INTEGUMENTARY SYSTEM(SKIN)
INTRODUCTION
? Integumentary System
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? Skin and its derivatives (hair and nail).Skin is outer covering of body.
Largest organ of body (16% of body weight).
? Consists of epidermis and dermis
? Epidermis is covered by keratinized stratified
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squamous epithelium
? Dermis consists of irregular connective tissue
? Beneath the dermis is hypodermis or a subcutaneous
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layer of connective tissue and adipose tissue that
forms the superficial fascia.
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FUNCTION OF SKIN? Protection- from injury.
? It provides a barrier to water.
? Thermoregulation-- sweating
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? Sensory perception- like pain, touch,temperature and pressure.
? Helps in production of vit.D.
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? Excretions through sweat of water, sodiumsalts, and nitrogenous waste.
? TYPES OF SKIN--
? Thick skin--Skin on the surface of palm and sole.
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? Epidermis is thicker than elsewhere.? Thick skin is hairless.
? Thin skin--present other places of body except
palm and sole.
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? Thin and hairy.
? MICROSCOPIC STRUCTURE OF SKIN--
? Skin consist of two layers-
? Epidermis
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? Dermis? EPIDERMIS--
? It consist of stratified squamous epithelium.
? Five layers in thick skin from deep to superficial.
i)Stratum basale
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ii)Stratum spinosumiii)Stratum granulosum
iv)Stratum lucidum
v)Stratum corneum
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? Stratum Basale (Germinativum)--- Deepest layer of epidermis
-Single layer of cuboidal cells that rests on the
basement membrane.
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- Cells attached by desmosomes and by
hemidesmosomes to basement membrane.
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-The newly produced cells move towardssuperficial layer
? Stratum spinosum--
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? Consist of several layers of polygonal cells.? During histological preparation, cells shrink
and intercellular spaces appear as spines
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? This layer well developed in friction and
pressure area of skin.
? Stratum granulosum--
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? Consists of 3-5 layers of flattened fusiform cells.? These cells are filled with keratohyalin granules.
? Stratum lucidum--
? Seen only in thick skin.
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? Cells are flattened, translucent.? These cells are filled with protein called keratin
and eleidin.
? Stratum corneum--
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? Most superficial layer of epidermis.? Composed of dehydrated dead cells.
? Cells are filled with keratin.
? Thickness is much more in thick skin.
? This layer is continuously sloughed off, this
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process takes 20-30 days.
? DERMIS--
? Made up of collagen bundles.
? It also contains elastic fibres, nerves, lymphatics
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and blood vessels.
? It is divided into two layers.
? Papillary layer
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? Reticular layer? Papillary layer--
? Narrow band of loose connective tissue in
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contact with basement membrane of st. basale.? Shows finger-like processes (dermal papilla)
projecting into under surface of epidermis.
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? Papilla contain type III collagen, elastic fibres,
nerves, blood vessels and connective tissue cells.
? Reticular layer--
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? It contains bundles of type I collagen, thickelastic fibres, nerves, blood vessels and few
connective tissue cells
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CELLS OF EPIDERMIS? Keratinocytes--
? Most abundant cell (90%).
? Produces keratin
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? Keratinocytes migrates from stratum basaletowards surface.
? Melanocytes--
? Derived from neural crest cells.
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? Located between st. basale and st. Spinosum.? Produce melanin pigments (responsible for skin
colour).
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? Melanin darkens skin colour and protect it fromultraviolet radiation.
? In white people melanin is degraded by
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lysosomes.
? In black people this pigment is more stable.
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? Langerhans Cells----Found in st. spinosum; part of immune system of
body
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--Are antigen-presenting cells of the skin.? Merkel's Cells--
--Sensory cells present in the st. Basale .
--Derived from neural crest.
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--Function as mechanoreceptors.--Abundant in fingertips, oral mucosa and hair follicle
DIFFERENCE BETWEEN THIN AND THICK SKIN
THIN SKIN
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THICK SKIN
LAYERS OF EPIDERMIS ST. LUCIDUM ABSENT PRESENT
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THICKNESS OF0.10-0.15 mm
0.6-4.5 mm
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EPIDERMIS
HAIR FOLLICLES
PRESENT
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ABSENT
SWEAT GLAND
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FEWMANY
SENSORY RECEPTOR
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LESS
MORE
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DISTRIBUTIONCOVERS ALL THE
PALM AND SOLE
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PARTS OF THE BODY
EXCEPT PALM AND
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SOLETHIN SKIN
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THICK SKIN
GLANDS OF SKIN
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? Sebaceous Gland
? Present in the dermis of skin.
? Simple acinar gland whose
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duct opens into the hairfollicle.
