Tissue Membranes Flashcards
Tissue Membranes
MEMBRANES ARE FLAT SHEETS OF PLIABLE TISSUE THAT COVER OR LINE A PART OF THE BODY
EPITHELIAL MEMBRANES
Consist of;
A) Epithelial cell layer
B) Lamina Propria (thin underlying layer of loose connective tissue layer)
EPITHELIAL MEMBRANES:
1) MUCOUS
- Lines body cavities
that open directly to the exterior - Digestive, respiratory, reproductive and parts
of urinary tract - Secrete mucous
- Epithelial layer- role in defense, secretion and absorption
- Rich in tight junctions and goblet cells
Epithelial layer: VARIOUS cells e.g. in large airways pseudo-
stratified ciliated columnar, SI non-ciliated simple columnar - Lamina Propria: AREOLAR connective tissue
CLINICAL SIGNIFICANCE MUCOUS
MEMBRANE
- Catarrh
- Inflammation of the
mucous membranes - Excessive & thickened
mucous - Symptom of common
cold, viruses, chesty
cough etc.
EPITHELIAL MEMBRANES 2) SEROUS
- Lines cavities that
DO NOT open directly
to the exterior - Covers organs that lie
within a cavity - Pericardial cavity
- Pleural cavity
- Peritoneal cavity
- Epithelial layer:
- Simple squamous epithelium
(mesothelium) - Secretes serous fluid
- Connective tissue: Areolar
*2 layers;
1)Parietal layer- attached to the cavity wall
2)Visceral layer- covers and attached to the
organs inside the cavity
CLINICAL SIGNIFICANCE: SEROUS
MEMBRANES
- Pericarditis
- Inflammation of the
pericardium - Accumulation of
pericardial fluid or
blood - Can occur as a result
of viral infections,
influenza & HIV
EPITHELIAL MEMBRANE: CUTANEOUS
- Largest organ (surface area and weight)
- 2 square meters &16% total body weight
- Epidermis- Superficial & Dermis- Deep
- Epidermis Keratinised squamous epithelial tissue
- Dermis
- Areolar & dense irregular connective tissue
- Subcutaneous
- Not officially part of skin
- Areolar/adipose
connective tissue
CUTANEOUS MEMBRANES:
EPIDERMIS
Epidermis
- Keratinized stratified
squamous epithelium
- 4 main cell types
- Keratinocytes-
keratin production - Melanocytes- melanin production
- Langerhans cells- immune response
- Merkel cells- touch receptors
CUTANEOUS MEMBRANES- Layers
- 4 layers (thin)
- Stratum corneum
- Stratum granulosum
- Stratum spinosum
- Stratum basale
- 5 layers (thick)
- Stratum lucidum
(between granulosum
and corneum)
Stratum basale
(germinativum)
-Single row keratinocytes with
scatters of other cells
- Cytoskeleton of
tonofilaments (intermediate
filaments) which attach to
desmosomes &
hemidesmosomes
* Essential for regeneration
Stratum spinosum
- Strength & flexibility
- Keratinocytes,
Langerhans cells and
melanocytes - 8 to 10 cell layers held
together by
desmosomes
Stratum granulosum
- Transitional zone
- 3-5 layers of flat apoptotic
cells - Lamellar granules- release
lipid rich secretion - Keratohyalin containing
granules- convert
tonofilaments into keratin
Stratum lucidum
- 5th layer of ‘thick’ skin
- Fingers tips, palms of
the hands, and soles
of the feet. - 3-5 layers of clear, flat,
dead cells - Keratin rich
Stratum corneum
- 25-30 layers of flat,
dead, keratinized cells
surrounded by lipids - Continuously shed
- Barrier to light, heat,
water, chemicals &
bacteria - Lamellar granules=
water-repellent
CUTANEOUS MEMBRANES-
Skin Grafts- CLINICAL SIGNIFICANCE
- Autograft- same
individual - Autologous- patients
own cultured
keratinocytes - Apligraft/Transite
CUTANEOUS MEMBRANES-
CLINICAL SIGNIFICANCE
Psoriasis
- Keratinocytes in
stratum basale
divide faster and
are shed prematurely
- Immature
keratinocytes make
abnormal keratin
- Scaly skin
CUTANEOUS MEMBRANES
CLINICAL SIGNIFICANCE- Stratum corneum
Friction will cause this
layer to increase in
depth with the
formation of a callus
CUTANEOUS MEMBRANE- DERMIS
- Mainly connective
tissue - Blood vessels,
nerves,
glands and hair
follicles - Papillary region
- Areolar connective
tissue - Dermal papillae
increase SA - Capillary loops,
Meissner corpuscles &
free nerve endings - Reticular region
- Dense irregular
connective tissue
CUTANEOUS MEMBRANE: COSMETIC
SIGNIFICANCE!
