weeks.
- Deep partial-thickness: Yellow/white, dry, and less painful; healing occurs in 3-8 weeks with scarring.
- Third Degree: White or charred, leathery, minimal pain; heals over 8 weeks, often needing grafting.
- Fourth to Sixth Degree: Involve deeper tissue damage with varying degrees of charred skin and exposed bone.
Mechanisms of Burn Injury
- Local acute changes: Protein denaturation and damage to cells.
- Surrounding tissues experience edema and release inflammatory substances.
- Affected areas include zones of coagulation, stasis, and hyperemia.
- Complications include hypovolemia, infections, necrosis, and scarring.
Generalized Heat Injury
-
Hyperthermia: Defined as body temperatures exceeding 37.5°C, not related to a change in the hypothalamic set-point.
-
Heat Cramps: Result from electrolyte loss; cause painful muscle spasms and require fluid and salt intake for prevention.
-
Heat Exhaustion: Common hyperthermic condition featuring weakness, nausea, and low blood pressure; usually treated by cooling and electrolyte replacement.
-
Heat Stroke: Severe condition with potential for mortality; marked by high body temperatures (>40°C), neurological symptoms, and circulatory shock.
Other Conditions
- Fever: Increase in body temperature due to a higher set-point.
- Malignant Hyperthermia: Inherited condition triggered by certain anesthetic drugs, causing a severe reaction in skeletal muscle when exposed to specific triggers.
Injury Due to Physical Agents
- Physical injuries arise from mechanical, thermal, electrical, and nuclear energy sources.
Temperature Injuries
-
Cold Injuries
- Localized: Includes frostnip (cold sensation without freezing) and frostbite (frozen tissue).
- Generalized: Hypothermia occurs when body temperature drops below 35°C (95°F).
-
Localized Cold Injury
- Frostnip: Skin appears cold, but no freezing damage.
- Trench foot/Immersion foot: Occurs from prolonged exposure to cold water.
- Frostbite: Superficial types may recover in weeks; deep types can cause necrosis and risk of reperfusion injury.
-
Generalized Cold Injury
- Hypothermia is especially risky for children and the elderly.
- Mild hypothermia (36-35°C): Peripheral vasoconstriction and shivering occur.
- Moderate hypothermia (<32°C): Symptoms include drowsiness and confusion.
- Severe hypothermia (<28°C): Can lead to coma and death.
-
Heat Injuries
- Localized heat injuries primarily manifest as burns.
-
Incidence of Burns
- About 450,000 burn cases treated yearly in medical facilities, with 40,000 hospitalizations and 3,500 fatalities.
- Roughly 30% of burns occur in children, commonly from scalds.
-
Causes of Burns
- Fire/flame (43%), scalds (34%), contact with hot objects (9%), electricity (4%), chemicals (3%).
Burn Classification
- First Degree: Involves only the epidermis; appears pink, dry, heals in 5-10 days without scarring.
-
Second Degree:
- Superficial partial-thickness: Red, blistered, wet, and painful; heals in approximately 3 weeks.
- Deep partial-thickness: Yellow/white, dry, and less painful; healing occurs in 3-8 weeks with scarring.
- Third Degree: White or charred, leathery, minimal pain; heals over 8 weeks, often needing grafting.
- Fourth to Sixth Degree: Involve deeper tissue damage with varying degrees of charred skin and exposed bone.
Mechanisms of Burn Injury
- Local acute changes: Protein denaturation and damage to cells.
- Surrounding tissues experience edema and release inflammatory substances.
- Affected areas include zones of coagulation, stasis, and hyperemia.
- Complications include hypovolemia, infections, necrosis, and scarring.
Generalized Heat Injury
-
Hyperthermia: Defined as body temperatures exceeding 37.5°C, not related to a change in the hypothalamic set-point.
-
Heat Cramps: Result from electrolyte loss; cause painful muscle spasms and require fluid and salt intake for prevention.
