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Anatomy II Exam 2: Lectures 9-16 > Lecture 10: Thermoregulation > Flashcards

Lecture 10: Thermoregulation Flashcards

1
Q

What type of gland is a mammary gland?

A

Apocrine gland

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2
Q

Which type of sweat gland so humans have a high density of but other mammals do not?

A

Eccrine gland

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3
Q

Where on the body do humans have the highest density of eccrine glands?

A

Palms of hands and soles of feet

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4
Q

Eccrine glands typically function in response to which type of stress?

A

Thermal stress

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5
Q

Where do other mammals have eccrine glands?

A

In non-hairy/furred regions (like nose and paws)

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6
Q

Old world primates are similar to humans in eccrine gland number and distribution with a few key differences. What are these differences?

A

Eccrine glands are found in hairy skin

May not be heat sensitive

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7
Q

What is the relationship between having a lot of body hair/fur and sweating?

A

mammals with hairy/furry coats would not benefit from sweating all over their bodies since their coat prevents air circulation close to skin. Sweat can only cool via evaporation and that requires air flow. A mammal that relies on evaporative cooling must have a reduced amount of body hair/fur which provides an explanation for the relatively hairless/furless body of humans.

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8
Q

What are some behaviors used for cooling by mammals that cannot sweat?

A

Panting
Covering in mud
Avoid activity during hot periods of day
Some avoid long bouts of behaviors that could overheat their bodies

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9
Q

How is thermoregulation related to the human ability to maintain long periods of metabolically expensive activities?

A

Humans ability to efficiently cool the body through evaporative cooling by sweating over large areas of the body

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10
Q

What is the trade off for humans being able to sweat a lot all over the body?

A

Fluid loss must be replenished so humans need to drink a lot of water compared to other species and humans need to consume more energy and maintain a thinker layer of fat to make up for a lack of insulation through thick hair or fur

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11
Q

Humans naturally have nearly ____ times the amount of body fat that would be predicted by our species average body size, but human fat cells are relatively ________ compared to other mammals/.

A

10 times

Small

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12
Q

Where are fat cells numerous in the body and why are they located here for thermoregulation?

A

Hypodermis because this is where heat-carrying blood vessels tend to run

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13
Q

How are the levels of body fat related to reproductive success?

A

Sexual dimorphism in fat stores is related to reproduction and higher levels of body fat increase reproductive success

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14
Q

Why would relatively higher amounts of fat in humans evolved with respect to offspring?

A

It probably evolved to support infant development and large brain growth

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15
Q

What is piloerection?

A

Erection or raising of hairs via function of the arrector pili muscles

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16
Q

What is thought about the location of arrector pili muscles on the bodies of early primates? Do any current species retain this?

A

Thought that they lacked them over their bodies and only had them in the tail. Lemurs and lorises retain this.

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17
Q

A weak or vestigial MAP on the body and on tail is what type of condition for primates?

A

Ancestral

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18
Q

How did lemurs and lorises evolve regarding MAP?

A

Prominent tail MAP but none of their bodies

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19
Q

What is the relationship between how tarsiers and lorises lost all MAP?

A

Independently

Derived state

20
Q

Describe MAP on anthropoids (monkeys and apes)

A

Widespread over the body and tail

21
Q

In many larger bodied primates what does MAP allow for?

A

Very strong piloerection especially on the back

22
Q

In smaller primates describe MAP

A

Less developed on the back but very developed on the head and face

23
Q

What areas are modern primates largely restricted to?

A

Tropical zones

24
Q

What areas were early primates widely distributed and occupied?

What time period did this occur?

What did it lead to a selection for?

A

Northern Europe and China

Paleocene-Eocene thermal maximum (PETM)

Led to a selection for a loss or lessening of MAP density of body and tail

25
Q

When was PETM and what were the temperatures like?

A

56mya

Global temperatures were 9 degrees warmer

26
Q

What type of selection would a possible coat thickness reduction be considered when reducing body heat as found in early primates?

A

Positive selection

27
Q

A retention of MAP in the tail for ancestral lemur maight have been related to what?

A

Tail use in locomotion for leaping

28
Q

What were some ways that smaller primates adapted to conserve their body heat post PETM?

A 
High energy diets
Being active during cooler parts of the day
Sunning
Huddling
Hibernation during cold/dry seasons
29
Q

During the middle Eocene what would the ancestral anthropoid require regarding MAP?

A

All over their body and tail

30
Q

What happened to those during Late Eocene, post PETM ?

A

If they could not adapt they died out at higher latitudes

31
Q

What contributes to the human skin color?

A

Hemoglobin from blood
Carotene from diet
Melanin

32
Q

What type of trait is skin color?

A

Polygenic

33
Q

What is the form of melanin called in darker skin?

A

Eumalanin

34
Q

What is the form of melanin called in lighter skin?

A

Pheomelanin

35
Q

What are the functions of melanin?

A

Absorb sunlight

Protect dermis from solar radiation

36
Q

Skin color of different populations correlates _____________ with ____________ and potential exposure to UV radiation

A

Inversely

Latitude

37
Q

Why might hominins evolving in sub-Saharan Africa might have developed melanin?

A

It was probably essential as body hair was reduced to protect from intense direct sunlight year round

38
Q

What is the sunlight like in higher latitudes like Europe and Asia?

A

Does not strike the Earth as directly and less intense

At very high latitudes the amount of sunlight sees dramatic seasonal shifts

39
Q

What is a hypothesis for vitamin D?

A

Humans migrating from lower latitudes to higher latitudes will have a shortage of vitamin D3 unless melanin production is reduced

Select for lighter and lighter pigmentation as you move further and further from the equator

40
Q

What is some criticism for the vitamin D hypothesis?

A

Stems from a lack of evidence to support the idea that people with different levels of skin pigmentation and latitudes actually have a clinically significant difference in vitamin D synthesis

Modern medicine, diet and behavior only serve to further complicate this issue

41
Q

What is the solar protection hypothesis?

A

Habitat and climate variable appear to account for 80% of observed variation in skin color

Still, the biogeography of human population skin pigmentation variation in the New World vs the Old World and Pacific Islands leaves a lot of questions

42
Q

What is the camouflage hypothesis for skin pigmentation?

A

Darker coloration is adaptive for hungers and human prey in tropical forests

Lighter skin might be effective in arctic areas

43
Q

What is the hypothesis of protection of nutrients in skin coloration?

A

Melanin may protect folates from breakdown

44
Q

What is the hypothesis for protection against tropical disease?

A

Some evidence that melanin has a role in protecting the skin from microbes

45
Q

What is the hypothesis for thermoregulation and skin coloration?

A

Darker skin may be able to conserve more energy that would be lost to thermoregulation because melanin absorbs radiation and allows solar heating of skin

Would be a disadvantage in the tropics though

46
Q

What is the hypothesis of sexual selection for skin coloration?

A

Like tends to attract like
Would lead to a pattern of positive assortative mating that would exaggerate differences among populations

Would see an increase in diversity of traits that had little adaptive value

Anatomy II Exam 2: Lectures 9-16 (9 decks)

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