Lecture 16: Integumentary System Flashcards
What are Membranes composed of?
Epithelium (epidermis) and connective tissue (dermis)
What are the 4 types of membranes?
Mucous, Serous, Cutaneous, Synovial
Which Membrane makes up skin?
Cutaneous membrane
What is the Epidermis of a Membrane?
Epithelium
What tissue is the Demis of a membrane made of?
Connective tissue
What is the Largest organ system?
The skin
How much of the body mass does skin account for?
15%
Why is skin a good indicator of health?
Because it is very accessible
What are the accessory structures of the Integumentary system?
Exocrine glands, Hair and Nails
How does the integumentary system respond directly to local influences?
Through calluses and scar tissue
What are Exocrine glands?
Glands that put the secretion via a duct onto the environment of the epithelium
What are Endocrine glands?
Glands that secrete directly into the bloodstream
What are the Major functions of the Integumentary System?
- Barrier
- Thermoregulation
- Sensation
- Metabolic functions
- Socials functions
How does Skin act as a barrier?
It bears the brunt of most injuries and recovers better than any other organ system
How does skin Thermoregulate?
- Constriction and dilation of blood vessels
* Sweating
What are the Metabolic functions of Skin?
- Vitamin D synthesis with UV rays
* Storage of energy as subcutaneous fat
What social functions does Skin have?
Identity for all animals
What is the function of Epithelium in the skin?
Covers the surface and forms the boundary from the outside world
What is the function of connective tissue in the skin?
- Supports epithelial tissue
* Provides strength and resiliency
What is the function of Muscle in the skin?
- Controls the diameter of blood vessels
* Adjusts hair position
What is the function of Nerves in the skin?
- Controls the smooth muscle in the CT
- Generates sensation
- Stimulates exocrine glands
How many layers does Epithelium have?
Multiple layers
How many layers does the Epidermis have?
5
What are the layers of the Epidermis from Bottom to Top?
Stratum Basale (germinativum) Stratum Spinosum Stratum Granulosum Stratum Lucidum Stratum Corneum
What is the thickest layer of the Epidermis?
Stratum Corneum
What do Keratinized Squamous cells produce in the Skin?
Keratin
What is Keratin?
A tough protein that helps epidermis with its protective properties
What is the Bottom layer of the Epidermis called?
Stratum Germinativum (Basal Layer)
How many types of cells is in the Stratum Germinativum layer?
3 types of cells
What is the deepest layer of the Stratum Germinativum composed of?
Large Basal Stem Cells
What do the Stem Cells in the Stratum Germinativum do?
They divide to give rise to new keratinocytes to replace the dead ones that flake off
What are the most abundant epithelial cells in the epidermis?
Keratinocytes
What do Keratinocytes do?
Synthesize Keratin
Which layer of the EPidermis forms the Basal Lamina?
Stratum Germinativum
What does the Basal Lamina ensure?
It ensures that the epithelium is firmly attached to the basal membrane with connective tissue
What two types of cells are found in Stratum Germinativum?
Merkel (tactile) cells and Melanocytes
Of the cell types found in the Stratum Germinativum which one is less common?
Merkel (tactile) cells
Where are Merkel (tactile) cells more abundant?
Where skin has no hair (fingertips, lips)
What are Merkel (tactile) cells important for?
Touch sensation
When are Merkel (tactile) cells called Tactile (Merkel) discs?
When it is connected with a dermal nerve fibre
What layer of the Epidermis are Melanocytes found?
Stratum Germinativum
What do the Processes on Melanocytes do?
Insert themselves between Keratinocytes
What do Melanin granules produced by Melanocytes do when in the presence of Keratinocytes?
Melanin granules are phagocytized by Keratinocytes and form an umbrella over the nucleus to prevent DNA from UV radiation
What does the number of Melanocyte cells depend on?
The region of the body (ex. Palm of hand) but NOT by people
What determines skin tone?
The activity of Melanocytes and how many melanin granules they have, not the amount of melanocytes
What is another name for the Stratum Spinosum layer of the Epidermis?
Spiny Layer
What cells are the Stratum Spinosum composed of?
Several layers of keratinocytes and Langerhans (dendritic) cells
What do the Keratinocytes in the Stratum Spinosum contain?
A bundle of Tonofilaments
What are Tonofilaments and what do they do?
Keratin protein filaments that cause the cell to flatten and reach for neighbouring cells
What attach Keratinocytes together?
Desmosomes
What occurs in the Stratum Spinosum?
Keratinocytes flatten and reach for each other and desmosomes attach keratinocytes together
In what layer are Langerhans (dendritic) cells found?
The Stratum Spinosum
What forms Desmosomes?
Tonofilaments
What are Langerhans (dendritic) cells?
A type of macrophage that originates from bone marrow and migrate to epidermis
Where do Langerhans (dendritic) cells originate?
The bone marrow
What type of cells are Langerhans (dendritic) cells?
Macrophages
What do Langerhans (dendritic) cells do?
Capture pathogens and offer them to the immune system
How do Langerhans (dendritic) cells play an important role?
