Structures of ventilation Flashcards
What are the 2 types of respiration?
- internal respiration
- external respiration
What occurs during internal respiration?
- within a cell
- CO2 produced - glycolysis, Krebs cycle
- O2 consumed - oxidative phosphorylation
What occurs during external respiration?
- ventilation
- exchange & transport of gases around the body
What is the function of the lungs?
an air pump, allowing exchange of gases with atmosphere. It has a huge surface area for gas exchange, allowing for efficient exchange of gases with the lungs
What type of pressure is in the pulmonary system?
low pressure system
What type of pressure is in the systemic system?
high pressure system
Why do we have control over our respiration?
the body detects the pH & CO2 levels in the blood, adjust accordingly
How many levels of branching occurs in the lungs?
23 levels of branching
What 2 pathways can branching have?
- conducting zone
- respiratory zone
What occurs in the conducting zone?
- doesn’t take part in gas exchange, but useful for getting gas in respiratory zone (first 16 layers)
- bronchi contains cartilage
- bronchioles are a smaller airways - lack cartilage (also can collapse during expiration)
What occurs in the respiratory zone?
- where gas exchange takes place
- contains alveoli - site of gas exchange
- lower levels have a huge surface area
What parts of the respiratory system are in the conducting zone?
- nose
- nasopharynx
- mouth (oropharynx)
- pharynx
- larynx
- trachea
- bronchial tree
What is the purpose in the nose?
conditions the incoming air - filter, warm, humidify & aids in filtering.
- turbulent flow allows particles to stick to mucus.
- warming the air as it travels through the nasal passage (to 37 degrees)
- solubility of gas changes with temperature - gas more soluble in a cold temperature
- warming of the blood therefore prevents bubbles in the blood.
- the air becomes saturated with water, preventing the airways from becoming desiccated (drying out)
What is the structure of bronchial wall?
- reinforced with cartilage
- smooth muscle
- mucus glands
- elastic tissues
What is in the respiratory epithelium?
- ciliated epithelia
- goblet cells
- sensory nerve endings
How large are bronchioles?
less than 1mm diameter
Describe the structure of bronchioles
- lack cartilage support
- lined by respiratory epithelium
- proportionately more smooth muscle - used to control diameter of airways
- more smooth muscle in bronchioles than in the bronchi
Describe the structure of alveoli
- large surface area
- fed from terminal bronchioles
- thin walled
- alveoli sacks - site of gas exchange
What is the air blood barrier?
- a ‘sandwich’ created by flattened cytoplasm of type 1 pneumocyte (epithelial cells) and the capillary wall
- type 2 pneumocyte - involved in surfactant production
What is necessary for gas exchange to occur?
gas exchange to take place barriers have to be crossed (large surface are for gas exchange 50-100m^2).
- aquaporin one also helps with gas transfer
What are the 2 processes involved in ventilation?
- inspiration
- expiration
What are the two types of inspiration & expiration ?
- quiet (at rest)
- forced (when active e.g. during exercise)
When does inspiration occur?
Pressure (atmosphere) > Pressure (alveoli)
When does expiration occur?
Pressure (atmosphere) < Pressure (alveoli)
Describe the physiological effect of quiet inspiration?
involves the primary muscles of inspiration:
- the diaphragm (pulled down)
- external intercoastal muscles
What is the effect of the physiological changes during quiet inspiration?
- increase thoracic & lung volume
What does it mean that air movement follows the principle of Boyle’s law?
- The increase in volume leads to a reduction in pressure
- air moves into the lungs down the pressure gradient
What occurs in forced inspiration?
The accessory (or secondary) muscle of inspiration are used:
- scalenes
- sternocleidomastoids
- neck & back muscles
- upper respiratory tract muscles
What occurs in quiet expiration?
quiet expiration is a passive process using elastic recoil.
- no primary muscles of expiration
- relaxation of external inter coastal muscles
- recoil of the lungs (elastic forced returning lungs to the original size)
- diaphragm relaxes
What is involved in forced expiration?
- accessory muscles
- abdominal muscles
- internal inter-coastal
- neck & back muscles
What is in the pleura?
pleura cavity filled with secretions
- prevents lungs from sticking to chest wall
- enables free expansion and collapse of lungs
- lines the outer part of lungs & inside of ribcage
- pleura membrane
- lungs expand as the chest wall to expand
Describe the forces in the lungs & chest at rest
- elastic nature of lungs would tend to cause them collapse inwards
- the chest wall would tend to expand
- at rest, these inward (form the lungs) & outward (from the chest) force balances - as a result the pressure in the intrapleural space is less than atmosphere
What is pneumothorax?
(collapsed lung) - usually a puncture in the chest wall
- this allows air into the intrapleural membrane, which leads to a loss of the balance.
- covering of hole will lead to reinflation of lung alongside the forces also coming to equilibrium
