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Intro. to Microbiology - Part 1 > Integumentary system: anatomy, physiology and function of skin > Flashcards

Integumentary system: anatomy, physiology and function of skin Flashcards

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Biology 101 flashcards
1
Q

skin composed of 2 main layers

A
  1. epidermis

2. dermis

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2
Q

subcutaneous layer is found beneath dermis and is not considered part of skin. T/F?

A

True

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3
Q

Skin

A
  • largest organ in the body
  • approx. 16% of total body weight of adult
  • weighs twice as much as brain
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4
Q

epidermis

A
  • composed of stratified keratinized squamous epithelium
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5
Q

epidermis is made up of 4 main types of cells

A
  1. keratinocytes (90% of cells in this layer)
  2. melanocytes (8% of epidermal cells)
    • responsible for producing pigment (melanin)
  3. langerhans: involved in immune response
  4. merkel cells: function in sensation of touch
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6
Q

epidermis is avascular (without blood vessels) and is dependent on blood vessels of dermis for:

A
  • oxygenation
  • metabolite provision
  • removal of metabolic wast products
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7
Q

epidermis layers

A
  • stratum basale: deepest layer
  • stratum spinosum (prickle cell layer)
  • stratum granulosum (granular layer)
  • stratum lucidum (finger tips, palms and soles)
  • stratum corneum (top layer)
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8
Q

Stratum basale

A
  • made up of single row of columnar keratinocytes
  • melanocytes and Merkel cells found within this layer
  • only layer within epidermis that consists of cells capable of division
  • nearest layer to dermis and located under epidermis
  • dermis contains blood supply and provides nourishment to stratum basale
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9
Q

keratin

A
  • fibrous protein

- protects skin from heat, chemicals and microorganisms

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10
Q

melanocytes

A
  • produce melanin
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11
Q

melanin

A
  • pigment that protects skin from harmful effects of ultraviolet (UV) light
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12
Q

Merkel cells

A
  • make contact with flattened process of a sensory neuron called a Merkel disc.
  • merkel cells + discs detect sensation of touch
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13
Q

Stratum spinosum

A
  • daughter cells of keratinocytes lose their ability to divide in this layer
  • they become rounder and ‘spikier’ in shape
  • daughter cells join together via desmosomes
  • this arrangement contributes to tensile strength and flexibility of skin
  • langerhans cells found here
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14
Q

Langerhans cells

A
  • developed from specialized dendritic cells of immune system
  • also found in dermis, lymph nodes and thymus
  • produced in red bone marrow
  • migrate to stratum spinous and participate in immune responses against microorganisms
  • function: attracting and phagocytosis microbes and presenting their antigens to T lymphocytes (activating them to destroy microbes)
  • crucial in helping other cells of immune system to recognize invading microorganisms and destroy them
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15
Q

Stratum granulosum

A
  • cells become longer and flatten horizontally to form this layer
  • cells go through apoptosis here
  • cells lose their nucleus and become keratinized and comprised entirely of tough pliable protein – keratin
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16
Q

keratohyalin

A
  • present in stratum granulosum
  • consists of darkly staining proteins that convert monofilaments to keratin
  • Odland’s bodies may be seen
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17
Q

Odland’s bodies

A
  • membrane-coating, lamellar granules that produce lipid, which extrudes into the spaces btwn the cells and helps them stick together
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18
Q

Stratum lucidum

A
  • only found in areas where skin is thick (e.g. palm and soles)
  • contains clear, dead keratinocytes that are flattened + large amounts of keratin + thickened plasma membranes.
  • lies btwn stratum granulosum and stratum corneum
  • provides some degree of waterproofing to skin
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19
Q

Stratum corneum

A
  • uppermost layer
  • cells are arranged in orderly, vertical stacks
  • cells contain protein keratin
  • intracellular lipid from lamellar granules in stratum granulosum cements cells together and vital in preventing cells from drying out
  • as cells move through here, they lose their stickiness and are shed singly or in clumps (squamae)
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20
Q

callous

A
  • abnormal thickening of the stratum corneum
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21
Q

dermis

A
  • lies below epidermis and above subQ layer
  • responsible for providing nutrients and physical support to epidermis
  • contains lymph vessels, nerve endings, hair follicles, and glands
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22
Q

blister

A
  • when dermis and epidermis become separated as a result of shearing forces or friction, allowing fluid to collect
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23
Q

dermis composed of 2 layers:

A
  1. reticular layer

2. papillary layer

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24
Q

papillary layer

A
  • contains the nerve and capillaries that nourish epidermis
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25
Q

reticular layer

A
  • made up of strong connective tissue containing collagen and elastic fibers
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26
Q

collagen and elastin

A
  • arranged in network of fibers that have significant tensile strength providing dermis with ability to stretch and contract
27
Q

collagen

A
  • protein that contributes to approx 70% of dry weight of dermis
28
Q

collagen fibers

A
  • when skin is stretched, these fibers prevent tearing as result of their high tensile strength
29
Q

elastin fibers

A
  • synthesized by fibroblasts

- finer than collagen and found woven among collagen bundles

30
Q

elastin

A
  • has elastic properties that allow skin to return to its normal position after stretching
31
Q

with age:

