Lecture 16- Anatomy of the thorax and breathing Flashcards
Which of these is not associated with the respiratory membrane? A. Capillary endothelium B. Simple squamous epithelium C. Type 1 pneumocytes D. Type 2 pneumocytes E. Fused basement membrane
D. Type 2 pneumocytes
Which cells remove debris from the alveoli?
A. Pseudostratified ciliated columnar epithelium
B. Goblet cells
C. Type 1 pneumocytes
D. Type 2 pneumocytes
E. Macrophages
E. Macrophages
What are all our body cavities lined with?
- Serous membranes
- Is a double layer of secretory tissue with fluid between layers to allow for the smooth movement of the organs contained within it (lubricant)
- The visceral layer is on the organ (inside)
- The parietal layer on body wall (outer)
What are the two body cavities?
- Thoracic cavity
- Abdominopelvic cavity
What are the two serous membranes contained in the thoracic cavity?
- Pericardium (around heart)
- Pleura (around each lung)
What is the Mediastinum?
Within the thoracic cavity. Takes up the middle region and include the heart, vessels and pericardium.
What are the boundaries of the thoracic cavity?
- Anterior: Sternum
- Posterior: Thoracic vertebrae
- Lateral: Ribs
- Superior: base of neck
- Inferior: diaphragm (only one that is not a bone)
Why are the lungs in two separate pleural cavities?
Independent, if one stops functioning, you have another
What is the relationship between pressure and volume in the lungs?
- Pressure is inversely proportional to volume in a relationship called Boyle’s law P=1/V
- If change one the other will change
How is pressure measured in the lungs?
By collisions:
- smaller space = more collisions = increased pressure
- bigger space = less collisions = decreased pressure
How do pressure changes drive ventilation?
To breathe, we need to establish a pressure gradient to make air move…
-Between breaths- pressure inside cavity = pressure
outside. No gradient therefore no movement
-Increase volume (therefore decrease pressure) – air
flows in= inhalation
-Decrease volume (therefore increase pressure) - air flows out= exhalation
What are alternative names of exhalation and inhalation and what happens to the volume of the thorax (one word answer)?
- Inhalation= Inspiration: volume increases
- Exhalation= Expiration: volume decreases
Where will air move?
To the lower pressure space
What are the names of the anterior thoracic joints? Where are the located?
-Sternocostal: Connect cartilage to the sternum
Synovial, Except 1st = cartilaginous
-Costochondral: Connect ribs to cartilage. Cartilaginous
-Interchondral: connect different parts of cartilage. Synovial
Do the ribs connect directly to the sternum?
No instead there is a band of hyaline cartilage
Why are there differences in the types of joints making up the thoracic cage?
- Cartilaginous is when a bit more stability is needed
- Synovial is when more movement is wanted
What are the names of the posterior thoracic joints? Where are the located?
In general articulate the thoracic vertebrae and the ribs
-Costotransverse: between rib and transverse
process of vertebrae
-Costovertebral between rib and body of vertebrae
What joint type are the posterior thoracic joints?
All synovial (want a bit of movement)
Which of the thoracic joints are NOT synovial joints?
-Costochondral (between cartilage and ribs)
-Also the 1st of the sternocostal.
Why? Because they require a bit more stability
What is the general role of respiratory muscles?
- Pull on the bones to create movement
- Move the rib cage to allow us to breathe
What are the two primary inspiratory
muscles?
- Diaphragm
- Intercostals (muscles between ribs)
What are accessory muscles in respiration?
-Several muscles that attach to the thoracic
cage and are active only when needed
-Some accessory muscles increase cavity volume for
forced inspiration. Other accessory muscles decrease cavity volume for forced expiration
What is the diaphragm and how does it differ when contracted as opposed to relaxed?
-Is a sheet of skeletal muscle that separates the thorax from the abdomen
-When relaxed is dome-shaped
-When contracted it flattens expanding the thoracic
cavity (and compressing abdominopelvic cavity)
What are the intercostal muscles and how do they differ when contracted as opposed to relaxed?
-Attach diagonally between neighbouring ribs a made of 2 bands of muscle
-External intercostals when contracted lift ribcage and
expand the cavity resulting in inspiration- quiet and
forced
-Internal intercostals when contracted depress ribcage and decrease cavity resulting in expiration- forced only
What happens to respiratory muscles in inspiration? How does this differ between quiet and forced inhalation?
During normal ‘quiet’ inspiration:
- Diaphragm contracts = flattens
- External intercostals contract = lifts ribs
During active ‘forced’ inspiration:
-As above, plus accessory muscles contract to further
expand thoracic cavity
What happens to respiratory muscles in expiration? How does this differ between quiet and forced exhalation?
During normal ‘quiet’ expiration:
- Passive process
- Diaphragm relaxes = dome shaped
- External intercostals relax = ribs no longer lifted
During active ‘forced’ expiration:
-As above plus:
-Internal intercostals contract = depress ribs
-Accessory muscles contract to further decrease cavity
volume
How do the lungs expand as the cavity does?
-Lung tissue is elastic and always trying to recoil
-Therefore the pleura make the lungs ‘stick’ to the
thoracic wall
-Lungs expand during inspiration
-Lungs decrease during expiration
What is the chain of events that occurs after there is an increase in volume of the thorax?
Increase volume of thorax means increase volume of lung means decrease pressure in lung means air flows in
