Download MBBS Integumentary System Skin Lecture PPT

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