Integumentary system

Question 1

What is the epidermis

Answer 1

• Epidermis is Avascular (Has no blood vessels)
• Outermost layer of the skin which forms primary Protective layer for the body (waterproof barrier) preventing water loss and maintaining Homeostatic balance
• Made up of three types of cells Keratinocytes, Melaninocytes and Lagerhans
• Produces new skin cells via the Stratum Basale Layer

Question 2

What are Keratinocytes

Answer 2

• Keratinocytes - Highly specialized cells which produce the protein keratin in order to form a protective barrier and stop foreign substances form entering the body.
• They also play a structural role in the skin forming tight bonds with other cells in order to maintain them in place by way of Dersmosomes
• Produced at the Stratum Basale Layer

Question 3

Melanocytes

Answer 3

• Melonynocytes produce the protein kown as melanin which is responsible for the skins pigment.
• Melanin protects against UV radiation

Question 4

What are Lagerhans

Answer 4

• Lagerhan cells are a form of dendretic cells (Antigen presenting cells) which perform phagocytoses (ingest and eliminate foreign substances) protecting against microorganisms and foreign substances.
• They are most common in the Stratum spinosum layer
• After performing phagocytoses the transport portions of the microbe they ingested to the cell membrane presenting it to other immune cells helpin to stimulate immune reactions

Question 5

What are Merkel cells

Answer 5

• Merkel cells are mechanoreceptors receptor which function as a sensory receptor fo touch
• Found in the stratum basal layer

Question 6

basement

Detail the Stratum basale layer

Answer 6

• Innermost (deepest) layer of the epidermis
• Also called Stratum Germinativum (as constantly germinating producing new cells)
• Contains Melaninocytes (skin pigment melanin producing) and Merkel Cells (mechanorecptors associated with touch)
• Each time mitosis occurs with a basal cell , one daughter cell is pushed up into the spinosum layer to begin specialization into a mature keratinocyte, with the other cell remaining to continue the germination process

Question 7

Spiny/prickly layer

Detail The stratum Spinosum layer

Answer 7

• Also reffered to as the Prickly or spiny layer. The Keratinocytes cells here have spiny/prickly intermidiate filamnets which span their cytosol attaching to desmosomesHence the name.
• Contains Largehans cells and
• Responsible for cytokin synthesis (protien that helps regulate immune response
• Thickest layyer of the epidermis

Question 8

granular layer

Detail the granulosum layer

Answer 8

• Thin layer, Consists of 3-5 cell layers
• Keratinisation process begins here (cells fill with keratin)
• As keratinocytes move through the epidermis they begin to flatten out with nuclei and organelles starting to disintergrate
• Keratinocytes become granular here accumulating kerathylin (help to form keratin) and lamellated granules
• Lamellated granules contain water resistant glycolipid and is a major factor in slowing water loss across the epidermis

Question 9

detail the stratum lucidium

Answer 9

• Appears translucent through light microscope
• Is made up of dead Keratinocytes (cells above the granulosum layer are to far away from the dermal capilaries and are cut of from vital nutrients by the glycolipids that coat their surface)
• Most commonly found on hairless parts of the body (soles/palms) and can only be seen on thick skin

Question 10

Detail the corneum layer

Answer 10

• 20-30 layers thick
• Contains flattened dead Keratinocytes known as corneocytes (cornified cells with no nucleus)
• Cornoecytes serve as hard protective layer against trauma and are eventually shed into the enviroment as dandruff or dust

Question 11

What is the importance of desmosomes connecting keratinocytes together

Answer 11

The skin is the outermost protective layer of the body so undergoes a lot of traumaand abrasion.
Desmosomes which are conecting junctions help hold the cell in the epidermis togther during this time of stress

Question 12

What is the dermo epidermal junction (basement membrane)

Answer 12

• Narrow multi layered undulating sturcture laying between the epidermis and the dermis providing cohession between the two layers
• Undulates between the epidermis and the dermis and is connected via ridges (rete ridges) Contains Cappillary loops supplying the epidermis with nutrients and oxygen

Question 13

What are the two layers of the dermis

Answer 13

• Lamina Lucida - Thinner layer directly underneath the epidermis basale layer
• Lamina Densa - Thicker layer in direct contact with the dermis

Question 14

What is the dermis

Answer 14

• Inner layer of the skin, much thicker than the epidermis
• Primary function is to sustain the epidermis by supplying it with nutrient saturated blood
• Protection - cushioning the deep structres from mechanical injury
• Playing an important role in wound healing
• Maid up of collagen and elastain

Question 15

What structures does the dermis contain

Answer 15

Blood vessles - supply nutrients and oxygen
Lymph vessles - supply skin with lymph mily like substance containg infection fightng cells
Hair folicles - sheath surroundign hair under the skin
**Sweat glands **- secrete sweat in order to regulate body temprature
Sebacious glands - secrete oil to keep skin supple and smooth
**Mast Cells **- part of the immune system important in inflammatory response
Fibroblasts - Secrete collagen for structural support

Question 16

What are the two layers of the dermis

Answer 16

Superficial Pappilary Layer and Recticular Layer

Question 17

Detail the charecteristics of the Papillary layer of the dermis

Answer 17

• Consissts of loosley woven tissue with interlacing collagen and elastic fibres as well as an abundacne of capillaries
• It’s looseness allows phyagcytes to wonder free and patrol for invading bacteria
• Dermal Pappilae (contain cappilary loops) increase the surface area of the dermis and indent the epidermis increasing the exchange of oxygen/nutrients and waste products between the two layers
• Dermal papilae also house other nerve endings and Meissners corpuscules (touch receptors)

Question 18

Detail the charecterisics of the reticular layer of the dermis

Answer 18

• Course irregularly arranged dense fibrous connective tissue
• The network of Blood vessels that nourish this layer are Cutaneus plexes and lie between this layer and the Hypodermis

Question 19

What is the Hypodermis Detail its features

Answer 19

• Also known as the subcutis or the subcutaneous layer, the hypodermis lies beneath the dermis
• Consists of mainly fat tissue
• Provides structure and support to the skin as well as insulation from the cold and shock absorption
• Contains blood vessels and nerves

Question 20

What are sweat glands

Answer 20

• Also known as sudoriferous glands they secrete sweat in order to regulate temprature
• This is done through the contraction of myoepethilial cells that contract when stimulated by nervous system
• This contraction forces sweat though the glands sweat duct to the surface of the skin

Question 21

What is an Eccrine sweat gland

Answer 21

• True sweat gland found over the entire body
• More abbundant then the Apocrine sweat glands
• Coiled tubular gland with the secretery part laying coiled in the dermis and the duct extending to the open por/channel at the surface of the skin

Question 22

What is a Apocrine Sweat gland

Answer 22

• Largely found in the armpits and genital areas
• Release there product by Exocytosis
• Larger than eccrine lying deeper in the dermis and even hypodermis
• Their ducts empty into the hair folicles
  secretion contains the same components as true sweat + fatty substances and protein