Respiratory 1 Flashcards
4 primary functions of respiratory system
- Exchange of gases between atmosphere and blood
- Homeostatic regulations of body pH
- Protection from inhaled pathogens and irritating substances
- Vocalization
By what mechanism does air exchange occur
Bulk flow
What principles does air exchange occur similar to CV system
- Flow from region of high to low pressure
- Muscular pump creates pressure gradients
- Resistance is influenced by diameter of tubes through which air is flowing
What is external respiration
Movement of gases between environment and cells within body
- all processes other than cellular respiration
What is the 4 steps of external respiration
Exchange 1: atmosphere to lung (ventilation)
2: lung to blood
3: transport of gases in the blood
4: blood to cells
What does external respiration require
Coordination between the respiratory and CV systems
- don’t want one working harder
3 structures involved in ventilation and gas exchange
- Conducting system or airways
- Bones and muscles of thorax
- Alveoli
What are muscles involved in ventilation
Sterocleidomastoids,scalenes, intercostals, diaphragm, abdominal
Upper airways
Nasal cavity, mouth, pharynx, larynx
What are lungs composed of
Light spongy tissue that is occupied mostly of air-filled spaces (alveoli filled with air)
Which lung is larger
Right lung: 3 lobes
Left lung: 2 lobes because cardiac notch for heart
What is each lung surrounded by
Double walled pleural sac
What are 2 parts of pleural sac surrounding lungs
Visceral pleura and parietal pleura
Visceral pleura
Connected to outside surface of lungs
Parietal pleura
Connected to inside surface of thoracic cavity
What exists between pleura layers
Fluid
What are functions of fluid between pleura
- created moist slippery surface (no friction)
- holds lungs tight to thoracic wall (they want to recoil but held together like two panes of glass with water between)
Stages of air flow
Nasal cavity/mouth -> pharynx-> larynx -> trachea -> primary bronchi -> smaller bronchi -> bronchioles -> alveoli
What is trachea
Semi flexible tube held open with 15-20 cartilage rings
How do airways follow similar branching to CV system
Every division 2 daughter airways have greater C.S.A. Than parent
What is velocity of airflow inversely proportional to
Cross sectional area
What surrounds bronchioles
Smooth muscle
How do upper airways and bronchi condition air before reaching alveoli
- Warm air to body temp
- Add water vapour
- Filtering out foreign material
What type of breathing is more efficient in conditioning air
Nose breathing
How does nasal cavity make conditioning air more efficient
Large surface area
Rich blood supply
Nasal hair (filters foreign material)
How does the shape of the nasal airway affect the efficiency of conditioning air
Causes particles to embed in mucus at back of pharynx and slide down to esophagus
Where does further filtration occur
Trachea and bronchi
What 2 cells are in the trachea for filtration
Ciliated epithelia and goblet cells
What do the epithelial cells produce
Saline
What do the goblet cells produce
Mucus
What covers the cilia
Saline covers cilia and mucus sits over the saline
What does mucus contain
Immunoglobulins
What is the mucocilliary escalator
Epithelial cells contain cilia which push mucus towards the pharynx
What do the cilia do
Beat upward pulling saline layer, which pulls mucus so anything imbedded will move up to pharynx and down esophagus or expelled
How do particles get imbedded in mucus
Trachea large so velocity of air flow rapid and turbulent, particles hit walls
Why is saline necessary for mucocilliary escalator function
Cilia move saline which pulls mucus layer upward
- without cilia would become embedded in thick mucus and unable to move
What is the CFTR channel (cystic fibrosis transmembrane conductance regulator)
Produces saline
Steps of CFTR channel
- NKCC transporter on basolateral layer moves Na, Cl, K, into cell
- CFTR allows CL to enter lumen and created electrochemical gradient
- Gradient draws Na from ECF to lumen
- NaCl movement created concentration gradient so water follows into lumen
What causes cystic fibrosis
Mutation in gene producing CFTR
Reduces production of saline
What happens in cystic fibrosis
Mucus cannot be cleared allowing bacteria to colonize in airways leading to lung infections
Also affects pancreas
What is the site of gas exchange
Alveoli
How many alveoli in adult respiratory system
300-600 million
Where are alveoli
Clustered at ends of bronchioles
What are characteristics of alveoli
Heavily vascularized- 80-90% covered
Huge surface area
What is alveolar structure
Type 1 alveolar cell
Type II alveolar cell
Macrophage
What is type I alveolar cell for
Gas exchange
95% of surface area
What is type II alveolar cell for
Produces surfactant for fluid
How much of total blood volume does pulmonary circulation contain
0.5L or 10% (75ml in capillaries)
Why is rate of blood flow through lungs high
CO is equal in pulmonary and systemic circuits
What is systolic and diastolic of pulmonary circuit
25/8 mmHg
How does pulmonary circuit maintain same rate with low pressure
- low resistance (shorter circuit, more distensible, larger CSA of arterioles)
- doesn’t pump against gravity
What does low pressure mean for filtration
Minimal filtration of fluid out
- lymphatics remove any fluid that does get filtered and keeps diffusion distance to minimum
