LO6

Question 1

Biochemical units of nutrition

Answer 1

BMR (Basal Metabolic Rate): energy requirement of a person at rest
○ Needed to maintain life-sustaining activities like breathing, heart rate,
etc.
● REE (Resting Energy Expenditure): measurement that accounts for BMR
+ energy to digest meals and do mild activities

Question 2

terminology

Answer 2

Metabolism: the sum of all biochemical reactions that take place in the body
cells to carry out vital processes for growth, generation of energy, waste
elimination, and other body functions.
● Catabolism: the breakdown of biochemical substances into more simple
substances. Example: muscle wasting during starvation.
● Anabolism: the synthesis of nutrients to produce more complex biochemical
substances. Example: the growth of bones from osteoclasts.
● Metabolic Rate: customarily expressed in calories as the heat liberated in the
course of metabolism.
○ The average basal metabolic rate (BMR) accounts for the heat produced by
the body at absolute rest and can account for up to 75% of the daily caloric
intake.

Question 3

role of liver in metabolism

Answer 3

Glucose Metabolism
○ Ingested glucose  to the liver and changed to glycogen.
○ Glycogen converts back to glucose through glycogenolysis and replaced
into the bloodstream as needed.
○ Can produce glucose (gluconeogenesis) if blood levels are low.
● Conversion of Ammonia
○ Converts ammonia into urea to be excreted in the urine.
● Protein Metabolism
○ Synthesizes almost all the plasma proteins in the body.
○ Vitamin K is used to synthesize clotting factors
Fat Metabolism
○ Metabolizes fatty acids to produce energy and ketone bodies for the
muscles.
○ Fatty acids are metabolized to synthesize cholesterol and other lipids.
● Drug Metabolism
○ Metabolizes many medications resulting in their inactivation
○ Metabolized medications are excreted in the feces and urine

Question 4

metabolic changes of aging

Answer 4

Change in size and weight of the liver
● Decreased hepatic blood flow
● Decreased efficiency of drug metabolism and clearance
● Decreased replacement of cells after damage or injury

Question 5

body temperature

Answer 5

Body temperature is sustained through thermoregulation which is “a
mechanism by which mammals maintain body temperature with tightly
controlled self-regulation independent of external temperatures” (Publishers,
2019).
● Body temperature is the difference between heat production and heat loss.
* When metabolism increases, heat production increases.
* When metabolism decreases, heat production decreases.
* Core Temperature: temperature of structures deep within the body.
* Temperature control mechanisms keep the body’s core temperature relatively
constant whereas body surface temperature fluctuates.
* Acceptable body temperature: 36 – 38 degrees Celsius

Question 6

Neural & Vascular Control

Answer 6

Hypothalamus: located between the cerebral hemispheres & controls body
temperature.
○ Senses minor changes in body temperature
○ Anterior hypothalamus: controls heat loss
○ Posterior hypothalamus: controls heat production
● When nerve cells in the anterior hypothalamus become heated above the set
point – impulses are sent to reduce body temperature. Mechanisms of heat loss
include:
○ Sweating
○ Vasodilation of blood vessels
○ Inhibits heat production
● When nerve cells in the posterior hypothalamus sense the body temperature
below the set point – heat conservative mechanisms are initiated:
○ Vasoconstriction of blood vessels
○ Shivering

Question 7

heat production

Answer 7

Heat is produced as a by-product of metabolism – the chemical reaction in all
body cells.
○ Food is the primary fuel source in metabolism.
● Activities requiring additional chemical reactions  increase metabolic rate
 increases heat production.
● Heat production occurs during:
○ Rest
○ Voluntary movements: exercise
○ Involuntary shivering
○ Non-shivering thermogenesis: occurs primarily in newborns due to their
inability to shiver. Sympathetic nerve endings secrete norepinephrine in
response to chilling, which stimulates fat metabolism to produce internal heat

Question 8

heat loss

Answer 8

The skin’s structure and exposure to the environment result in constant and
normal heat loss through:
○ Radiation
○ Conduction
○ Convection
○ Evaporation
○ Diaphoresis

