Leo - L3 part 2

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Questions and Answers

How does the cardio-circulatory system respond during the prodromal phase of fever?

In the prodromal phase, the cardio-circulatory system exhibits superficial vasoconstriction and increased heart rate, typically resulting in tachycardia.

What respiratory changes occur due to fever and what severe condition can result from very high fever?

Fever leads to increased respiration rate, or polypnea, and can result in dyspnea at very high temperatures.

Describe the impact of fever on the digestive system.

Fever causes digestive impairment characterized by slowed intestinal motility and symptoms like anorexia, nausea, and vomiting.

What neurological symptoms may accompany high fever?

High fever can result in dullness, agitation, muscular adynamia, asthenia, and even hallucinations or delirium. Signup and view all the answers

What role does fever play in the immune system's response?

Fever stimulates both humoral and cell-mediated immune responses effectively when thermal gains remain below 40 °C. Signup and view all the answers

What is the significance of understanding the course of fever in clinical practice?

Understanding the course of fever helps identify its cause and determine appropriate treatment options. Signup and view all the answers

Describe the three phases of continuous fever.

The three phases of continuous fever are the prodromal phase, fastigium phase where the fever remains constant, and the defervescence phase where the fever starts to lower. Signup and view all the answers

What distinguishes remitting fever from continuous fever?

Remitting fever lacks distinct prodromal and defervescence phases, showing daily temperature fluctuations of more than one degree. Signup and view all the answers

Explain the term 'intermittent fever' and its types.

Intermittent fever is characterized by periods of fever interspersed with periods of normal temperature, including daily, tertian, quartan, and quintain types. Signup and view all the answers

Why is it important not to immediately treat fever with antipyretic drugs?

Delaying treatment allows for the observation of the fever's progression, aiding in diagnosing the underlying cause. Signup and view all the answers

What metabolic alterations occur during a fever?

Metabolic alterations during fever include increased basal metabolism, elevated hepatic and muscle glycogenolysis, and changes in lipid and protein metabolism. Signup and view all the answers

What is the role of antipyretic drugs in fever management?

Antipyretic drugs, such as NSAIDs and glucocorticoids, inhibit the production of prostaglandins and reduce inflammation to manage fever. Signup and view all the answers

How does lipid metabolism change during fever?

Lipid metabolism increases fatty acid mobilization from adipose tissue, leading to higher ketone body production in the blood. Signup and view all the answers

Identify one condition characterized by quintain fever.

Rickettsial infections are typically associated with quintain fever. Signup and view all the answers

What is a potential consequence of high fever on kidney function?

High fever can lead to tubular damage, potentially resulting in the appearance of urinary albumin. Signup and view all the answers

What stimulates the thermoregulation center during a fever?

Endogenous pyrogens stimulate the thermoregulation center, particularly acting on the preoptic region of the hypothalamus. Signup and view all the answers

Explain the role of PGE2 in the context of fever.

PGE2 acts as a mediator that influences the hypothalamic neurons, either directly by crossing the BBB or indirectly through other inflammatory mediators. Signup and view all the answers

Describe the two methods the body uses to increase temperature during fever.

The body increases temperature through thermoconservation and neothermogenesis. Signup and view all the answers

What occurs during the fastigium phase of fever?

The fastigium phase is characterized by a stable, elevated body temperature with balanced thermogenesis and thermal dispersion. Signup and view all the answers

How is fever classified based on degree of body temperature increase?

Fever is classified into low fever (1°C), medium (1-2°C), high (2-3°C), and hyperpyrexia (over 41.5°C). Signup and view all the answers

What physiological changes characterize the thermal increase phase of fever?

During the thermal increase phase, there is an increase in thermogenesis, peripheral vasoconstriction, and a sensation of cold. Signup and view all the answers

In what ways can body temperature decrease during the defervescence phase?

In the defervescence phase, body temperature decreases through increased thermal dispersion via peripheral vasodilation and sweating. Signup and view all the answers

What triggers the release of hormones during neothermogenesis?

The stimulation of the hypophysis triggers the release of hormones like TSH and ACTH during neothermogenesis. Signup and view all the answers

What are the key factors leading to the production of endogenous pyrogens?

Endogenous pyrogens are produced following stimuli such as necrosis, inflammation, and immune responses. Signup and view all the answers

What is the primary nervous system change prompted by endogenous pyrogens during fever?

Endogenous pyrogens influence neurons in the hypothalamus, leading to an increased thermal set point. Signup and view all the answers

What are the primary causes of hypothermia, and how do they affect the body's thermal balance?

Hypothermia can be caused by external factors like frostbite or prolonged exposure to cold and internal factors such as hypovolemic shock and hormonal deficiencies. These causes lead to increased thermal dispersion and decreased thermogenesis, resulting in a dramatic drop in body temperature. Signup and view all the answers

Explain the significance of a body temperature dropping below 25°C.

A body temperature below 25°C indicates a critical point where systemic hypothermia can lead to heart failure and potentially death. This 'no return' point emphasizes the severity of extreme hypothermia. Signup and view all the answers

How does fever function as a systemic reaction in the body?

Fever serves as a systemic reaction to infections and other stimuli, involving decreased thermal dispersion and increased thermogenesis. It acts as a defense mechanism by raising the body's set point temperature temporarily. Signup and view all the answers

What role do exogenous pyrogens play in the fever response?