? It secretes oily substance
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called sebum.
? Sebum keeps the skin smooth
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to prevent it from drying? Mode of secretion is
holocrine.
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? Sweat Gland
? Present in the deeper part of
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dermis and is widely distributed.? Simple coiled, tubular gland
whose duct opens on the
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epidermal surface.
? watery secretion helps in
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maintaining body temperature.? Two types of sweat glands
? Eccrine:
Widely distributed throughout skin.
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Densely in the palms and soles.Watery secretion.
? Apocrine:
Found in axilla, groin areola of breast.
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Thick viscous secretionRESPIRATOTY SYSTEM
INTRODUCTION
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? Consists of nose, pharynx, larynx, trachea and
lungs.
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? Functions:--? Perception of smell
? Filtration of inhaled air
? Phonation
? Respiration
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? Maintenance of blood pH? Functionally respiratory system consists of two
parts.
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? Conducting part--? Nasal cavity
? Pharynx
? Larynx
? Trachea
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? Bronchi? Bronchioles & terminal bronchioles.
? Respiratory part--
? Respiratory bronchioles
? Alveolar duct
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? Alveolar sac & alveoli.Conducting part
? General structure of the conducting part
? Respiratory tract made of four coats--
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1.Mucosa--epitehelial lining and underlying laminapropria.
Epithelium is usually pseudostratified ciliated
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columnar with goblet cells.
2.Submucosa--layer of loose connective tissue
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containing mixed gland.3.cartilage layer--mostly hyaline cartilage and
smooth muscle.
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4.Adventitia--fibroelastic connective tissue.
? Epiglottis--
? Consists of a plate of elastic cartilage.
? On the both sides of cartilage there is
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presence of lamina propria.
? Lamina propria contains seromucous gland.
? Anterior surface & upper part of posterior
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surface lined by stratified squamous
epithelium.
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? Posterior surface lined by pseudostratifiedciliated columnar epithelium with goblet cells.
? Trachea--
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? The wall of the trachea consists of mucosa,submucosa, hyaline cartilage, and adventitia.
? Trachea is kept patent (open) by 16-20 C-
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shaped hyaline cartilage rings.
? The gap between the posterior ends of the
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hyaline cartilage is filled by the smoothtrachealis muscle.
? The lumen of the trachea is lined by
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pseudostratified ciliated columnar epithelium
with goblet cells.
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Respiratory part? Respiratory bronchioles--
? Transition from conducting part to respiratory part.
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? Less than 0.5mm diameter.? Lining epithelium is simple cuboidal with cilia.
? Alveoli--
? Thin walled polyhedral sacs about 200 um in
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diameter.
? Alveoli are closlely packed, so the alveolar wall is a
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partition or septum between two alveoli.? Interalveolar septa contains network of capillaries.
? There may be opening in septa called as pores.
? Lined by simple squamous epithelium.
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? Blood-air barrier--
? The air in alveolus is separated from blood in
capillary by three structures.
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? Endothelium of capillary
? Lining epithelium of alveolus
? Fused basal lamina of endothelium and
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epithelium.? This is thin (1.5-2 um) and facilitates the
diffusion of oxygen and carbon dioxide.
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? Cells of alveolar wall--
? Type I alveolar cells (pneumocyte I)
? Very thin squamous cells
? Cover 95% of alveolar surface
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? Type II alveolar cells (pneumocyte II)? Large rounded cells contains microvilli
? Secretory in nature and secretes pulmonary
surfactant, which lower surface tension and
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prevents alveoli from collapsing during expiration
? Type II alveolar cells also gives type I alveolar cells
? It also produces surfactant protein A, B, C and D
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? Brush cells--? These cells found occasiniolly in alveolar epithelium.
? Serve as receptor to monitor the quality of air
entering in lung.
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? Alveolar macrophage--
? Found in connective tissue of interalveolar septa
? First line defence against pulmonary infection.
? They phagocytes dust particles so called as dust cells.
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? In patients of heart failure the erythrocytesaccumulate in alveoli which is phagocytosed by
macrophage and acquire brick red colour so called as
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heart failure cells.
Difference between Bronchus & Bronchiole
BRONCHUS
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BRONCHIOLE
DIAMETER > 1 MM
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DIAMETER< 1 MMPSEUDOSTRATIFIED CILIATED SIMPLE COLUMNAR OR
COLUMNAR
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SIMPLE CUBOIDAL
SMOOTH MUSCLE
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SMOOTH MUSCLE & ELASTICFIBRES
CARTILAGE PRESENT
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CARTILAGE ABSENT
GLANDS PRESENT
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NO GLANDS