Thermoregulation

Question 1

What are the main processes responsible for heat production in the body? 7

Answer 1

Metabolism (glycolysis), voluntary actions (physical activity), shivering, brown fat metabolism, vasoconstriction, piloerection, and neuroendocrine regulation.

Question 2

How does the body lose heat through sweating?

Answer 2

Eccrine sweat glands secrete sweat, which evaporates from the skin surface, causing heat loss.

Question 3

What are the primary methods of heat loss in the body?

Answer 3

Conduction/convection (60%), radiation (25%), and evaporation (15%).

Question 4

What is the role of the hypothalamus in temperature regulation?

Answer 4

The hypothalamus maintains core temperature by adjusting metabolic and autonomic responses.

Question 5

What is core temperature, and why is it important?

Answer 5

Core temperature is the internal body temperature, essential for enzymatic reactions and bodily functions.

Question 6

How does fever (pyrexia) develop in response to an infection?

Answer 6

Pyrogens induce PGE2 release in the hypothalamus, raising the body’s set temperature.

Question 7

What is the difference between fever and hyperthermia?

Answer 7

Fever results from an altered hypothalamic set point, while hyperthermia occurs due to excessive heat production or environmental exposure.

Question 8

What are common treatments for fever?

Answer 8

Paracetamol, NSAIDs, aspirin, cooling methods, and exposure to fans.

Question 9

What are the classifications of body temperature?

Answer 9

Hypothermia (<35°C), normal (36.5-37.5°C), fever (>37.5 or 38.3°C), hyperpyrexia (>40 or 41.5°C).

Question 10

What are the primary causes of hyperthermia?

Answer 10

Exertion, situational factors, drugs, and pyrexia.

Question 11

What is the most significant method of heat loss in the human body?

Answer 11

Conduction/convection

Question 12

Which of the following processes is responsible for heat production in neonates?

Answer 12

Brown fat metabolism

Question 13

Where is the primary temperature control center in the brain?

Answer 13

Hypothalamus

Question 14

Which of the following is NOT a cause of hypothermia?

Answer 14

Increased metabolic rate

Question 15

How do pyrogens induce fever?

Answer 15

By stimulating the release of PGE2 in the hypothalamus

Question 16

What physiological response is responsible for increasing heat loss when the body is overheating?

Answer 16

Vasodilation

Question 17

Which of the following treatments is NOT typically used to reduce fever?

Answer 17

Beta-blockers

Question 18

What happens to enzymatic activity when temperature increases by 10°C?

Answer 18

It increases by 2.5 times

Question 19

What is a life-threatening level of hyperthermia?

Answer 19

41.5°C

Question 20

What is the primary mechanism by which antipyretic drugs like aspirin reduce fever?

Answer 20

Blocking the production of PGE2

Question 21

Why do biological systems operate under a tight range of conditions?

Answer 21

Enzymes and metabolic processes require a stable environment for optimal function.

Question 22

How does a 10°C increase affect enzymatic activity?

Answer 22

It increases enzymatic activity by approximately 2.5 times.

Question 23

At what temperature does protein denaturation occur?

Answer 23

Above 45°C.

Question 24

What is the functional temperature range for “conscious intelligence”?

Answer 24

Between 35 – 40°C.

Question 25

How does core temperature compare to skin temperature?

Answer 25

Core temperature is approximately 0.5°C higher than skin temperature.

Question 26

How does core temperature change throughout the day?

Answer 26

It is lowest just before waking up and rises as the day progresses.

Question 27

How does the menstrual cycle affect core temperature?

Answer 27

It increases by about 0.5°C at ovulation.

Question 28

Why is temperature relevant in fertility investigations?

Answer 28

Tracking ovulation temperature changes can help assess fertility.

Question 29

What are the different types of temperature measurement methods?

Answer 29

Thermometer, skin temperature thermometer, tympanic (ear) thermometer, oesophageal thermometer, and rectal temperature.

Question 30

Which temperature measurement is commonly used in children?

Answer 30

Skin temperature thermometer, often on the scalp.

