Respiratory system Flashcards
How much alveoli do lungs contain?
Lungs contain about 500 million tiny alveoli air sacs
How wide are the alveoli
The alveoli are 250µm wide and are surrounded by capillaries
How does the alveolar epithelium maximise gas exchange?
- Excellent blood supply
- Thin cellular membrane
- Large surface area
Why is breathing required?
Breathing (physical ventilation) is required to maintain high O2levels and low CO2
at respiratory surfaces / arterial blood
What does diaphragm and rib muscle contractions lead too?
Diaphragm and Rib muscles contract to create small negative
pressures of 1 – 2 mmHg that sucks air in to the lungs
What are breathing disorders in humans?
Lungs are delicate and affected by serious disorders:
Acid based disorders caused by insufficient/ excess breathing
- In obstructive and chronic obstruction pulmonary diseases forced vital capacity is reduced e.g. asthma
What is CNS control of breathing
1) Pons enables voluntary control and smooths the transition between breathing in and out
2) Medulla detects pH changes due to increased CO2 levels and controls breathing rate. Rhythm is set by neurons
3) Nerves from medulla respiratory groups stimulate the diaphragm and rib muscles to inhale and exhale
What is the peripheral control of breathing rate?
Sensors in the carotid artery detect blood O2 and CO2 and pH levels to help regulated the activity of the medulla
What do proprioreceptors do?
Sensors in muscles and tendons
(proprioceptors) also help increase
respiratory rate during movement