-
Heat Exhaustion: Common hyperthermic condition featuring weakness, nausea, and low blood pressure; usually treated by cooling and electrolyte replacement.
-
Heat Stroke: Severe condition with potential for mortality; marked by high body temperatures (>40°C), neurological symptoms, and circulatory shock.
Other Conditions
- Fever: Increase in body temperature due to a higher set-point.
- Malignant Hyperthermia: Inherited condition triggered by certain anesthetic drugs, causing a severe reaction in skeletal muscle when exposed to specific triggers.
Injury Due to Physical Agents
- Physical injuries arise from mechanical, thermal, electrical, and nuclear energy sources.
Temperature Injuries
-
Cold Injuries
- Localized: Includes frostnip (cold sensation without freezing) and frostbite (frozen tissue).
- Generalized: Hypothermia occurs when body temperature drops below 35°C (95°F).
-
Localized Cold Injury
- Frostnip: Skin appears cold, but no freezing damage.
- Trench foot/Immersion foot: Occurs from prolonged exposure to cold water.
- Frostbite: Superficial types may recover in weeks; deep types can cause necrosis and risk of reperfusion injury.
-
Generalized Cold Injury
- Hypothermia is especially risky for children and the elderly.
- Mild hypothermia (36-35°C): Peripheral vasoconstriction and shivering occur.
- Moderate hypothermia (<32°C): Symptoms include drowsiness and confusion.
- Severe hypothermia (<28°C): Can lead to coma and death.
-
Heat Injuries
- Localized heat injuries primarily manifest as burns.
-
Incidence of Burns
- About 450,000 burn cases treated yearly in medical facilities, with 40,000 hospitalizations and 3,500 fatalities.
- Roughly 30% of burns occur in children, commonly from scalds.
-
Causes of Burns
- Fire/flame (43%), scalds (34%), contact with hot objects (9%), electricity (4%), chemicals (3%).
Burn Classification
- First Degree: Involves only the epidermis; appears pink, dry, heals in 5-10 days without scarring.
-
Second Degree:
- Superficial partial-thickness: Red, blistered, wet, and painful; heals in approximately 3 weeks.
- Deep partial-thickness: Yellow/white, dry, and less painful; healing occurs in 3-8 weeks with scarring.
- Third Degree: White or charred, leathery, minimal pain; heals over 8 weeks, often needing grafting.
- Fourth to Sixth Degree: Involve deeper tissue damage with varying degrees of charred skin and exposed bone.
Mechanisms of Burn Injury
- Local acute changes: Protein denaturation and damage to cells.
- Surrounding tissues experience edema and release inflammatory substances.
- Affected areas include zones of coagulation, stasis, and hyperemia.
- Complications include hypovolemia, infections, necrosis, and scarring.
Generalized Heat Injury
-
Hyperthermia: Defined as body temperatures exceeding 37.5°C, not related to a change in the hypothalamic set-point.
-
Heat Cramps: Result from electrolyte loss; cause painful muscle spasms and require fluid and salt intake for prevention.
-
Heat Exhaustion: Common hyperthermic condition featuring weakness, nausea, and low blood pressure; usually treated by cooling and electrolyte replacement.
-
Heat Stroke: Severe condition with potential for mortality; marked by high body temperatures (>40°C), neurological symptoms, and circulatory shock.
Other Conditions
- Fever: Increase in body temperature due to a higher set-point.
- Malignant Hyperthermia: Inherited condition triggered by certain anesthetic drugs, causing a severe reaction in skeletal muscle when exposed to specific triggers.
Injury Due to Physical Agents
- Physical injuries arise from mechanical, thermal, electrical, and nuclear energy sources.
Temperature Injuries
-
Cold Injuries
- Localized: Includes frostnip (cold sensation without freezing) and frostbite (frozen tissue).
- Generalized: Hypothermia occurs when body temperature drops below 35°C (95°F).
-
Localized Cold Injury
- Frostnip: Skin appears cold, but no freezing damage.
- Trench foot/Immersion foot: Occurs from prolonged exposure to cold water.
