Partial 3 - Thermoregulation

Question 1

Heat production:

Answer 1

1) Basal metabolism (Exothermic reactions where most heat is generated by brain, heart, liver and glands at rest. Skeletal muscle produces 20-30% at rest, but can increase 30-40 times during exercise).
(2) Muscle activity (shivering)
(3) Thyroxine effect on cells
(4) Epinephrine effect on cells
(5) Temperature effect on cells.

Question 2

Heat loss:

Answer 2

(1) Radiation (60%) when body temperature is greater than the surroundings
(2) Evaporation (22%) when the body temperature is near the surroundings
(3) Conduction (3%) when body is in direct contact with an object
(4) Convection (15%) which is heat loss due to air movement.

Question 3

Thermoregulatory center is located in hypothalamus in?

Answer 3

Preoptic area

Question 4

Heat loosing center mechanism

Answer 4

Dilates the arteries of the skin
Increases sweating
Increases respiration
Inhibits heat-promoting center

Question 5

Heat promoting center mechanism

Answer 5

Constricts vessels of the skin
Stimulates arrector pili muscles
Leads to shivering
Inhibits heat-loss center

Question 6

Heat exhaustion occurs when

Answer 6

an individual is exposed to high temperatures leading to heat-loosing centers being activated which decreases BP and blood to the brain

Question 7

Compensatory mechanisms of heat exhaustion

Answer 7

SNS, Aldosterone and ADH

Question 8

Symptoms of heat exhaustion

Answer 8

Headache
Nausea
Active sweating
Skin being cool and pale
Fainting

Question 9

Heat stroke occurs when

Answer 9

when core temperature is 41 Celsius and happens to individuals with compromised hemostatic mechanisms (young children and Elderly) and healthy individuals under strenuous exercise.

Question 10

Heat stroke leads to

Answer 10

Renal and splenic vasoconstriction
Decreased peripheral blood flow
Impaired thermoregulation
Cerebral edema
Increased intracranial pressure
Protein denaturation

Question 11

Complications of heat stroke

Answer 11

Rhabdomyolysis (breakdown of skeletal muscle)
Multiple organ failure (heart, liver, and kidney)
DIC
CNS hallucinations
Coma
Anhidrosis (Inability to sweat normally)

Question 12

Causes of hyperthermia

Answer 12

Increased heat production
Drugs
Decreased heat loss

Question 13

Increased heat production causes

Answer 13

External hyperthermia
External heat stroke
Malignant hyperthermia
Neuroleptic malignant syndrome
Lethal catatonia
Thyrotoxicosis
Pheochromocytoma
Delirium tremens
Status epilepticu
Tetanus

Question 14

Drugs that causes hyperthermia

Answer 14

β-blockers
Sympathomimetics
Anti-cholinergic
Salicylate toxicity

Question 15

Decreased heat loss causes

Answer 15

Classic heat stroke
Occlusive dressings
Dehydration
Autonomic dysfunction

Question 16

What leads to fever and how?

Answer 16

Pyrogens lead to fever by increasing the set point

Question 17

Types of pyrogenes

Answer 17

Exogenous pyrogens (ex. bacteria, viruses, fungus, and allergens)
Endogenous pyrogenes (ex. IL1, TNF, and IL-6).

Question 18

Fever enhances host defences by

Answer 18

leading to increased neutrophil function (Enhanced migration and enhanced superoxide production), and increased mononuclear function (Enhanced interferon production and T-cell proliferation).

Question 19

Fever alterates what

Answer 19

Endocrine alterations
Autonomic alterations
Behavioral changes
Hematologic alterations
Altered hepatocyte function

Question 20

Endocrine alterations of fever

Answer 20

Increased production of CRH (which will increase ACTH and GC), GH, Aldosterone, insulin, glucagon, and acute phase reactants
Decreased production of TSH and ADH

Question 21

Autonomic alterations of fever

Answer 21

Cutanenous vasoconstriction, increased HR, increased BP, and decreased sweating

Question 22

Behavioural changes of fever

Answer 22

Seeking warmth
Shivering
Anorexia
Somnolence (sleepiness)
Malaise (general discomfort)

Question 23

Hematologic alterations of fever

Answer 23

Leukocytosis, thrombocytosis, and decreased erythrocytosis

Question 24

Altered hepatocyte function of fever

Answer 24

Increased production of acute phase proteins (CRP, serum amyloid A and fibrinogen)

Question 25

Patterns of temperature change in fever

Answer 25

Intermittent
Remittent
Sustained
Relapsing

Question 26

Intermittent fever

Answer 26

An intermittent fever is one in which temperature returns to normal at least once every 24 hours. These are commonly associated with conditions such as gram-negative/-positive sepsis, abscesses, and acute bacterial endocarditis

Question 27

Remittent fever

Answer 27

In a remittent fever, the temperature does not return to normal and varies a few degrees in either direction.

Question 28

Sustained fever

Answer 28

In sustained or continuous fever, the temperature remains above normal with minimal variations. These are seen in persons with drug-induced fever.

Question 29

Relapsing fever

Answer 29

A recurrent or relapsing fever is one in which there is one or more episodes of fever, each as long as several days, with one or more days of normal temperature between episodes. Relapsing fevers may be caused by a variety of infectious diseases, including tuberculosis, fungal infections, Lyme disease, and malaria.

Question 30

How many stages of fever?

Answer 30

4

Question 31

First stage (prodromal stage) of fever

Answer 31

In prodromal stage body temperature rises, and there are nonspecific complaints such as mild headache and fatigue, general malaise, and fleeting aches and pains.

Question 32

Second stage of fever

Answer 32

During the second stage there is sensation of being cold and the onset of generalized shaking, although the temperature is rising. When the shivering has caused the body temperature to reach the new set point of the temperature control center, the shivering ceases, and a sensation of warmth develops

Question 33

Third stage of fever

Answer 33

In the third stage cutaneous vasodilation occurs, and the skin becomes warm and reddened

Question 34

Fourth stage of fever

Answer 34

The fourth stage of the febrile response is marked by the initiation of sweating

Question 35

During fever, the body switches from glucose to metabolism based on

Answer 35

Protein and fat breakdown

Question 36

Metabolic acidosis can occur in fever if

Answer 36

Fat breakdown is rapid

Question 37

Body temperature of 41 Celcius leads to

Answer 37

Delirium and seizures

Question 38

Body temperature of 42 Celcius leads to

Answer 38

Coma, CNS damage and even death

Question 39

Difference between fever and hyperthermia

Answer 39

(1) In fever, hypothalamic set-point is increased by cytokines, and peripheral mechanisms generate and conserve heat
(2) In hyperthermia hypothalamic set-point is normal, but peripheral mechanisms fail to match the set-point.