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Case 5: Histophysiology 1 - Coggle Diagram
Case 5: Histophysiology 1
List the Functions of the Respiratory System
Respiratory System is responsible for:
Moving air to and from exchange surfaces of the lungs along the respiratory passageways
Provide an extensive surface area for the gas exchange between the air in the Lungs and in the Blood
Protects the respiratory surfaces from Dehydration, temperature changes and defending against Pathogens
Producing sound for communication
Facilitates detection of odours
Outline the anatomy of the Respiratory System
Respiratory system is divided into:
Upper Respiratory Tract
Nose
Nasal cavity
Paranasal sinuses
Pharynx
Lower Respiratory Tract
Larynx
Trachea
Bronchi
Bronchioles
Alveoli of the Lungs
Divide the Respiratory System functionally
The respiratory system can be divided into:
The Conducting Zone
Conducting Zone is from the nose to the Terminal Bronchioles
It is responsible for filtering, moistening, warming and conducting air to the Lungs
The Respiratory Zone
Respiratory zone is from the Respiratory Bronchioles to the Alveoli
It is responsible for the gas exchange with Blood
The Structure of the Respiratory Epithelium at different sites within the Respiratory Tract
Outline the Structure of the Respiratory Epithelium at different sites within the Respiratory Tract
Nasal cavity and Upper Respiratory Portion of the Pharynx
Lined by a Ciliated, Pseudostratified Columnar Epithelium
It is a Respiratory Mucosa, with Mucosal cells and Mucous Escalator
Pharynx
Lined by a Stratified Cuboidal epithelium
It provides protection of the epithelium from abrasion and chemical attacks
Conducting portion of the Lower Respiratory Tract
Lined by a typical Respiratory Mucosa
Finer Bronchioles
Lined by a Simple Cuboidal epithelium
Alveoli
Alveoli, which are the gas exchange surfaces are lined by a delicate Simple Squamous Epithelium
The distance between the air and the blood in the adjacent capillaries is very small
Nasal Cavity
Outline the structure of the Nasal Cavity
Nasal cavity is divided into 3 structurally different parts:
Vestibule
Respiratory Region
Olfactory Region
Vestibule
Outline the structure of the Vestibule
Vestibules are lined with a keratinized Stratified Squamous Epithelium
They have Course Hairs (vibrissae) to filter particles from inspired air
Vestibules also have Sebaceous glands and Sweat glands present
List the functions of Vestibules
Vestibules are responsible for trapping and filtering out particles and bugs from inspired air
Respiratory Region
Outline the structure of the Respiratory Region
Respiratory region is lined by a Ciliated, pseudostratified Columnar Epithelium with mucous producing Goblet Cells
This is known as a typical Respiratory Epithelium
Lamina Propria has mucous and Serous Glands and cavernous Bodies
Stem cells
List the functions of Respiratory Region
Respiratory region is responsible for:
Filtration of air using mucous traps and cilia
Moisture of air using mucous and serous glands
Warming inspired air using its rich vascular supply
Mucous production speeds up following exposure to dust, noxious vapors and pathogens
Olfactory Region
Outline the structure of the Olfactory Region
Olfactory region is lined by the specialized Olfactory Epithelium
The Olfactory Epithelium is made up of:
Cilia formed from Olfactory cells (Bipolar neurons)
Cilia lack motility
Basal cells which are Stems cells
Olfactory glands called Bowman's glands that produce mucous
Supporting cells with microvilli
Pharynx
Describe the Structure and Function of each of the regions of the Pharynx
Pharynx is split into 3 main regions:
Nasopharynx
Oropharynx
Laryngopharynx
Nasopharynx
Nasopharynx is made of the Respiratory Epithelium with mucosal cells and mucosa as well as the Lamina Propria
Nasopharynx is responsible for the movement of air ONLY
Oropharynx
Oropharynx is made of the Non-Keratinized Stratified Squamous epithelium
Oropharynx is responsible for the movement of air and food
Laryngopharynx
Laryngopharynx is made up of the Non-Keratinized Stratified Squamous Epithelium
Laryngopharynx is responsible for the movement of air and food
Lymphocytes frequently accumulate beneath the epithelium of the pharynx (Tonsils)
Larynx
Outline the structure and features of the Larynx
Larynx connect the Pharynx and Trachea