- Frostbite: Superficial types may recover in weeks; deep types can cause necrosis and risk of reperfusion injury.
-
Generalized Cold Injury
- Hypothermia is especially risky for children and the elderly.
- Mild hypothermia (36-35°C): Peripheral vasoconstriction and shivering occur.
- Moderate hypothermia (<32°C): Symptoms include drowsiness and confusion.
- Severe hypothermia (<28°C): Can lead to coma and death.
-
Heat Injuries
- Localized heat injuries primarily manifest as burns.
-
Incidence of Burns
- About 450,000 burn cases treated yearly in medical facilities, with 40,000 hospitalizations and 3,500 fatalities.
- Roughly 30% of burns occur in children, commonly from scalds.
-
Causes of Burns
- Fire/flame (43%), scalds (34%), contact with hot objects (9%), electricity (4%), chemicals (3%).
Burn Classification
- First Degree: Involves only the epidermis; appears pink, dry, heals in 5-10 days without scarring.
-
Second Degree:
- Superficial partial-thickness: Red, blistered, wet, and painful; heals in approximately 3 weeks.
- Deep partial-thickness: Yellow/white, dry, and less painful; healing occurs in 3-8 weeks with scarring.
- Third Degree: White or charred, leathery, minimal pain; heals over 8 weeks, often needing grafting.
- Fourth to Sixth Degree: Involve deeper tissue damage with varying degrees of charred skin and exposed bone.
Mechanisms of Burn Injury
- Local acute changes: Protein denaturation and damage to cells.
- Surrounding tissues experience edema and release inflammatory substances.
- Affected areas include zones of coagulation, stasis, and hyperemia.
- Complications include hypovolemia, infections, necrosis, and scarring.
Generalized Heat Injury
-
Hyperthermia: Defined as body temperatures exceeding 37.5°C, not related to a change in the hypothalamic set-point.
-
Heat Cramps: Result from electrolyte loss; cause painful muscle spasms and require fluid and salt intake for prevention.
-
Heat Exhaustion: Common hyperthermic condition featuring weakness, nausea, and low blood pressure; usually treated by cooling and electrolyte replacement.
-
Heat Stroke: Severe condition with potential for mortality; marked by high body temperatures (>40°C), neurological symptoms, and circulatory shock.
Other Conditions
- Fever: Increase in body temperature due to a higher set-point.
- Malignant Hyperthermia: Inherited condition triggered by certain anesthetic drugs, causing a severe reaction in skeletal muscle when exposed to specific triggers.
Mechanical Injury
- Causes of deaths from trauma: approximately 160,000/year
- Breakdown of causes:
- Motor vehicle accident: 44,000
- Firearms: 30,000 (55% suicide, 40% homicide, 5% accidental or law enforcement related)
- Acute toxic exposure: 26,000
- Falls: 17,000
- Suffocation including drowning: 13,000
- All other: 31,000
- Types of injuries:
- Abrasion: scraping the skin surface, damaging superficial layer of skin
- Contusion or bruise: blunt force, causing hemorrhages under intact skin
- Laceration and incision: tearing (blunt force) and cutting (sharp object)
- Avulsions and fracture: tendon insertions and bones
- Extended compression: ulcers
- Gravity alteration: accelerated aging
- Mechanical energy (E) is transferred into the tissue due to action of forces (F) or force fields, causing displacement (∆x) and change in velocity (v)
- E = F∆x = ∆mv2/2
Pressure Ulcer
- Ischemia with compression or shear forces
- Stages of pressure ulcer: 1-4, depending on depth
- Preceding stage 1 changes:
- Sensation
- Temperature
- Tissue firmness
- Early detection methods:
- Subepidermal micro-edema, micro-vascularisation, micro-hemorrhages
- High-frequency ultrasound
- Thermography IR with adjacent skin comparison
- Spectroscopy (Hb)
- Skin electric conductance (most reliable)
Electrical Injuries
- Causes: electrocution and lightning strike
- Physics of electrical injuries:
- Current flows in a closed circuit from high energy to low energy of electrical charges
