Histo mod 9 (respi) part 1

respiratory system

provides for exchange of O2 and CO2 to and from the blood

lungs

bronchial tubes

respiratory system is consist of

thoracic cage

intercostal muscles

diaphragm

elastic components of the lung tissue

air is moved through the lungs by

3 intercostal muscles

subcostalis

transversus thoracis

muscles that make up the thorax wall

external

internal

innermost

3 layers of intercostal muscles

3 elastic fiber systems

3 ___ are present and develop independently in the lung

pleura intersegmental and interlobular CT

blood vascular system

bronchi and respiratory units

3 elastic fiber system

anatomic

functional division

divisions of respi system

upper respiratory tract

lower respi tract

anatomic division

conducting portion

respiratory portion

functional divisions of the respiratory system

nasal cavities

pharynx

larynx

trachea

bronchi

bronchioles

terminal bronchioles

conducting system

respiratory bronchioles

alveolar ducts

alveoli

respiratory portion

conducting portion of respiratory tract

cleans and humidifies inspired air

provides conduits for sir movement to and from alveoli

respiratory portion

where the systems main function of gas exchange occurs

alveoli

the cellular sites of the exchange of O2 and CO2 between inspired air and blood

2. small, air-filled, saclike structures

3. make up most of the lung structure

mucosa

submucosa

adventitia

conducting portion lining

lining (respiratory) epithelium

lamina propria

conducting portion mucosa

dense irregualr connective tissue

glands

cartilage

conducting portion submucosa

Thick collagenous fibers

adventitia conducting portion

nasal cavities

Opens posteriorly into the nasopharynx, the first part of the Pharynx

• Both left and right have 2 components

external dilated vestibule

, internal nasal cavity

The left and right nasal cavities each have two components:

external dilated vestibule

includes sweat glands, sebaceous glands, and coarse, moist vibrissae (hairs)

epithelium loses its keratinized nature and undergoes a transition to typical pseudostratified columnar epithelium which also lines the nasal cavities.

olfactory epithelium

specialized region of the mucous membrane

olfactory neurons

supporting cells

basal cells

olfactory glands (of Bowman)

olfactory epithelial cells

olfactory neurons

• bipolar neurons

• apical (luminal) pole is its dendrite end and has a knoblike swelling from which long cilia project into the overlying aqueous layer

• receptors respond to odoriferous substances

supporting cells

columnar, with narrow bases and broad, cylindrical apexes containing the nuclei and extending microvilli into the fluid layer

• express abundant ion channels that maintain a microenvironment conducive to olfactory function and survival

basal cells

are small, spherical, or cone-shaped cells near the basal lamina.

-stems cells, replacing olfactory neurons every 2-4months

olfactory glands (of Bowman)

-produce a constant flow of fluid surrounding the olfactory cilia -facilitates access of new odoriferous substances

- secretes IgA, mucus

olfactory bulb

A rounded mass of tissue that contains several types of nerve cells that are involved in the sense of smell.

2 olfactory bulbs

there are ___ olfactory bulbs on the bottom side of the brain, one above each nasal cavity

respiratory epithelium

pseudostratified ciliated columnar epithelium lines the mucosa of most of the nasal cavities and the conducting portion of the system • It has 5 major cell types

ciliated columar epithelium

goblet cells

brush cells

small granule cells (Kulchitsky cells)

Basal cells

5 major cell types

ciliated columnar epithelium

The most abundant, each with 250-300 cilia on its apical surface

goblet cells

Filled with granules of mucin glycoproteins

brush cells

Columnar cell, in which a small apical surface bears sparse, blunt microvilli

chemosensory receptors

small granules cells (Kulchitsky cells)

Part of diffuse neuroendocrine system (DNES) cells

secretory endocrine cells

basal cells

Mitotically active stem and progenitor cell

chemosensory receptors

signal transduction components and synaptic contact with afferent nerve endings on their basal surfaces

paranasal sinuses

• bilateral cavities in the frontal, maxillary, ethmoid, and sphenoid bones of the skull