Larynx has Vocal Folds
Vocal folds of the Larynx control airflow and allows the production of sound
Larynx is composed of cartilages, ligaments and muscle
Epiglottis
Vocal Fold
Vestibular Fold
Glottis
Outline the structure of the Epiglottis
Epiglottis is made up of Elastic Cartilage
Epiglottis has:
Lingual/Pharyngeal Surface which faces the mouth
Laryngeal Surface which faces the Lungs
Lingual/Pharyngeal Surface is lined with Stratified Squamous Epithelium
This because the Lingual/Pharyngeal Surface is exposed to food and abrasion attacks
Laryngeal Surface which is lined with Ciliated Pseudostratified Columnar Epithelium
Larynx
Outline the structure of the Larynx
Larynx is lined by a Ciliated Pseudostratified Columnar Epithelium
Except of the Vocal folds of the true vocal cords
Vocal folds are lined by Non-Keratinized Stratified Squamous Epithelium
This is because the when sound is produced the vocal folds vibrate and they can rub against each other resulting in abrasion
Trachea
Outline the structure of the Trachea
Trachea is lined by the Respiratory Epithelium (Ciliated Pseudostratified Columnar Epithelium)
The Trachea is also known as the windpipe
It is a fairly short tube that is 10-12 cm long with a diameter of 2 cm
Trachea is made up of C-Shape Cartilage Rings
C-Shaped cartilage rings of the trachea prevent the trachea from collapsing and allow it to maintain the Lumen of the trachea
Trachea has a Trachealis muscle
The Trachealis muscle is a smooth muscle that is found at between ends of the C-Shaped Cartilage Rings
Smooth Trachealis muscle helps to maintain the diameter of the Trachea (Airways)
Trachea
List the 4 Layers of the Trachea
Trachea is made up of 4 Histological layers:
Mucosa
Submucosa
Cartilaginous Layer
Adventitia
Outline the Histological Features of the 4 Layers of the Trachea and their respective functions
Mucosa
Trachea has a Respiratory Mucosa (Epithelium and Lamina propria)
Respiratory epithelium is the Ciliated Pseudostratified Columnar Epithelium
Respiratory epithelium propels mucous towards the Pharynx
Respiratory epithelium contains mucous secreting Goblet Cells
As well as Basal Stem Cells that replace damaged cells
There is a Prominent Basement Membrane
The Lamina Propria is made up of Loose Connective Tissue
Lamina Propria contains:
Collagen fibres that provide tensile strength
Elastic fibres that allow for Stretching and Recoil
Blood vessels to warm the inspired air
Lymphocytes and mast cells for defence
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Respiratory Epithelium
The Respiratory tract is line by the Respiratory Epithelium
The epithelium is a Ciliated Pseudostratified Columnar Epithelium
It contains:
mucous secreting Goblet cells
Serous Cells
Basal Cells that act as Stem cells
Small Granule
Cilia that assist in moving particles out of the airway
Conducting Portion of the Respiratory System
List the cells of the Respiratory Epithelium in the Conducting portion as well as their functions
Ciliated Columnar Cells
Columnar cells have a basal Nuclei
On their Apical side they have Cilia
This Ciliated Columnar cells are responsible for moving mucous and trapped particles to the Nasopharynx
Goblet Cells
Goblet Cells produce Mucinogen containing mucin (protein)
Mucinogen is responsible for hydration of the Lumen
Basal Cells
Basal cells are short, undifferentiated cells
Basal cells are stem cells that are used for the regeneration of the epithelium
Small Granule Cells
Small granule cells are also known as Bronchial cells of Kulchitsky
These are neuroendocrine cells located near the Bifurcations
They are implicated in Bronchial Carcinoid Tumours endocrine/paracrine signaling
Brush Cells
Brush cells are small granule mucous cells
They are narrow, cylindrical cells
On their Apical side they have Microvilli
On their Basal side they are associated with nerve endings in the Lamina Propria
Serous Cells
Serous cells are tall cells with Microvilli and Apical Granules
Serous cells are responsible for secreting granules containing Serous Fluid
Smoking causes a Chronic irritation resulting in the Loss of the Mucocililary Function
This can lead to Squamous Metaplasia
Cilia
Define cilia structure
Cilia are cell surface specializations located int he respiratory mucosa
Outline the structure of the Cilia
Cilia are cytoplasmic extensions containing Axoneme
