Download MBBS (Bachelor of Medicine and Bachelor of Surgery) Latest Integumentary System Skin Lecture PPT
INTEGUMENTARY SYSTEM(SKIN)
INTRODUCTION
? Integumentary System
? 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
squamous epithelium
? Dermis consists of irregular connective tissue
? Beneath the dermis is hypodermis or a subcutaneous
layer of connective tissue and adipose tissue that
forms the superficial fascia.
FUNCTION OF SKIN
? Protection- from injury.
? It provides a barrier to water.
? Thermoregulation-- sweating
? Sensory perception- like pain, touch,
temperature and pressure.
? Helps in production of vit.D.
? Excretions through sweat of water, sodium
salts, and nitrogenous waste.
? TYPES OF SKIN--
? Thick skin--Skin on the surface of palm and sole.
? Epidermis is thicker than elsewhere.
? Thick skin is hairless.
? Thin skin--present other places of body except
palm and sole.
? Thin and hairy.
? MICROSCOPIC STRUCTURE OF SKIN--
? Skin consist of two layers-
? Epidermis
? Dermis
? EPIDERMIS--
? It consist of stratified squamous epithelium.
? Five layers in thick skin from deep to superficial.
i)Stratum basale
ii)Stratum spinosum
iii)Stratum granulosum
iv)Stratum lucidum
v)Stratum corneum
? Stratum Basale (Germinativum)--
- Deepest layer of epidermis
-Single layer of cuboidal cells that rests on the
basement membrane.
- Cells attached by desmosomes and by
hemidesmosomes to basement membrane.
-The newly produced cells move towards
superficial layer
? Stratum spinosum--
? Consist of several layers of polygonal cells.
? During histological preparation, cells shrink
and intercellular spaces appear as spines
? This layer well developed in friction and
pressure area of skin.
? Stratum granulosum--
? Consists of 3-5 layers of flattened fusiform cells.
? These cells are filled with keratohyalin granules.
? Stratum lucidum--
? Seen only in thick skin.
? Cells are flattened, translucent.
? These cells are filled with protein called keratin
and eleidin.
? Stratum corneum--
? 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
process takes 20-30 days.
? DERMIS--
? Made up of collagen bundles.
? It also contains elastic fibres, nerves, lymphatics
and blood vessels.
? It is divided into two layers.
? Papillary layer
? Reticular layer
? Papillary layer--
? Narrow band of loose connective tissue in
contact with basement membrane of st. basale.
? Shows finger-like processes (dermal papilla)
projecting into under surface of epidermis.
? Papilla contain type III collagen, elastic fibres,
nerves, blood vessels and connective tissue cells.
? Reticular layer--
? It contains bundles of type I collagen, thick
elastic fibres, nerves, blood vessels and few
connective tissue cells
CELLS OF EPIDERMIS
? Keratinocytes--
? Most abundant cell (90%).
? Produces keratin
? Keratinocytes migrates from stratum basale
towards surface.
? Melanocytes--
? Derived from neural crest cells.
? Located between st. basale and st. Spinosum.
? Produce melanin pigments (responsible for skin
colour).
? Melanin darkens skin colour and protect it from
ultraviolet radiation.
? In white people melanin is degraded by
lysosomes.
? In black people this pigment is more stable.
? Langerhans Cells--
--Found in st. spinosum; part of immune system of
body
--Are antigen-presenting cells of the skin.
? Merkel's Cells--
--Sensory cells present in the st. Basale .
--Derived from neural crest.
--Function as mechanoreceptors.
--Abundant in fingertips, oral mucosa and hair follicle
DIFFERENCE BETWEEN THIN AND THICK SKIN
THIN SKIN
THICK SKIN
LAYERS OF EPIDERMIS ST. LUCIDUM ABSENT PRESENT
THICKNESS OF
0.10-0.15 mm
0.6-4.5 mm
EPIDERMIS
HAIR FOLLICLES
PRESENT
ABSENT
SWEAT GLAND
FEW
MANY
SENSORY RECEPTOR
LESS
MORE
DISTRIBUTION
COVERS ALL THE
PALM AND SOLE
PARTS OF THE BODY
EXCEPT PALM AND
SOLE
THIN SKIN
THICK SKIN
GLANDS OF SKIN
? Sebaceous Gland
? Present in the dermis of skin.
