Skin and Mucous Membranes Flashcards
what are the different functions of skin
- protection
- thermoregulation
- water regulation
- sensation
- absorption
- storage and synthesis
what is another term used to describe skin and mucous membranes
integumentary system
what are examples of what the skin can protect the body from
pathogens
UV
injury
how does skin carry out thermoregulation
via blood vessels, sweat and hair
how does skin carry out water regulation
by preventing moisture loss
what sensations is the skin responsible for
touch, temperature and pain
what are examples of molecules that the skin can store
vitamin D, fat, glucose, water and salt
what are the different layers to skin
- epidermis
- dermis
- subcutaneous layer
what are som e associated structures of the skin
nails, sweat glands, sebaceous glands, and hair follicles
what is the epidermis
the epithelium - the outer layer
what is the subcutaneous layer
“hypo-dermis” which lies underneath the dermis
what is the structure of the epidermis
a stratified squamous epithelium;
- layered, flat, scale like cells
- basic tissue type
what is the tissue type found within the epidermis
basic
are there blood vessels within the epidermis
no
how many layers are there in the epidermis
4-5
what makes up the bulk of the epidermis
stratum spinosum
what are the names of the different layers within the epidermis
- stratum corneum
- straum lucisum
- stratum granulosum
- stratum spinosom
- stratum basale
- dermis
what does the stratum granulosum accumulate
granules
what is the stratum lucidum
a clear cell layer found only in thick skin, like on the heels of feet
what cells of the epidermis are the sensory receptors
merkel cells
what cells make up the most of the epidermis
the keratinocytes - 95%
what are langerhan cells responsible for within the epidermis
antigen presenting cells - takes foreign bodies and presents them to the immune system - particularly t lymphocytes
what are melanocytes responsible for within the epidermis
production of melanin
where are merkel cells found in the epidermis
the basal cell layer
where are langerhans cells found in the epidermis
the stratum spinosum
where are melanocytes found in the epidermis
the basal layer - just above the dermis
where are keratinocytes found within the epidermis
the stratum spinosum
how do cells attach to each other in epithelium
desmosomes and hemidesmosomes
what are desmosomes made up of
various proteins including keratin and desmoglein
do skin and mucosa have the same structures
yes
where are desmosomes found
between epithelial cells
where do hemidesmosomes act
between basal cells and basement lamina
what type of skin is stratum lucidum found
thick
what are the differences between thick and thin skin
thick skin contains stratum lucidum, has a thicker stratum corneum - such as on the palms of hands and soles of feet.
thin skin has no stratum lucidum, all the strata are thinner, and it covers the rest of the body
what is the dermis
a strong, flexible connective tissue layer rich in collagen and elastic fibres
what does the dermis contain
- fibroblasts
- macrophages
- a few adipocytes
- nerve endings
- blood vessels
- glands
- smooth muscle
- lymphatics
- hair follicles
how many layers make up the dermis
2
what are the two layers of the dermis called
the papillary layer and the reticular layer
what is the papillary layer of the dermis
this projects into intervals between epidermal ridges. it is richly supplied with capillaries and nerve endings
what is the reticular layer of the epidermis
a dense connective tissue with fibre components
what is psoriasis
an autoimmune disease that causes an accelerated turnover of epithelial cells
does psoriasis affect the oral cavity
in extremely rare cases, yes
what is pemphigus
autoimmune skin condition whereby the host antibodies target the protein that forms desmosomes known as desmoglein.
the antibodies attach to the desmoglein and weaken attachment of epithelial cells.
the spaces between the cells fill with fluid, leading to blisters and ulcerations on the patient.
leads to impaired water regulation of the skin. can affect the oral cavity if there are blisters within the mouth.
