L6 Resp Zone and Blood Supply Flashcards
4x components of Respiratory Zone
- Respiratory bronchioles (limited gas exchange)
- Alveolar ducts
- Alveoli Sacs
- Alveoli (individual)
17th Generation of branching
Infection threshold crosses
end of conducting zone (defense against infection)
Lobule
Tube supplied by a terminal bronchiole
Acini
Supplied by respiraotry bronchiole (individual units)
related to lower regions and end of respiratory tree
Difference between terminal and respiratory bronchiole
Respiratory bronchiole has small holes/buds of alveoli in the walls
-can start undergoing gas exchange
Smooth Muscle in respiratory zone
Large elastic bands spiralling randomly around
+ elastic fibres
Respiratory bronchiole epithelium
Simple Ciliated cuboidal epithelium
Majority of cells: Club/Clara cells
Thick. No gas exchange
Club cells
Clara cells
Dome shaped
1) act as stem cells to regenerate the lower airways. 2) Secretory cells. Watery secretion to keep airways hydrated. secretions contain lipoproteins that prevent
a) luminal adhesion if the airway was to collapse.
b) anti-microbial properties.
Efficient use of space in lung
No tube/airway
will be backed fill with alveoli tissue (filling space around tube)
-spongy= majority of surface area of lung is alveoli
Alveolar Duct
Hallway with doors on either side
-Smooth muscle pegs (identifying feature)
-door frames of smooth muscle (entrances to alveoli)
Sometimes respiratory bronchiole will go straight into alveolar sac
Type I Pneumocytes
95% Majority of alveoli SA
Squamous cells (thin barrier, faster diffusion rate)
Cytoplasm + nucleus
-bulk of air is exchanged
Type II Pneumocytes
Surfactant cells
-5% of SA beucuase limited gas exhcange
-premature birth, Neonatal Resp. Distress Syndrome, babies born too early with insufficient Type II surfactant cells
Secrete Surfactant lining surface of all squamous cells = Decreased surface tension in alveoli
Ruffled Border
Contain busy/metbaolic lamallar cells (active function)
Surfactant
Type II surfactant cells
Secrete Surfactant lining surface of all squamous cells
-phospholipid
1) = Decreased surface tension in alveoli
=want to keep alveoli relatively open (lil recoil via elastic). avoid extra energy to reinflate millions of alveoli
2) + moist walls of alveoli. so if alveoli do collapse surfactant makes it much easier to reinflate
3) Reduces work of breathing
Alveolar Macrophages
Last defence
-important in heart failure
Wandering cells /Dust cells
(pac man) Phagocytose/consume/chop up debris (impaired muco-ciliary clearance. fine carbon particles in smog/industrial area)
-never get rid of some carbon particles
1) macrophages work upwards and get trapped in mucus and removed/broken down
2) wander into Inter-alveolar Septa and sit forever sitting with black fibres
Alveolar Septa/walls
contains connective tissues
a) collagen: support capillary entrance and exit + alveoli
b) elastin: expand + elastic recoil to push air out through
- fibrotic lung disease
Diffusion distance
0.5 microns
endothelium + alveolar epithelium type I + some surfactant
Lamalar bodies
Increased contents/busyness= increased metabolic activity
-characteristic of secretory cells/esp. surfactant
Fibrotic lung disease
increased collagen = thicker and stiffer =harder to inflate alveoli = increased diffusion distance for air (more hypoxic - higher partial pressure gradient in alveoli)
Emphesema
Decreased elasticity in lung
1) Inflammatory Enzymes: stimulates by noxious particles (smoking)
=destroys elastin and collagen
a)=reduces recoil
= air get trapped, cant push air out (no Smooth muscle)
=barrel chest
b) =decreased SA available for gas exchange
=destruction of interalveolar septa (one big grape)
Pulmonary Circulation
DEO blood into lungs –> heart –> OX blood out of lungs
Low pressure
Short system
Bulk flow of gases
1) Large/same size Pulmonary artery w. bronchus (O2 poor, large, low pressure) (thin wall and large lumen)
-narrows simulatenously with branching
2) less second to get through capillary to get oxygenated
3) Ct septa through bronchopulomanary segments
4) branch of pulmonary vein through lung parenchyma thin sheets of CT
5) hilum
Systemic Circulation
Bronchiole circulation
Blood supply for metabolic need of mucus production, cilia beating
-in walls of airway
-smaller (micro)
-Artery –> Capillary –> Vein (Bronchial + Azygous)
Pulmonary artery vs Pulmonary vein
Location
-pulmonary artery always next to airway
-shared CT
Vein: lonely
Pulmonary and Systemic Anastomoses
Bronchopulmonary anastomoses b/w
1. Bronchial arteries (oxygenated) + Respiratory Bronchiole’s P arteries
2) Systemic Capillaries + Pulmonary Veins (Ox)
-decreases partial pressure of O2 down. important for respiratory drive
=mixed venous blood
Pulmonary Circuit Function, Arteries, Veins + Pressures
Function: conducting
Arteries: next to bronchi
Vein: in parenchyma
Pressures: arteries: 25-15mmHg. vein: 5-0mmHg
Systemic Circuit Function, Arteries, Veins + Pressures
Function: supply tissue of lung with O2 + remove CO2
Arteries: in walls of airways
Vein: anastomose –> drain into azygous
Pressures: arteries: 120-80mmHg —> 40mmHg. vein:
