The Integumentary System - Skin and Accessory Structures

Question 1

Explain what is the integument and examples;

Answer 1

outer covering of the body
Skin, glands, hair, nails

Question 2

What are the 5 functions of the integument?

Answer 2

• Protection
  Abrasion
  UV light
• Microorganisms
  Water loss
• Sensation
• Vitamin D production
• Temperature regulation

-Excretion

Question 3

The skin - largest organ of the body; whats it made up of?

Answer 3

a) Epidermis - he surface epithelial layer
= prevents water loss and abrasion damage

b) Dermis - An underlying dense connective tissue layer
= structural strength

c) The subcutaneous layer = not really skin - lowest of the three parts

Question 4

a) Epidermis properties;
layers, cells, cell turnover

Answer 4

• Avascular
• Layers /strata
  4/5 layers
  Stratum Lucidum (palms/soles of feet)
• Cells generated in basal layer / stratum basale
• Migrate
• Keratinisation
  waterproof

-Cell Turnover ~ 35 days

Question 5

What is the process of ‘cells slough off’?

Answer 5

shedding dead surface cells from the skin which happens through MITOSIS - cell migration and keratinaisation

Question 6

What are the cell types of epidermis?

Answer 6

1) Basal cells (precursor of keratinocytes)

2) Keratinocytes
Over 90% of cells present in skin
Contain keratin

3) Melanocytes
pigment-producing cells (5% of the total)
filter ultraviolet light

4) Langerhans cells
dendritic (branched) - immune cells
Merkel Cell – sensory receptor cells (touch)

Question 7

Epidermis: Cell layers (Strata) - list the 3 types

Answer 7

Stratum germinativum (growth layer) –
stratum basale and stratum spinosum

Stratum basale (base layer) —
Basal cells; only these cells undergo mitosis
migrate up - become Keratinocytes
Merkel cell (information); Melanocyte (protection)

Stratum spinosum (spiny layer) —
Keratinocytes: held together (desmosomes)
Strength /flexibility
Begin to generate keratin and lipid
Some basal cells: Only v limited cell division
Langerhans cells (engulf bacteria)

Stratum granulosum (granular layer)—
Cells – lots of deposits of keratin / keratohyalin
Granules - grainy
Superficial cells: begin to degenerate

Stratum lucidum (clear layer)—
dead cells
Cell walls filled with keratin / keratohyalin

Stratum corneum —
Dead cells filled with keratin (barrier area)
15-30 layers
Constantly shed
Cells surrounded by lipids

Question 8

What are the functions of Epidermis?

Answer 8

Stratum corneum (in particular)—
Keratin/keratohyalin – protect against water loss

Drug delivery:
lipid-soluble substances will diffuse through lipid layers

Question 9

In detail, how does Epidermis (Stratum cornem) prevent water loss?

Answer 9

> prevents penetration of microbes

> the dehydration of underlying tissues

> mechanical protection against abrasion for the more delicate, underlying layer

Question 10

Dermis structure:

Answer 10

Structural Strength
Connective tissue fibres:
Collagen / elastic fibres
Fibroblast cells

Question 11

What are the layers of Dermis? (2)

Answer 11

Papillary layer (superficial)
Reticular layer (deep)

Question 12

There are 3 layers of dermis, list:

Answer 12

Dermis Contains:
Hair follicles / associated muscles
Sensory receptors
Sweat and sebaceous glands
Blood vessels
Lymphatic vessels
All carry out key functions of skin

Papillary layer
Fine collagenous and elastic fibers
Blood vessels: supply epidermis
Oxygen/nutrients
Dermal papillae:  increase strength of bond to epidermis
finger prints

Reticular layer
denser, collagenous fibers and elastic fibers

Question 13

What is responsible for strength and stretchability in the dermis?

Answer 13

Collagen & Elastic fibres

Question 14

Key functions of dermis;

Answer 14

Strength, temperature regulation, nutrients to epidermis

Question 15

DERMAL growth and repair;

Answer 15

Dermis does NOT continually shed and regenerate itself

Collagen fibres (generally)
Some predominant direction
cleavage lines
Surgery : Incision made across the cleavage lines
> produce considerable scar tissue
Surgery: Incision made parallel with the lines
> produce less scar tissue

Question 16

Wound healing in dermis:

Answer 16

fibroblasts proliferate

Question 17

Stretch marks/ striae is simply…..

Answer 17

overstretched skin > overstretched skin

Question 18

Types of Glans (sweat Glands)

Answer 18

> Ecrine Sweat Glands
Most Common,
Open directly through sweat pores
Function throughout life
Secretion: mostly water with a few salts
Secrete perspiration or sweat;
eliminate wastes; and cools body

> Apocrine Sweat Glands
Open into hair follicles
Limited distribution—arm pits/ genitalia
Limited function in humans
Begin to function at puberty
Body odour

Question 19

Gland secretion and shed skin = Surface film

Answer 19

• protective barrier = mixing of secretions of sweat and sebaceous glands

Question 20

Glands - Sebaceous glands

Answer 20

Hair folicle

Secrete sebum—
oily substance – lubricant for hair and skin
prevents excessive water loss from the skin

Lipid - antifungal activity

Question 21

Functions of glands

Answer 21

Antibacterial, antifungal activity
Lubrication
Hydration of skin surface
Buffer of caustic irritants
Blockade of toxic agents

Question 22

What determines skin colour? (excluding race)

Answer 22

Pigments (melanin, beta carotene)
Blood (haemoglobin)
Thickness of stratum corneum

Melanin
Production (by melanocytes)
Production affected by - UV, Homrones, Genetics

Question 23

Melanin are produced by

Answer 23

Melanocytes

Question 24

Melanin into vesicles called _______

Answer 24

melanosomes

Question 25

Phagocytosed by epitheliad cells (keratinocytes)

Answer 25

form nuclear cap

Question 26

Skin Pigmentation

Answer 26

Annular erythema
skin reaction that can be triggered by an infection or some medicines

Question 27

Explain the process of vitamin D production

Answer 27

UV light converts a form of cholesterol to cholecalciferol (D3)— a precursor to vitamin D

Blood transports precursor/Cholecalciferol to liver and kidneys,
where vitamin D is produced

Vitamin D is essential for normal absorption of
calcium and phosphorous
Essential for bone function