Skin Color and Geography QOD: How would you describe the distribution of skin color around the world, based on what you know? Consider the skin color

Skin Color and Geography


QOD: How would you describe the distribution of skin color around the world, based on what you know? Consider the skin color of indigenous populations, in other words, people who evolved where they currently live and haven’t migrated (voluntarily or otherwise) in the last 500 years. Why do you think skin color has the pattern it has?

QOD: How would you describe the distribution of skin color around the world, based on what you know? Consider the skin color of indigenous populations, in other words, people who evolved where they currently live and haven’t migrated (voluntarily or otherwise) in the last 500 years. Why do you think skin color has the pattern it has?

Solar radiation worldwide

Solar radiation worldwide

QuickTime™ and a decompressor

are needed to see this picture.

Which explains…Which explains…

…why these people evolved near the equator.

…why these people evolved near the equator.









And…And…

…why these people evolved in the north

…why these people evolved in the north







…but it doesn’t explain …but it doesn’t explain

…why these people evolved in the most northern latitudes in the world (the arctic circle)

…why these people evolved in the most northern latitudes in the world (the arctic circle)








Skin Color and Geography Humans, like all species, are subject

to the laws of evolution and natural selection

Evolutionary fitness depends on reproductive success

You have to live long enough to have babies to reproduce

Q: What is the reproductive advantage of having dark skin where UV light is more intense? What is the reproductive advantage of having light skin where UV light is less intense? What about the Inuits?

Humans, like all species, are subject to the laws of evolution and natural selection

Evolutionary fitness depends on reproductive success

You have to live long enough to have babies to reproduce

Q: What is the reproductive advantage of having dark skin where UV light is more intense? What is the reproductive advantage of having light skin where UV light is less intense? What about the Inuits?


Skin Color and Geography Each team gets a set of cards. Divide the

cards into 2 piles: 1) cards that give facts about advantages of darkly pigmented skin 2) cards that give facts about advantages of lightly pigmented skin

Make 2 columns in your I.N. (INPUT page) for each group or cards and record the information that belongs in each column

Once you have gathered and recorded all the information given, Write a 1 paragraph explanation (on binder paper, to be turned in) for the pigmentation of Northern Europeans, West Africans and the Inuit and other people of the Arctic circle.

Each team gets a set of cards. Divide the cards into 2 piles: 1) cards that give facts about advantages of darkly pigmented skin 2) cards that give facts about advantages of lightly pigmented skin

Make 2 columns in your I.N. (INPUT page) for each group or cards and record the information that belongs in each column

Once you have gathered and recorded all the information given, Write a 1 paragraph explanation (on binder paper, to be turned in) for the pigmentation of Northern Europeans, West Africans and the Inuit and other people of the Arctic circle.

Physiology: T 10.4Physiology: T 10.4

TCBVideo group: please send me an email explaining exactly which parts of the project you were responsible for. (this is separate from the weekly email assignment)

GOALS/AGENDAReview yesterday’s activity, write or complete paragraph explanation.

Structure & function of skin

TCBVideo group: please send me an email explaining exactly which parts of the project you were responsible for. (this is separate from the weekly email assignment)

GOALS/AGENDAReview yesterday’s activity, write or complete paragraph explanation.

Structure & function of skin

The integumentary system

The integumentary system

Includes skin, hair, nails and glands

FunctionsProtection (UV, injury, infection)Vitamin D productionTemperature regulationHolds in moistureSense organRemoves wastes

Includes skin, hair, nails and glands

FunctionsProtection (UV, injury, infection)Vitamin D productionTemperature regulationHolds in moistureSense organRemoves wastes

The skin has 2 layersThe skin has 2 layers Epidermis:

