~Constantly supply blood with O2, and remove CO2 ~Regulate blood pH ~Passageways to lungs purify, humidify, and warm incoming air ~Capture foreign particles ~Smell ~Speech ~Push
What does respiratory system do?
Supplies body with oxygen and removes CO2 waste
What 4 distinct processes must occur to supply body with O2 and remove CO2 waste
1) Pulmonary ventilation moving air in and out of the lungs
2) External respiration: gas exchange between air and blood in lungs
3) Transport of respiratory gases = job of cardiovascular system
4) Internal respiration: gas exchange between blood and tissues
Upper Respiratory Organs
Lower Respiratory System
Right and left primary bronchus
Right and left lung
Site of carina
Only externally visible part of the respiratory system
How does air enter nose?
Through external nostrils (nares)
What does interior of nose consist of?
Nasal cavity divided by a nasal septum
What does nasal cavity consist of?
Anatomy of Nasal Cavity
Olfactory receptors are located in mucosa on superior surface
Rest of cavity is lined with respiratory mucosa
Lateral walls have projections called conchae
Separated from oral cavity by the palate
What does respiratory mucosa do?
Trap incoming foreign particles
What do conchae do?
Inc surface area
Inc air turbulence within nasal cavity
What is anterior hard palate made of?
What is posterior soft palate made of?
Muscular passage from nasal cavity to larynx
Three regions of pharynx
Superior region behind nasal cavity
middle region behind mouth
inferior region attached to larynx
What are oropharynx and laryngopharynx common passageways for?
air and food
Voice box - plays role in speech
Routes air and food into proper channels
Made of eight rigid hyaline cartilages and a spoon-shaped flap of elastic cartilage (epiglottis)
True vocal cords
Vibrate with expelled air to create sound (speech)
opening between vocal cords
4 in long tube that connects larynx with bronchi
Walls reinforced with C-shaped hyaline cartilage
Lined with ciliated mucosa - beat continuously in opposite direction of incoming air and expel mucus loaded with dust and other debris away from lungs
Pseudostratified columnar epithelium locations
Respiratory tract from nasal cavity to bronchi
What do the relaxation/contraction of circular smooth muscles lining the "airways" do?
Determines how easily airflow can occur (bronchodilation vs. bronchoconstriction)
Most gas exchange occurs in ~8M alveolar sacs
What is found between lungs and thoracic wall?
What drives ventilation cycle?
Movement of thoracic wall by skeletal muscles
From a thin double-layered serosa. Parietal pleura covers thoracic wall and superior face of diaphragm. Visceral pleural covers external surface of the lung
Formed by pleurae, lives in pleural cavity. Provides lubrication of lung to prevent friction while breathing
Infection or inflammation of pleura and often results from pneumonia. This results is roughening of the pleura, which creates friction and a stabbing pain with each breath. As the disease progresses there is a build-up of fluid, which hinders breathing
Occupy most of thoracic cavity - heart occupies central portion called mediastinum
Apex is near clavicle (superior portion)
Base rests on diaphragm (inferior portion)
Each is divided into lobes by fissures - Left has two lobes, right has three lobes
Respiratory Zone structures
Alveoli (air sacs)
Site of gas exchange = alveoli only
Respiratory Membrane (Air-blood Barrier)
On one side of it is air and on the other side is blood flowing past
Thin squamous epithelial layer of respiratory membrane
lines alveolar walls
Alveolar pores of respiratory membrane
connects neighboring air sacs
Pulmonary capillaries of respiratory membrane
cover external surfaces of alveoli
What are bronchioles and clusters of alveoli surrounded by?
How are CO2 and O2 exchanged across capillary and alveolar walls?
What does extensive branching of alveoli produce?
Lots of surface area for exchange between air and blood
What do thin walls of alveolar and capillary walls permit?
Rapid diffusion of gases
Where is the site of gas exchange?
What do Type II alveolar produce?
What is surfactant?
Detergent-like substance that reduces the surface tension by disrupting the cohesive forces between water molecules
What do surfactants result in?
An increase in lung compliance and a decrease in the force needed to inflate the lungs
When does surfactant synthesis begin in humans?
Not until late gestation
Measure of lung's "stretchability"
What happens when lung compliance is abnormally high?
