Functions of the respiratory system
- supply body with O2, removal of CO2
- provides airway for respiration
- moistens and warms entering air
- filters and cleans inspired air
- serves as a resonating chamber for speech
- houses olfactory receptors
trachea
- located anterior of esophagus
- cartilage rings prevent from collapsing
- mucous secreted into lining to trap debris
- cilia beat to push debris trapped by mucous upwards towards pharynx
conducting zone
- nose, nasal cavities, pharynx, larynx, trachea, bronchi, terminal bronchioles
>conducts air to respiratory zones
>filters, humidifies and warms air
respiratory zone
- respiratory bronchioles, alveolar ducts, alveoli
> site of gas exchange
conducting zone structures
trachea > primary bronchi > secondary bronchi > tertiary bronchi > terminal bronchioles
respiratory zone structures
respiratory bronchioles > alveolar ducts > alveolar sacs
nose
produces mucus, filters, warms and moistens air, resonance chamber for speech
paranasal sinuses
mucus lined, air filled cavities in cranial bones surrounding nose
- same as nose except no receptors for smell
- lightens skull
pharynx
passageway connecting nasal cavity to larynx and oral cavity to esophagus
- passageway for air and food
larynx
connects pharynx to trachea
has framework of cartilage and dense connective tissue
opening can be closed by epiglottis or vocal folds
- air passage way, prevents food from entering lower respiratory tract
developmental aspects
- lungs dont work in fetus
- blood bypasses lungs
- blood is oxygenated and co2 removal is via placenta
- at birth respiratory centres activated, alveoli inflate and lungs start to function
- 2 wks after birth before lungs are fully inflated
aging and the respiratory sistem
- respiratory efficency decreases
- reduced lung compliance
- reduced exercise restricts usage and inflation
- bones ache, limiting inflation
- poor nutritional status
- clearance poor (inc. aspiration pneumonia)
- development of chronic conditions (COPD)
- possible strokes, circulatory problems
links to other body systems
- provide oxygen for muscle activity and normal neural activity
- blood is medium transport for O2 and CO2
- digestive system provides nutrients needed by respiratory organs
- kidney dispose of metabolic wastes of the respiratory system
inspiration
- external intercostal muscle contract > rib cage elevates
- diaphragm contracts > move downwards & causes intrapulmonary pressure to decrease
- air flows from high pressure to low pressure withing lungs> leads to air flowing into the lungs
expiration
- external intercostal muscles relax > rip cage return to original position
- diaphragm relaxes > move back upwards and cause thoracic cavity vol to decrease
- air flows from high pressure (in lungs) to low pressure > air flows out of lungs
gas exchange
- movement of O2 and CO2 by simple diffusion along a concentration gradient
- occurs between lung and blood ( external respiration)
- between blood and tissues (internal respiration)
Boyles law
- ventilation > movement of air in and out of lungs
- gas pressure and vol are inversley related
- thoracic vol inc > intrapulmonary pressure decreases > air enters lungs
- thoracic vol dec. > intrapulmonary pressure inc >air exits lungs
Daltons law of partial pressure
- total pressure exerted by mixture of gases = sum of pressures exerted by each gas
- partial pressure
> pressure exerted by each gas in mixture
> directly proportional to its percentage in mixture
Henrys law
gas mixtures in contact w/ liquid
- each gas dissolves in proportion to its PP
- @ equilibrium, pp in 2 phases will be equal
- amount of each gas that will dissolve depends on
> solubility- CO2 20 times more soluble in water than O2; little N2 dissolves in water
> temperature - as temp rises, solubility decreases
external respiration
- exchange of O2 and CO2 across respiratory membrane in lungs between alveoli and pulmonary capillaries
- pp o2 higher in alveoli compared to in pulmonary capillaries > O2 diffuses into blood from alveoli (oxygenating blood)
- pp presure co2 higher in pulmonary capillaries compared to alveoli > CO2 diffuses into alveoli from blood to be exhaled
external respiration influencers
- thickness and surface area of respiratory membrane
- partial pressure gradients and gas solubility
- ventilation-perfusion coupling
internal respiration
- exchange of co2 and o2 in body tissues between cells and systemic capillaries
- pp and diffusion gradients reversed compared to external
> pp o2 in systemic capillaries higher compared to in cells - oxygen diffuses from blood tissues (o2 to be used by cells)
> pp co2 in cells higher compared to in systemic capillaries - co2 diffuses from tissues to blood (co2 to be transported to lungs for removal)
oxygen transport
- 1.5% dissolved in plasma
- 98% loosely bound to iron atoms present in hemoglobin present within red blood cells
- 4 molecules o2 per Hb
co2 transport
3 forms:
- 7-10% dissolved in plasma
- 20% bound to globin of hemoglobin (carbaminohemoglobin)
- 70% transported as bicarbonate ions in plasma