• communicate with the nasal cavities through small openings

• mucus produced there is moved into the nasal passages by the activity of the ciliated epithelial cells

respiratory epithelium of paranasal sinuses

thinner with fewer goblet cells

• a few small glands

• continuous with the underlying periosteum

nasopharynx (epipharynx)

1st part of the pharynx

respiratory epithelium

Oropharynx (throat)

the posterior part of the oral cavity leading to the larynx and esophagus

stratified squamous epithelium

pharnyx

its mucosa contains the medial pharyngeal tonsil and the openings of the two auditory tubes which connect to each middle ear cavity

larynx

short (4 cm × 4 cm) passage for air between the pharynx and the trachea

Wall:

• Rigid, reinforced by hyaline cartilage and smaller elastic cartilages, all of which are connected by ligaments.

• movements of these cartilages by skeletal muscles participate in sound production during phonation

epiglottis

flattened structure projecting from the upper rim of the larynx

• serves to prevent swallowed food or fluid from entering that passage

• Lining epithelium: stratified squamous transitions to ciliated pseudostratified columnar (respiratory) epithelium

Epiglottis,

supraglottis,

vocal cord,

glottis,

subglottis

parts of larynx

epiglottis

stratified squamous transitions to ciliated pseudostratified columnar (respiratory) epithelium

vestibule of larnyx

seromucous glands -secrete a watery product)

vocalis muscle

large bundles of striated fibers allow each vocal fold to be moved

vestibular fold

seromucous glands & lymphoid nodules & covered by Respiratory Epithelium)

vocal fold/cord

nonkeratinized stratified squamous epithelium

T

the larynx is larger and the vocal cords longer in male than female

trachea

10-12 cm long in adults

MUCOSA

• respiratory epithelium

• lamina propria contains numerous seromucous glands

SUBMUCOSA AND ADVENTITIA

• C-shaped rings of hyaline cartilage

• trachealis muscle a bundle of smooth muscle

trachea

dozen C-shaped rings of hyaline cartilage between the submucosal and adventitia reinforces the wall and keeps the tracheal lumen open

trachealis muscle

The open ends of the cartilage rings are on the posterior surface, against the esophagus, and are bridged by a bundle of smooth muscle called the trachealis muscle and a sheet of fibroelastic tissue attached to the perichondrium.

• relaxes during swallowing to facilitate the passage of food

• strongly contracts in the cough reflex

larger bronchi

structurally similar to the tracheal mucosa except for the organization of cartilage and smooth muscle

primary bronchi

most cartilage rings completely encircle the lumen, but as the bronchial diameter decreases, cartilage rings are gradually replaced with smaller isolated plates of hyaline cartilage

primary bronchus

branches repeatedly, with each branch becoming progressively smaller until it reaches a diameter of 1-2 mm.

small mucous and serous glands

with ducts opening into the bronchial lumen

lamina propria

contains crisscrossing bundles of spirally arranged smooth muscle and elastic fibers

lymphatic nodules

are present, especially at the branching points of the bronchial tree

-numerous lymphocytes are found both within the lamina propria and among the epithelial cells.

bronchioles

intralobular airways with diameters of 1 mm or less

• lack both mucosal glands and cartilage

• dense connective tissue is associated with the smooth muscle

mucosa of larger bronchioles

ciliated pseudostratified columnar

mucosa of smallest terminal

ciliated simple columnar/cuboidal epithelium

mucociliary apparatus or escalator (cilia + mucus)

the ciliated epithelial lining of bronchioles begins in the ___

important in clearing debris and mucus by moving it upward along the bronchial tree and trachea.

lamina propria of bronchioles

Lamina propria contains elastic fibers and smooth muscle, producing folds in the mucosa

terminal bronchioles

Last division of the conducting zone/system

club cells

surfactant lipoproteins and mucins

antimicrobial peptides and cytokines

detoxification of inhaled xenobiotic compounds

chemosensory brush cells

DNES small granules cells

stem cells

terminal bronchioles

club cells

bronchiolar exocrine cells (previously called Clara cells)

