UoA A Medsci 201 Resp + Lab

Divisions of Airways: Anatomical Tracts

Upper Tract = Nares → Pharynx

Lower Tract = Larynx → Alveoli

Divisions of Airways: Functional Zones

-Conducting Zone = (end branch 17) Nares → Terminal Bronchioles

-Respiratory Zone = Respiratory Bronchioles → Alveoli

Divisions of Lungs: Number of Lobes

RL = 3 Lobes: Sup, Mid, Inf

LL = 2 Lobes: Sup, Inf (with distinct linguila of sup)

Divisions of Lungs: Number of Segments

RL = 10 Bronchopulmonary Segments

RL = 8 Bronchopulmonary Segments

-Have their own blood, lymph, nerves

-In a distinct CT sheet

→Can remove a full section without complication, sectioning → haemorrhage.

Components of Nose and Nasopharynx

-Vibrissae = Nose gairs to filter coarse particles >4μm

-Nasal Vestibule = region enclosed by cartilage. Has skin epithelium.

-Nasal Cavity Proper = region with resp epithelium

→Conchae made of turbinate bones

-Internal Nares

-Eustacian Tube

Components of Nose and Nasopharynx: Conchae

-Force turbulence wich mixes air and throws particles against the mucous of the respiratory epithelium (pseudostrat ciliated columnar and secretory)

-Rich capillary presence for warming

-↑SA

Components of Nose and Nasopharynx: Subepitherlial Seromucous Glands

-Add waterdroplets to the air to humidify

-Form a mucous gel layer to trap particles

Nose Cycling

30min → 2¹/₂ hours

-Occlusion by the swelling of lower conchae vessels

Gelsol Mucous Layers

-Upper Gel layer of mucous

-Lower Sol layer up to level of approximately Cilia

#CF = no sol only gel

Histological Features: Trachea

-Respiratory epithelium

→pseudostrat ciliated columnar and secretory

-SM in the submucosa (serves little function for patency)

-Elastic fiber

-C shaped rings

Histological Features: Bronchi

Cartilage Plates

SM

Elastic fibres

Glands

Goblet Cells

Levels of Bronchi and Bronchioles

1° = Main Bronchi

2° = Lobar Bronchi

3° = Segmental Bronchi

Histological Features: Bronchiole

-Show transition of cell height

-Have club/clara cells as opposed to goblet cells

-NO CARTILAGE IN BRONCHIOLES

-NO SUB EPITHELIAL GLANDS

#muscle contracts in mortis

Asthma

-Day to Day = Submucosal swelling esp of bronchi

-Attack = Bronchoconstriction

#ventalin = Bronchodilator

Levels of Alveolar Structure

Resp bronchiole → Alveolar Duct → Alveolar Sac → Alveoli

Alveolar Structure: Elastic Fiber in CT

-In CT under pneumocytes

-Provide recoil

-Keep alveoli open

Alveolar Structure: Pores of Kahn

-10μm

-Likely for collateral airsupply

Alveolar Structure: Type II Pneumocyte

-Cuboidal cells filled with secretory Vesicles

-Surfactant secreting cells minimize surface tension.

Alveolar Structure: Pathology: Chronic obstructive pulmonary disease (COPD)

eg emphysema

-↓subpneumocyte elastin

-destroy alveoli → one big sac

-↓SA ↓Recoil

→Barrel Chesting

Alveolar Structure: Fused Basement Membranes

-In adults and full term babies the BM of Type I pneumocyte and capillary endothelial cell are fused

→Lumen to lumen diffussive distance of 0.5μm

-This distance is increased with pulmonary oedema or fibrosis from damage

Smoking on the Lungs

-Toxins paralyse cilia

-Goblet hyperplasia and hypertrophy in response to irritant buildup

#goblet cells have microvilli (secretory) rather than cilia

Vasculature of the Lungs: Pulmonary Circuit Function

-A low pressure system to carry blood for oxygenation

Vasculature of the Lungs: Systemic Circuit Function

-A system to carry nutrients and oxygen to the functional cells of the lung

→Supply Trachial, Bronchial, Bronchiolar walls

#Do not need to supply respiratory bronchioles

Vasculature of the Lungs: Pulmonary Circuit Arteries

-Pulmonary Artery run with the airway

-Relatively thin SM wall

-Medium Sized

-CO₂ rich

Vasculature of the Lungs: Systemic Circuit Arteries

-Bronchial Arteries

-Medium-Small musculature arteries

-O₂

→Supply Trachial, Bronchial, Bronchiolar walls

#Do not need to supply respiratory bronchioles

Vasculature of the Lungs: Pulmonary Circuit Veins

-Pulmonary Veins run through the CT septa, from the substance of the lungs

-Barely 2-3SM layers

-Larger lumen

Vasculature of the Lungs: Systemic Circuit Veins

-Broncial Veins drain the systemic capillaries

-O₂ poor

-Does not exit out via septa as does not enter "substance" of the lungs

Vasculature of the Lungs: Pulmonary Artery Pressures

25mmHg

Vasculature of the Lungs: Pulmonary Vein Pressures

5mmHg

Vasculature of the Lungs: Bronchial Artery Pressures

80-120mmHg

Vasculature of the Lungs: Bronchial Vein Pressures

30-80mmHg

Lung Development: 26d - 7w

-Lung bud arises as a ventral outpouching from the foregut endoderm

→3 levels of branching for lungs, lobes, and segments. with associated vasculature (1°, 2°, and 3° Bronchi)

Lung Development: 5w - 17w

-Branching for further generations creates bronchioles and terminal bronchioles

-Macroscopically the lung looks like a gland.

