Respiratory review Flashcards
What are the two portions that make up the respiratory tract? What happens in each portion?
Ventilation portion - where air moves
Respiratory portion - where gas is exchanged (AKA lung parenchyma)
Describe the pathway air takes when being inhaled from nares
Nasal cavity Nasopharynx Larynx Trachea Primary bronchi Secondary bronchi Tertiary bronchi Bronchioles Alveolar duct Alveoli
What defines a lung, lobe, primary and secondary lobule?
Portion of tissue supplied by... Lung - primary bronchi Lobe - secondary bronchi Lobule - tertiary bronchi Secondary lobule - terminal bronchioles
What is the difference between bronchi and bronchioles?
Bronchioles have no cartilage - made up of smooth muscle and elastic tissue
Bronchioles have no submucosal glands
What is different about lungs of the pig?
Marbled lobes
Lots of CT between lobules
What epithelium lines the respiratory tract?
Respiratory epithelium:
Pseudostratified ciliated columnar epithelium
What do terminal bronchiole supply?
Secondary lobules
What 3 cells are found in alveoli? What shape are they and what do these cells do?
Type I alveolocytes - simple squamous
Type II alveolocytes - cuboidal shape, produce surfactant
Alveolar macrophages - phagocytes to clear particles that evaded defence in URT
In embryology, what does the respiratory tract develop from?
Cardiac tube of foregut
Why are neonates prone to respiratory distress?
Respiratory development finishes after birth
Surfactant is produced after birth to lower surface tension
What are the 5 histological phases of respiratory embryology?
Embryonic Psuedoglandular Canalicular Terminal sac Alveolar
What happens during the embryonic phase of respiratory embryology?
Segmental bronchi being to form
What happens during the pseudo glandular phase of respiratory embryology?
Vascularisation begins
What happens during the canalicular phase of respiratory embryology?
Further vascularisation and formation of bronchioles
What happens during the terminal sac phase of respiratory embryology?
Alveoli form
Cuboidal epithelium forms type I and type II alveolocytes
Surfactant production begins
What happens during the alveolar phase of respiratory embryology?
Increased surfactant production
Vessels associate with alveoli
(Phase continues after birth)
Air moves due to pressure differences. What causes the decreased pressure that causes inhalation? Is exhalation active or passive?
External intercostals and diaphragm contract
Expand thoracic cavity
Causes decreased pressure compared to atmospheric pressure –> inhalation
Mainly passive
What is the name of the reflex that stops inspiration? What is the purpose of this?
Hering-Breur reflex
Stop overinflation of lungs and damage elastic tissue that allows recoil
The lungs move during respiration. What attaches the lungs to the body wall?
Visceral pleura
Where is the greatest resistance in the respiratory tract and why?
URT
Turbulent airflow
What factors affect resistance to airflow?
Turbulence
Diameter
Length (increased length increases resistance)
What factors does lung compliance depend on?
Surface tension
Elasticity
What is the equation for partial pressure?
Pp = portion of gas X total pressure
Is oxygen soluble? How can more oxygen be soluble?
Not very soluble but dissolves until equilibrium reached
To get more to dissolve need higher pressure gradient
What happens to the partial pressure of oxygen as it travels from the atmosphere into the respiratory tract? What are the 2 reasons for this?
PP of O2 decreases
- Humidifies - need to take into account PP of H20
- In alveoli gas exchange is constant, so PP of O2 not always high
What is the reversible equation for H2O + CO2?
H2O + CO2 –> H2CO3 –> H+ + HCO3-
What is cooperative binding?
Binding of oxygen to haemoglobin changes the affinity for other molecules to bind
Same with offloading - easier to lose
What affects offloading of oxygen from haemoglobin?
Temperature, pH, CO2, DPG
What is DPG?
Molecule which adjusts haemoglobin’s affinity for oxygen
Does oxygen saturation ever reach 100%?
No
What are the 3 ways that carbon dioxide can be carried?
Bicarbonate ions (HCO3-)
Dissociated in plasma
Carbamino acids
How does fast and deep breathing change concentration of CO2 in blood?
Decreases CO2 concentration
Shifts equation to right
Increases pH
What is pH?
Log of H+
What is the normal pH of blood? What is it outside of these ranges?
7.4
<7.35 = acidosis
>7.45 = alkalosis
H+ has respiratory and metabolic origin. What are the 3 ways that control amount of H+ in the body?
Kidneys
Buffering
Lungs/ventilation
When experiencing metabolic acidosis, how does breathing change?
Increases and more deeply to remove H+ ions
During respiratory acidosis, what do the kidneys do to lower pH?
Form and retain bicarbonate ions for buffering
Excrete H+
How is gas exchanged maximised?
Increase ventilation and perfusion
Ventilation:perfusion should be matched
Which nervous system varies ventilation? Is this effective?
Autonomic NS
No - overwhelmed by local factors of lung
How is blood flow to alveoli varied?
By hypoxic pulmonary vasoconstriction
Autonomic NS
Nitric oxide
If blood flow speed increase, what does nitric oxide do?
Causes vasodilation
What controls respiration? How?
Respiratory centre in medulla oblongata and pons
Have central and peripheral chemoreceptors and Hering-Breur receptors (stretch)
Conscious control
Joints and muscle receptors inform about exercise
What do alpha and beta receptors do in terms of vessel size? (Same as in cardiovascular)
Alpha - vasoconstriction
Beta - vasodilation
What causes the oxygen dissociation curve to shift left?
Decreased temperature
Decreased DPG
Decreased H+
What causes the oxygen dislocation curve to shift right?
Increased temperature
Increased DPG
Increased H+