Exogenous pyrogens, such as bacterial endotoxins, stimulate vascular cells to produce inflammatory mediators like cytokines and prostaglandins. This process facilitates the body's systemic inflammatory response, contributing to the fever mechanism. Signup and view all the answers

Differentiate between systemic hypothermia and frostbite.

Systemic hypothermia refers to a dangerous overall drop in body temperature, while frostbite is localized damage to body tissues due to freezing. Hypothermia can lead to life-threatening conditions, whereas frostbite primarily affects extremities. Signup and view all the answers

Describe how hypothyroidism can contribute to hypothermia.

Hypothyroidism decreases hormone production, which in turn reduces the basal metabolic rate and thermogenesis, leading to increased vulnerability to hypothermia. Low metabolic rates hinder the body's ability to generate heat. Signup and view all the answers

What mechanisms does the body employ to adjust its temperature during fever?

During fever, the body decreases thermal dispersion and increases thermogenesis through adaptations in circulation, aided by the resetting of hypothalamic thermoregulatory centers. This helps maintain a higher temperature to fight off infection. Signup and view all the answers

What are the implications of alcohol consumption on thermoregulation?

Alcohol can increase thermal dispersion due to peripheral vasodilation, which shifts blood flow to the skin and diminishes the body's ability to retain heat, thereby increasing the risk of hypothermia. This can be particularly dangerous in cold environments. Signup and view all the answers

Study Notes

Hypothermia

Hypothermia is characterized by a significant decrease in body temperature due to increased thermal dispersion and decreased thermogenesis.
Causes include external factors (e.g., prolonged exposure to cold) and internal factors such as:
- Frostbite
- Hypovolemic shock
- Alcohol consumption, leading to peripheral vasodilation and increased thermal dispersion.
- Hypothyroidism and hypocortisolism, which lower hormone production and reduce basal metabolism.
Systemic hypothermia results in risking vital damage and can lead to death if body temperature drops below 25°C, indicating a critical point for heart failure.

Hyperthermia and Fever

Fever is a systemic response, not a disease, acting as a protective mechanism against infections, trauma, autoimmune diseases, and cancer.
It involves:
- Decreased thermal dispersion and increased thermogenesis.
- Temporary elevation of the body's temperature set point, controlled by the hypothalamus through mechanisms involving pyrogens.

Pyrogens

Two types of pyrogens exist:
- Exogenous pyrogens: originate from external sources, such as bacterial toxins (e.g., endotoxins from Gram-negative bacteria).
- Endogenous pyrogens: produced by the body, often in response to infection, necrosis, or inflammation, including cytokines and prostaglandins.
Pyrogens function by acting on the hypothalamus to reset the temperature set point.

Mechanisms of Thermoregulation

Endogenous pyrogens influence the hypothalamus directly or indirectly via mediators like PGE2.
Thermoregulation actions include:
- Thermoconservation: reduces heat loss through peripheral vasoconstriction.
- Neothermogenesis: stimulates the production of heat through increased basal metabolism via hormonal release (TSH, ACTH).

Phases of Fever

Three phases of fever:
- Thermal increase/prodromal phase: Body temperature rises due to thermoconservation and increased thermogenesis. Symptoms include chills, shivering, and increased heart rate.
- Fastigium phase: Stable, high fever where body temperature remains elevated.
  - Various classifications of fever based on temperature increase: low (1°C rise), medium (1-2°C), high (2-3°C), hyperpyrexia (over 41.5°C).
- Defervescence phase: Decrease in temperature through increased thermal dispersion, leading to sweating and vasodilation.

Types of Fever

Continuous fever: Steady high temperature without fluctuations, often seen in pneumonia.
Remitting fever: Daily fluctuations of temperature without distinct phases, linked to infections like sepsis.
Intermittent fever: Alternating fever and normothermia, with specific patterns (e.g., quotidian, tertian, quartan) related to conditions like malaria.
Odd and recurrent fevers: Characterized by marked variations in body temperature, often associated with chronic conditions.

Treatment of Fever

Antipyretics should be used judiciously to understand the fever's course before treatment.
Common antipyretic drugs include NSAIDs and glucocorticoids, which inhibit prostaglandin synthesis and can decrease inflammation.

Metabolic Alterations During Fever

Increased basal metabolism contributes to heat production.
Glucidic metabolism: Heightened glycogenolysis can lead to temporary hyperglycemia.
Lipid metabolism: Involves increased utilization of fatty acids and could result in ketonemia.
Protein metabolism: Negative nitrogen balance seen as increased urinary nitrogen excretion.
Hydro-saline metabolism: Higher sweating leads to reduced diuresis and loss of vital electrolytes.

Systemic Effects of Fever

Cardiovascular: Increased heart rate and potential for tachycardia; bradycardia possible in specific infections.
Respiratory: Increased respiratory rate possibly leading to dyspnea.
Digestive: Impaired motility resulting in anorexia, nausea, and vomiting.
Nervous system: Altered mental status, potential agitation, or delirium.
Immune system: Enhanced immune response at temperatures below 40°C.

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Description

This quiz covers the concept of hypothermia, detailing its causes, effects on body temperature, and related physiological mechanisms. It explores how factors like external conditions, hypovolemic shock, and hormonal imbalances contribute to hypothermic states.