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Biomedicine basics > Integumentary system - skin > Flashcards

Integumentary system - skin Flashcards

1
Q

The skin is the largest organ of the human body. Approximately how many square meters does it cover and give its range of thickness.

A

2 square meters

0.5mm - 4mm thick

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2
Q

The skin is an epithelial membrane. Name 3 accessory structures…

A
  1. Glands
  2. Hair
  3. Nails
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3
Q

The skin consists of 3 main layers, name them

A
  1. Epidermis
  2. Dermis
  3. Subcutaneous / adipose layer
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4
Q

What is the epidermis?

A

The superficial layer of the skin formed of epithelial tissue.
(Tightly packed cells)
Epi = above

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5
Q

What is the dermis?

A

The middle layer of skin, formed of connective tissue.

Also contains accessory structures such as glands, hairs and sebaceous glands.

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6
Q

What is the subcutaneous / adipose layer?

A

An insulating and protective layer of fatty tissue that connects the dermis to the deep-lying muscle and bone.

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7
Q

What is the epidermis formed of?

A

Keratinised epithelium

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8
Q

What is keratin?

A

A type of protein that forms the outer layer of the skin, hair and nails as well as the lining of some organs. It is protective and water-proof.

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9
Q

There are 3 main epidermis cell types - name them, what they do and the percentage found in the body.

A
  1. 90% are Keratinocytes. Keratin is a tough fibrous protein that protects from heat, microbes and chemicals.
  2. 8% are Melanocytes. Melanin is a pigment contributing to skin colour and absorbs UV light. Melanin surrounds the nuclei of keratinocytes on the side toward the skin surface protecting it from UV light.
  3. 2% are langerhans cells - immune cells
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10
Q

Name the 2 types of Melanin in the skin and their colours.

A
  1. Eumelanin - brown/black

2. Pheomelanin - reddish/yellow

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11
Q

the epidermis has 5 stratum (layers) - name them…

A
  1. Stratum Corneum
  2. Stratum Lucidum
  3. Stratum Granulosum
  4. Stratum Spinosum
  5. Stratum Basale
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12
Q

How many layers does the stratum corneum have?

A

25 - 30 layers of flattened dead keratinocytes

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13
Q

Where is the stratum lucid present and how many layers does it have?

A

Present in thick skin areas like the heel of the foot. Contains 3-5 layers of dead cells.

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14
Q

What is the stratum Granulosum and how many layers does it have?

A

3-5 layers of cells undergoing apoptosis - therefore half living
apoptosis = cell suicide

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15
Q

What is the stratum spinosum?

A

8-10 layers of new keratinocytes (living cells)

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16
Q

Which layer does the following describe;

Single row dividing to form new keratinocytes

A

Stratum Basale

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17
Q

Approximately how many days does it take for complete replacement of the epidermis

A

40 days

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18
Q

Pigmentation of the skin is due to varying degrees of melanin produced by melanocytes. People of different races have the same number of melanocytes but different amounts and types of melanin.
Name the two types of melanin and their pigmentation colour

A
  1. Eumelanin = brown/black pigment

2. Pheomelanin = reddish/yellow pigment

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19
Q

If the skin is yellow what might that imply?

A

Yellowing of the skin could imply jaundice from a pathology. A natural yellow colour could be caused by carotenes in food.

20
Q

‘the thickest layer of the skin, formed of connective tissue, containing a matrix of collagen and elastic fibres’.

What is this layer called?

A

The Dermis

21
Q

What does the dermis layer contain? Name 4

A
  1. Arterioles and capillaries (thermoregulation)
  2. Lymph vessels and sensory nerve endings
  3. Sweat glands and ducts, hairs and arrestor pili muscles, sebaceous glands and ducts.
  4. Fibroblasts (making collagen and elastic fibres) and immune cells - macrophages and mast cells.
22
Q

Which areas of the body are sweat glands most numerous?

A

palms, soles of feet, axillae (armpits) and groin

23
Q

What do sweat glands excrete?

A

Excretion of Urea

Excessive sweating leads to dehydration and sodium depletion.

24
Q

Main job of sweat glands?

