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Pathophysiology > Topic 2 - Pathogenic action of physical factors > Flashcards

Topic 2 - Pathogenic action of physical factors Flashcards

1
Q

What are the effects of mechanical factors on the body?

A
  • Accelerated movement called kinetosis
  • Organs and liquids are displaced in the direction opposite to the direction of movement
  • Impaired respiration, pulmonary blood circulation and gas exchange
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2
Q

What is the effect of gravity on the human body?

A

Stimulation of bone mineralisation and muscle mass

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3
Q

What is the effect of a lack of gravity on the human body

A

Bone demineralisation and muscle wasting

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4
Q

What is hyperthermia?

A

An increase in body temperature due to the exposure of the whole body to a high ambient temperature.

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5
Q

What is the aetiology of hyperthermia?

A

Industrially produced heat or natural climate

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6
Q

How is hyperthermia initially managed by the body?

A

Compensation by conduction, convection, radiation and evaporation

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7
Q

What is the limitation of evaporation?

A

High humidity

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8
Q

What is the limitation convection?

A

Air temperatures higher than 30 degrees Celsius

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9
Q

What is decompensation of hyperthermia?

A

It is when the compensatory reactions are exhausted.

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10
Q

What happens in hyperthermia when decompensation occurs?

A
  • temperature rises
  • tachypnoea occurs
  • tachycardia
  • peripheral vasodilatation
  • sequestration of large amounts of blood and effective reduction in circulating blood volume
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11
Q

What consequences can excess evaporation have?

A

Dehydration and electrolyte imbalances. Increased blood viscosity and resulting cardiac insufficiency.

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12
Q

What is thermal shock/heat stroke?

A

Acute overheating and rapid body temperature increase.

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13
Q

What happens in heat stroke if the aetiological factor is not removed?

A

Convulsions develop and death occurs because of disordered circulation and respiation.

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14
Q

Describe the stage of developing a burn from least severe to most

A
  • Local effect of high temperature
  • First degree – redness of skin
  • Second degree – acute exudative inflammation of the skin, formation of blisters and epidermis scaling
  • Third degree – partial skin necrosis and ulceration
  • Fourth degree – transepidermal necrosis
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15
Q

What is the difference between extensive burns and local burns?

A

In extensive burns systemic effects predominate over local ones. This is burn disease.

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16
Q

Describe burn disease

A

It comprises one or more of burn shock, intoxication, infection, dehydration and exhaustion.

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17
Q

What happens to the region of a burn if the patient starts to recover?

A

If the patient starts to recover then defects are filled with granulation and wounds are epithelized.

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18
Q

What is hypothermia?

A

Decrease in body temperature due to exposure of whole body to low ambient temperature

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19
Q

What happens during compensation for hypothermia?

A
  • Heat emission decrease happens by means of perspiration decrease and peripheral angiospasm
  • Heat production increase happens by means of increased metabolic rate, increased gluconeogenesis and more muscular activity (shivering)
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20
Q

What happens during the decompensation phase of hypothermia?

A
  • During decompensation a reduction in metabolism and oxygen consumption is observed.
  • Vital functions fail. Impairment of respiratory and circulatory systems leads to hypoxia.
  • If the action of cold does not cease then death comes.
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21
Q

Why would hypothermia be clinically induced?

A

During cardiac arrest, blood doesn’t flow to the organs of the body. The brain may also not get enough blood. That’s why many people don’t recover after cardiac arrest. The lack of blood flow can cause lasting damage to the brain. The person may be unable to regain consciousness. Lowering the body temperature right away after cardiac arrest can reduce damage to the brain. That raises the chances that the person will recover.

22
Q

What are the three main types of ionising radiation an what are they composed of?

A

Alpha which is composed of a helium nucleus, beta which is composed of a high energy electron and gamma which is composed of electromagnetic waves

23
Q

What is the penetrative power of each of the three main forms of ionising radiation

A

Alpha will not penetrate skin, Beta will penetrate skin and some tissues slightly and Gamma will penetrate tissues deeply.

24
Q

What is the mechanism of direct radiation damage on the body?

A

Direct effect is damage of chemical bonds in macromolecules by radiation itself. May target any organic macromolecules such as DND, lipids, phospholipids, enzymes, proteins, vitamins, hemoprotein etc.

25
Q

What is the mechanism of indirect radiation damage on the body?

A

Indirect damage is damage of macromolecules by water radiolysis products. These are biochemically very active and cause extensive non-enzymatic oxidation.

26
Q

Describe the radiolysis of water

A

• First ionized water molecules, then free hydrogen and hydroxyl radicals and then a chain of new products are formed including hydrogen peroxide, hydroperoxide and oxygen.

27
Q

How are radiotoxins formed in the body?

A

Radiotoxins are formed when unsaturated fatty acids and phenols are oxidized resulting in the formation of lipid and quinone radiotoxins.

28
Q

What are the mechanisms of the damaging effects of radiotoxins on a cell?

A

Radiotoxins inhibit nucleic acid synthesis, influence DNA as chemical mutagens, change enzyme activity and damage intracellular membranes. Enzymes are damaged directly and indirectly. Damage of cell nucleus (swelling, pycnosis, lysis), chromosomal aberrations, subtle mutations that change the synthesis of DNA, specific proteins and subsequently affect hereditary properties of cells. All other cell organoids are damaged too. Free radicals target phospholipids of intracellular membranes. Damage of lysosomes releases lysosymes damaging nucleic acids, cytoplasmic and nuclear proteins. Impairment of mitochondria leads to energy deficit
If a cell with a mutation is not eliminated it becomes a cell with changed heredity. Somatic cells can become malignant. Mutations in germ cells may cause hereditary diseases in descendants.