Lung Development: 16w - 25w

-Each terminal bronchiole gives rise to two or more respiratory bronchioles

-These divide into 3-6 alvolar ducts (lined by cuboidal cells)

-These cells (pneumocytes) become progressively attenuated (flat)

Lung Development: 24w - term

-Alveolar ducts give rise to primitive alveoli = thin walled terminal air sac

-Squamous type I cells become closely associated with blood and lymph capillaries

-Type two cells develop and begin to produce surfactant

Lung Development: Late foetal - 8yo

-The number of terminal sacs increases

-Alveoli mature through continued thinning

-BM of pneumocytes and endothelial cells further thin and fuse

Lung Development: Tracheoesophageal Fistula

-Congenital disorder involving an abnormal connection between the trachea and oesophagus

Lung Development: Overview

#Stages overlap because cranial segments mature earlier than caudal ones

-Pulmonary groove (3¹/₂ w) appear in midventral floor of pharynx (endodermal)

-Blind pocket → 2 lung buds

→divide

Lung Development: Periods

-Embryonic

-Pseudoglandular

-Canalicular

-Saccular

-Alveolar

Lung Development: Periods: Embryonic and Pseudoglandular

-Form major airway and bronchial tree

-Form portions of respiratory Parenchyma (cells)

-Acinus birth

Lung Development: Periods: Canalicular

-Last generation or lung tree

-Epithelial differentiation

-Air-Blood barrier formed

Lung Development: Periods: Saccular

-Begins ~d24

-Expansion of airspaces

-Surfactant detectable after d25 (in amniotic fluid)

Lung Development: Periods: Alveolar

-Secondary Septation

=The formation of 2° septa (which define alveoli) as outgrowths from the 1° septa (which define sacculi)

Lung Development: Neonatal Respiratory Distress Syndrome

→Insufficient surfactant thus extra work → exhaustion

-Surfactant is only produced in sufficient amounts for respiration by the 8th month

~Treatment: Surfactant administration and positive end-expiratory pressure

#Ideally give glucocorticoids to delay onset of labour.

Tibeal Vessels: Arterial and Venous Pressure Gradient

From Heart to Feet

-Venous pressure 0-90mmHg

-Arterial pressure 90-180mmHg

From Heart to Hand above head

-Arterial pressure 90-40mmHg

Common Staining Colours for Muscular Arteries

Not told about stain but we are typically given

Collagen = pink

-SM = pink

-Elastin = black (IEL = strong black line)

# in Musc Arteries the fibres (SM, elastic, collagen) are interspersed,

#Elastic Arteries = layered SM, collagen, elastin = lamellar units

Subvascular Vasculature

Vaso Vasorum = Supply vasa in adventitia

Vaso Nervorum = Supply veins

End Stage Atherosclerotic Plaque

Dense fibrous cap

-Plaque is calcified

#largely in large arteries

Defining Layers of SM for Venules and Arterioles

Venule = 2 or less layers

Arterioles = 3 or less

Lab Facts: Aorta

BP: 120-80

Diameter = 1.5-2cm

Proportion of total wall thickness that is intima (at thickest) = 1/8 to 1/4

CT Fiber Distribution: Muscular Artery

-Sub endo CT = loose CT fibres

-Fenestrated IEL which is smooth in life but folds in death

-Media = interspersed CT fibres with SM

-Adventita = loose mess of fibres

CT Fiber Distribution: Elastic Artery

-Sub endo CT = loose CT fibres #important: many longitudinal elastic fibres

-Fenestrated IEL present but hard to distinguish from other ELs

-Media = 50-60 Lamellar units of EL, collagen and SM

-Adventita = loose mess of fibres

Histology: Artery or Vein

-Due to minimal media veins tend to collapse in mortis (arterioles don't)

-Veins have thinner tunicae than arterioles

Histology: Bronchi vs Bronchioles

-Cartilage Plates vs None

-Spiral SM vs minimal SM

-Cartilage vs None

-Sub mucosal mucous glands vs None

-Goblet Cells vs Club Cells

#If it is a terminal bronchiole "bronchiole" is insufficient

Histology: Pulmonary Arteries

-Run with Bronchi

-Large tunica media ("artery")

-Has Adventita and thus doesn't share CT (??)