Skin Structure & Function Flashcards

1
Q

What is the Epidermis, and what are its properties?

A
  1. Outermost layer of skin
  2. Avascular - lack of blood vessels
  3. Acts as a protective barrier
  4. Contains 4 main types of cells; Keratinocytes, Melanocytes, Langerhans and Merkel
  5. Has 5 layers; Stratum corneum, Stratum lucidum, Stratum Granulosum, Stratum spinosum, Stratum basal.
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2
Q

What are Melanocytes, and what are their properties?

A
  1. Cells which produce Melanin, a protective skin darkening pigment
  2. Protects against UV radiation
  3. Located in the Stratum basal layer 4. Stimulates keratinocyte production, thickening the epidermis
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3
Q

What are Langerhans, and what are their properties?

A
  1. Dendritic cells located in the stratum spinosum
  2. Alerts immune system of harmful substances
  3. Highly specialised macrophages, take part in destruction of pathogens
  4. Part of hypersensitivity and allergic reactions
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4
Q

What are the five layers of the epidermis?

A
  1. Stratum Corneum
  2. Stratum Lucidum
  3. Stratum Granulosum
  4. Stratum Spinosum
  5. Stratum Basal
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5
Q

What are Keratinocytes, and what are their properties?

A
  1. Cells which produce keratin
  2. Forms a protective barrier resistant to physical and chemical damage
  3. Held together by desmosomes
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6
Q

What are properties of the Stratum basal layer?

A
  1. Comprised mostly of keratinocytes
  2. Also include melanocytes and merkel cells
  3. Stem cells mitose to produce keratinocytes here, replacing corneocytes which have shed (in the stratum corneum layer)
  4. The cells are attached to the dermo-epidermal junction by hemi desmosomes
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7
Q

What are properties of the Stratum Spinosum layer?

A
  1. Cells from the basal layer migrate upwards to this layer and change shape to polygonal.
  2. Develop keratin filaments (tonofilaments)
  3. Some tonofilaments project out of the cell desmosomes
  4. These filaments fill with others and form intercelluar bridges to add resilience.
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8
Q

What are Desmosomes?

A
  1. Bridges between cells
  2. Provide robust barrier against trauma, particularly shearing forces

3 Loss of adhesion could result in blistering diseases,

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9
Q

What are properties of the Stratum Granulosum?

A
  1. Cells migrate up to this level and begin to flatten out from their polygonal shapes
  2. Cells begin to lose nuclei and organelles, undergoing programmed cell death
  3. Granules of keratohyalin organise keratin into thick bundles, increasing strength
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10
Q

What is filaggrin and why is it important?

A
  1. it is a filament associated protein which binds to keratinocytes
  2. They are important as they retain the water within keratinocytes
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11
Q

What are properties of the Stratum Lucidum?

A
  1. visible on soles, palmes, fingertips and anywhere with thick skin.
  2. thin layer of dead keratinocytes.
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12
Q

What are properties of the Stratum Corneum?

A
  1. Uppermost layer, filled with Keratin and filaggrin
  2. Cells change shape to hexagonal, and become cornified.
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13
Q

What is Desquamation?

A
  1. Essentially the shedding of the skin
  2. Includes breaking the desomosome links between corneocytes
  3. Can only function well in the presence of a well-hydrated Stratum corneum
  4. Desquamation is abnormal in the absence of hydration, leading to thick and dry skin.
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14
Q

What are properties of the dermis?

A
  1. Cells - composed of mainly fibroplasts, but also contains lymphocytes, langerhans, macrophages and mast cells
    • Fibres - 70% collagen, the protein which gives toughness and strength. Also contains Elastin, which makes the skin pliable
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15
Q

What are the layers of the Dermis?

A
  1. Papillary
  2. Reticular
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16
Q

What are the properties of the Papillary layer of the dermis?

A
  1. Composed of loosely woven collagen
  2. Contains most of the blood/lymphatic vessels
  3. DERMAL PAPILLAE & EPIDERMAL RETE RIDGES connect dermis to the epidermis
17
Q

What are the properties of the Reticular layer of the Dermis?

A
  1. Consists of dense irregular tissue
  2. has Courser, horizontally running bundles of collagen
  3. Covers underlying subcutaneous tissue
18
Q

What are Fibroplasts, and their properties?

A
  1. Cells which are responsible for the synthesis and degradation of connective tissue proteins
  2. Imperative for Tissue repair
19
Q

What are Mast Cells, and their properties?

A
  1. Cells which release a variety of inflammatory mediators (e.g. histamine)
  2. Are derived from Bone marrow
20
Q

What is Adipose tissue?

A

Connective tissue mainly consisting of fatty/adipose cells

21
Q

What is the Hypodermis, and its properties?

A
  1. Consists of Adipose tissue
  2. Insulates the body, and serves as an energy supply
  3. Thickened over the heel and metatarsal heads
  4. Acts as sealed chambers of fat
  5. With mechanical forces, acts as a fluid cushion to absorb force of walking
22
Q

Which subsystem of the Nervous system concerns sensation/touch?

A

Somatosensory system

23
Q

Which Skin Receptor is stimulated by pressure and touch?

A

Mechanoreceptors

24
Q

Which skin receptor is stimulated by temperature changes?

A

Thermoreceptors

25
Q

Which skin receptor is stimulated by pain?

A

Nociceptors

26
Q

What are Merkel discs and their properties?

A
  1. Mechanoreceptors distributed throughout the Epidermis
  2. Disc-like structures on the terminal twigs of nerve branches
  3. Attached to merkel cells
  4. Sensetive to light touch and superficial pressure

5.

27
Q

What are pacinian corpuscles and their properties?

A
  1. Mechanoreceptors located in deep layer of dermis
  2. Detect deep pressure and touch and are responsible for Proprioception
  3. Rapidly adaptive
28
Q

What are Meissners Corpuscles (Tactile) and their properties?

A
  1. Mechanoreceptors situated in papillary layer of Dermis
  2. Respond to touch/pressure
  3. found in areas of high sensetivity (e.g arch of foot)
29
Q

How do Blood vessels prevent heat loss in cold conditions?

A

Shunt vessels dilate, meaning less blood flows through the capillaries near the skin surface, meaning less heat is lost through radiation in blood

30
Q

What are properties of Hair?

A
  1. Composed primarily of Keratin
  2. Follicles contain the muscle ‘arrector pili’ which contracts in response to emotion
  3. hair follicles have associated glands (oil/sebacious)
31
Q

What are the function and properties of Sebacious glands?

A
  1. Produces and releases sebum excreted through the hair follicle
  2. Sebum protects the skin keeping it smooth and supple
  3. Not present on Glaborous skin (palms or soles)
32
Q

Label all cells and epidermal layers

A
33
Q

What is this?

A

Sebacious Gland

34
Q

What are these?

A

Red - Pacinian Corpuscle

Blue - Ruffini’s Corpuscle

Green - Meissner’s Corpuscle

35
Q

Complete the labels

A