Tri B - Skin

Question 1

Describe the Skin

Answer 1

Largest organ, surface area = 1.5-2m2
Continuous with other mucosa at external openings

Question 2

What is the function of the Skin?

Answer 2

Protection - forms waterproof layer
Controls body temperature - sweating
Excretion - salt, garlic, spices
Formation of vitamin D
Sensory receptors

Question 3

Name and describe the function of some specialist cells

Answer 3

Pacinian corpuscles - sense pressure
Merkel cells - sense light touch, shape determination
Meissner’s corpuscles - sense light touch
Langerhans cells - attach to antigens
End organ of Ruffini - sensitive to skin stretching

Question 4

What is glabrous skin?

Answer 4

Non-hairy skin
E.g. soles of feet, palms of hands

Question 5

Describe the epidermis

Answer 5

Outer layer of skin
Squamous epithelium
No blood vessels or nerve endings

Question 6

Name the ‘strata’ of the epidermis

Answer 6

Stratum basale
Stratum spinosum
Stratum granulosum
Stratum lucidum
Stratum corneum

Question 7

Describe the stratum basale of the epidermis

Answer 7

Deepest layer
Single layer of columnar epithelium
Continuous division - stem cells
Melanocytes - differing pigment, melanin
Most sensitive to radiation

Question 8

Describe the stratum spinousum of the epidermis

Answer 8

8-10 layers of polygonal, closely packed cells
Thorn like projections from cell surface
Provide strength and flexibility

Question 9

Describe the stratum granulosum of the epidermis

Answer 9

3-5 layers of keratin forming cells
Grains seen in cytoplasm
Cells begin to lose nuclei and die in this layer

Question 10

Describe the stratum lucidum of the epidermis

Answer 10

3-5 layers of closely packed, clear cells
More pronounced in fingertips, palms, soles
Absent in hairy skin

Question 11

Describe the stratum corneum of the epidermis

Answer 11

Outer layer
20-30 layers of flattened cells with no nuclei
Continuously sheds and replaced
Forms barrier

Question 12

Describe the Dermis

Answer 12

Tough and elastic
Connective tissue - collagen and elastic fibres
Contains blood vessels, nerves, glands, hair follicles
2 layers - papillary and reticular

Question 13

Describe the papillary layer of the dermis

Answer 13

Outer layer
Consists of areolar connective tissue
Surface area increased by small projections - dermal papillae
Some papillae contain touch receptors
Nerve endings present - feel temp, pain, itching

Question 14

Describe the reticular layer of the dermis

Answer 14

Inner layer
Dense irregular tissue - collagen bundles, elastic fibres
Space between fibres contain follicles, glands, nerves
Pacinian corpuscles found
Collagen and elastic fibres give stretch and strength
Extreme stretching can cause striae

Question 15

Describe the subcutaneous layer

Answer 15

Contains adipose tissue
Fibres from dermis anchor it to subcutaneous layer
Storage for fat, and contains large blood vessels