They are important for the immune response if pathogens penetrate the superficial layer
Where are Langerhans cells found in great numbers?
Oral cavity, esophagus, anal canal, and vaginal canal
What is the Stratum Granulosum composed of?
2-5 layers of flat keratinocytes
What does the Stratum granulosum produce?
Large quantities of keratohyalin granules
What do Keratinocytes in the Stratum granulosum secrete?
Lipid filled membrane coating vesicles that fill spaces between keratinocytes and form water-repellent sealant
What do the lipid-filled membranes secreted by keratinocytes in the Stratum Granulosum do?
Fill spaces between keratinocytes and form water-repellent sealant
What does the Sealant secreted by the keratinocytes of the Stratum Granulosum ultimately do?
Prevents cell diffusion that leads to keratinocyte death above the granular layer
Where in the body would you find excess production of the sealant produced?
In thicker skin like sole of foot and palm of hand
What does excess production of the sealant lead to?
Calluses
What is Keratinization?
Accumulation of keratin from deep to superficial layer
In what parts of the body is the Stratum Lucidum layer found?
In areas with thick skin and no hair like the palm of the hands and the bottoms of the feet
What does the Stratum Lucidum (clear layer) contain?
Large amounts of keratin and thickened plasma membranes. The cells have no nucleus or organelles
What is the most superficial layer of the skin?
The Stratum Corneum
What is the Stratum Corneum composed of?
Multiple layers of flattened, dead, interlocking keratinocytes (up to 30 layers)
What is the shedding of the Stratum Corneum known as?
Dander
What is Dandruff?
Clumps of dander from the Stratum Corneum stuck together with oil from the scalp
What is the main function of the Stratum Corneum?
Protection against abrasion and microbial invasion
How long does it take to go from the Basal layer to the Stratum Corneum?
30-40 days
What does the peak and valley interface between the dermis and epidermis allow for?
A tight bond between different layers of skin that can resist shearing stress
What are the two components of the Interface between the dermis and epidermis?
The Epidermal ridge and the Dermal Papilla
Which areas have a tall Dermal Papillae and why?
Sensitive areas (lips, genitals) to allow nerve fibers and capillaries closer to the surface
Where is the Interface very unique?
In the fingertips
What are the two layers of the Dermis?
The Papillary layer and the Reticular layer
Which layer of the Dermis is the connection to the epidermis?
The Papillary layer
What is the Papillary layer of the dermis composed of?
Areolar connective tissues (loose CT) that contains nerve ending and many capillaries
What does the Papillary layer of the dermis contact with the epidermis vary with?
The area of the body
What kind of tissue is the Papillary layer of the dermis composed of?
Areolar connective tissue (loose CT)
What kind of tissues is the Reticular layer of the Dermis composed of?
Dense irregular connective tissue, collagen bundles and elastic fibres
What does the Reticular layer of the dermis allow for in the skin?
Extensibility and elasticity to skin
What sits in the reticular layer of dermis?
Blood vessels, nerves, lymphatics, hair follicles, glands, adipocytes between fibre bundles, attachment to skeletal muscles of the face
What do Collagen fibers of the dermis align themselves with?
the areas of natural tension
What are Stretch Marks?
Scarring due to internal damage of collagen bundles and stretching of vasculature. Red = tearing of vessels, white = lack of vasculature after tearing
What is another name for the Hypodermis?
Superficial fascia or subcutaneous tissue
What does the Hypodermis do?
Stabilizes the position of skin relative to underlying tissues
What kind of tissue is the Hypodermis made of?
Loose connective tissue
What does the Loose Connective tissue of Hypodermis store?
Fat
What does the Fat of the Hypodermis do?
Pads the body, serves as energy reservoir, provides thermal insulation
What 3 Pigments are responsible for skin tone?
Melanin, Hemoglobin, Carotene
What colors is melanin responsible and which layer of skin is it found in?
Yellow/tan/brown/black and in Stratum basale and spinosum
What stimulates melanin synthesis?
UV stimulus
What is Hemoglobin?
The red pigment found in dermal blood vessels that gives skin a pink hue
What color does Carotene give to the skin and where is it found?
Yellow/orange in stratum corneum and hypodermis
What color is Cyanosis and what does it demonstrate?
Blue and lack of O2
What is erythema and what color is it?
Pooling of RBCs and Red
What color is Jaundice and what does it signify?
Yellow and excess bilirubin
What does Paleness signify?
Low blood flow
What color are hematomas and what do they signify?
Bruising - clotted blood, purple
What can destroy skin?
Excess UV radiation, heat, electricity, chemicals
What does Tissue Damage do to skin?
Destroys skins important contribution to homeostasis: protection against microbial invasion, dehydration, regulation of body temperature, alters composition of dermis and forms premature wrinkling
Which layer of the skin is affected in a 1st degree burn?
The epidermis
What are the characteristics of 1st degree burns?
Mild pain, erythema, flaking
Which layers of the skin are affected in 2nd degeee burns?
