Integumentary system Flashcards

1
Q

What are the accessory organs of the integumentary system?

A

Hair
Nails
Cutaneous glands- sweat, sebaceous and mammary

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2
Q

What are the three gross layers from outer to inner?

A

Epidermis
Dermis
Hypodermis (areola or adipose tissue between skin and muscle)

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3
Q

What are the two zones of the dermis?

A

Papillary layer

Reticular layer

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4
Q

What is the papillary layer of the dermis?

A

Thin region of loose connective tissue allowing mobility of leukocytes, mast cells and macrophages

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5
Q

What is the reticular layer of the dermis?

A

Thick layer of dense irregular tissue, less cells, but often with adipocyte clusters for stretch of skin in weight gain

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6
Q

What are fibroblasts?

A

Produces proteins laminin and fibronectin of the ECM

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7
Q

What other structures are found in the dermis?

A
Fibroblasts
Accessory organs
Rich supply of blood and lymphatic cells
Atriovenous enastemoses 
Numerous nerve endings
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8
Q

What is the structure of the dermal-epidermal boundary?

A

Wavy boundary of finger like projections
Made of dermal papillae and epidermal ridges
Tall dermal papillae facilitate nerve fibres reaching closer to the surface in areas of high sensitivity

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9
Q

What are the differences between thick and thin skin?

A

Thick- palms of hands and feet, no hair, 5 layers

Thin- rest of the body and only has 4 layers

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10
Q

What are the layers of the epidermis from the bottom upwards?

A
Stratum basale
Stratum spinosum
Stratum granulosum
Stratum lucidum (only in thick skin)
Stratum corneum
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11
Q

What cells in the epidermis retain the ability to replicate?

A

Only ones that are in contact with the basement membrane

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12
Q

Stratum basale

A

Keratinocytes most prevalent and are mitotically active on the basement membrane
Contains melanocytes which gives the skin colour
Contains merkel disc sensory receptors

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13
Q

What are the two kinds of melanin produced in the stratum basale?

A

Pheomelanin- red soluble pigment

Eumelanin- brown insoluble pigment

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14
Q

What is the function of melanocytes?

A

Release melanin which is UV absorbant, an antioxidant and is radical scavenging which all helps to protect the skin from UV damage

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15
Q

What else does the pigment of the skin depend on other than melanocytes?

A

Carotene pigments give a yellow/orange colour in subcutanous fat and the stratum corneum
Amount of blood and its oxygen content- haemoglobin gives red colour

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16
Q

Stratum spinosum

A

Several layers of keratinocytes and is usually the thickest layer (apart from thick skin which is the stratum corneum)
Deepest cells are mitotic and are pushed upwards so they cease to divide
Produce keratin filaments causing cells to flatten
Tight junctions for water retention of skin

17
Q

What are desmosomes?

A

Strongly link keratinocytes together in the stratum spinosum

18
Q

Stratum granulosum

A

3-5 layers of flat keratinocytes, post-mitotic
Contain dark staining keratohyalin granules which bind to cytoskeleton and are converted to keratin
Cells undergo apoptosis
Produce glycolipid filled vesicles to form a waterproof layer between spinosum

19
Q

Stratum lucidum

A

Thin translucent layer which is only present in thick skin
Keratinocytes densely packed with no nuclei or organelles
Indistinct cell boundaries
Granules of eleidin within proteoplasm- product of keratinohyalin

20
Q

Stratum corneum

A

Most superficial, 15-20
Terminally differentiated dead keratinocytes that continually flake off
Resistant to abrasion, water loss and penetration

21
Q

What is the cornified envelope of the stratum corneum made up of?

A

Keratins enclosed within an insoluble amalgam of proteins
Cross linked by transglutaminases
Surrounded by lipid envelope

22
Q

Structure of nails

A

Derivatives of the stratum corneum and composed of dead scaly cells densely packed with hard keratin fibres
New cells are added by mitosis in the nail matrix

23
Q

How can appearance of the nails indicate underlying health issues?

A

Iron deficiency- become flat or concave

Long term hypoxemia- become clubbed

24
Q

Structure of hair

A

Slender filament of dead keratinised cells from follicles

25
What are the three stages of hair changing during lifetime?
Lanugo- fine, downy, unpigmented, in the foetus Vellus- similarly fine and unpigmented Terminal- coarse, pigmented
26
What are the three layers of the hair matrix?
Medulla- loosely arranged cells Cortex- keratinised cuboidal cells Cuticle- surface layer of scaly cells
27
How does hair grow?
Hair bulb grows around a bud of vascular connective tissue- dermal papilla The hair matrix above is mitotically active
28
What are the 5 different types of glands present in the skin?
Merocrine sweat glands, apocrine sweat glands Sebaceous glands Ceruminous glands Mammary glands
29
What is the function of merocrine glands?
Watery perspiration to skin | Associated with myoepithelial cells
30
What is the function of apocrine sweat glands?
Ducts lead to follicles | Scent glands responding to stress and sexual stimulation
31
What is the function of sebaceous glands?
Produces oily sebum which lubricate skin and hair
32
What is the function of ceruminous glands?
In the external ear and produces ear wax
33
How is skin a physical barrier?
Cross linked keratin layer upon a scaffold of keratinocytes
34
How is skin a biochemical barrier?
Slight acidity of pH 4-6 Bacteriocidal agents- saturated and unsaturated fatty acids inhibit the growth of bacteria and lysozymes cleave the cross linkages in bacterial cell walls
35
How is the skin an immunological barrier?
Langerhans cells of the stratum spinosum are able to self renew and take up and process antigens by either migrating to lymph nodes for antigen presentation or present antigens to the skin lymphocytes which activate an immune response
36
How does the skin regulate temperature in terms of blood flow?
Countercurrent heat exchange between arterial and venous blood flow in the dermis of extremities
37
How does the skin regulate temperature using sympathetic fibres?
Postganglionic- release norepinephrine which causes vasoconstriction Preganglionic- release ACh which causes vasodilation, mediated by formation of bradykinin Muscarinic ACh receptors for sweat glands