Outermost Origin of glands, hair follicles, glands

Mostly epithelial Growth and cell division at deepest part pushes cells outward

Outermost epidermis is dead, flattened cells which flake away

Many keratinocytes which make keratin for waterproofing

Melanocytes make melanin

Epidermis: Outermost Origin of glands, hair follicles, glands

Mostly epithelial Growth and cell division at deepest part pushes cells outward

Outermost epidermis is dead, flattened cells which flake away

Many keratinocytes which make keratin for waterproofing

Melanocytes make melanin



Skin colorSkin color Melanin provides basic lightness or darkness

Equal numbers of melanocytes, difference is in how much melanin they produce

Other pigments: carotene, hemoglobin

Melanin provides basic lightness or darkness

Equal numbers of melanocytes, difference is in how much melanin they produce

Other pigments: carotene, hemoglobin



The skin has 2 layersThe skin has 2 layers Dermis:

Deeper than epidermis

Connective tissue Tough and strong- collagen fibers

Flexible- elastin fibers

Can separate from epidermis, space fills with fluid…blister. Ouch.

Contains blood vessels and nerves

Dermis: Deeper than epidermis

Connective tissue Tough and strong- collagen fibers

Flexible- elastin fibers

Can separate from epidermis, space fills with fluid…blister. Ouch.

Contains blood vessels and nerves



Exocrine GlandsExocrine Glands Secrete substances that leave the body through ducts

Found w/in dermis but derived from epidermis (epithelial) Sebaceous gland: produces oil, found near hair follicles

Sweat gland: temperature regulation & chemical signals

Secrete substances that leave the body through ducts

Found w/in dermis but derived from epidermis (epithelial) Sebaceous gland: produces oil, found near hair follicles

Sweat gland: temperature regulation & chemical signals



SweatSweat

Made of: water, dissolved salts, wastes, other substances

2 types of sweatStimulated by temperatureStimulated by stress, pain, hormones

Made of: water, dissolved salts, wastes, other substances

2 types of sweatStimulated by temperatureStimulated by stress, pain, hormones

OilOil

Sebum Sebaceous glands found everywhere except palms of hands and soles of feet

Softens and lubricates skin and hair, helps kill bacteria and keep skin from cracking

Sebum Sebaceous glands found everywhere except palms of hands and soles of feet

Softens and lubricates skin and hair, helps kill bacteria and keep skin from cracking

Hair Hair

Keratinized cells Growth at the root Straight or curly depends on angle of follicle and shape of hair shaft

Keratinized cells Growth at the root Straight or curly depends on angle of follicle and shape of hair shaft



Below the SkinBelow the Skin Deeper than the dermis is the layer called the hypodermis

Technically not considered part of skin

Primarily adipose and connective tissue

Deeper than the dermis is the layer called the hypodermis

Technically not considered part of skin

Primarily adipose and connective tissue



Sweaty fingersSweaty fingers

What happens when you have to talk in front of a large group?

Sweaty palms? Find out what else makes you sweat.

NotebookTitlePurposeObservations (follow to do and notice)Interpreting your observations Qs

What happens when you have to talk in front of a large group?

Sweaty palms? Find out what else makes you sweat.

NotebookTitlePurposeObservations (follow to do and notice)Interpreting your observations Qs

Examining structure of skin

Examining structure of skin

View slides of scalp, draw in notebook Line up slide so that epidermis is visible at the edge

label epidermis, dermis, follicle, hair shaft, sebaceous gland, sweat gland, any other structures you can find

take your time- make these the best microscope drawings you’ve ever done. Use colored pencil, draw individual cells and tissue layers

Make sure labels point inside the field of view and clearly point to structures

Will be graded separately when notebooks are collected

View slides of scalp, draw in notebook Line up slide so that epidermis is visible at the edge

label epidermis, dermis, follicle, hair shaft, sebaceous gland, sweat gland, any other structures you can find

take your time- make these the best microscope drawings you’ve ever done. Use colored pencil, draw individual cells and tissue layers

Make sure labels point inside the field of view and clearly point to structures

Will be graded separately when notebooks are collected

Physiology: W 10.5Physiology: W 10.5

TCBHomework checkMovieAssessments

GOALS/AGENDASweaty fingersFinish skin presentation

TCBHomework checkMovieAssessments

GOALS/AGENDASweaty fingersFinish skin presentation

Documents

Skin Color and Geography QOD: How would you describe the distribution of skin color around the world, based on what you know? Consider the skin color