Question 31

How does a tympanic thermometer work?

Answer 31

It uses infrared technology to measure temperature in the ear.

Question 32

Where are temperature receptors found in the body?

Answer 32

Skin, GI tract, great veins, and hypothalamus.

Question 33

What type of neurons are temperature receptors?

Answer 33

Specialized outgrowths of neurons.

Question 34

Are there more hot or cold receptors in the skin?

Answer 34

There are 10 times more cold receptors than hot receptors.

Question 35

Which nerve fibers are involved in temperature sensation?

Answer 35

Aδ and C fibers.

Question 36

Which part of the brain predominantly controls body temperature?

Answer 36

The anterior hypothalamus.

Question 37

What is the function of the "set point" thermostat in the hypothalamus?

Answer 37

It regulates the body's core temperature to maintain homeostasis.

Question 38

What are the two main systems involved in temperature regulation?

Answer 38

Heat-increasing mechanisms and heat-loss mechanisms.

Question 39

hy are extreme ages more prone to hypo/hyperthermia?

Answer 39

They may lack the ability to regulate clothing or move to adjust temperature.

Question 40

How do incubators help newborns?

Answer 40

They maintain a controlled temperature environment.

Question 41

How does metabolism contribute to heat production?

Answer 41

The respiratory cycle generates heat as a byproduct.

Question 42

How much can shivering increase heat production?

Answer 42

Up to 5 times the normal rate.

Question 43

Where does shivering predominantly occur?

Answer 43

The trunk.

Question 44

Why is shivering metabolically expensive?

Answer 44

It requires significant energy and oxygen consumption.

Question 45

What is the function of brown fat in heat production?

Answer 45

It generates heat through ß3 receptor-mediated metabolism.

Question 46

In which populations is brown fat most relevant?

Answer 46

Neonates and some animals.

Question 47

What paradoxical effect can prolonged cold exposure cause?

Answer 47

: Increased blood flow to the skin.

Question 48

What controls piloerection?

Answer 48

Sympathetic nervous system.

Question 49

What hormones are involved in neuroendocrine thermoregulation?

Answer 49

Catecholamines (adrenaline/noradrenaline) and potentially thyroxine.

Question 50

What are the three main methods of heat loss?

Answer 50

Conduction/convection (60%), radiation (25%), and evaporation (15%).

Question 51

How does sweating help in heat loss?

Answer 51

It evaporates from the skin, carrying heat away.

Question 52

What is the normal daily sweat production?

Answer 52

Up to 1000 ml/day

Question 53

How does acclimatization affect sweating?

Answer 53

It increases sweat production to 2000 ml/day.

Question 54

Why does urea concentration increase near the skin surface?

Answer 54

It contributes to body odor.

Question 55

How do animals lose heat without sweating?

Answer 55

By panting and ventilating their dead space.

Question 56

What is hypothermia?

Answer 56

A core temperature below 35°C.

Question 57

When is hypothermia considered severe?

Answer 57

When core temperature falls below 28°C.

Question 58

What are common causes of hypothermia?

Answer 58

Behavioral factors, hypothyroidism, dermatological conditions, and sepsis.

Question 59

What are clinical features of hypothermia?

Answer 59

Confusion, coma, and cardiovascular collapse

Question 60

How is hypothermia managed?

Answer 60

ABC assessment, controlled warming (Bear hugger, tin foil, cardiopulmonary bypass).

Question 61

What is the temperature threshold for hyperthermia?

Answer 61

>38°C.

Question 62

When is hyperthermia life-threatening?

Answer 62

When core temperature exceeds 40°C.

Question 63

What are the clinical signs of hyperthermia?

Answer 63

Confusion, seizures, coma, and cardiovascular collapse.

Question 64

What causes pyrexia?

Answer 64

An altered hypothalamic set point.

Question 65

What are common causes of fever of unknown origin?

Answer 65

Infection, blood transfusion reactions, inflammation, malignancy, and hypothalamic damage.

Question 66

What physical methods can reduce fever?

Answer 66

Tepid sponging, cooling packs, ice, exposure, and fans.