Lungs might fail to hold themselves open, and are prone to collapse
What happens when lung compliance is abnormally low?
The work of breathing is increased
Two major determinants of lung compliance:
1) Stretchability of lung tissues
2) Surface tension at the air-water interfaces within the alveoli
How does gas cross the respiratory membrane?
Where does oxygen enter in gas exchange?
Where does CO2 enter in gas exchange?
What are alveolar macrophages?
What do alveolar macrophages do?
Add protection by picking up bacteria, carbon particles, and other debris
What does surfactant do in gas exchange?
coats gas exposed to alveolar sufaces
Completely mechanical process that depends on volume changes in the thoracic cavity
Phases of pulmonary ventilation
What do volume changes during pulmonary ventilation lead to?
Pressure changes, which lead to flow of gases to equalize pressure
What does Boyle's law say?
That at a constant temperature the pressure of gas varies inversely with its volume
The pressure of a fixed number of gas molecules is inversely proportional to the volume of the container
Pressure and volume enjoy an inverse relationship
Always relative to atmospheric pressure
measured in mmHg or atmospheres(atm)
760 mmHg or 1 atm at sea level
Pressure different in mountains...duh
Function of pressure differences between alveoli (Palv) and atmosphere (Patm) divided by airflow resistance (r)
Presence of air in intrapleural space/causes lung collapse/air in space decreases pressure on that side of thorax, collapsing lung
Puncture of plural sac
Always negative compared to the atmosphere.
Why must intrapleural pressure be negative compared to the atmosphere?
In order to exert a pulling action on the lungs.
Number for intrapleural pressure
Varies from -4 mmHg at end of expiration to -8 mmHg at end of inspiration
What happens during inspiration?
Diaphragm and external intercostal muscles contract
Size of thoracic cavity increases
What causes external air to be pulled into lungs during inspiration?
Increase in intrapulmonary volume
Decrease in gas pressure
What does expiration depend on?
natural lung elasticity - largely a passive process
As muscles relax in expiration, why is air pushed out of the lungs?
Decrease in intrapulmonary volume
Increase in gas pressure
How can forced expiration occur mostly?
By contracting internal intercostal muscles to depress the rib cage
Normal pressure within pleural space
Is always negative (intrapleural pressure)
Inequality for when does air enter lungs
P alv < P atm
Inequality for when air exits the lungs
P alv > P atm
What is inspiration the result of?
The expansion of the thoracic cage in response to skeletal muscle contraction
What does expansion of the thoracic cage reduce?
Alveolar pressure (Palv) below Patm, so air moves into the lungs
What is expiration the result of?
Reducing the volume of the thoracic cage; in a resting person, this occurs in response to skeletal muscle relaxation
What does thoracic cage volume reduction increase?
Alveolar pressure (Palv) above Patm, so air moves out of lungs
What do differences in lung and pleural space pressures do?
Keep lungs from collapsing
Volume moved in or out during a normal breath
Inspiratory reserve volume
volume that can be inhaled during forced breathing in addition to tidal volume
expiratory reserve volume
volume that can be exhaled during forced breathing in addition to tidal volume
volume that remains in lungs at all times
Vital Capacity (VC)
the maximum volume which can be ventilated in a single breath
VC=IRV + TV + ERV
Total Lung Capacity (TLC)
VC + residual volume
What is the concentration of each gas proportional to?
Its partial pressure
What does all passage happen through?
Gases dissolved in water
Factors affecting diffusion rates:
Solubility (Henry's Law)
routing blood to areas well perfused with blood
What does uptake of CO2 lead to?
Production of carbonic acid, then bicarbonate with H+ ions. Those H+ ions bind to oxyhemoglobin, decrease affinity for O2, liberated oxygen diffuses across
Why can you live for a few minutes after respiratory arrest?
There is still O2 bound to hemoglobin for a few minutes
Which gases compete for binding sites?
O2 and CO2
Does 02 or CO2 bind more tightly?
CO2 at 210 times as tightly
Physiological adaptations of bar-headed geese
Breathe more deeply and efficiently under low oxygen conditions
Hemoglobin of their blood has higher affinity for oxygen
Left ventricle that is responsible for pumping oxygenated blood to body has sig more caps
Larger wing area
Birds have no dead space
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