lecture 24 Flashcards
The anatomy of respiratory system
Air flow enters:
1. Nasal cavity –> filters and conditions air
2. Pharynx —> shared tube for air and food
3. Larynx —> at the bottom of the pharynx, voice box
BRANCH POINT: splits into two (trachea and esophagus)
4. Trachea—> air goes into trachea and splits into 2 bronchi
5. Left and right bronchi —> split into smaller and smaller bronchioles
6. Bronchioles —> split into teeny tiny terminal bronchioles
7. Alveoli –> air sacs, site of gas exchange
anything below the larynx we are considering the ________
lower respiratory system
Main functions of the respiratory system
- Gas exchange: O2 uptake and CO2 release
- Homeostatic regulation of body pH: how much CO2 your expelling vs. how how your retaining can help regulate blood pH
- Conditioning inspired air: filtering it and adding water vapor
- Protection: filtering and clearing foreign particles
- vocalization: Larynx
Ventilation
moving the respiratory medium over the respiratory surface (that’s inhaling and exhaling)
Inspiration
air moves into lungs
Expiration
air moves out of lungs
The steps of external respiration
- exchange between atmosphere and lungs: trading in O2 and CO2 out
- exchange between lungs (alveoli) to blood: short diffusion distance because they are one cell layer thick
- exchange between blood to tissues: carting O2 to tissues that need stand taking CO2 away
lungs are located in _____________
thoracic cavity
which lung is smaller and why
the left lung and because of the cardiac notch
Rib cage
- protects lungs and the muscles connecting your ribs to pull ribs up and out when they contract which will increase the volume of thoracic cavity which will allow you to breath
What muscles are used in normal quiet inspiration
- external intercostals (
- diaphragm
What muscles are recruited in during forced inspiration
- sternocleidomastoids
- scalene
how to increase volume of thoracic cavity
- external intercostals will contract and will pull rib cage up and out
- diaphragm will contract and move down and flattens
The pleural membranes
- the parietal membrane: sticks to the rib cage and the wall of thoracic cavity, so when your ribs expand and move out the parietal membrane will too
- the visceral membrane: sticks to the organ itself, it is stuck to the elastic tissue of the lungs
- intrapleural fluid has a polar nature and adhesive nature so you can’t rip the two membranes apart
What happens when there is a puncture in sealed space
- lung would collapse because we pulled the visceral membrane and lung tissue away from parietal membrane because there is air in the sales space
- this is called pneumothorax
main role of airways
- filter out foreign substances (ciliated epithelium lining trachea and bronchi)
- warm air to body temperature
- adding water vapour because exchange between wet air and blood is more efficient and maximizes exchange
Can we modify the diameter of the trachea
NO! because it is surrounded by a cartilage ring so the only way we could change the diameter is to stuff smt inside like mucous which would be a respiratory infection or bronchitis
The primary bronchus divided ___ more times, terminating in a cluster of alveoli
22
What are mechanisms to modify airflow to lungs
bronchoconstrict: increase resistance, decrease air flow
bronchodilate: decrease resistance, increase air flow
mucus layer
traps inhaled particles
watery saline layer
allows cilia to push muscous toward pharynx
what happens to mucous if watery layer isn’t there
mucous will tend to sit in place and stay
what disease are u prone to have when missing the watery layer
systic fibrosis
resistance depend on total cross sectional area
- resistance is high in trachea and bronchi (small cross sectional area)
- resistance is low in bronchioles because it has a large cross sectional, but bronchoconstriction can increase resistance to reduce flow of air
modulation of bronchiolar resistance (bronchodilation)
- decreased resistance and increase air flow
- paracrine response to CO2: CO2 will build up around lungs and smooth muscles of bronchioles and act as a bronchodilator which increase air flow
- SNS response: norepinephrine/epinephrine bind to B2 adrenergic receptors in wall of bronchioles and are coupled to Gs proteins that activate AC and lead to activation of cAMP which causes relaxation of bronchiole smooth muscle
modulation of bronchiolar resistance (bronchoconstriction)
- increased resistance and decrease to air flow
- paracrine response to histamine released by local mast cells in an immune response
- PNS response: acetylcholine binds to m3 muscarinic and they are coupled to Gq proteins which activate PLC —> IP3 which triggers release of Ca2+ and bronchioles will bronchoconstrict
Features that allow or facilitate for exchange
- very short diffusion distance
- large surface area
- concentration gradient of gases
alveoli
- site of gas exchange
- make up bulk of lung tissue
- each alveolus is made up of one layer of epithelial tissue
Type 1 alveolar cells
- make up 95% of alveolar surface
- one layer of epithelium meaning short diffusion distance and good for gas exchange
Type 2 alveolar cells
- make up 5% of alveolar space
- make and secrete surfactant which helps keep lungs inflated
Fused basement membrane
sticky proteins that help hold alveoli and capillaries close together
muscles used in forced expiration
- internal intercostals and abdominal muscles