- Reticular region
of Dermis - Stretch
marks/striae - Small tears in the
dermis
CUTANEOUS MEMBRANES:
TATTOOING
- Pigment deposited
into the dermis
using a needle - Lasers can be used
to dissolve the ink
particles causing
removal by the
immune system
CUTANEOUS MEMBRANES- SKIN
COLOURATION
- Skin Colour Pigments:
1) Melanin produced by
Melanocytes
(epidermis) - Pheomelanin
(yellow/red) - Eumelanin
(brown/black)
2) Heamoglobin
3) Carotene - Freckles & age spots
- Accumulations of
melanin
SKIN COLOURATION IN
DIAGNOSTICS
Cyanotic
Erythema
Jaundice
Pallor
Melanin - Eye and Hair Colour
CUTANEOUS MEMBRANES: CLINICAL
SIGNIFICANCE
- Skin cancer
- Link to UVA/B over
exposure - 78% Basal Cell
carcinoma - 20% Squamous cell
carcinoma - 2% Malignant
melanoma
CUTANEOUS MEMBRANES- SKIN
COLOURATION
- Albinism
- Inherited deficiency in
melanin production - Melanocytes unable to
synthesise tyrosinase
Vitiligo
- Partial/complete
loss of
melanocytes
from patches of
the skin - Immune system
attacks
melanocytes
CUTANEOUS MEMBRANE:
WOUND HEALING
Primary Intention
Repair with normal function
Secondary Intention
Repair with loss of function
CUTANEOUS MEMBRANE: WOUND
HEALING
TWO TYPES OF WOUND HEALING
1)EPIDERMAL WOUND HEALING
- Edges of wound: slight damage to superficial
epidermal cells
- Central portion: damage may extend to dermis
2) DEEP WOUND HEALING
- Injury extends to dermis and subcutaneous layer
- May get loss of function due to scar tissue
formation
CUTANEOUS MEMBRANE: DEEP
WOUND HEALING
- 4 stages
1)INFLAMMATORY PHASE
Prepare tissue for fixing
Wound Repair
2) MIGRATORY PHASE
3) PROLIFERATIVE PHASE
4) MATURATION PHASE
PATHOLOGIC REPAIR
- Fibrosis (process of scar tissue
formation) - Similar to normal wound healing but…
- Continuous scar tissue formation
- Dysregulation of collagen synthesis &
degradation processes - Fibrosis is the final common pathogenic
process for almost all forms of chronic tissue
injury - Features in 40% of all diseases
SCAR TISSUE- FIBROSIS
Dysregulation of collagen synthesis &
degradation processes
Hypertrophic scar
Keloid scar
SYNOVIAL MEMBRANES
Synovial membranes line joints and
contain ONLY CONNECTIVE, not epithelial tissues
Connective tissue is composed of;
1) a discontinuous layer of SYNOVIOCYTES
2) A layer of AREOLAR AND ADIPOSE
CONNECTIVE TISSUE
Rheumatoid arthritis
-Autoimmune disease
- Inflammation of synovial
membrane & increased
synovial fluid
- Production of ‘Pannus’- an
abnormal tissue which
erodes articular cartilage
- Fibrous tissue joins the
exposed bone ends
immobilising joint
