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Flashcards in BIPEDALISM AND SKIN Deck (36)
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What are the 3 types bipedalism

Facultative: temporal basis for particular function

Habitual: on a regular basis

Obligate: when only form of hominin locomotion


What are the 2 phases of the human walking gait style

First: Stance phase where the leg is on the ground

Second: Swing phase when leg is off the ground


What are some of the advantages of bipedalism

Freeing arms to carry objects (like offspring or weapons)

Access to sees and berries in lower branches of trees

Better thermoregulation (less body in sun)

Visual surveillance

Long distance travel

Carrying things on back


What is arboreal quadrapedalism

Equal limbs for gait efficiency

Bending of elbows and knees

Diagonal couple gait, one limb moves forward while others grasp a support


Explain the locomotion in organutans, gorillas and bonobos/ chimpanzees

Orangutans: brachiation, climbing, arboreal quadrapedalism

Gorillas: Quadrapedal, knuckle walking, occasional bipedalism, can climb

Bonobos and chimpanzees: knuckle walking, sometimes bipedal, climbing/swinging


What is a mental eminence

A chin first seen in homo sapiens


What are the 4 types of hand positions in quadrupedal motion

Palmigrade (palm grasp)

Digitigrade (digits horizontal)

Knuckle walking

Suspensory (grasping branch


What are parts of our anatomy that have evolved due to bipedalism

Vertebral column
Foramen magnum
Gluteal muscles
Femur and tibia
Talus, big toe and longitudinal arch
Limb proportion


Explain how the vertebral column evolved due to bipedalism

S shaped spine in stead of C shaped due to secondary curvatures

Increase in vertebra size from cervical to lumbar

wide sacrum


Explain how the foramen magnum and nuchal plane evolved due to bipedalism

Placed more superiorly in modern humans due to perpendicular vertebral column to ground

Nuchal plane (bottom of occipital bone) is parallel to ground in humans


Explain how the pelvis evolved due to bipedalism

Pelvic inlet cannot be too large in human so centre of gravity does not change

Ilium is short and wide and acetabulum is larger to distribute upper body force evenly


Explain how the gluteal muscles evolved due to bipedalism

Larger in primates

Gluteus medius and minimus are placed more at the back of primates and laterally in humans.

This is due to widening and shortening of pelvis and the use of these muscles of abductors not extensors (like in primates)


Explain how the femur and tibia evolved due to bipedalism

Head and condyles are larger and shaft is longer in humans

Bicondylar angle is angled in humans and 90º in a primate.

Articulation with tibia is larger due to human body weight distribution


Explain how the talus, big toe and longitudinal arch evolved due to bipedalism

Talus: parallel articular surface instead of angled more stability in not more motion

Big toe: were divergent in primates for grasping, more for stability now

Longitudinal arch: So blood vessels and nerves are not touching ground, also stabilises


Explain how limb proportion evolved due to bipedalism

Index calculated by dividing length of forelimbs by hindlimb and x 100.

Humans < 100 arms smaller than legs

Baboons = 100

Gibbons > 100 long forelimbs


What are the parts of the integumentary system

Skin, hair, nails, sweat/oil/mammary glands


What are the functions of the integumentary system

resistance to trauma and infection

barrier to UV light





Outline the specialised cells in the epidermis

Keratinocytes principle cells composed of keratin proteins.

Melanocytes specialised for production of melanin

Merkel cells associated with nerve terminals and sensation

Langerhans cells wondering phagocytic cells of immune response


Outline the layers of the epidermis

1st: stratum corneum and granulosom contain dead and dying cells

2nd: Stratum spinoum containing keratinocytes and langherans cells

3rd: stratum basal includes mitotic stem cells and merkel cells.


Outline the dermis

Strong flexible CT below epidermis. Blood vessels and nerves of skin

Papillary layer contains dermal papillae to increase nutrients and gas exchange

Reticular layer: fibrous tissue


What are the accessory structures of the skin

Sebaceous glands
Sweat glands


What are the different parts of a hair

Bulb: swelling at base in dermis or hypodermis

Root: Epithelial cells produce hair shaft

Shaft: portion above skin surface

Piloerector muscle: erects hair

Inner medulla: soft flexible keratin

Outer cortex: hard keratin

Cuticle: outermost protective layer


What are the different types of hairs

Lanugo: fine, unpigmented, foetus

Vellus: fine, unpigmented, over body

Intermediate: change in distribution (e.g. upper and lower limbs)

Terminal hairs: heavy, pigmented, eyebrows, pubic hair, scalp


Explain sebaceous glands and nails

Sebaceous glands: secrete sebum which coats hairs

Nails: keratinous structure produced by nail root.


Explain sweat glands

In dermis, produce sweat

Apocrine: activated in puberty, large, connected to hair follicle in armpit or pubic area

Merocrine: Small, collected multiples at bottom of sweat pore


What are the factors skin colour can be influenced by

Carotene: orange-yellow to red pigment body synthesises into vitamin A

Hemoglobin: red pigment when combined with O2

Melanin: explained in another


Explain what melanin is

Dark pigment produced by melanocytes of epidermis

no. of melanocytes in everyone is the same

Melanocytes project dendrites into keratinocytes, transfer to mature melanosomes (which contain melanin)


What is skin colour intensity due to

Number of melanosomes and dispersion and degradation

Rate of melanin production

degree of melanisation of melanosomes

Rate of transport to keratinocytes

chronological age


What are the 2 types of melanin

Eumelanin: Most abundant, high conc in darker skin, produces brown hair

Pheomelanin: High conc in redhead people. Produces blonde hair


What happens when melanin dies

Produce grey, wavy hair