1. The stratum corneum, ahir follicle, nails, sweat glands, oil glands,and strat

Question

1. The stratum corneum, ahir follicle, nails, sweat glands, oil glands,and stratum basale are discussed. Can you make a distinction regarding whether these structures are part of the integumentary system only or both the integumentary system and the integument?

2. identify what affects the thickness of the skin (dermis and epidermis). What is the relationship between what affects the thickness of the skin and the thickness of the hypodermis?

3. What is the dermoepidermal junction? By analyzing its anatomical componenets, what inference can you make regarding its function?

4. In terms of leaving less noticeable scar, why should an incision on the front of the thigh be made at a different angle than on an incision on the back of the thigh?

Explanation / Answer

1. These are the part of integumentary system and integuments. As integument is the outer covering of an organism or organ. Therefore, skin and its accessory components constitute the integumentary system and are integument.

The stratum corneum is the outermost layer consisting of rows of dead cells keratinocytes. This layer provides elasticity to skin and protection from drying out.

Stratum basale is the single layer of cells between dermis and epidermis. It consists of rapidly dividing cells and helps in repair of the skin. As newly divided cells are formed the older cells are pushed towards the skin surface. Thereby replaces lost epidermal cells.

Hair follicles extend into the dermis. Oil glands are present all over the body except sole of foot and palm secrete sebum and empties at the base of the hair follicle.

2. Factors that affect the thickness of skin are as follows:

Hypodermis is the layer below dermis. It helps in attaching skin to the underlying bones and muscles thereby supplying it with nerves and blood vessels. Hypodermis consists of about 50% of the body fat. The relationship between factors affecting skin and hypodermis remains on the fact that (a) hypodermis consists mostly of fat tissue with the increasing age, as the fat tissues are lost, the skin also becomes thin. (b) Diet : Type of diet also affects the thickness of hypodermis and hence skin. High calorie food, helps deposit fat on hypodermis thereby increasing its thickness and hence overall thickness of skin is increased.   

3.

3. Dermoepidermal junction is the junction or area in which dermal and epidermal layer of skin is joined. It consists of four layers:

(a) Basal epidermal layer: It is the dermal surface of the basal cell membrane and is irregularly convoluted with interdigitating cytoplasmic projections and dermal invaginations. Its is about 7-9nm in thickness. It constitutes a layer of hemidesmosomes.

(b) lamina lucida: It is the intermembranous space separating the plasma membrane from basal lamina. It is composed of the anchoring filament laminin and is about 20-40nm in thickness.

(c) lamina densa: It is the intermediate zone of anchoring filaments of epidermis and anchoring fibrils from dermis layer. It is about 30-60nm in thickness. Lamina densa layer thickness with age. It is mainly composed of collagen IV and laminin apart from heparin sulphate proteogylcans.

(d) fibrillar zone: It is about 20-60nm in thickness and composed of anchoring fibrils.

Functions of dermo-epidermal junction are:

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