29
Q

What are the two basic forms of radiation sichness?

A

Acute and chronic

30
Q

Give 4 types of acute radiation sickness

A

Medullary, gastrointestinal, haematopoietic and cerebral

31
Q

Describe acute gastrointestinal radiation sickness

A

Nausea, vomiting, pain in the bowels, blood streaked stool and diarrhoea

32
Q

How does chronic radiation sickness develop?

A

Repeated small doses of radiation

33
Q

How does the haematopoietic form of acute radiation sickness come about?

A

Aplastic anaemia results from radiation injury to pluripotential and multipotential stem cells in the bone marrow. Radiation hematotoxicity is mediated via genotoxic and other specific toxic mechanisms, leading to aplasia, cell apoptosis or necrosis, initiation via genetic mechanisms of clonal disorders, in cases such as the acute radiation-acquired form of aplastic anaemia.

34
Q

How does the haematopoietic form of acute radiation sickness present?

A

The clinical signs displayed in reticulocytopenia, anemia, granulocytopenia, monocytopenia, and thrombocytopenia. The number of marrow CD34+ cells (multipotential hematopoietic progenitors) and their derivative colony-forming unit{granulocyte-macrophage (CFU-GM) and burst forming unit {erythroid (BFU{E) are reduced markedly in patients with aplastic anaemia.

35
Q

Give the natural mechanisms of protection against radiation

A
  • Natural anti-oxidant systems
  • The ability of cells to restore DNA
  • Natural radioprotectors which neutralize water radiolysis products and radiotoxins
  • Immunological reactivity kills mutant cells
  • Enzymes which detach damaged fragments
  • DNA polymerase
36
Q

Give the possible harmful effects of infrared radiation

A

• Medical studies indicate that prolonged IR exposure can lead to lens, cornea and retina damage, including cataracts, corneal ulcers and retinal burns, respectively.

37
Q

Give the harmful effects of UVA

A

UVA exposure has an initial pigment-darkening effect (tanning) followed by erythema if the exposure is excessive. Overexposure to UVA has been associated with toughening of the skin, suppression of the immune system, and cataract formation.

38
Q

Give the harmful effects of UVB

A

Harmful effects can include erythema (sunburn), cataracts, and development of skin cancer.

39
Q

Give the harmful effects of UVC

A

In humans, UVC is absorbed in the outer dead layers of the epidermis. Accidental overexposure to UVC can cause corneal burns, commonly termed welders’ flash, and snow blindness, a severe sunburn to the face.

40
Q

Describe photosensitivity

A
  • Sunlight can trigger immune system reactions.
  • People develop itchy eruptions or areas of redness and inflammation on patches of sun-exposed skin.
  • The diagnosis is usually based on a doctor’s evaluation.
  • These reactions typically resolve without treatment.
41
Q

Describe the effect on the body of low atmospheric pressure

A
  • Under low atmospheric pressure there is hypobaria and hypoxic hypoxia
  • Hypobaria results in gaas expansion in the internal cavities like the sinuses, bowels and pleural and peritoneal cavities.
42
Q

Describe the effect on the body of decompression and decompression syndrome

A
  • Decompression syndrome is the range of phenomena associated with low atmospheric pressure.
  • In the process of decompression man feels pain in the sinuses, in the abdomen and joints. Epistaxis occurs as a result of expansion and eruption of small vessels.
43
Q

Describe the effect on the body of high atmospheric pressure

A
  • Under hyperbaria excess gas is dissolved in the blood or tissues of man
  • Nitrogen is liposoluble and affects nervous tissue the most causing nervous excitement resembling euphoria or when worse intoxication.
  • Under increased pressure oxygen ats as a strong oxidizer oxidizing lipids, proteins and nucleic acids
  • Thus formation of free radicals and peroxide causes affection of DNA and tissue enzymes.
44
Q

How is the danger of nitrogen avoided in diving?

A

Nitrogen is supplemented with helium in diving tanks

45
Q

What happens is there is hyperoxia after decompensation?

A

Tissue asphyxia

46
Q

Describe the first degree of chronic radiation sickness

A

First degree proceeds as reversible functional disorders of most sensitive systems. Sometimes the patient feels quite well but blood study reveals stable leukopenia and thrombocytopenia.

47
Q

Describe the second degree of chronic radiation sickness

A

Second degree has more significant changes in the nervous and hematopoietic systems. Leukopenia and lymphopenia become stable and thrombocyte count is reduced. Haemorrhage syndrome and immunodepression are revealed.

48
Q

Describe the third degree of chronic radiation sickness

A

• Third degree has deep dystrophy of tissues and irreversible organ changes. The function of the pituitary gland and suprarenal glands is exhausted. Haemopoiesis is suppressed, vessel tone is lowered, vessel perpeability is increased. Necrotic defects of mucous membranes are observed. Infection and inflammation take a necrotic course.

49
Q

Give two general effects of chronic radiation sickness

A

Gene disorders may cause neoplasia. Organism grows old prematurely.

50
Q

Give the pathogenic action of electric current

A
  • Electrical energy transforms into other types of energy (mechanical, heat, chemical)
  • Skin burns
  • Tissue rupture and bone fractures are a manifestation of the mechanical effect
  • Has an electrolysis effect which causes ion redistribution, changes in biological potentials and the state of voltage gated ion channels, causes cellular membrane depolarization and appearance of action potentials in excitable tissues. As a consequence the functional state of cells changes.
  • Nerve and muscle tissue are most excitable and have highest sensitivity thus muscle spasms develop.
  • The state of biocolloids is changed. Coagulative of colliquative necrosis results from colloid movement and swelling. Cellular protoplasm may coagulate.

Pathophysiology (4 decks)

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