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BMA1901-Module 2 > Mod2-Obj6: The skin > Flashcards

Mod2-Obj6: The skin Flashcards

1
Q

skin contains the 4 primary tissues

A 
1.) Stratified squamous 
Epithelial tissue in the epidermis
2.) Connective tissue
In the dermis
3.) Smooth muscle tissue
In the arterioles attached to hairs
4.) Nervous tissue
In sensory nerves
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2
Q

The skin

A

Largest and heaviest organ
-Covers the entire body and weighs 4-5kg
-Part of the integumentary system (skin, glands, hair, nails)
Integument=covering

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3
Q

Layers of the skin

A 
Consists of 2 layers
1.) Epidermis
Outer epithelial layer
2.) Dermis
Supporting layer of dense connective tissue
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4
Q

Hypodermis

A

Loose connective tissue and fat

  • Anchors skin to the body
  • Not part of the skin
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5
Q

The epidermis: Avascular

A

Like other epithelium

-Oxygen and nutrients obtained from dermis

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6
Q

The epidermis: Dynamic steady state

A

Cells constantly die and renew

-New cells originate from stem cells

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7
Q

The epidermis: Constant renewal

A

Epidermis replaced every 25-45 days

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8
Q

The epidermis

A

Cells move from deepest layer to more superficial layer

  • Flatten
  • Produce large amounts of keratin
  • Continually replenished
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9
Q

The 5 epidermal layers (strata)

A
  1. ) Stratum basale (basal/deepest layer)
  2. ) Stratum spinosum
  3. ) Stratum granulosum (cells begin to die)
  4. ) Stratum lucidum
  5. ) Stratum corneum (most superficial layer)-cells are dead, produce large amounts of keratin providing waterproofing for the surface of the body
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10
Q

The epidermis: Stratum corneum (top)

A

20-30 cell layers

-Dead keratinised flattened cells

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11
Q

The epidermis: Stratum basale (bottom)

A

Stem cells

-Old cells pushed to surface

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12
Q

5 cells of the epidermis

A 
1.) Karatinocytes 
Produces keratin 
2.) Melanocytes
Produces melanin
3.) Merkel cells
Touch receptors (tactile)
4.) Langerhanan's cells
Immune system (macrophages), bone marrow
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13
Q

The dermis

A 
-Bulk of the skin
Connective tissue
-Fibroblasts and macrophages 
-Collagen and elastin fibres
-Strength and flexibility
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14
Q

Dermis contains

A
  • Blood vessels
  • Nerves and sensory receptors
  • Glands
  • Hair follicles
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15
Q

Blood supply to the skin

A

Dense capillary network in hypodermis
-Capillary loops project up through dermis
Blood flow through loops regulates by capillary sphincters
-temperature control (homeostasis)-vasoconstriction/vasodilation

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16
Q

Nerve supply to the skin: Network of nerve fibres

A

Dense network of fibres
Control:
-Blood flow (via sphincter)
-Glandular secretion i.e.) sweat

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17
Q

Nerve supply to the skin: Sensory information

A

Collect sensory information

  • Pain
  • Temperature
  • Touch and pressure
18
Q

6 Functions of the skin

A
  1. ) Protection (chemical, physical, biological)
  2. ) Sensation
  3. ) Metabolic function
  4. ) Blood reservoir
  5. ) Excretion
  6. ) Temperature regulation
19
Q

Function of the skin: Protection

A

Offered by chemical, physical and biological barriers

20
Q

Protection: Chemical barriers

A
  • Low pH secretions (acid mantle) prevent bacterial growth
  • Defensins secreted by skin to kill bacteria/fungi
  • Melanin protects DNA in underlying cells from UV damage
21
Q

Protection: Physical/mechanical barriers

A
  • Keratin and oily secretions block most water and water soluble substances
  • Some penetration of skin by lipid-soluble substances, some drugs (topical)
22
Q

Protection: Biological barriers

A

Macrophages dispose of viruses and bacteria that penetrate the epidermis

23
Q

Functions: Sensation

A

Cutaneous sensation

3 receptor types (providing information about external environment)

24
Q

Function: Sensation; Pain receptors

A

Noiceceptors

25
Q

Function: Sensation; Temperature receptors

A

Thermoreceptors

26
Q

Function: Sensation; Touch, pressure and vibration receptors

A

Mechanoreceptors

27
Q

Functions: Metabolism

A

Synthesis of vitamin a precursor

28
Q

Functions: Blood reservoir

A

Can hold 5% of blood volume

29
Q

Functions: Excretion

A

Nitrogenous wastes and salts excreted in sweat

30
Q

Function: Temperature regulation

A

At elevated temperature dermal blood vessels dilate and sweat gland activity increases
-Cools the body

31
Q

Function: Temperature regulation (heat input and output balanced)

A
  • Monitored by thermoreceptors
  • Information sent to thermoregulatory centre (hypothalamus)- set point
  • Coordinated response via circulatory system (vasoconstriction/vasodilation) and sweat glands
  • Homeostasis
32
Q

Skin colour: Melanin

A

Produced by melanocytes

  • Melanin migrates to keratinocytes
  • Forms ‘pigment shields’ for DNA
33
Q

Skin colour: Freckles and pigment moles

A

Local accumulation of melanin

34
Q

Skin colour: Melanocytes stimulated when exposed to sunlight

A

Darker skin produces more melanin

35
Q

Diseases and altered colour: Cyanosis (blue)

A

Lack of oxyhaemoglobin

36
Q

Diseases and altered colour: Erythema (redness)

A

Inflammation, allergy, fever

37
Q

Diseases and altered colour: Pallor (white)

A

Anaemia, low BP, stress

38
Q

Diseases and altered colour: Jaundice (yellow)

A

Liver disorder

39
Q

Diseases and altered colour: Bronzing (metallic bronze)

A

Adrenal cortex problem or pituitary gland tumor

40
Q

Diseases and altered colour: Bruises (black/blue)

A

Blood clots

41
Q

Development and ageing

A

The effects of abrasion, sun, chemicals

  • Skin thins-Cell number
  • Wrinkles form-Collagen&elastin
  • Dry and itchy-Oil and sweat glands
  • Increased chance of skin cancer-Melanocyte number
  • Age spots, hair loss, grey hair, colder skin, thicker nails

BMA1901-Module 2 (7 decks)

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