Respiration Flashcards
(31 cards)
What are the two forms of respiration?
Tissue - aerobic metabolism in cells
Ventilation - Gas exchange and all associated processes
At rest what is the PO2 and PCO2?
PO2 = 100 mmHg PCO2 = 40 mmHg
What is the pathway for air to enter the lungs?
Air enters into nasal/oral cavities Pharynx Larynx Trachea/Bronchi Lungs Alveoli
What is the role of the upper airways?
Filter and humidify air, keeps surface of the system from being damaged and removes particles in air
Describe the process of quiet breathing.
During inspiration, diaphragm contracts and external intercostal muscles contract causing the thoracic cavity to expand, this means the intrapleural pressure drops below the atmospheric pressure making a pressure gradient so air flows into the lungs.
The process of normal expiration is passive, elasticity of the lung tissue causes the lung to recoil, as the diaphragm and intercostal muscles relax following inspiration. In turn, the thoracic cavity and lungs decrease in volume, causing an increase in interpulmonary pressure. The interpulmonary pressure rises above atmospheric pressure, creating a pressure gradient that causes air to leave the lungs.
What accessory muscles contract in forced breathing to aid the diaphragm and external intercostal muscles?
Muscles of the neck
Accessory muscles of the abdomen - obliques (force organs against diaphragm)
Internal intercostals - compress rib cage
What are conducting zones?
Areas of the respiratory tract where gas exchange does not occur
Nose, pharynx, larynx, trachea, bronchi, bronchioles
What are the two types of alveolar cells?
Type 1 epithelial cell - occupy 97% of SA and site of gas exchange
Type 2 epithelial cell - occupy 3% and produce a surfactant to act as a lubricant to reduce surface tension
What are the two circulation systems of the lung?
Pulmonary circulation - bring deoxygenated blood to the lungs to become oxygenated before returning to heart for circulation
Bronchial circulation - brings oxygenated blood to the lung parenchyma
What is the normal V/Q ratio?
0.8
Where is ventilation the greatest in the lung and why?
Ventilation not evenly distributed throughout lung due to gravity. Greater Ventilation at base of alveoli than at apex, therefore greater perfusion at the base than apex.
How is the respiratory and CVS systems specialised?
Large SAs for gas exchange
Large partial pressure gradients
Specialised mechanisms for transporting O2 and CO2
How can oxygen be transported around the body?
Dissolved - proportionate to partial pressure, for every 1mmHg O2 there is 0.003ml/100m2 of O2
Bound to haemoglobin - major transport system molecule
What can be used to determine oxygen saturation in the body?
Pulse oximeter
What does a V/Q ratio of 0.8 indicate?
The body produces 80 molecules of CO2 for every 100 molecules of oxygen inhaled
How is CO2 transported?
Dissolved - 7%
Bound to haemoglobin - 23%
Bicarbonate - 70%
How is bicarbonate produced?
Catalyzed by carbonic anhydrase, carbon dioxide (CO2) reacts with water (H2O) to form carbonic acid (H2CO3), which in turn rapidly dissociates to form a bicarbonate ion (HCO−
3 ) and a hydrogen ion (H+)
Where can carbonic anyhdrase be found?
In the blood
Duodenum
What is needed to maintain a 7.4 pH of the blood?
20:1 bicarbonate to carbonic acid ratio
Mainly mediated by pH sensors in medulla oblongata and probably in kidney
Where in the brain controls breathing and through which signal receptors?
In the brainstem through:
- Sensory Chemoreceptors and Baroreceptors - Feedback on PO2, PCO2 and pH in blood.
- Mechanoreceptors - found in walls of lungs
These signals will be sent via vagus nerve to the NTS in the brainstem.
Where are baroreceptors found in relation to the aorta?
In the aortic arch
In the carotid sinuses of the common carotid arteries
Where are chemoreceptors found in relation to the aorta?
In the aortic and carotid bodies
What is the Total Lung Capacity?
The volume in the lungs at maximum inflation, the sum of vital capacity and residual volume.
What is the Tidal Volume?
Vol of air moved into or out of the lungs during quiet breathing, approx 500mL per inspiration
