skin (integumentary system)

Question 1

two main layers of skin (cutaneous membrane)

Answer 1

epidermis - superficial layer composed of stratified squamous epithelium
dermis - deep layer composed of connective tissue and containing blood vessels. lymph vessels and nerves

Question 2

skin functions

Answer 2

blood resivior, secretion, excretion, vitamin d metabolism, protection, thermoregulation, sensory reception.

Question 3

four epidermal cells

Answer 3

keratinocytes - produce keratin. it toughens skin and makes it waterproof. found in all epidermal layers.
merkel cells - found in stratum basal. respond to light touch and are associated with sensroy nerve endings within the dermis below
langerhan cells - arise from bone marrow and migrate to epidermis dispersing through stratum spinosum. ingest foriegn material and activate immune system as needed
melanocyres - found in stratum basal. produce melain which is a pigment taken up by keratinocytes to provide them protection from uv rates. responsible for skin colour

Question 4

four layers of epidermis

Answer 4

4th layer (bottom) - stratum basale (keratinocytes, merkel cells and melanocytes)
3rd layer - stratum spinosum (langerhan cells, keratinocytes)
2nd layer - straum granulosum (keratinocytes)
sometimes layer - stratum lucidity (only on palms of hands and soles of feet. heaps of dead keratinocytes to reduce friction between layers)
1st layer (top) - stratum corneum (keratinocytes) made up of layers of dead keratinocytes

Question 5

dermis and its layers

Answer 5

thick connective tissue layer that loies just below the straum basal. contains heaps of nerve endings.
reticular layer - deep layer, 80% of dermis contains some adipose tissue and composed of dense irregular CT
paillary layer - 20% of dermis, superficial layer, composed of areolar CT, contain dermal ridges and papillae.

Question 6

appendages of the skin

Answer 6

nails - composed of hardened keratinisied cells, used like tools for picking and stretching
hair and hari follicles - guards against heat loss and UV radiation. sheilding eyes and filtering air we breathe. act as sensitive touch receptor
sebaceous oil glands - softens and lubricates hair and skin, slows water loss from skin and kills come bacteria
sweat glands - eccrine glands - everywhere in skin, produce basic sweat (water and inorganic chemicals) apocrine glands - found in armpit and anogenital regions, dont appear till puberty as they are associated with hair follicles like pubic hair. profuce sweat that contain lipids and proteins (organic chemicals)
play major role in thermoregulation.