Skin and Mucous Membrane Flashcards
What are the functions of the skin?
Protection
Thermoregulation
Water regulation
Sensation
Absorption
Storage and synthesis
What are the basic parts of the skin?
Epidermis, dermis, subcutaneous layer
What are the associated skin structures?
nails
sweat glands
sebaceous glands
hair follicles
What is the structure of the epidermis?
Epidermis is made from stratified squamous epithelium which is organised in consistent structure. The cells are flat
No blood vessels in the middle of the epithelium. Only directly underneath the epithelium
Where does the epidermis get oxygen and nutrients?
It gets them from the deeper tissue, the dermis
They are close enough to the blood supply in the dermis to get the adequate oxygen and nutrients for survival
Describe the layers of the epidermis
Stratum basale is the basal layer where cells are synthesised
Stratum spinosum has lots of desmosomes which helps cells attach to each other. The cells shrink causing the desmosomes to become clear and appear prickly
Stratum granulosum cells start to lose their nuclei and cytoplasmic organelles
Stratum lucidum (only in thick skin) no nuclei here, transparent layer
Straum corneum is layers of dead cells which are reduced to flattened squames filled with densely packed keratin, squames on the surface of the layer flake off
Why do cells of the stratum spinosum look like prickles?
Cells shrink slightly during fixation but the desmosomes from neighboring cells remain tightly bound to each other so these connections look like prickles
What are the cells of the epidermis?
Keratinocytes
Langerhans cells
Merkel cells
Melanocytes
What are keratinocytes?
They are also called prickle cells
Most common cell
Make up the majority of cells in the epidermis
What are langerhans cells?
Antigen presenting cells
Present in all layers of the epidermis & in the upper dermis around small blood vessels
What are merkel cells?
Granular basal epidermal cells
Attached to a free nerve ending which finishes at the basal layer where the sensory nerve ending is
Mostly found in thick skin
What are melanocytes?
Produce melanin - has protective function against UV
Present in basal cell layer and the melanin is taken out by the epithelial cells
Present in oral cavity but not active
What causes pigmentation in skin?
activity of melanocytes, not number of them
What is the difference between thick and thin skin?
In thick skin stratum lucidum is present and has more keratin in the stratum corneum. There are also more layers in the epithelium.
In thin skin there is no stratum lucidum and generally layers are thinner
What is the dermis?
a strong connective tissue layer underneath the epidermis
What cells does the dermis contain?
Fibroblasts
Macrophages present in case of infection
Fat cells (adipycytes)
Nerve endings
Blood vessels
Gands
Smooth muscle
Lymphatics
Hair follicles
What is the layer of dermis directly underneath the epidermis?
Papillary layer is right underneath the epidermis. It projects into epidermal ridges filling the gaps. Richly supplied with capillaries and nerve endings.
What is the reticular layer of the dermis?
dense connective tissue and fibre components
What is the subcutaneous layer of skin?
deepest layer of skin for insulation, shock absorption, made from adipose (fat) cells
What is acne?
Acne is when there is an overproduction of sebum from glands and therefore infection occurs. A change in hormones can cause this, diet, smoking.
What is psoriasis?
Psoriasis is an autoimmune disease. Mucus membranes are not affected, only skin primarily. Rapid turnover of epithelial cells, only 7 days instead of 20 days. Thicker epidermis quick turnover causes inflammation.
What is pemphigus?
Autoimmune condition where desmoglein is attacked by auto antibodies
Causes very painful raw areas
Coritsone can bring condition to remission
What is vitiligo?
Vitiligo is a autoimmune condition. Auto antibodies attack the melanocytes or the melanocyte creating hormone.
What is mucous membrane?
specialised epithelial lining which produces lubricating fluid containing the protein mucin
What are the functions of mucous membranes and where are they found?
Protective -oral cavity, oesophagus, nasal cavity
Secretory -stomach
Absorptive -small intestine
What are the layers?
epithelium
lamina propria (mucousae)
What is the epithelium cells made from?
many stratified squamous types
What is lamina propria?
Lamino propria is a loose areolar layer
What is the trachea composed of?
goblet cells, ciliated psedoustratified columnar epithelium. elastic, fibre rich lamina propria
Does the oesophagus have mucus glands?
yes
What are the functions of the oral mucousa?
secretion, protective, sensation, permeability and absorption
What epithelium is found in oral mucousa?
stratified squamous
Where is the epithelium keratinised in the oral mucousa?
Hard palate masticatory has a thick layer of keratin. They are paler are they have keratin
Where is the epithelium specialised?
Gustatory is where taste buds are -tongue
What is cystic fibrosis?
Mucus becomes very thick and stagnated. Bodies only get mucus secretions and cilia helps get it out
Pathogens can growth in the mucus and cause infection
What are the 4 layers of the GI tract?
mucosa (epithelium, lamina propria, and muscular mucosae)
submucosa
muscularis propria (inner circular muscle layer, outer longitudinal muscle layer)
serosa/adventita
What are the 4 main layers in the respiratory tract?
respiratory mucosa, (epithelium and supporting lamina propria)
submucosa
cartilage and/or muscular layer
adventitia.
What cells are present in lamina propria?
fibroblasts, macrophages