- Amount of current (I) is related to:
- Voltage exposed to
- Resistance of the body tissues and of skin at the point of entry and exit
- Available moving electrical charges (electrons and ions)
- Severity of tissue damage is dependent on the amount of energy transferred into the tissue: E = I2Rt = VIt = V2t/R
- Two major effects:
- Passage of current producing heat
- Interfering with the function of electrical tissues: alteration of electrons and ions flow across membranes
Ionizing Radiation Injury
- Sources of exposure:
- Natural radiation (cosmic, earth, inside living organisms)
- Nuclear bombs
- Nuclear reactor
- Diagnostic and therapeutic purposes
- Radiation terminology:
- Rad: a measure of the energy absorbed per unit mass of the tissue
- Gray: the SI unit that replaced the rad
- Roentogen (R): a unit of radiation exposure
- Sievert (Si) and rem (radiation equivalent man): biological equivalent dose
- Types of ionizing radiation:
- Mechanism of radiation injury:
- Direct action: changes molecules in the cells themselves
- Indirect action: causes formation of free radicals
- Mechanism of radiation injury:
- Effects of radiation injury:
- Cellular injury, necrosis, or apoptosis
- Mostly fibrosis
- Vascular anomalies
- Neurological effects
- Production of cancer in irradiated cell
- Production of congenital abnormalities in germ cell line
Nonionizing Radiation
- Energy of nonionizing radiation can move atoms in a molecule or cause them to vibrate, but it is not sufficient to displace bound electrons from atoms
- Cells have mechanosensitive and electrosensitive structure interconnected to all cellular functions
- Disruption of electric and mechanical homeostasis needs to be investigated
Ultraviolet Radiation
- Effects:
- Sun burn
- Accelerated aging of the skin
- Skin cancer
- Basal cell carcinoma
- Squamous cell carcinoma
- Malignant melanoma
- Signs that a mole may be turning into a malignant melanoma:
- Asymmetry
- Border
- Color
- Diameter
- Evolution
Visible, Infrared, Microwave, and Radio
- Classified as a category 2B agent = potentially carcinogenic by International Agency for Research on Cancer (IARC)--Agenda of World Health Organization (WHO)
Mechanical Injury
- Approximately 160,000 deaths/year from trauma
- Causes of deaths from trauma: • Motor vehicle accident: 44,000 • Firearms: 30,000 (55% suicide, 40% homicide, 5% accidental or law enforcement related) • Acute toxic exposure: 26,000 • Falls: 17,000 • Suffocation including drowning: 13,000 • All other: 31,000
- Types of injuries: • Abrasion: scraping the skin surface, damaging the superficial layer of skin • Contusion or bruise: blunt force causing hemorrhages under intact skin • Laceration and incision: tearing (blunt force) and cutting (sharp object) • Avulsions and fracture: tendon insertions and bones • Extended compression: ulcers • Gravity alteration: accelerated aging
- Mechanical energy (E): transferred into the tissue due to action of forces (F) or force fields, causing displacement (∆x) and change in velocity (v) • E = F∆x = ∆mv²/2
Pressure Ulcer
- Caused by ischemia with compression or shear forces
- 1-4 stages, depending on depth
- Preceding stage 1 are changes significant for detection: • Sensation • Temperature • Tissue firmness
- Early detection possible based on:
• Subepidermal micro-edema
• Micro-vascularisation
• Micro-hemorrhages
- Using high-frequency ultrasound
- Thermography IR with adjacent skin comparison
- Spectroscopy (Hb)
- Skin electric conductance (most reliable)
Abnormal Gravity Effects
- Microgravity in space flight: accelerated aging documented on: • Musculoskeletal • Cardiovascular • Respiratory • Neurologic • Blood and CSF redistribution • Metabolic • Endocrine • Eyes
- Mostly reversible with appropriate intervention after returning to Earth gravity
Electrical Injuries
- Causes: electrocution and lightning strike
- Physics of electrical injuries:
• Current flows in a closed circuit from high energy to low energy of electrical charges