what is vitiligo
loss of skin pigment - believed to be an autoimmune disease. does not affect the oral cavity
what are the different forms of skin cancer
squamous cell carcinoma
basal cell carcinoma
malignant melanoma
how can tumours form on the skin
when keratinocytes in the epidermis grow out of control
where can skin cancer occur
any part of the body, although usually on areas that are exposed to the sun or previous damages. appear as scaly or crusty areas of skin with a red and inglamed base
how can malignant melanomia be preventing
avoiding over exposure to the sun
what are the risk factors for melinoma
- uv radiation
- moles
- fair skin with freckles
- sunburn
- family history
what are moles
collections of melanocytes
what are mucous membranes
specialised epithelial lining with produces a lubricating fluid containing mucin which traps microbes and dirt particles and protects any body structure with is continuous with the external environment
should all mucous membranes always be wet
yes
what are the functions of mucous membranes
- protection
- secretion
- absorption
- sensation
what do mucous membranes protect
body structures exposed to the external environment such as the oral cavity, nasal cavity and oesophagus
where are secretoty mucous membranes found
stomach
where are absorbative mucous membranes found
entire small intestine
what is the basic structure of mucous membranes
two layers - the epithelium and lamina propria, or mucosae
what is the lamina propria
also known as the mucosae, it is a supportive areolar layer found immediately beneath the mucosal epithelium and its basement membrane
what are areolar layers
loose fibrous connective tissue
what cells are found within the lamina propria
fibroblasts, immune cells and almost no adipocytes
what is found in the extracellular matrix of the lamino propria mucosae
collagen and elastin fibres
what constitutes mucosa
the epithelium and the laminoa propria mucosae
what is the trachea composed of
a ciliate, pseudostratified epithelium and an elastic, fibre rich lamina propria
what are the functions of the oral mucosa
- protection
- sensation
- secretion
- permeability
how does oral mucosa contribute to sensation
it contains touch, taste, and pain
what is permeability and absorption utilised in
drug delivery
what happens to the oral mucosa as people age
it thins out and the barrier function is diminished
what does the oral mucosa contain that aids with secretion
minor salivary glands which maintain a moist surface essential for oral health and function
what is lichen planus
autoimmune condition that affects both skin and the mucous membranes
what is cystic fibrosis
an inherited autosomal recessibe disease of ion transport
caused by an abnormality in chloride channel protein
can cause abnormal viscous secretions
affects the epithelial lining of the respiratory, gastrointestinal and reproductive tracts
can also affect salivary glands
what are the three main types of oral mucosa
lining mucosa
masticatory mucosa
specialised mucosa
how is the oral mucosa divided into its different types
function and histology
what is the lining mucosa
this is the non keratinised stratified squamous epithelium that is found almost everywhere in the oral cavity, including the alveolar mucosa, and the lining between the buccal and labial mucosae
what is the masticatory mucosa
the keratinised stratified squamous epithelium found on the dorsum of the tongue, the hard palate, and the attached gingiva
what is the gustatory mucosa
the mucosa found on the dorsum of the tongue, that contains papillae and taste buds
what is another name for the gustatory mucosa
the specialised mucosa
what is the lamina propria
the thin layer of connective tissue that forms part of the moist linings known as mucous membranes which line various tubes in the body
what form of epithelium is the oral mucosa
stratified squamous
what layer of skin is thicker in thick skin than in thin skin
the epidermis
give a breakdown on the features found in thick skin
no hair follicles
sweat glands
pacinian corpuscles
what are pacinian corpuscles
these are sensory receptors that sense course touch, pressure and high frequencing vibrations
they have concentric lamellae of modified schwann cells, and an outer capsule of connective tissue
describe the structure of hair follicles
they have a hair shaft composed of dead keratinocytes, and a bulb that that contains specialised basal epithelial cells that produce the keratinocytes that eventually become the hair shaft as well as the inner root sheath
how thick is the thin epidermis
1-2mm
what are the layers to the epidermis
- corneum
- lucidum
- granulosum
- spinosum
- basalis
describe the corneum
the outermost layer of the epidermis composed of dead keratinocytes filled with keratin filament. at this layer, the desmosomes joining the keratinocytes together gradually break down and the cells desquamate from the surface
what does desquamate mean
they shed away
what are the three layers to the skin
the epidermis, the dermis and the hypodemis
describe the lucidum
this is only seen in very thick skin. and is a lighter colour. usually 2-3 cell layers thick. at this layer, the keratinocytes have lost their nuclei and organelles
describe the granulosum
this is 3-5 cell layers thick and is composed of flattened cells
describe the spinosum layer of the epidermis
synthesises keratin
describe the basalis layer of the epidermis
this is a single layer of cuboidal or columnar germ cells attached to the basement membrane
describe the cells of the epidermis
all of the skin cells of the epidermis are keratinocytes except for the germ cells on the basalis layer.
they are attached to each other via desmosomes, and through their development they are pushed to the surface by the newly formed cells below. they gradually become flatter in appearance, where they are found on the corneum as they are dead
describe the junction between the dermis and the epidermis
it is irregular, and contains projections into the dermal layer known as dermal papillae. the dermal papillae contain mechanoreceptors known as meissner’s corpuscles which are sensory receptors that respond to physical pressure or movement of the skin
why are dermal papillae useful
they provide adhesion between the epidermis and the dermis.
where are hair follicles located
in the dermis
what does the hypodermis consist of
adipose tissue and connective tissue
what is another name for the skin
integument
what are the layers of the dermis
the papillary layer and the reticular layer
describe the papillary layer of the dermis
this is the region where the dental papillae are located. also contain meissners corpuscles
describe the reticular layer of the dermis
this is a layer of dense irregular connective tissue that contains sweat glands and sensory receptors called pacinian corpuscles
describe the sweat glands located in the dermis of the skin
they are eccrine sweat glands that are structured as coiled tubular glands and ducts with a central lumen. the walls of these glands consist of stratified cuboidal epithelium. the ducts stain dark purple
what are sebaceous glands
these produce and secrete oily and highly lipid fluid called sebum. the cells are called sebocytes. and the cytoplasm is full of fat droplets
what are the main functions of mucous membranes
protection and lubrication
what is the principle constituent of mucous
mucin
what are mucous membranes
the membrane lining body cavities
describe the structure of mucous membranes
surface layer of epithelial cells over a deeper layer of connective tissue
the epithelial layer can be stratified squamous or simple columnar epithelium
