Lecture 10 Flashcards by Danielle Rabjohn

What is the metabolic hormone

Thyroid hormone T3 and T4

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What is another name for a parafollicular cell

C cell

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What is another name for a C cell

parafollicular cell

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What is the function of calcitonin

Lowers blood calcium

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What produces calcitonin

C cells/parafollicular cells

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What do parafollicular cells produce

Calcitonin

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What is calcitonin secreted in response to

Increase of blood levels of calcium

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What stage of life is calcitonin the most important

Childhood for the skeleton

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What is the definition of the MR

body’s rate of energy expenditure per hour = total heat

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What are the two ways BMR can be measured

Direct - water
Indirect - see how much oxygen you consume

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Name for “energy cost of living”

BMR

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what unit is BMR reported as

kcal/m^2/hr

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Which sex is BMR higher in

males; more skeletal muscle

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What is the major determining factor of BMR

Body surface area

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Why is body surface area the major BMR determining factor

You need to maintain heat, higher surface area, quicker you lose heat

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BMR is ______ proportional to age

inversely

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How can stress increase metabolic rate

epi increases metabolic rate by increasing fat catabolism; heat generates

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_______ and BMR are tightly associated

Body temp

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What is the most important hormonal
factor in regulating BMR

Thyroid hormong
(metabolic hormone)

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High MR; poor heat tolerance; weight loss

Hyperthyroidism
(too much heat, too much MR, therefore you lose weight)

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Low MR; obesity, poor cold tolerance

Hypothyroidism
(not generating enough heat, not enough MR, too cold)

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What is TMR

total metabolic rate

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What is the sum of BMR and voluntary activities

TMR

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what is food induced thermogensis

eat food
energy needed to digest
rapid increase in TMR

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does fasting/low caloric intake increase or decrease MR

decrease

Heat produced by skeletal muscle can be ______ times that of rest of body

30-40

what is the average body temp

37 degrees celcius

For every 1 degree rise in temp, rate of catalytic reactions increases by ____

10%

What happens if your body temp is too high

Proteins start to get denatured

What temp is the limit for life

43 degrees

what temp do convulsions in adults begin

41 degrees

is an increase or decrease in body temp tolerated better

decrease

Loss of heat by infrared waves

Radiation

Loss of heat by infrared waves

What percent of body heat loss is by radiation

50%

What kind of heat exchange? movement of heat via waves

Radiation

What kind of heat exchange? Direct physical contact; through a material medium

Conduction

Give an example of radiation

cool room warming when filled with people

What kind of heat exchange? Warm air rises, cold air sinks Cool air absorbs heat, rises and process repeats

Convection

Forced convection

Convection enhanced by wind or fan (forces air across body)

Heat of vaporization

Water molecules absorb enough heat to escape as gas

Insensible water loss

basal heat loss due to continuous evaporation from lungs

Insensible heat loss

Heat loss we cannot regulate/control

What percent of basal heat production is insensible

When does evaporation become a sensible heat loss

when body temps rise

Where are the thermoregulatory centers found

Hypothalamus

What are the two thermoregulatory centers

Heat loss Heat promoting

Where are peripheral thermoreceptors

The shell

Where are central thermoreceptors

In the core - sensitive to blood temp

what does the hypothalamus receive afferent input from

peripheral and central thermoreceptors

The input from what thermoreceptor is most important

central

lowering of shell temp can alert hypothalamus to do what

preserve core temp

Name the 4 heat promoting mechanisms

vasoconstriction of skin BV Shivering Increase metabolic rate Release more thyroxine

Increase in MR is also known as

chemical/nonshivering thermogenesis

what kind of fat in adults can generate heat by burning triglycerides and glucose

brown fat

What two heat conserving mechanisms is not seen in adults

Increase in MR Increase thyroxine release

Why is shivering so effective

muscle activity generates a lot of heat

Most heat loss mechanisms occur through the ______

skin

Name the 3 main heat loss mechanisms

Vasodilation of skin BV Enhanced sweating Behaviour modifications

Sweat glands are strongly activated by which NS

sympathetic

When does hyperthermia occur

when normal heat loss procedures are ineffective

Hyperthermia is an example of a _______ feedback cycle

Positive

Explain the positive feedback cyc;e with hyperthermia

Temp increases as a result, MR increases as a result, temp increases as a result, MR increases etc

what is coined as controlled hyperthermia

fever

what releases pyrogens

macrophages

macrophages release what in regards to temp

pyrogens

What do pyrogens do

cause a reset of hypothalamic thermoregulatory centers

What kind of molecule is a pyrogen

cytokine signaling

the majority of energy output is in the form of ____

heat

define hunger

a physiological need to eat

appetite

desire for specific types of foods

satiety

satisfatction of hunger not hungry

What two nuclei are key centers in appetite regulation

arcuate nucleus solitary nucleus

where is the solitary nucleus

in the brain stem

where would you find the VMN and LHA neurons

Hypothalmus

What is the role of the VMN nerons

tell us that we had enough to eat

What is the role of the LHA neurons

tell us when were hungry

What does the VMN release to signal satiety

CRH (corticotropin releasing hormone)

What does the LHA neurons to release to stimulate hunger

orexins

POMC/CART neurons release what, and work on what

melanocortin VMN neurons

What is the long name of VMN

ventromedial nucleus

What is the long name for LHA

lateral hypothalamic area

What stimulates the LHA

release of neuropeptide Y and agouti-related peptide (NPY/AGRP)

What does ARC stand for

arcuate nucleus

The LHA is to hunger as the _____ is to satiety

VMN

What group of neurons in the ARC stimulates satiety

VMN

What group of neurons in the ARC stimulate hunger

LHA

What is the most important short term hunger hormone

Insulin - satiety signal

Does protein make you feel fuller for longer or shorter

Longer

What released from stomach is a potent hunger stimulator

Ghrelin

Where is ghrelin released from

Stomach

When do glucagon levels rise

During fasting

What does cholecystokinin do for appetite

Depresses hunger

Does increased body temp increase or depress hunger

depress higher body temp, higher MR, probably due to eating

What is leptin

a peptide hormone

What releases leptin

adipose tissue

What does leptin inhibit and increase

Inhibits NPY secretion Increases CART expression

More adipose tissue = more _____

Leptin

Does leptin increase or supress appetie

Supresses, so you use up the adipose tissue stored