• Amount of current (I) is related to:
- Voltage exposed to
- Resistance of the body tissues and of skin at the point of entry and exit
- Available moving electrical charges (electrons and ions) • Severity of tissue damage is dependent on the amount of energy transferred into the tissue: E = I²Rt = VIt = V²t/R
- Two major effects:
• Passage of current producing heat – happens in any tissue or object
• Interfering with the function of electrical tissues: alteration of electrons and ions flow across membranes
- Effects on: • Muscles: spasm, mostly for AC • Cardiac conduction tissue: ventricular fibrillation • Depression of respiratory centers
- Low energy electric and electromagnetic fields or radiation may not be life-threatening but still pathological
• Alteration of electrons and ions flow across membranes = classical view of electric current effects
• Alteration of voltage-gated ion channels
- Most sensitive appears to be voltage-gated calcium channel (VGCC) – multiple effects due to increased intracellular Ca
- Electric (and magnetic) fields can also be beneficial by: • Restoring electromagnetic “homeostasis”: muscle rehab, tissue growth, and repair • Resetting activity of electrical dependant tissue: e.g. defibrillator in cardiac arrest
Ionizing Radiation Injury
- Sources of exposure: • Natural radiation (cosmic, earth, inside living organisms) • Nuclear bombs • Nuclear reactor • Diagnostic and therapeutic purposes
- Radiation terminology:
• Rad: measure of the energy absorbed per unit mass of the tissue (1 rad = 100 ergs per gram of tissue)
• Gray (Gy): SI unit that replaced the rad (1 Gy = 1J/kg = 100 rads)
• Roentgen (R): unit of radiation exposure (For X-ray, 1R ~ 1 rad)
• Sievert (Si) and rem (radiation equivalent man): biological equivalent dose (BED)
- BED (in Si) = D (in Gy) x Q (“quality” factor) • Q: how effective is radiation in damaging tissue compared with X-ray or high-energy electrons
- Types of ionizing radiation:
• Direct action: changes molecules in the cells themselves
- “Direct hit”: Membrane, DNA • Indirect action: causes formation of free radicals
- Damage to cells and especially rapid dividing cells (bone marrow, epithelial, endothelial cells)
- Effects of radiation injury:
• Cellular injury, necrosis, or apoptosis
- Cytoplasmic swelling
- Mitochondrial distortion
- Degeneration of the endoplasmic reticulum
- Plasma membrane breaks/focal defects may be seen
- Chromosomal and nuclear changes • Mostly fibrosis, like after chronic inflammation • Vascular anomalies, with fibrosis, collagenous hyalinization, thickening of the intima, thrombosis, scaring • Neurological effects: shown in exposure to cosmic radiation and radiotherapy • Production of cancer in irradiated cells • Production of congenital abnormalities in germ cell line
- Factors that influence the severity of tissue damage: • Dose • Penetration of tissues • Sensitivity of tissues • Duration of exposure
- Effects of total body irradiation
Nonionizing Radiation
- Energy of nonionizing radiation (UV and infrared light, microwave, and sound waves) can: • Move atoms in a molecule • Cause them to vibrate • Alter “free” moving ions and electrons (ion channels and ETS)
- Cells have mechanosensitive and electrosensitive structures interconnected to all cellular functions, so disruption of electric and mechanical homeostasis needs to be investigated
Ultraviolet Radiation
- Causes:
• Sunburn
• Accelerated aging of the skin
• Skin cancer
- Basal cell carcinoma
- Squamous cell carcinoma
- Malignant melanoma
- Signs that a mole may be turning into a malignant melanoma: • Asymmetry • Border • Color • Diameter • Evolution
Visible, Infrared, Microwave, and Radio
- Classified as a category 2B agent = potentially carcinogenic by International Agency for Research on Cancer (IARC)--Agncy of World Health Organization (WHO)
Mechanical Injury
- Trauma accounts for approximately 160,000 deaths annually.
