integumentary system

Question 1

What are the main cell types of the Epidermis?

Answer 1

• Keratinocytes: main cell type, produce keratin, found deep in epidermis
• Melanocytes: secrete melanin (pigment), found deepest in epidermal layer
• Merkel cell: specialised sensory cell, responds to light/ touch
• Dendritic cell: ingests invading pathogens/ foreign materials, activates immune defences of the body

Question 2

What are the epidermal layers?

Answer 2

• Stratum corneum: cells become more squamous, become dead and fall away
• Stratum granulosm- keratin starts to be layered down
• Stratum spinosum: cells begin to change
• Stratum Basale: dividing stem cells that create daughter cells and gradually move up through skin.

Question 3

What does the dermis contain?

Answer 3

• Collagen fibres
• Nerve endings
• Sweat glands
• Blood vessels
• Hair follicles
• Elastic fibres

Question 4

What are the two layers of the dermis?

Answer 4

Papillary & reticular layer

Question 5

What are the dermal papillae?

Answer 5

They are located between epidermis and dermis and help increase surface area for nutrient exchange, contribute to sensory perception and regulate hair growth by interacting with hair follicles.

Question 6

What are the 4 skin functions? Briefly describe each one

Answer 6

• Protection- Infection, dehydration and chemical resistant layer, physical damage- melanocytes protecting against UV.
• Temperature regulation- Eccrine sweat glands come to surface, hypothalamus senses temp changes and can cause vasodilation of blood vessels. Erector pills muscles connect hair follicles to connective tissue and create goose bumps.
• Secretion- sebaceous glands are associated with hair follicles and create sebum which is oily and secretes oil. Apocrine glands produce yellow sweat through anogenital & axillary areas, starts during puberty.
• Cutaneous sensation- free nerve endings have a role in sense of touch.

Question 7

What are three signs of non-verbal communication?

Answer 7

• Body odour/ stress
• Blushing
• Pheromones

Question 8

What can skin colour be affected by?

Answer 8

• Haemoglobin
• Melanin
• Carotene

Question 9

What is abnormal colouration?

Answer 9

• Cyanosis
• Jaundice
• Pallor
• Albinism
• Haematoma

Question 10

What are the stages of scaring of the skin?

Answer 10

1. Fibroblasts lay down a framework of fibres to replace damaged tissues.
2. Fibres are laid down as irregular arrangement.
3. Sweat glands/ hair follicles don’t regenerate
4. Irregular framework- different pattern of blood vessels. Which produces scar.
   E.g., stretch marks because they are dermal tears.

• Epidermal regeneration is usually very efficient, dermal regeneration is less well organised

Question 11

What are the two main layers of the skin?

Answer 11

• Epidermis
• Dermis

Question 12

What is sloughing?

Answer 12

Shedding dead surface cells from skin. It is a normal part of skin regeneration cycle.
Outer layer ‘epidermis’ replaced every 21-45 days.

Question 13

What is the stratum lucidum (clear layer)?

Answer 13

• Found only in thick, non hairy skin
• Consists of thin, translucent band
• 2 – 3 layers
• flat, dead keratinocytes
• Lies superficial to the stratum granulosum