Question 9

radiation

Answer 9

The transfer of heat from the surface of one object to the surface of another
without direct contact between the two.
● Up to 85% of the human body’s surface area radiates heat to the
environment.
● Peripheral vasodilation or vasoconstriction increases or minimizes radiant heat
loss.
● Radiation increases as the temperature difference increase
○ Example: if the environment is warmer than the skin, the body absorbs
heat through radiation.
● Patient positioning can enhance radiation heat loss
○ Example: lying in a fetal position minimizes heat radiation

Question 10

conduction

Answer 10

The transfer of heat from one object to another through direct contact.
● Heat is conducted through contact with: solids, liquids, and gases.
● When warm skin touches a cooler object, heat is lost.
● Accounts for a small amount of heat loss.
● Example: a cool compress to decrease a fever.

Question 11

convection

Answer 11

The transfer of heat away from the body by air movement.
● Convection heat loss increases when wet skin comes into contact with moving
air.
● Example: an electric fan

Question 12

evaporation

Answer 12

The transfer of heat energy when a liquid is changed to a gas.
● The body loses 600-900 mL/day by evaporation from the skin and lungs –
resulting in heat loss.
● Example: sweating
● The anterior hypothalamus signals the sweat glands to release sweat when
the body temperature rises. The sweat evaporates, resulting in heat loss.
● Diaphoresis: visible perspiration.

Question 13

evaporation

Answer 13

The transfer of heat energy when a liquid is changed to a gas.
● The body loses 600-900 mL/day by evaporation from the skin and lungs –
resulting in heat loss.
● Example: sweating
● The anterior hypothalamus signals the sweat glands to release sweat when
the body temperature rises. The sweat evaporates, resulting in heat loss.
● Diaphoresis: visible perspiration.

Question 14

the skin in temperature regulation

Answer 14

The skin regulates temperature through:
○ Insulation of the body: the skin, subcutaneous tissue and fat keep heat
inside the body.
○ Vasoconstriction: the degree of vasoconstriction determines the amount
of blood flow and heat loss to the skin.
○ Temperature sensation
● The internal body organs produce heat.
● Example:
○ During exercise, the amount of heat produced is greater than the usual
core temperature. Blood flows from the internal organs to the body
surface. The heat is then lost to the environment through heat-loss
mechanisms (evaporation).

Question 15

behavioural control in temperature regulation

Answer 15

Health individuals can voluntarily act to maintain a comfortable body
temperature when exposed to temperature extremes.
● A person’s ability to control body temperature depends on:
○ The degree of temperature extreme
○ The persons ability to sense feeling comfortable or uncomfortable
○ Thought processes or emotions
○ The person’s mobility or ability to remove or add clothes.
● Body temperature control is difficult if any of these abilities are absent.
● The nurse needs to assess for factors that place a patient at risk for
ineffective thermoregulation.

Question 16

age

Answer 16

Temperature –control mechanisms are immature in infants.
○ Temperature may respond dramatically to changes in the environment
○ Newborns lose 30% of body heat through the head.
○ Normal newborn temperature: 36.5-37.6 degrees Celsius.
● Temperature regulation is unstable until children reach puberty.
● Older person’s have a lower and narrower rang of body temperatures.
○ Average body temperature is 36 degrees Celsius.
○ More sensitive to temperature extremes
○ Decreased vasomotor control (vasoconstriction/vasodilation)
○ Reduced amount of subcutaneous tissue
○ Reduced seat gland activity
○ Reduced metabolism

Question 17

exercise

Answer 17

Exercise requires increase in blood supply and carbohydrate/fat breakdown
 increased metabolism  increased heat production.
● Prolonged strenuous exercise can raise the body temperatures up to 41
degrees Celsius.

Question 18

hormone level

Answer 18

Women experience greater fluctuations in body temperature than men.
● Hormonal variations in progesterone during the menstrual cycle cause body
temperature fluctuations.
○ During ovulation  increased progesterone  raise body temperature
● Body temperature changes can occur during menopause.
○ Women may experience intense body heat and sweating – “hot flashes”
○ Skin temperature may increase by up to 4 degrees Celsius.