A

to regulate body temperate - cool down

25
Q

There are 3 types of sensory nerve endings in the skin. Name them…

A
  1. Meissners corpuscle - sensitive to light pressure
  2. Pacinian corpuscle - sensitive to deep pressure
  3. Free nerve ending - sensitive to pain and temperature
26
Q

What are hairs made from?

A

Hairs are concentric columns of dead keratinised cells bonded together by proteins.

27
Q

Hair colour is genetically determined.
Hormones influence distribution of hair.
The more melanin pigments in the hair the darker the colour.

What is the smooth muscle that connects to the hair follicle called?

A

arrector pili

28
Q

How might hair help regulate body temperature?

A

When hair is erect it traps a layer of air next to the skin which is then warmed by body temperature - part of thermoregulation

29
Q

What do sebaceous glands secrete and what does that do?

A

Sebaceous glands secrete sebum, which keeps hair soft, provides water-proofing for the skin and is anti-microbial

30
Q

When does sebum activity increase and decrease?

A

Increases in puberty and decreases with age.

31
Q

What does the fatty acids in sebum inhibit?

A

bacterial growth

32
Q

Name the 6 functions of the skin…

A
  1. Protection
  2. Thermoregulation
  3. Vitamin D production
  4. Sensation
  5. Absorption
  6. Excretion
33
Q

The skin protects against dehydration and external factors such as chemicals, toxins, trauma, light and microbes. Name the 5 things that make the skin a protective barrier….

A
  1. Physical barrier - closely packed keratinised cells and melanin
  2. Sebum - contains fatty acids which inhibit microbial growth
  3. Sweat - contains lysozyme which are enzymes that breakdown bacteria
  4. Desquamation - shedding of skin cells helps remove microbes
  5. Nerve sensors - induce protective reflexes.
34
Q

The skin helps with thermoregulation. Where are the temperature control centres? (2)

A
  1. Hypothalamus

2. Medulla oblongata (brain stem)

35
Q

Temperature regulation by the skin occurs via 2 activities, name them…

A
  1. Activity of sweat glands to cool the body

2. Activity of blood vessels - vasodilation / vasoconstriction to cool the body or warm it.

36
Q

Heat is a natural bi-product of metabolism. Heat is produced by … name the 3 organs.
Adipose tissue is an insulator

A
  1. liver
  2. muscles
  3. digestive organs
37
Q

At what temperatures do Hypothermia and Hyperthermia occur

A
  • Hypothermia occurs when the core temperature drops below 35 degrees C
  • Hyperthermia occurs when the core temperature elevates above 38.5 degrees C
38
Q

UV light on the skin activates a vitamin D precursor . Read the below.

A

The liver and kidneys convert vitamin D (produced in the skin and taken up in the diet), into the active hormone, which is called calcitriol. Active vitamin D helps to increase the amount of calcium the gut can absorb from eaten food into the bloodstream and also prevents calcium loss from the kidneys.

39
Q

What is Dihydrocholesterol?

A

A derivative of cholesterol present in the skin. It can be converted to cholecalciferol (Vit D3) by the action of ultraviolet radiation

40
Q

The skin absorbs and excretes substances.

Give examples of each….

A

Absorption:
Lipid- soluble molecules: Vit A, D, E, K. Some medications, essential oils, O2 and CO2.
Toxins: acetone, carbon tetrachloride, lead and mercury, arsenic, poison oak and poison ivy.

Excretion:
Salt (sodium chloride) Water, Urea, Ammonia

41
Q

What does a superficial wound describe?

A

A wound that has damaged only the epidermis of the skin. Includes abrasions and light burns.

42
Q

Wound healing in a superficial wound - Basal cells move across the gap until contact inhibition occurs. Epidermal growth factor causes multiplication of the basal cells until the space is filled.

What does contact inhibition mean?

A

the cessation of cell division in cells that have touched each other

43
Q

which layers of skin are affected by a deep wound?

A

epidermis, dermis and subcutaneous layer

44
Q

name the 3 phases of deep wound healing…

A
  1. Inflammatory phase
  2. Proliferation phase
  3. Remodelling phase
45
Q

Name two types of scar tissue:

A
  1. Hypertrophic scar - stays within the boundary of the wound
  2. Keloid scar - takes up a larger space than the wound, normally raised

Biomedicine basics (9 decks)

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