Lecture 2 - Integumentary System Flashcards
the outermost layer of skin on the body
epidermis
the middle layer of skin on the body
dermis
integumentary system
the body’s outer layer consisting of epidermis, dermis, glands, hair and nails
the deepest layer of skin
aka hypodermis, subcutaneous tissue containing mostly body fat
what is in the subcutaneous layer?
loose connective tissue with fat cells (adipocytes)
what is thin skin?
- contains 4 layers
- covers most of the body
what is thick skin?
- contains five layers
- covers area prone to abrasion (palms, feet)
what does thick/thin skin refer to?
it refers to number of layers in the epidermis and NOT the actual deepness of skin
examples of accessory structures of the skin
hair, nails, sweat (sudoriferous) glands and sebaceous (oil) glands
what are the four cell types in the epidermis?
1.) keratinocytes
2.) melanocytes
3.) tactile cells
4.) dendritic cells
what layer is missing/absent in thin and thick skin?
the stratum lucidum
–> absent = 4 layers
–> present = 5 layers
where is collagen found?
in the dermis layer
what are cleavage lines?
- represents separations between underlying collagan fibre bundles in the reticular dermis
- run circularly in trunk
- run longitudinally in limbs
- surgical incisions parallel to cleavage lines heal better than those made across them
what are the layers in the epidermis?
stratum basale (aka stratum germinativum)
stratum spinosum
stratum ganulosum
stratum lucidum
stratum corneum
a nipple-shaped projection or strucure
papillary
the most superficial layer of dermis but deep to the epidermis is called…
the papillary layer
what is found in the papillary layer?
- contains dermal papillae and capillaries which help exchange waste, nutrients, gas and blood to the dermis
- helps supply stratum basale + stratum spinosum
network of intercellular fibre /connective tissue
reticulum
deepest layer of the dermis
reticular layer
what kind of tissue is found in the reticular layer?
dense, irregular connective tissue including LOTS of collagen and elastin (proteins)
protrusions of dermal connective tissue into the epidermal layer that help with gas, waste, nutrient exchange
dermal papillae
network of small arteries in the papillary layer of the dermis
papillary plexus
interconnections of blood supply that attach to adipose tissue and supply hair follicles, glands and other structures
cutaneous plexuses
what do capillary loops do?
follow the contour of the epidermal-dermal boundary
speicalized cell of fat/adipose tissue
adipocytes
the most abundant cell in epidermis
keratinocyte
what is the lifecycle of a keratinocyte?
1.) mitosis in the stratum basale and a cell gets pushed through the layer toward the surface
2.) differentiate in the stratum spinosum (looks spiney) and produce bundles of keratin protein called tonofibrils
3.) cells start to die as they get futher from the nutrient source (stratum basale)
4.) keratohyalin forms granules in the stratum granulosum which dehydrate the cell and cause cross-linking of keratin filaments. Cells release lipid-rich susbtances that coat them = water-resistant layer
5.) in thick skin, cells become part of clear layer called stratum lucidum which lack organelles/nuclei before becoming part of superficial layer of epidermis
6.) cells are dead in the stratum corneum. only flattened, scale-like, dehydrated cells that contain bundles of parallel keratin filaments remain
granules that insoluble in water and promote dehydration of the cell
keratohyalin
bundles of keratin proteins/filaments
tonofibrils
what is a melanocyte?
- a packet of a pigment called melanin (occurs when it accumulates in organelles)
- positions ebtween nucleus and surface of skin to protect DNA from damage
type of cells found in the stratum basale
tactile cells
what do tactile cells do?
- release chemicals that stimulate sensory nerve endings
cells found prominnently in the stratum spinosum
dendritic cells
what do dendritic cells do?
- immune cells in skin
- phagocytosis of pathogens that penetrate the superficial layers of epidermis
waxy, oily secretions
sebum from sebaceous glands
what are sebaceous glands?
- glands attached to hair follicles
- secrete sebum
- contain alveoli that burst when accumulates fat
what are sudoriferous glands?
- produce sweat/ watery solution
- 2 types: apocrine and merocrine glands
what are apocrine glands?
- coiled, tubular glands associated with hair folicules that secrete cloudy, viscous substances at adolescence
- apocrine glands become active in adolescence in axillary, aoerial and anagenital regions
what are eccrine/merocrine glands?
- glands that secrete clear sweat (water)
- not associated with hair; palms and soles
- important for thermoregulation and protection
what glands secrete cerumen?
ceremonious glands
what are ceremonious glands?
glands that secrete cerumen (ear wax) into external ear canal
glands that secrete milk
mammary glands
what are the two types of apocrine glands?
- ceremonious glands
- mammary glands
what is it called when a whole cell is secreted?
holocrine secretion
what is dermacidin?
a antimicrobial peptide secreted by merocrine sweat glands that attack bacteria on the skin
alveoli containing cells that spherical in shape
alveolar gland
melanoma
when malignant (cancer) cells form in melanocytes (cells that colour the skin)
role of melanocytes
produce melanin pigment which give skin its colour
role of tactile cells
helps to pick up touch
role of dendritic cells
immune cells in the skin
role of keratinocytes
helps with skin repair and protection
ABCDE of melanoma
A = asymmetry
B = border is not smooth
C = colour is not the same
D = diameter is large
E = evolving over time
what factors contribute to skin colour?
- determined by the type of melanin pigment present in epidermis (black, yellow-brown, or brown)
- determined by blood supply in dermis (red or blue)
compare the exocrine glands
- sebaceous glands secrete oily liquid which helps with waterproofing and inhibiting bacteria
- sudoriferous glands produce watery sweat help with body temperature
components of epidermis
- 4 cell types (keratinocytes, melanocytes, tactile cells and dendritic cells)
- 5 layers of skin (stratum basale, stratum spinosum, stratum granulosum, strum lucidum, stratum corneum)
components of dermis
- papillary layer (and papillary plexuses)
- reticular layer
components of hypodermis
- cutaneous plexuses
what is melanin?
a substance in your body that produces hair, eye and skin pigmentation
what are sweat glands?
sudoriferous glands
what is a melanosome?
- an organelle in which melanin (pigment) is synthesized
- produced by melanocytes