Question 19

circadian rhythm

Answer 19

Body temperature normally changes 0.5-1 degree Celsius during a 24 hour
period.
● Temperature is usually lowest between 0100-0400 hours.
● Maximum body temperature is usually reached at about 1800 hours.
● It takes 1-3 weeks for temperature patters to reverse in people who work
night shifts.
● The circadian temperature rhythm does not change with age.

Question 20

fever/pyrexia

Answer 20

Occurs due to heat-loss mechanisms being unable to keep pace with excess
heat production.
● Body temperature rises to an abnormal level.
● Considered not harmful if below 39 degrees Celsius.
○ Remember – a single temperature reading may not indicate a fever

Question 21

why do we get a fever

Answer 21

Pyrogens: bacteria and viruses invade the body and cause a rise in body
temperature.
○ Act as antigens and trigger an immune response
○ Hypothalamus reacts to raise the “set point” and the body conserves
heat.
● An important defense mechanism – enhances the body’s immune system.
● Fever initiates white blood cell production and the reduction of concentration
of iron in blood plasma – suppressing the growth of bacteria.
● Fever also stimulates the production of interferon – the body’s natural virus-
fighting substance.
● Analysis of a fever pattern assists in diagnoses.
○ Fever of unknown origin: a fever that does not have a determined
cause

Question 22

phases of fever

Answer 22

The chill phase:
○ The body conserves heat and experiences chills, shivers, and feeling
cold.
○ Resolves when the new set point (higher temperature) is achieved.
2. The plateau:
○ Chills subside
○ Person feels warm and dry
3. Third phase of febrile episode:
○ Occurs if the new set point is “overshot” or the pyrogens are removed
(antibiotics)
○ Set point drops – initiating the heat loss response
○ Skin becomes warm and flushed (vasodilation
○ Diaphoresis (heat loss through evaporation)
● When the fever breaks, the person becomes afebrile.

Question 23

results of fever

Answer 23

Cellular metabolism increases and oxygen consumption rises.
○ If the oxygen demand cannot be met – cellular hypoxia occurs.
○ Myocardial hypoxia causes chest pain
○ Cerebral hypoxia causes confusion
● Heart and respiratory rate increases to meet metabolic needs.
● Patients with cardiac or respiratory problems may be more affected by a
febrile episode.
● A prolonged fever can weaken and exhaust energy stores.
● Water loss/dehydration due to increased respiration and diaphoresis.

Question 24

hyperthermia

Answer 24

An elevated body temperature as a result of the body’s inability to
promote heat loss or reduce heat production.
○ Differing from fever – which is a shift in the “temperature set point”
● Any disease or trauma to the hypothalamus can impair heat-loss
mechanisms.
● Types of hyperthermia:
○ Heatstroke
○ Heat Exhaustion

Question 25

heat stroke

Answer 25

Prolonged exposure to the sun or high environmental temperatures can
overwhelm the body’s heat-loss mechanisms as well as depress hypothalamic
function.
● A dangerous heat emergency with high mortality rate.
● At risk individuals:
○ Very young
○ Older adults
○ Those with cardiovascular disease, hypothyroidism, diabetes, spinal cord
injury, or alcoholism
○ Those taking medications that decrease the body’s ability to lose heat
○ Those who engage in strenuous physical labour.
- hot and dry skin

Question 26

heat exhaustion

Answer 26

Occurs when profuse diaphoresis results in excessive water and electrolyte
loss.
● Individual exhibits signs and symptoms of fluid volume deficit
● Treatment includes:
○ Transfer to a cooler environment
○ Restoring fluid and electrolyte balance.

Question 27

hypothermia

Answer 27

Heat loss during prolonged exposure to cold, overwhelming the body’s ability
to produce heat.
● Classified by core temperature measurements:
● Can be unintentional (falling through the ice of a frozen lake) or intentional
(during surgical procedures) to reduce metabolic demand on the body.

Question 28

frostbite

Answer 28

occurs when the body is
exposed to subnormal temperatures.
○ Ice crystals form inside cells and can
result in permanent circulatory and
tissue damage.
○ Areas susceptible to frostbite
include: earlobes, tip of nose,
fingers, and toes.
○ Injures areas become white, waxy,
firm to the touch, and loss of
sensation occurs.
○ Interventions include:
■ Gradual warming
■ Analgesia
■ Protection of the injured tissue