Axoneme is composed of microtubules, which are hollow tubular structures
There are 2 types of Microtubules in the Cilia: Alpha and Beta Tubulin Proteins
In Cilia there are 2 microtubes in the centre and 9 pairs of microtubules forming an outer circle
Cilia also contain Linking Proteins that bind the whole structure together and form a functioning Microtubule
Linking proteins also allow the structures of the Microtube to move together and provide Motile power to a Cilia
Cilia extend from the Basal bodies
Cilia are important in certain pathological processes and syndrome
Microscopic Structure of Cilia
Describe the microscopic structure of Cilia
Cilia are composed of the following microscopic structures:
Adaptor proteins and Linking proteins that provide motility
Outer Dynein arm and Inner Dynein arm
These two arms are known as Motor Proteins
Dynein is able to convert ATP to derive motion energy
The change in shape is affected thus resulting in movement of the microtubules in relation to each other
This affects the movement of the Cilia
In order for the Cilia to move in a Beating motion there needs to be a conformational change in the Dynein arms which requires ATP
Central pair of Microtubules
Radial spoke
A Tubule and B Tubule
Kartagener's Syndrome
Outline Kartagener's Syndrome
Kartagener's Syndrome is due to a mutation in Dynein Gene
This results in an Immotile Cilia and failure of the Mucocililary Elevator and respiratory function
Kartagener's syndrome results in infertility due to immotile cilia structures of the Spermatozoa called Flagella
And also the immotile cilia structures in the Female reproductive structure
Pathological Processes that can affect the Respiratory Tract
List the Pathological Processes that can affect the Respiratory Tract
Cystic Fibrosis
Outline the condition of Cystic Fibrosis
Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) is important for the hydration of the Mucous barrier
Cystic Fibrosis is caused by the mutation of the CFTR gene
Cystic fibrosis affects the Mucocililary Elevator
The CFTR channel is permeable to Chloride ions (Cl-) when ATP is bound and the regulatory domain is phosphorylated
The CFTR Channel allows for the transport of Chloride ions and HCO3- ions across the plasma membrane of the cell
As a result of Osmosis, the water will follow the Chloride ions into the airways
The water will then liquify the mucous produced by the Goblet Cells resulting in the formation of Serous Fluid which hydrates the Mucocililary Elevator
Therefore, in patients with Cystic Fibrosis there will be a defective or absent CFTR channel
This prevents the movement of Chloride ions across the cell membrane as well as Water
And the cell will takes up extra Na+ ions
This will cause the mucous produced by the Goblet Cells to become thick and trap bacteria
Pulmonary Lobe
Outline the structure of the pulmonary Lobe
Pulmonary lobe is the functional unit of the respiratory system
Pulmonary Lobe contains Pulmonary veins, Pulmonary arteries
Respiratory airways are located in the Pulmonary Lobe
Respiratory pathway then forms the Respiratory portion plus the Alveoli of the airways where Gas Exchange takes in the Pulmonary Lobe
Conducting portion leads into the Respiratory Portion
The Pulmonary Lobe is also innervated by the Nerve Fibres
Nerve fibres regulate the action of the smooth muscles forming the Respiratory airways and the contractile properties of the airways
Pulmonary Lobe is surrounded by Connective Tissue Septum
Pulmonary Lobe contains Arteries, Veins and Lymphatics that supply the Pulmonary Lobe
Pulmonary Lobe has a Visceral Pleura that allows the Pulmonary Lobe to maintain the stability of the whole structure (Shape)
Visceral Pleura is a fibroelastic connective tissue which is made up of Simple Squamous Mesothelial cells
Pulmonary Vasculature
Describe the structures that make up the Pulmonary vasculature
Pulmonary artery
Pulmonary artery is distal and it is an Elastic Artery
Bronchial/Bronchiolar distal portions are muscular arteries
Pulmonary veins and Muscular Artery
Intima thickens with age (older than 50 years) becomes fibro-collagenous
Bronchial Artery
Bronchial artery is a Muscular Artery
The Intima thickens with age resulting in increased smooth muscle cells in individuals older than 20 years
Also increases with some chronic forms of Lung disease
