What is Cystic Fibrosis?
Structures in the lungs
Endothelium
a single layer of squamous epithelial cells to create a short diffusion distance
Types of epithelium
What type of epithelial cells are found in the lungs?
pseudostratified ciliated columnar epithelium
fake - has layers, has cilia, tall
Cilia
hair like structures beat and move mucus up and out of lungs
Basement membrane
holds cell in position, touching connective tissue
Goblet cell
produces mucus which is released into the airway
Apical membrane
in touch with gases and mucus
How does the structure of alveoli and surrounding capillaries ensure there is rapid diffusion across the gas exchange surface?
How does the rate of diffusion change as an object gets bigger?
the rate of diffusion doesn’t change we just expect it to travel further
Diffusion
the net movement of particles from a high concentration to a low concentration (down a concentration gradient) until equilibrium is achieved
PASSIVE
Factors affecting diffusion
-concentration gradient
-surface area
-diffusion distance
(-temperature –> not relevant as body temperature)
How do we maintain the concentration gradient?
- lots of ventilation (breathe in/out)
Fick’s Law
the rate of diffusion is proportional to the (surface area x concentration difference) / membrane thickness
What happens in the lungs of a CF sufferer?
Typical cell membrane
phospholipid bilayer
Phospholipid
has a phosphate head and 2 fatty acid tails (is made by removing a fatty acid from a triglyceride and replacing it with a phosphate)
Why does a bilayer form?
What is the most stable arrangement for phospholipids?
a bilayer
Phospholipid bilayer function
provides stability, fluidity and selective permeability (to small non-polar molecules)
Proteins and glycoproteins function (protein and carbohydrate)
many diverse functions: channels, transporters, receptors, enzymes
Glycolipid function (lipid and carbohydrate)
involved in cell cell recognition
Cholesterol function
reduces membrane fluidity