Respiratory Systems Flashcards
What is external respiration?
The delivery and removal of gases to and from tissues and cells.
What is partial pressure?
The pressure of a single gas within a mixture of gases.
What influences diffusion?
Partial pressure gradient. Gas molecule diameter. Temperature. Gas solubility. Gas exchange surface surface area. Gas exchange surface thickness.
What is Fick’s Law?
Rate of diffusion =
DCSA(PP difference/interface thickness)
What is the order of the structures of the human respiratory system?
Nasal cavity Pharynx Larynx Trachea Primary bronchus Lungs
Where is the dead space in the lungs?
Includes trachea, bronchi, bronchioles and terminal bronchioles.
What is the function of the dead space?
Transfers gases to the alveoli.
Warming/Humidifying.
Filtration.
What muscle separates the abdomen and the thorax?
The diaphragm.
How do birds maximise gas exchange?
They use unidirectional airflow. This means oxygen is received during inhalation and exhilation.
What structures do birds possess that allow unidirectional flow?
Posterior and anterior air sacs.
Define ventilation.
Convection of a respiratory medium over the gas exchange surfaces.
What covers the lungs of mammals?
2 pleural membranes.
Is intrapleural pressure positive or negative? Why is this important?
Negative, to ensure the lungs are inflated.
Is inspiration active or passive?
It is an active process as it requires muscle contraction.
What is the sequence of inspiration?
Diaphragm and external intercostals contract.
Thoracic volume increases.
Intrapleural pressure decreases.
Alveoli expand.
Alveolar pressure < atmospheric pressure so air flows into lungs.
Is expiration active or passive?
Passive excluding forced expiration.
What is the sequence of expiration?
Elastic recoil of the lungs and chest wall reduces thoracic volume.
Intrapleural pressure increases.
Alveoli recoil.
Alveolar pressure > atmospheric pressure so air flows out of lungs.
What are the 3 resistive forces which oppose airflow during inspiration?
Airway resistance.
Pulmonary tissue resistance.
Inertia of the air and tissues.
What are the 2 resistive forces which assist airflow during expiration?
Elastic recoil of the lungs and chest wall.
Alveoli surface tension.
How do laminar flow and turbulent flow differ?
Laminar flow = slow flow + parallel streams
Turbulent flow = high flow + disorganised streams
What is radial traction?
As the lungs expand, connective tissue pulls on bronchioles so diameter increases and airway resistance decreases.
Is radial traction passive or active?
It is passive.
Is dynamic compression active or passive?
It is active.
What is dynamic compression?
This process only occurs at low lung volume or during forced expiration. It involves the airways compressing/closing in order to expel air.
What can cause bronchioconstriction?
Irritants causing a reflex.
Parasympathetic stimulation.
Fall in PCO2.
Asthma.
What can cause bronchiodilation?
Autonomic stimulation.
Sympathomimetic agents.
How can infections increase airway resistance?
Via tissue inflammation or mucus overproduction.
What fibres are found in alveolar walls that give them elastic recoil?
Elastin and collagen.
Alveoli are fluid lined. What problems can this air-fluid interface cause?
Surface tension can oppose expansion.
Promotes collapse of smaller alveoli, leading to a lower SA.
Can cause transudation from the capillaries.
Which cells secrete pulmonary surfactant?
Type II alveolar cells.
What does pulmonary surfactant do?
Lowers surface tension of liquid layer.
Prevents alveolar collapse.
Where do pleural membranes converge?
At the Hilum of the Lung.
What is the benefit of countercurrent flow?
Allows up to 100% of O2 to diffuse into the gills compared to 50% of O2 with a concurrent system.
What shape is the oxygen dissociation curve?
Sigmoidal.
What is the average resting PO2 in a systemic capillary?
40mmHg.
What is the average resting PO2 at a pulmonary capillary?
100mmHg.
What are 4 causes of the Bohr Shift?
PCO2 increasing.
Acidity increasing.
Temperature increasing.
2,3-BPG concentration increasing.
What does the Bohr Shift do?
Promotes oxygen release.
What is an important trait of foetal haemoglobin?
It has a greater oxygen affinity than maternal haemoglobin, in order for the foetus to utilise oxygen from its mother’s blood.
How is CO2 carried in chemical combination in blood plasma?
CO2 + H2O = H2CO3 = H+ + HCO3- = H+ + CO3-2
Guard cells control air and water entry into the plant. What causes them to open?
Potassium ion influx.
Increased turgor pressure.
Where is the pattern generator for breathing?
The medullary respiratory centre.
What controls inspiration?
The Pre-Botzinger Complex.
What controls expiration?
The Retrotrapezoid Nucleus.
What are the 4 receptors found in the lungs?
Stretch receptors.
Juxta-pulmonary receptors.
Irritant receptors.
Proprioreceptors.
What other receptors can influence breathing?
Nociceptors (pain receptors).
Baroreceptors.
Thermoreceptors.
What are the 2 classes of chemoreceptors in the body?
Central and peripheral.
Where are central chemoreceptors found?
Near the medulla.
Where are peripheral chemoreceptors found?
Near the carotid and aortic arteries.
How do central and peripheral chemoreceptors differ in terms of responding to change?
Central = slower response time + insensitive to PO2
Peripheral = faster response time + increased PO2 results in increased firing.
Does high PCO2 or low PO2 cause us to breathe?
Generally, high PCO2 is the main drive to breathe.
What is the term for low PO2?
Hypoxia.
What is the term for high PCO2?
Hypercapnia.
What occurs during the diving reflex in mammals?
Reduced heart rate.
Increased peripheral vasoconstriction.
Lactate accumulation in muscles.
Energy conservation.