Lymphatic Vessels
Small lymphatics are located at the respiratory bronchioles (not present in the Alveolar wall) and above the respiratory bronchioles
Diseases of Vascular Origin
Describe the Diseases of vascular origin
Embolism, Infarction, Haemorrhage
Mechanical injury: Increases shear stresses
Biochemical injury: Increases fibrin deposition in recurrent thromboses
Leads to vascular endothelial cell and Smooth Muscle Cell malfunction
Respiratory Zones
Describe the structures making up the Respiratory Zones
Smooth muscle fibres are orientated concentrically, in a spiral fashion
Elastic fibres are orientated longitudinally
Pulmonary acinus is made up of the following structures:
Alveolar Duct
Alveoli
Alveolar sac
Pores of Kohn
Elastic fibres around the Alveoli, maintain the shapes of the airway
Smooth muscle fibres regulate the diameter of the airway through contraction and dilation
Gaseous exchange occur at the walls of the Alveolar sac
Alveoli are linked together by the Pores of Kohn, that allow the cells to migrate across the alveoli to perform gaseous exchange
The Bronchi
Describe the structures of the Bronchi
Cartilage Plates
This is different from the C-shaped cartilage rings of the Trachea, this indicates that the Bronchi is not a rigid structure
There is flexibility
Ring of Smooth Muscle
Smooth muscle contributes to the flexibility of the Bronchi
Allows for an increase of decrease in diameter through Dilation and Constriction
Presence of the Smooth muscles increases as we move down the Respiratory Zone
Pseudostratified Ciliated Columnar epithelium
Pseudostratified Ciliated Columnar epithelium is slightly folded to allow for an increase or decrease diameter
Seromucous glands
Seromucous glands that secrete mucous and serous fluid to trap foreign material
Blood vessels
Humidification
Bronchioles: Terminal Bronchioles
Describe the structure of the Terminal Bronchioles
Terminal bronchioles have the following structures:
Ciliated Simple Columnar epithelium - Cuboidal
Epithelium is increasingly folded to allow for contraction and dilation of the Terminal Bronchioles during respiration
Epithelium becomes a Simple Cuboidal Epithelium as we move down the Terminal bronchioles to the Respiratory Bronchioles
Fewer or Absent Mucous-producing Goblet cells
This is because the smaller airways would become blocked by the Mucous secretion
Prominent Smooth Muscle
Smooth Muscle layer to allow for the dilation and contraction of the bronchiolar lumen
Club (Clara) Cells
Club cells are secretion portions in conducting airways
No Glands
No Cartilage
Pulmonary Defense Mechanisms
Outline the Pulmonary Defense Mechanisms
Innate Pulmonary defense mechanism involves the following processes:
Trapping
Trapping involves the trapping and the removal of pathogens via the Mucocililary mechanism
Phagocytosis
Alveolar macrophages that are able to move via the mucous phagocytose foreign material in the lower airways
Alveolar macrophages migrate to the Lymph nodes
Phagocytosis and Lysis
Neutrophils phagocytose and lyse
Complement activation
Opsonin enhance phagocytosis via complement activation
Migration to local lymph nodes (Hilar Lymph Nodes)
Outline the Pulmonary Defense Mechanisms
In the Adaptive Pulmonary defense mechanism there is antibody secretion
Adaptive Pulmonary defense mechanism involves the following processes:
IgA secretion
IgA bind bacteria
IgG and IgM
IgG and IgM located in the fluid lining assist in enhancing Complement activation which increases Opsonin response
Thus further enhancing Phagocytosis
T-Cell accumulation
Bronchiole Histological structure and relation to Asthma
Explain the Bronchiole Histological structure and relation to Asthma
In Asthma, through allergen binding to IgE receptor on the Mast cell surface
Mast Cells become activated resulting in:
Increased Permeability of blood vessels which causes Edema (accumulation of fluid)
Activation of inflammatory cells such as Eosinophils
Release of IL-13 which stimulates smooth muscles and can cause smooth muscle hypertrophy
Increased mucous production resulting in Mucous Hypersecretion which causes obstructed airways
Terminal Bronchiole and Alveolar Duct Histological Structures
Describe the Terminal Bronchiole and Alveolar Duct Histological Structures
Terminal Bronchiole forms part of the Conducting Portion