Epidermis and some dermis
What are the characteristics of 2nd degree burns?
Blister formation, edema, redness, pain and scarring after 3-4 weeks
Which layers are involved in third degree burns?
All layers through to the hypodermis
What are the characteristics of 3rd degree burns?
Skin functions lost, numb (no sensory ending), granulation forms, skin grafting may be needed
What are the 3 types of glands?
Merocrine, Apocrine, Holocrine
What is an example of a Merocrine gland?
A sweat gland
What is an example of an Apocrine gland?
Mammary gland
What is an example of a Holocrine gland?
Sebaceous gland
How do Merocrine glands secrete?
Normal exocytosis
How do Apocrine glands secrete?
The Apical surface is pinched off
How do Holocrine glands secrete?
The release the entire cell
What are the 4 types of Exocrine Cutaneous Glands?
- Sweat glands
- Sebaceous glands
- Ceruminous glands
- Mammary glands
What do Sweat glands secrete?
Water and Electrolytes
What are the two types secretion that Sweat Glands use?
Merocrine secretion (most common) & Apocrine secretion (puberty)
What do Sebaceous glands secrete?
Oily lipid (sebum) that coats hair and skin surface
What do Ceruminous glands secrete and through what type of secretion?
Earwax through apocrine secretion
What do Mammary glands secrete?
Breast milk
Where are Apocrine Sweat Glands found?
Axilla, groin, breast areola, male facial hair
What are Apocrine sweat glands strongly influenced by?
Hormones
What produces odor in Apocrine sweat glands?
Bacteria
When are Apocrine sweat glands activated?
During emotional stress and arousal
What do Merocrine sweat glands secrete?
Water and electrolytes (regular sweat)
Where are Merocrine sweat glands the most numerous?
On the Palms, soles, and forehead
What do Merocrine sweat glands regulate?
Body temperature
What are Merocrine sweat glands controlled by?
The sympathetic nervous system
What are Mammary glands regulated by?
Interaction of sexula and pituitary hormones
What does the Sebum from Holocrine glands inhibit?
Bacterial growth
What do Sebaceous glands usually open onto?
A hair follicle but some grow directly onto skin
What do Sebaceous glands do?
Keep hair and skin from becoming dry, brittle, and cracked
What causes Acne?
Inflammation of sebaceous glands and follicles due to blocked ducts and bacterial infection
What are Hair and Nails composed of?
Dead keratinized cells with HARD keratin
What is a Pilus (pili)?
A slender filament of keratinized cells that grow from a tube (follicle)
What surfaces does hair not cover?
Hands, feet, lips, nipples and genitals
How does hair differ from person to person?
Texture and pigmentation
What are the 3 types of hair?
Lanugo
Vellus
Terminal hair
Describe Lanugo
Fine hair from Foetus to birth
Describe Vellus
Most hair on body surfaces
Describe Terminal Hair
Longer, coarser and pigmented
What is Hair important for?
UV protection and thermal insulation for head, particle filtration for eyes and nose, touch sensation for the body
What are the 3 parts of the hair follicle?
Shaft, Root, Bulb
What two sheaths do Hair follicles have?
Epithelial root sheath and a CT root Sheath
Which sheath are Hair Neve fibers found?
The Epithelial root sheath
What do Arrector Pili muscle in hair follicles do?
Make the hair stand up to trap heat and is stimulated by the sympathetic nervous system
Which part of the hair follicle is above the skin?
The shaft
Which part of the hair is in follicle?
The root
Where does the Bulb of hair originate?
The Dermis
What is the Sole source of nutrition for the hair?
The papilla that has blood vessels
What changes the curl of the hair?
The cross sectional shape
What changes the texture of hair?
Keratin
What is color of hair determined by?
Pigment in the cells of the cortex
What are the 3 layers of hair from inside to outside?
Medulla, Cortex, Cuticle
What is in the Cortex of hair made out of?
Densely packed Keratinized cells
What is the Cuticle of hair?
Single layer of scaly cells that resist pulling on hair
What are the 3 stages of hair growth and hair loss?
Growth stage, Regression stage, Resting stage
What occurs in the Growth stage of hair?
Stem cells from bulge multiply and are added to the root as they push upwards they keratinized and die
How long does the growth stage take?
3-6 years
What occurs in the regression stage?
Cells stop dividing, follicle trophies and hair stops growing
How long does the regression stage take?
2-3 weeks
What occurs in the resting stage?
Hair loses it anchorage and old hair root falls out/push out of the follicle and new division occurs
How long does the resting stage take?
3 months
What stage is the majority of hair cells in?
Growth stage (85%)
What is the white part at the base of nail known as?
Eponychium (cuticle)
What is the part of the nail that we cut known as?
The free edge
What is the little piece of skin under the part of the nail that we cut known as?
Hyponychium
What is the part where the outside meets the nail known as?
The Eponychium
Why are nails pink?
Because of oxygen in the dermal layer
What is the Cuticle made of?
A band of epidermis
What is the nail made of?
Hard keratin
