1b - structure of cardio-respiratory system Flashcards
What is the pathway of air coming into the lungs?
- Mouth/nose
- Trachea
- Bronchi
- Bronchioles
5.alveoli
Why are alveoli well adapted?
- Very small and there are lots of them
- Have moist walls which are 1 cell thick
- Short diffusion pathway
- Surrounded by many capillaries
What happens during inspiration?
The intercostal muscles contract and the diaphragm contracts downwards to make more space in the chest cavity
What happens during expiration?
Intercostal muscles relax and the diaphragm relaxes upwards so chest cavity gets smaller.
This results in an increase of atmospheric pressure in the lungs so air is forced out
What is tidal volume?
Amount of air that enters the lungs at rest - the same amount leaves
What is inspiratory reserve volume?
Amount of extra air that can be inspired during a deep breath
What is expiratory reserve volume?
The amount of extra air expired during a forceful breath out
What is residual volume?
Amount of air that is left in the lungs after a forceful breath out. There is always a residual volume
What are the characteristics of arteries?
- Thick muscular walls to withstand pressure
- Small lumen (diameter)
- They go away from the heart
What are the characteristics of veins?
- They go towards the heart
- Thin walls - less pressure
- Larger lumen
- Contain valves to stop back flow
What are capillaries?
They join arteries to veins around organs
Thin walls for gaseous exchange
Small lumen
What is the pathway of blood in the heart?
- Vena cava
- Right atrium
- Right ventricle
- Pulmonary artery
- Lungs - becomes oxygenated
- Pulmonary vein
- Left atrium
- Left ventricle
- Aorta
What is cardiac output?
Volume of blood ejected from the heart. Usually measured in L/min
What is stroke volume?
The volume of blood ejected from the heart in one contraction
What is the equation for cardiac output?
Cardiac output = Stroke volume x Heart rate
