2. Respiratory System
• Conducting Part-responsible for passa
ge of air and conditioning of the inspire
d air. Examples:nasal cavities,pharynx, tr
achea, bronchi and their intrapulmonary co
ntinuations.
• Respiratory Part-involved with the exch
ange of oxygen and carbondioxide bet
ween blood and inspires air.Includes the
lungs
3.
4. RESPIRATORY SYSTEM HISTOLOG
Y
• Trachea
• Bronchus
-Primary bronchus
-Secondary bronchus
-Tertiary bronchus
• Bronchiole
• Lung
16. Bronchus
• Principal bronchus
-same as trachea
• Secondary /Lobar
• bronchus
-Irregular hyaline cartilage
-Pseudo stratified ciliated colu
mnar
• Tertiary /Segmental bronch
us
-Columnar epithelium
-Patches of cartilage
17. Changes as bronchi become smaller
• Cartilage-irregular and smaller. Absent in bronc
hioles.
• Muscle- increases as bronchi becomes smaller.
(Spasm of these muscles bring difficulty in breat
hing in allergic conditions)
• Subepithelial Lymphoid Tissue-increases with
decrease in the diameter of bronchi.
• Glands-few.Absent in the walls of capillaries.
• Epithelium- pseudostratified ciliated columnar e
pithelium in principal bronchi later simple ciliated
columnar,non-ciliated columnar and later cuboid
al in respiratory bronchioles
23. Differences between Bronchi an
d Bronchioles
Bronchioles
• No glands
• No cartilage
• No goblet cells
• Thick smooth muscle
layer
• Presence of Clara cells
• Many elastic fibres
29. Cells seen in the respiratory pas
sages
• Goblet cells
• Non-ciliated serous cells
• Basal cells
• Cells of Clara
• Brush cells
• Argyrophil Cells similar
to diffuse endocrine
cells of gut
• Lymphocytes
30. • Goblet cells: numerous and secrete mucous.
Mucous traps the dust particles and is move
d by ciliary action towards pharynx.
• Non-ciliated serous cells: secretes watery flu
id that keeps the epithelium moist
• Cells of Clara: are non-ciliated cells predomi
nantly seen in terminal bronchioles. Secrete
a fluid that spreads over the alveolar surface
forming a film that reduces surface tension.
May function as stem cells
31. • Basal cells: Multiply and transform into o
ther cell types replace the lost cells.
• Argyrophil cells: cells similar to diffuse e
ndocrine cells of the gut containing granul
es, secrete hormones and active peptides
including serotonin and bombesin.
• Lymphocytes and other leucoctes may b
e present in the epithelium.
35. Alveoli
• 200 million in a normal lung
• Total area-75 square meters
• Total capillary surface area available for e
xchange-125square meters
• Are spongy and form the parenchyma of lu
ng.
• Sac like evaginations present at the termin
al end of the bronchial tree.
36. • In section, they resemble a honeycomb
• Alveoli are separated by interalveolar septum lyi
ng between thin epithelial lining of two neighbour
ing alveoli
• Interalveolar septum contains anetwork of capill
aries supported by reticular and elastic fibres, oc
cassionally fibroblasts, macrophages and mast c
ells.
• Septum containspores(ALVEOLAR PORES OF
KOHN) help in passage of air from one alveolus
to another, thus equalizing Pressure in the alveo
li
37. • Elastic fibres-enable the alveoli to expand
during inspiration and passively contract d
uring expiration.
• Reticular fibres support and prevent overdi
stention of the alveoli
38. Cells in the Alveoli
• Type I Pneumocytes
• Type II Pneumocytes
• Macrophages or Dust cells
39. Alveolar Macrophages or Dust c
ells
• Derived from Monocytes
and are part mononuclear
phagocytic system.
• Either seen in the septa or
alveoli
• Cytoplasm contains
phagocytosed inhaled
carbon and dust particles
• Inhaled carbon and dust
particles are passed on to
them from pneumocyte I
through pinocytic vesicles
40. Alveolar Macrophages or Dust c
ells
• Migrate from septum to
alveolar surface and are
carried to the pharynx
through sputum
• Main function is to
clean the alveoli of
invading
microorganisms and
inhaled particulate
matter by phagocytosis
42. The skin: is the interface (surface) between human & environment
• is one of the largest organs in the body
• Its surface area is of 1.8 - 2 m2
& makes up approximately 16% of our
body weight ≈ 4kg
• is a window through which the physician can "see" the entire body
46. thickness vary from 0.1mm in eyelids to 1mm
in palm & sole
No blood vessels
Keratinocytes make 85% of it, other cells are
melanocytes, langerhans cells, merkel cells
Transit time: is the time needed for cell
maturation from basal layer to the surface,
normally = 60 days
Skin normal histology Epidermis:
47. The skin is often referred to as the "integumentary
system" composed of epithelial, mesenchymal, glandular
and neurovascular components.
• The integumentary system
is synonymous with:
1- The skin and its derivatives:
sweat glands, nails, hair,
sebaceous glands, arrector
pili muscles.
2- Mammary glands and
3- Teeth
48.
49.
50. Functions of the Skin
• barrier to physical agents
• protects against mechanical injury
• prevents dehydration of body through fluid loss
• reduces the penetration of UV Radiation
• helps to regulate body temperature
• provides a surface for grip
• acts as a sensory organ
• acts as an outpost for immune surveillance
• plays a role in Vitamin D production
• has a cosmetic association
51. 1. Protection against:
• chemicals, particles horny layer
• UV radiation melanocytes
• Antigens, haptens langerhans cells
• Microbes langerhans cells
2. Preservation of horny layer
balanced internal
Environment
3. Prevents loss of horny layer
water, electrolytes, macromolecules
Functions of the skin
53. Based on the thickness of the epidermis,
skin can also be classified as thick or thin:
1) Thick skin
- covers palms and soles,
- has sweat glands, but lacks hair follicles,
arrector pili muscles, and sebaceous glands
2) Thin skin
- covers most of the rest of the body
- contains sweat glands & hair follicles, arrector
pili muscles, and sebaceous glands.
54. Tissues and cells. Histology of the s
kin
Figure 2 Structure of the skin showing the various types of cells and tissues: (
a) epithelial cells in the epidermis; (b) connective tissue; (c) muscle; (d) epithe
lial cells lining the duct of a sweat gland; (e) adipose tissue below the dermis.
55. 1. Basal layer ( stratum basalis):
deepest layer,
single layer of columnar layer
Keratinocytes have
hemidesmosomes attached them
to underlying lamina densa
In normal skin 30% of basal
cells are preparing for division
(growth fraction)
Layers of epidermis
56. 2. Spinous (prickle) cell layer:
keratinocytes larger than basal layer
7-9 layers of cells
Keratinocytes firmly attached by cytoplasmic
process (desmosomes) & intercellular
glycoprotein cement
Tonofilaments are small fibers running from
cytoplasm to desmosomes
Tonofilaments packed into bundles called
tonofibrils, more numerous in this layer
57. 3. Granular layer:
• 2-3 layers
• Cells flatter than spinous layer,
• No nucleus
• No intracytoplasmic organelles
• More tonofibrils
• Contain irregular basophilic granules of
keratohyalin.
58. 4. Stratum Luidum: palms & soles
5. Stratum corneum: SC:
Made of layers of flattened dead cells
(corneocytes), has no nuclei or
cytoplasmic organelles.
Bricks-stuck together by intercellular lipids
Cytoplasm is picked with keratin filaments,
embedded in a matrix, enclosed by an
envlope derived from keratohyalin granules
give corneocytes toughness allow skin to
withstand chemical & mechanical insults