• with nonciliated, dome-shaped apical ends containing secretory granules

autonomic nervous system

muscular contraction in both the bronchi and the bronxhioles is controlled primarily by nerves of the

Parasympathetic

slows breathing rate

bronchial tubes to narrow

the pulmonary blood vessels to widen

respiratory bronchioles

Subdivide from terminal bronchioles, which always include saclike alveoli

• the first-part of this system's respiratory region

mucosa of respiratory bronchioles

resembles that of the terminal bronchioles

• have a few openings to alveoli where gas exchange occurs

• epithelium consists of club cells, with simple squamous cells at the alveolar openings and extending into the alveolus

• lamina propria consists of smooth muscle and elastic connective tissue

alveolar ducts

Branching out at the distal ends of respiratory bronchioles

• completely lined by the openings of alveoli

mucosa of alveolar ducts

Epithelium - extremely attenuated squamous cells

• Thin Lamina propria - a strand of smooth muscle cells surrounds each alveolar opening

• a network of elastic and collagen fibers supports both the duct and its alveoli

alveolar sacs

form the ends of alveolar ducts distally and occur occasionally along their length

• lamina propria - extremely thin, consisting of a web of elastic and reticular fibers that encircles the alveolar openings and closely surrounds each alveolus

• a network of capillaries also surrounds each alveolus

Alveoli

saclike evaginations, each about 200 μm in diameter responsible for the spongy structure of the lungs • Each adult lung has approximately 200 million alveoli with a total internal surface area of 75 m2

• Air in these structures exchanges O2 and CO2 with the blood in surrounding capillaries, through thin specialized alveolar walls that enhance diffusion between the external and internal environments.

interalveolar septa

Lie between neighboring alveoli

• scattered fibroblasts and sparse extracellular matrix (ECM), notably elastic and reticular fibers, of connective tissue.

• Elastic fibers enables alveoli to move during breathing

• Reticular fibers prevent both collapse and excessive distention of alveoli

• Vascularized with the richest capillary networks in the body

interalveolar septa

total thickness: 0.1 to 1.5 μm

• Presence of macrophages and other leukocytes

• Alveolar pores (of Kohn) • 10-15 μm in diameter

• connect neighboring alveoli that open to different bronchioles

• equalize air pressure in the alveoli • permit collateral circulation of air if a bronchiole becomes obstructed.

capillary endothelial cells

type I alveolar cells / type 1 pneumocytes

alveolar macrophages (dust cells)

type II alveolar cells (type II pneumocytes or septal cells)

cells of alveoli

capillary endothelial cells

very thin, but continuous (not fenestrated) • very thin and demonstrate highly efficient gas exchange.

• most prominent features in the flattened portions of the cell: numerous pinocytotic vesicles

Type I alveolar cells (pneumocytes)

extremely attenuated cells lining the alveolar surfaces

• the alveolar side of the blood-air barrier

• make up about 95% of the alveolar lining

• Pinocytotic vesicles play a role in the turnover of surfactant and the removal of small particulate contaminants from the outer surface.

• have tight junctions and desmosomes that prevent the leakage of tissue fluid into the alveolar air space

Alveolar macrophages (dust cells)

phagocytose erythrocytes lost from damaged capillaries and airborne particulate matter that has penetrated as far as alveoli

Type II alveolar cells (type II pneumocytes or septal cells)

cuboidal cells bulging into the air space, interspersed among the type I alveolar cells and bound to them with tight junctions and desmosomes

lamellar bodies of type II alveolar cells

vesicles of type II alveolar cells that contain a variety of lipids, phospholipids, and proteins

o The surfactant material secreted by exocrine club cells and type II alveolar cells is an oily mixture of cholesterol, phospholipids and surfactant proteins, which forms a film and lowers surface tension in alveoli.

tracheal brush cells (BCs)

specialized epithelial chemosensors that use the canonical taste transduction cascade to detect irritants