A
  • reduction in number of collagen fibers , which stiffen and break up
  • results in collagen fibers losing their shape and becoming tangled
  • elastin fibers lose some of their elasticity, thicken into bundles and fray
32
Q

glands in dermis (sweat glands)

A
  • 3-4 million sweat glands

- function: release sweat into hair follicles or on to skin surface through pores

33
Q

2 types of sweat glands

A
  1. eccrine glands
  2. apocrine glands
  • based on their structure, location and type of secretion
34
Q

Eccrine glands

A
  • simple, coiled glands
  • specifically in skin of forehead, palms and soles of feet
  • produce sweat
35
Q

sweat composed of:

A
  • water
  • sodium and chlorine ions
  • urea
  • uric acid
  • ammonia
  • amino acids
  • glucose
  • lactic acid
36
Q

sweat glands

A
  • have important role in thermoregulation through evaporation
37
Q

Apocrine glands

A
  • not active during childhood
  • activated by sex hormones during puberty
  • simple coiled tubular glands
  • mainly found in axillae, groin, areolae of breasts, and bearded regions of face
  • unlike eccrine glands, sweat produced is slightly viscous with milky or yellowish appearance
  • this sweat has no smell when it leaves the gland
  • however when bacteria metabolize sweat components to produce musky odor (body odor)
38
Q

Sebaceous glands

A
  • simple branched acinar glands
  • most are connected to hair follicles
  • commonly found on face, neck and back
  • secrete sebum
39
Q

acinar gland

A
  • gland that has a sac-like secretory unit and an obvious lumen
40
Q

sebum

A
  • oily substance composed of a combination of triglycerides, cholesterol, proteins and organic salts
  • covers surface of hairs and protects them from drying and becoming brittle
  • inhibits excessive evaporation of water from skin so that skin remains soft and supple
  • lubricant
  • has anti fungal and antibacterial properties
41
Q

blackheads

A

open comedones

42
Q

whiteheads

A

closed comedones

43
Q

Ceruminous glands

A
  • found in external ear
  • modified sweat glands
  • these glands produce waxy lubricating secretion
  • this + secretions from sebaceous glands produce a yellowish substance called cerumen
44
Q

cerumen

A
  • yellowish substance formed by combo of secretions from ceruminous and sebaceous glands
  • function: provide sticky barrier to inhibit entrance of foreign bodies and insects into the ear
  • also prevents bacteria and fungi from entering cells because of its waterproofing ability
45
Q

2 main networks of cutaneous arteries

A
  1. deep plexus (network of blood vessels) found where dermis and subQ fat layer join
  2. superficial plexus
46
Q

deep plexus

A
  • supplies dermis and subQ layers of tissue with blood
47
Q

superficial plexus

A
  • branches off and carrie blood vessels to epidermis and dermis boundary
48
Q

hair

A
  • made up of columns of dead, keratinized epidermal cells connected together with extracellular proteins
49
Q

hair shaft

A

?

50
Q

hair root

A
  • surrounded by a hair follicle
51
Q

hair follicle

A
  • made up of an external and internal root sheath -> together make up the epithelial root sheath
52
Q

epithelial root sheath

A

external + internal root sheath

53
Q

dermal root sheath

A
  • dermis that encircles hair follicle
54
Q

hair bulb

A
  • base of each hair follicle and surrounding dermal root sheath
  • has similar shape to an onion
  • contains layer of cells called hair matrix
55
Q

hair matrix

A
  • hair matrix cells arise from stratum basale (layer where cell division occurs)
  • hair matrix cells responsible for growth of existing hairs
  • also produce new hairs when old hairs are shed
56
Q

3 stages of hair follicle growth cycle

A
  1. growth
  2. regression
  3. resting
57
Q

growth stage

A
  • cells of hair matrix divide
  • new cells added at base of hair so that existing cells are pushed p through half and hair grows longer
  • during this process, hair becomes keratinized and dies
58
Q

regression stage

A
  • hair stops dividing
  • hair follicle atrophies
  • hair no longer grows
59
Q

resting stage

A

…

60
Q

arrestor pili muscle

A
  • connected to follicle

- responsible for appearance of goosebumps

61
Q

finger and toe nails

A
  • made of sheets of keratin and are tough
  • function: protect ends of the digits and allow performance of intricate movements
  • grow from germinal cells called nail root
62
Q

nail root

A
  • germinal cells where nails grow from
63
Q

hyponychium

A
  • the tip of the finger, lying beneath distal end of the nail
  • area of thickened epidermis that allows for greater protection of the digit ends
64
Q

functions of skin

A
  • sensation
  • thermoregulation
  • protection and synthesis of vitamin D

Intro. to Microbiology - Part 1 (11 decks)

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