Epithelia & Skin Flashcards
Name the characteristics of the epithelial tissue?
Surface specialisations at apical/luminal pole of cells
Junctional complexes – little intercellular substance
Basement membrane underlying basal pole of cells
Regularity of cell arrangement
Diffusion of nutrients from underlying connective tissue layer
Name each type of epithelium, its location and function?
Simple squamous: - alveoli,
heart lining, BVs and lymph V
- allows material to pass via diffusion and secrete lubricating substance
Simple cuboidal: - in ducts and secretroy portions of glands (and kidney)
- secretes and absorbs
Simple columnar: - ciliated tissue in bronchi, uterus, GI and bladder
- absorbs and also secretes mucous and enzymes
Stratified squamous: - oesophagus, mouth and vagina
- protects against abrasion
Stratified cubodial: - in the glands
- protective tissue
Stratified columnar: male urethra and gland ducts
- secretes and protects
Psuedostratified columnar: - ciliated tissue lines the trachea and the resp tract
- secretes mucus, and cilia moves mucus
Transitional epithelium: - bladder, urethra and ureters
- allows urinary organs to expand and stretch
Where is stratified cubodial/columnar tissues found?
In large glands (sweat, salivary and mammary)
What are glands?
They are large massess of epithelium which secrete substances into or out of the body
What are the different sizes of glands?
Single cell such as goblet
Small such as sweat
Large such as the liver
Name and explain the 2 different types of glands?
Exocrine: have ducts, substance transported out
Endocrine: no ducts, straight into the bloodstream
What are the characteristics of the exocrine gland?
Secretory component:
- columar/cuboidal cells on base mem and myoeithelial
- cell with contracile filament to allow secretion
Duct: 2-layered
- cuboidal/columnar epithelium
Name the types of gland and duct structure, with examples?
Tubular: - simple (intestinal) and simple branched (gastric)
- compound (duodenal)
Alveolar: - simple (non) and simple branched (sebaceous)
- compound (mammary)
Tubuloalveolar (sweat) which is a mixture of both
Name and explain the modes of secretion from exocrine glands?
Eccrine/ Merocrine – secretion occurs by exocytosis
Eg: salivary glands
Apocrine – membrane bound vesicle leaves cell
Eg: mammary gland
Holocrine – cell membrane disintegrates to release secretion
Eg: sebaceous glands
Name the 3 major salivary glands and their location?
Parotid (parallel to the ear)
Sub-mandibular (beneath the mandible)
Sublingual (beneath the tongue)
What is the glandular structure and the secretion method of salivary glands?
Tubuloacinar and secretes via eccrine
What are the components of the saliva?
It is hypotonic and watery
Containing mucus, enzymes and antibodies
Name the key histological landmarks of the major 3 glands?
Sublingual: pale, mainly mucous and lower conc of nuclei
Parotid: dark, completely serous and high conc of nucelei
Submand: pale and dark, mix of mucous and serous
What is the role of the epithelium?
It lines body surfaces, and is a selective barrier between the external and internal environment
What is the epithelium attached to?
Basement membrane
Name the basic components of the skin?
Hair, sebaceous glands, nerves, capillaries, sweat gland, muscle, arteriole and fat
What are the 4 primary tissues of the skin?
Epithelium, CT, muscle and nerves
Name the skin cell
Keratinocyte
What hint can the skin portray?
Provides important external evidence of underlying systemic conditions
What is the function of the epidermis?
Prevents water loss by evaporation
What is the function of the dermis?
Reduces risk of external injury
Maintains blood flow to epidermis
Permits body cooling
What is the function of the skin as a whole?
Immune surveillance
UV protection
Energy storage
Sensory information
What is the structure of the skin?
2 layers:
Epidermis - epithelium and forms boundary between internal and external (keratin layer)
Dermis - CT and gives structural strength
Hypodermis - fatty CT layer and anchors skin to underlying structure
Name each epidermal cell and their function?
Keratinocytes: - contain keratin (S), hard and resist abrasion, waterproof and constantly divide for self-regen
Melanocytes: - pigmentation
Langerhans: - immune surveilliance
Merkel: - touch receptors
Name the epidermal layers?
Top to bottom: Stratum corneum Lucidum Granulosim Spinosum Basale Dermis
ABCD
Asymmtery
Border
Colour
Diameter
What is keratinisation?
Organic process whereby
keratin is deposited in cells
and these become horny
as in dead skin, nails, hair
Psoriasis = autoimmune disorder affecting keratinisation
What are the different types of epidermal thickness and where can it be located?
Thick: - hands and feet
Thin: - abdominal
Thin skin likely to have hair
What are the layers of the dermis?
Papillary
Reticular
What is the papillary layer
Loose CT and cellular
What is the reticular layer?
Denise irregular CT and fibrous
What changes our skin colour?
Melanin (melanocytes)
Melanin protects against UV
What is the role of hair?
Vanity and responsive to cold air
Explain the origin of the hair follicles?
From epidermis in utero Downgrowth of epithelial cells Invasion of knot of blood vessels Growth of hair Continuity with layers of epidermis
(Grow down into the dermis, to form follicle and then hair grows up)
What are the characteristics of the hair follicle?
Hair and sheath
Arrector pili muscles
Attached to follicle root and base epidermis
Follicle at angle
Hair straightens when muscle contracts
Sebaceous glands
Between follicle and arrector pili muscle
Secretes sebum
Function uncertain
Eccrine sweat glands? overview
Simple tubular gland Located in dermus Coiled Spiral channel in epidermis Watery secretion and thermoreg
Ways of thermoregulation?
Sweat
BV dilation
Hair
The skin as a sense organ?
Numerous sensory nerve endings:
Meissner’s corpuscles - light touch - fingertips Paccinian corpuscles - vibration & pressure Pain receptors Thermoreceptors
Explain the process of skin repair?
After trauma, a blood clot forms and forms a scar
Underneath granulation tissue forms, this creates an inflammatory reaction that allows the infiltration into the wound allowing restoration