Simple Columnar Ciliated epithelium which becomes a Simple Cuboidal Epithelium
Alveolar duct forms part of the gaseous exchange surfaces
Alveoli
Simple Squamous epithelium to aid gaseous exchange
Describe the structures of the Terminal Bronchiole
Club (Clara) Cells (80%)
Clara cells produce surfactant component
Regulate Transport of Chloride ions
Secrete enzymes for detoxification
Secrete antiproteases
"Stem Cells"
Ciliated Cuboidal Cells (20%)
Lamina propria
Lamina propria has a Fibro-elastic tissue with 1-2 Smooth muscles
Adventitia
Adventitia has radiating connecting elastic fibres
Alveolar Wall/Septum
List the structures found in the Alveolar Wall
Alveolar macrophages
Pore of Kohn
Pore of Kohn allows macrophages to pass between alveoli
Type 1 Pneumocytes
Type 1 Pneumocytes are within the wall
Type 2 Pneumocytes
Type 2 Pneumocytes are outside the wall
Capillaries
Fibroblasts
Elastin and Collagen fibres
Macrophages can travel through he septum
Phagocytose iron from destructed Haemoglobin, carbon monoxide
Blood-Air Barrier
Describe the Blood-Air Barrier
Blood-Air Barrier ( 0.5 micro-meter) is formed by the:
Type 1 Pneumocytes
Very thin
Endothelial Cell of Blood capillary
Endothelial cell form a continuous, thin endothelial lining
B. Basement Membrane
Thin Basement Membrane separate the Type 1 Pneumocytes and the Endothelial Cell
Gaseous Exchange occurs via diffusion across the Blood-Air Barrie.
Gaseous Exchange depends to the Gradient created across the Blood-Air barrier
Alveolar Macrophages
List the functions of the Alveolar Macrophages
Alveolar Macrophages are responsible for the following:
Phagocytosis of debris and bacteria
Carbon uptake from pollution/tobacco components
Black tint
Iron Uptake from damages Erythrocytes which indicates Left-Sided cardiac Failure
Blue tint
Ferritin-laden macrophages
Macrophages can exit the Alveoli via the Mucocililary Mechanism or migrate into the interstitial as part of the lymphatic drainage
Type 2 Pneumocytes
Type 2 Pneumocytes are lung surfactant secreting cells of the Alveoli
Lung surfactant is a substance that reduces the surface tension in Lung Alveoli
This is because if there is a high surface tension, Lung Alveoli (delicate structures) would collapse
Type 2 Pneumocytes release several components:
Apoproteins:
SP-A and SP-D: Innate immunity
SP-B and SP-C: Increase the spreading rate over cell surface
Lipids
Dipalmitoyl Phosphatidylcholine (DPPC)
Cholesterol
Neutral lipids
Neonatal Acute Distress Respiratory Syndrome
Neonatal Acute Distress Respiratory Syndrome occurs when there is insufficient surfactant
If surfactant coat is not present or produced in low amounts in a premature infant
Results in an increase in Alveolar Surface Tension, alveoli will collapse
Hypoventilation will then cause low oxygen (Hypoxia) and retention of CO2
Resulting in Pulmonary Hypoperfusion
The Pulmonary hypertension will cause Endothelial cell damage
Which leads to Fibrin and other proteins forming a Hyaline Membrane exudate preventing or reducing gas Diffusion
Endothelial Cell Damage can lead to Acute Distress Respiratory Syndrome
Endothelial cell damage (endotoxin and proteases) can increase the permeability resulting in fluid and cell leakage into the Alveoli
Fibrin and protein form a Hyaline Membrane
Fibrin inhibits the synthesis of surfactant by Type 2 Pneumocytes
Neutrophil infiltration
Resulting in Atelectasis (collapse of Alveoli)
Repair
During repair the Type 2 Pneumocytes will proliferate and differentiate into Type 1 Pneumocytes
The severe damage leads to interstitial and alveolar fibrosis
Loss of flexibility and poor diffusion
Gaseous Exchange Regulation
Good Gaseous Exchange needs elastic/compliant Lungs, this depends on the Protease/Anti-protease Balance
Elastic fibre in the Interalveolar space are maintained
Elastase from the Neutrophils, binds to Serum alpha1-antitrypsin from blood capillaries
Thus, preventing the break down of elastic fibres
Chronic Insults such as smoking disturb the Protease/Anti-protease Balance
Smoking results in recruitment and activation of leukocytes and the release of free radical which are reactive oxygen species
Free radicals inhibit the Alpha1-antitrypsin resulting in the recruitment of neutrophils and macrophages
And an increased amount of Elastase breaking down Elastic fibres resulting in Fragmented Elastic fibres
