Topic 3 - lungs Flashcards
Ciliated Epithelium
Trachea, bronchi, bronchioles – ciliated epithelial cells with cilia on the free surface.
Ciliated columnar epithelium appears to be stratified ! But each cell is in contact with the basement membrane. Nucleus on different levels – pseudostratified.
Epithelial Cells
Squamous (pavement) . epithelial cells - work together to make an epithelium.
Epithelium sits on a basement membrane (protein fibres)
Epithelium in the walls of the alveoli is squamous.
Epithelial tissue
Epithelial cells form a thin, smooth, flat layer.
This makes them ideal when rapid diffusion is needed.
An example is the alveoli in the lungs which provide a short diffusion pathway to allow rapid diffusion of oxygen into the blood and carbon dioxide into the lungs.
Emphysema
Smoking can damage the epithelium cells. Smoking irritates and causes inflammation and scarring in the epithelium tissue of the lungs.
The alveoli walls become thicker due to scarring and produce more mucus.
The damage to the air sacs causes emphysema and the lungs lose their natural elastically.
This causes:
Breathlessness
Persistent coughing
Phlegm
Endothelial tissue
Endothelial tissue consists of a layer of flattened cells, one layer thick.
It is found lining the heart, blood vessels and lymphatic vessels.
The cells provide a short diffusion pathway for the movement of various substances, eg.
Products of digestion into blood capillaries
Blood plasma and tissue fluid in and out of blood capillaries
Risk factors
There are a number of risk factors that can cause damage to the endothelium.
Carbon monoxide and high blood pressure can damage the inner lining of the arteries.
White blood cells repair the damage and encourage the growth of smooth muscle and deposition of fatty substances such as cholesterol under the endothelium lining of arteries, not on the surface.
Atherosclerosis
The process of deposition is called atherosclerosis.
These deposits called atheroma and may build up enough to break through the inner endothelial lining of the artery.
This eventually forms a plaque in the lumen of the artery.
This reduces the size of the lumen and restricts blood flow.
Lung Structure – Cellular Level
Ciliated epithelial cells line the airways with goblet cells
Goblet cells produce the mucus
Cilia, hair like structures, beat and move the mucus
Basement membrane holds it in position
Columnar Epithelium
Small intestine
Column-shaped cells make up the epithelium.
Surface facing the intestine lumen normally covered in microvilli- to
increase the surface area
gas exchange
Gas exchange occurs within the lungs.
Connected to the outside air with a set of tubes.
The trachea starts at the back of the moth and branches to form 2 bronchi.
One bronchus goes into each lung.
Each bronchus branches many times getting smaller and smaller form tubes called bronchioles.
All of these tubes have cartilage rings for support, except the microscopic ones.
At the end of the bronchioles are the alveoli.
Each alveolus is folded top for a set of interconnected spaces.
There are many alveoli, providing a very large surface area for gas exchange.
The alveoli are surrounded by blood capillaries transporting blood to and from the lungs
Trachea / Bronchiole
Cartilage – airways open / air resistance low
Trachea – ‘C’ shaped
Bronchi – blocks
Bronchioles smooth muscle
Warming / moistening
Hairs – traps large particles
Trachea / Bronchi – goblet cells trap small particles (very few in bronchiole)
Ciliated cells – beat to remove trapped mucus into the throat
Macrophages – Bacterial scavengers
Alveoli
Inner surface moist –prevents drying from air.
Surfactant – prevents surfaces sticking
Macrophages.
Epithelium cells – flattened for easy diffusion.
Single layer cells in capillaries.
LSA.
Large diffusion gradient for both gases
Rate of diffusion – 3 properties of gas exchange surface
Surface area – rate of diffusion is directly proportional.
Concentration gradient- rate of diffusion is directly proportional to the difference in concentration across the GE surface.
Thickness of the GE surface- rate of diffusion is inversely proportional to the thickness of the GE surface. Thicker surface, slower the diffusion.