? Simple acinar gland whose
duct opens into the hair
follicle.
? It secretes oily substance
called sebum.
? Sebum keeps the skin smooth
to prevent it from drying
? Mode of secretion is
holocrine.
? Sweat Gland
? Present in the deeper part of
dermis and is widely distributed.
? Simple coiled, tubular gland
whose duct opens on the
epidermal surface.
? watery secretion helps in
maintaining body temperature.
? Two types of sweat glands
? Eccrine:
Widely distributed throughout skin.
Densely in the palms and soles.
Watery secretion.
? Apocrine:
Found in axilla, groin areola of breast.
Thick viscous secretion
RESPIRATOTY SYSTEM
INTRODUCTION
? Consists of nose, pharynx, larynx, trachea and
lungs.
? Functions:--
? Perception of smell
? Filtration of inhaled air
? Phonation
? Respiration
? Maintenance of blood pH
? Functionally respiratory system consists of two
parts.
? Conducting part--
? Nasal cavity
? Pharynx
? Larynx
? Trachea
? Bronchi
? Bronchioles & terminal bronchioles.
? Respiratory part--
? Respiratory bronchioles
? Alveolar duct
? Alveolar sac & alveoli.
Conducting part
? General structure of the conducting part
? Respiratory tract made of four coats--
1.Mucosa--epitehelial lining and underlying lamina
propria.
Epithelium is usually pseudostratified ciliated
columnar with goblet cells.
2.Submucosa--layer of loose connective tissue
containing mixed gland.
3.cartilage layer--mostly hyaline cartilage and
smooth muscle.
4.Adventitia--fibroelastic connective tissue.
? Epiglottis--
? Consists of a plate of elastic cartilage.
? On the both sides of cartilage there is
presence of lamina propria.
? Lamina propria contains seromucous gland.
? Anterior surface & upper part of posterior
surface lined by stratified squamous
epithelium.
? Posterior surface lined by pseudostratified
ciliated columnar epithelium with goblet cells.
? Trachea--
? The wall of the trachea consists of mucosa,
submucosa, hyaline cartilage, and adventitia.
? Trachea is kept patent (open) by 16-20 C-
shaped hyaline cartilage rings.
? The gap between the posterior ends of the
hyaline cartilage is filled by the smooth
trachealis muscle.
? The lumen of the trachea is lined by
pseudostratified ciliated columnar epithelium
with goblet cells.
Respiratory part
? Respiratory bronchioles--
? Transition from conducting part to respiratory part.
? Less than 0.5mm diameter.
? Lining epithelium is simple cuboidal with cilia.
? Alveoli--
? Thin walled polyhedral sacs about 200 um in
diameter.
? Alveoli are closlely packed, so the alveolar wall is a
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.
? Blood-air barrier--
? The air in alveolus is separated from blood in
capillary by three structures.
? Endothelium of capillary
? Lining epithelium of alveolus
? Fused basal lamina of endothelium and
epithelium.
? This is thin (1.5-2 um) and facilitates the
diffusion of oxygen and carbon dioxide.
? Cells of alveolar wall--
? Type I alveolar cells (pneumocyte I)
? Very thin squamous cells
? Cover 95% of alveolar surface
? Type II alveolar cells (pneumocyte II)
? Large rounded cells contains microvilli
? Secretory in nature and secretes pulmonary
surfactant, which lower surface tension and
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
? Brush cells--
? These cells found occasiniolly in alveolar epithelium.
? Serve as receptor to monitor the quality of air
entering in lung.
? Alveolar macrophage--
? Found in connective tissue of interalveolar septa
? First line defence against pulmonary infection.
? They phagocytes dust particles so called as dust cells.
? In patients of heart failure the erythrocytes
accumulate in alveoli which is phagocytosed by
macrophage and acquire brick red colour so called as
heart failure cells.
Difference between Bronchus & Bronchiole
BRONCHUS
BRONCHIOLE
DIAMETER > 1 MM
DIAMETER< 1 MM
PSEUDOSTRATIFIED CILIATED SIMPLE COLUMNAR OR
COLUMNAR
SIMPLE CUBOIDAL
SMOOTH MUSCLE
SMOOTH MUSCLE & ELASTIC
FIBRES
CARTILAGE PRESENT
CARTILAGE ABSENT
GLANDS PRESENT
NO GLANDS
This post was last modified on 30 November 2021