- Leading causes include:
- Motor vehicle accidents: 44,000 deaths
- Firearms: 30,000 deaths (55% suicide, 40% homicide, 5% accidental/law enforcement)
- Acute toxic exposures: 26,000 deaths
- Falls: 17,000 deaths
- Suffocation (including drowning): 13,000 deaths
- Other causes: 31,000 deaths
- Types of mechanical injuries:
- Abrasion: Scraping of the skin's surface, affecting the superficial layer.
- Contusion: Bruise from blunt force, with hemorrhage beneath intact skin.
- Laceration and Incision: Result from tearing (blunt force) or cutting (sharp object).
- Avulsions and Fractures: Involvement of tendon insertions and bones.
- Extended Compression: Can lead to ulcers.
- Gravity Alteration: Linked to accelerated aging.
- Mechanical energy (E) is calculated as (E = F \Delta x = \Delta \frac{mv^2}{2}), indicating the transfer of energy into tissue from forces.
Pressure Ulcers
- Develop from ischemia due to compression or shear forces.
- Classified into 1 to 4 stages based on tissue depth.
- Early indicators include changes in sensation, temperature, and tissue firmness.
- Early detection methods involve:
- Subepidermal micro-edema
- Micro-vascularization
- Micro-hemorrhages
- Techniques like high-frequency ultrasound and thermography
- Skin electric conductance is the most reliable method.
- Microgravity effects in space contribute to accelerated aging across various bodily systems but are mostly reversible upon return to Earth.
Electrical Injuries
- Caused by electrocution and lightning strikes.
- Current flows in a closed circuit from high to low energy; severity relies on current amount, voltage, and tissue resistance.
- Tissue damage severity is determined by energy transfer, computed as (E = I^2Rt = VIt = \frac{V^2t}{R}).
- Major effects include:
- Heat production during current passage impacting all tissues.
- Disruption of electrical tissue function, causing muscle spasms and potential cardiac issues.
- Low-energy electric fields may cause pathological effects but can also provide therapeutic benefits, aiding in muscle rehab and tissue repair.
Ionizing Radiation Injury
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Sources of Exposure:
- Natural radiation (cosmic, terrestrial, biological)
- Nuclear bombs and reactors
- Medical diagnostics and treatments
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Radiation Terminology:
- Rad: Measure of energy absorption (1 rad = 100 ergs/g tissue)
- Gray (Gy): SI unit replacing rad; 1 Gy = 1 J/kg = 100 rads
- Sievert (Sv): Biological equivalent dose for radiation effects in humans.
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Mechanisms of Radiation Injury:
- Direct action: Damages cellular molecules (membrane, DNA).
- Indirect action: Creates free radicals that harm rapidly dividing cells.
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Effects of Radiation Injury:
- Cellular damage can lead to necrosis or apoptosis.
- Common consequences include fibrosis, vascular anomalies, and neurological effects from cosmic radiation.
- Increases risk of cancer and congenital abnormalities.
- Severity of damage influenced by dose, tissue penetration, tissue sensitivity, and exposure duration.
Nonionizing Radiation
- Includes UV, infrared, microwaves, and sound waves; sufficient energy to move atoms but not to displace bound electrons.
- Alters free ions and electrons, impacting cellular functions through mechanosensitive and electrosensitive structures.
Ultraviolet Radiation
- Causes sunburn, accelerates skin aging, and increases skin cancer risks, including:
- Basal cell carcinoma
- Squamous cell carcinoma
- Malignant melanoma
- Signs of potential malignant melanoma transformation include changes in asymmetry, border, color, diameter, and evolution of moles.
Visible, Infrared, Microwave, and Radio
- Classified as potential carcinogens (Category 2B) by the International Agency for Research on Cancer (IARC).
Mechanical Injury
- Trauma causes approximately 160,000 deaths annually.
