L21 Respiratory Physiology 1 Flashcards
What are the two types of respiration?
Internal and external respiration
What are the stages of internal respiration?
Within the cell,
Glycolysis, Krebs cycle - CO2 produced
Oxidative phosphorylation - O2 consumed
What does external respiration do?
- Ventilation (inhalation and exhalation)
- Exchange and transport of gases around the body
Which major process does respiration rely on?
Diffusion
What happens to the time taken for oxygen to diffuse through a solution if the distance increases?
If distance of diffusion increases then the time increases since it takes longer to cross
The lungs are separated into two sections. What are they?
Conducting zone
Respiratory zone
What happens in the conducting zone of the lungs?
Filter, warm and humidify the incoming air.
How does air travel to the lungs?
Trachea —> bronchi —> bronchioles —> alveolar ducts —> alveolar sacs
What is involved in the conducting zone?
- Nose
- Nasopharynx
- (Mouth) Oropharynx
- Pharnyx
- Larynx (voice box)
- Trachea (windpipe)
-Bronchial tree
By the time air reaches the respiratory zone, it has undergone significant changes within the conducting zone. What are these changes?
Air has been:
Warmed
Humidified
Filtered
Cleansed
What tissue layers are there within the bronchial wall?
Cartilage- provides structural support
Smooth muscle - Controls diameter of airways
Mucous glands - Secrete mucus to trap particles and keep airways moist
Elastic tissue - Allows airways to stretch and recoil during breathing
Describe the structure of the respiratory epithelium
Cilitated epithelia - hair like projections called cilia that move mucus and trapped particles upwards towards the pharynx
Goblet cells - secrete mucus to trap inhaled particles
Sensory nerve endings
Why do we reinforce the bronchial wall with cartilage?
Prevents the airway from collapsing
Describe the structure of the bronchioles
Lack cartilage support (rely on surrounding lung tissue and elastic fibres for structural support)
Lined by respiratory epithelium
Proportionately more smooth muscle (allows for broncho- constriction/dilation)
Less than 1mm diameter
Describe the structure of the Alveoli
Large surface area
Terminal bronchiole ( crucial link between bronchi and respiratory zone where gas exchange occurs)
Thin walled
What is the air blood barrier?
Also known as the alveolar - capillary membrane, is an incredibly thin interface where the magic of gas exchange happens in the lungs
What are the two types of cells that create the air blood barrier?
Type 1 alveolar cells: Extremely thin, flat cells that cover most of the alveolar surface area
Endothelial cells: Cells line the capillaries that surround the alveoli
How is the air blood barrier adapted for efficient gas exchange? (4)
- Extreme thinness - minimises distance that gases must travel to diffuse across
- Large surface area - 50-100m^2
- Close proximity to alveoli and capillaries - fresh supply of blood
- Surfactant - Type II alveolar cells, reduces surface tension which prevents alveoli from collapsing, ensuring they remain open for gas exchange
Are inspiration and expiration quiet or forced?
Both of these processes can be quiet (at rest) or forced (when active e.g. during exercise)
What happens to the pressure during inspiration and expiration?
During inspiration: atmospheric pressure > alveoli pressure so air moves into the lungs
During expiration: Palv> Patmos so air moves out of the lungs
What is involved in quiet inspiration?
Diaphragm and external intercostal muscle contractions which increases thoracic cavity volume which decreases pressure within the lungs, relative to atmospheric pressure which allows air to flow in
What happens to the diaphragm and external intercostals during inspiration? What is the effect?
Diaphragm contracts so moves down
External intercostals contracts so expands
Effect - increase thoracic and lung volume
Which muscles are involved in forced inspiration?
Primary muscles: diaphragm and external intercostal muscles
Accessory muscles: Sternocleodomastoid, scalene muscles, neck and back muscles, upper respiratory tract muscles
What is involved in quiet expiration?
Passive process using elastic recoil
Relaxation of external intercostals muscles
Recoil of the lungs (elastic forces returning lungs to original size)
Diaphragm relaxes
Which muscles are involved in forced expiration?
Accessory muscles
Internal intercostals
Abdominal muscles
Neck and back muscles
What is the function of the pleura?
Pleural cavity filled with secretions
Prevents lungs from sticking to the chest wall
Enables free expansion and complete collapse of lungs
What happens to the elastic nature of lungs at rest?
Elastic nature of lungs would tend to cause them to collapse inwards
Chest wall would tend to expand
At rest, these opposing forces would balance - resulting the pressure in the intrapleural space to be less than the atmospheric pressure
What happens to the chest wall at rest ?
They would tend to expand
At rest, why is the counterbalance pressure between lungs and the chest wall at rest important?
The counter forces (inwards of lungs and outwards of chest at rest) results the pressure in the intrapleural space to be less than the atmospheric pressure
What happens to a collapse lung ?
Medically known as a pneumothorax, occurs when air leaks into the space between your lungs and chest wall. This buildup of air puts pressure on the lung, preventing it from fully expanding as you inhale