- Motor vehicle accidents contribute 44,000 deaths; firearms account for 30,000 with 55% attributed to suicide, 40% to homicide, and 5% to accidental or law enforcement-related incidents.
- Other contributors include acute toxic exposure (26,000), falls (17,000), suffocation (including drowning, 13,000), and remaining causes (31,000).
Types of Mechanical Injuries
- Abrasion: Scraping of skin leading to superficial damage.
- Contusion: Bruising due to blunt force trauma, resulting in hemorrhage under intact skin.
- Laceration and incision: Tearing from blunt force and cutting from sharp objects.
- Avulsions and fractures: Involves detaching tendon insertions and breaking of bones.
- Extended compression: Leads to ulcers due to sustained pressure.
- Gravity alteration can accelerate aging.
Mechanical Energy Fundamentals
- Energy (E) is transferred to tissues through force (F) action, causing displacement (Δx) and a change in velocity (v).
- Energy equation: E = FΔx = Δ(1/2 mv²).
Pressure Ulcers
- Pressure ulcers develop from ischemia caused by compression or shear forces, categorized into stages 1 to 4 based on depth.
- Early detection signs include changes in sensation, temperature, and tissue firmness.
- Detection techniques: high-frequency ultrasound, IR thermography, spectroscopy, and skin electric conductance are useful for early identification.
Microgravity Effects
- Microgravity from space flight accelerates aging in multiple systems including musculoskeletal and cardiovascular, often reversible with interventions post-return to Earth.
Electrical Injuries
- Common causes include electrocution and lightning strikes.
- Current flows from high to low energy through a closed circuit, calculated using I = V/R, where I is current, V is voltage, and R is resistance.
- Severity of damage depends on energy transferred: E = I²Rt = VIt = V²t/R.
Effects of Electrical Currents
- Current passage creates heat and can disrupt the function of electrically active tissues, leading to muscle spasms, cardiac arrhythmias, and respiratory depression.
- Low energy electric fields can have pathological effects by altering ion flows and voltage-gated ion channels, particularly affecting calcium channels.
Ionizing Radiation Injury
- Sources include natural radiation, nuclear activities, and medical procedures.
- Radiation exposure measured in rads (1 rad = 100 ergs/g), with the Gray (Gy) as the SI unit replacing rad (1 Gy = 100 rads).
- Biological equivalent dose is expressed in Sieverts (Si), factoring in quality (Q) of radiation.
Mechanism of Radiation Injury
- Direct action involves changes in cell molecules leading to membrane and DNA damage.
- Indirect action results in free radical formation damaging rapidly dividing cells, notably in bone marrow and epithelial cells.
Effects of Radiation Injury
- Cellular necrosis or apoptosis, resulting in cellular swelling and mitochondrial distortion.
- Potential for chronic fibrosis, vascular anomalies, neurological effects from cosmic radiation, cancer development, and congenital abnormalities in germ cells.
Factors Influencing Radiation Damage
- Severity influenced by dose, tissue penetration, tissue sensitivity, and duration of exposure.
Nonionizing Radiation
- Nonionizing radiation includes UV, infrared, microwaves, and sound waves; it can alter moving ions but doesn’t have sufficient energy to displace bound electrons.
- Disruption of cellular electric and mechanical homeostasis can affect overall cellular function.
Ultraviolet Radiation Effects
- Causes sunburn, accelerates skin aging, and is linked to skin cancers: basal cell carcinoma, squamous cell carcinoma, and malignant melanoma.
- Malignant melanoma assessment involves evaluating asymmetry, border irregularity, color variation, diameter, and evolution of moles.
Classification of Nonionizing Radiation
- UV, visible light, infrared, microwave, and radio classified as potential carcinogens per the International Agency for Research on Cancer (IARC).
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Description
This quiz examines injuries caused by physical agents, including temperature effects, mechanical trauma, electrical current, and radiation. Topics include frostbite, hypothermia, burns, and hyperthermia. Test your understanding of various thermal injuries and their classifications.
