6.5 - Human Gas Exchange System Flashcards
(12 cards)
Adaptations of pulmonary capillaries for gas exchange (5):
- Thin walls(one endothelial cell thick) - This maintains a short diffusion distance.
- Red blood cells pressed against capillary walls- Thisreduces diffusion distance.
- Large surface area-This increases diffusion speed.
- Movement of blood- Thismaintains steep diffusion gradient.
- Slow blood movement - Thisallows more time for diffusion.
What does the pulmonary blood vessels consist of (3):
- the pulmonary artery - this delivers deoxygenated blood from heart to pulmonary capillaries
- the pulmonary veins - delivers oxygenated blood from capillaries to heart
- pulmonary capillaries - site of gas exchange between blood and alveoli
Adaptations of the alveoli for gas exchange (8):
- Wall consists of one layer of squamous epithelial cells- This allows rapid diffusion.
- Large surface area- Thisincreases rate of gas exchange.
- Partially permeable- This means that only certain gases can move across the wall.
- Surrounded by dense network of capillaries- These bring blood close to air for gas exchange.
- Ventilation of air- Thismaintains steep diffusion gradient.
- Elastic fibres- These allow stretching and recoiling.
- Collagen fibres- These contain strong collagen that prevents alveoli from bursting and limits overstretching.
- Moist inner surface - Thisallows gases to dissolve, and lung surfactant helps alveoli remain inflated.
How does the alveoli carry out gas exchange? (2)
- oxygen diffuses from the alveoli into the pulmonary capillaries where it binds to haemoglobin in RBCs
- CO2 dissociates from haemoglobin and diffuses from the blood into the alveoli
What does gas exchange occur across?
across the alveolar membrane of alveoli
What are alveoli, what is it surrounded by and what does this allow?
tiny air sacs clustered at the end of bronchioles - surrounded by a network of capillaries so gases can be exchanged between the air in the alveoli and the blood
Structure and adaptations of bronchioles (4):
The bronchioles are smaller airways branching from the bronchi that carry air to the alveoli.
Adaptations:
- No cartilage, can change shape.
- Smooth muscle can contract or relax to constrict or dilate the airway and change airflow.
- Elastic tissue contains elastic fibres with elastin that allows stretching and recoiling.
- Simple squamous epithelium (only larger bronchioles have a ciliated epithelium).
Bronchi structure and adaptations (4):
two main branches extending from the trachea that carry air into each lung
Adaptations;
- Reinforced with cartilage to keep the airway open.
- Smooth muscle can contract or relax to constrict or dilate the airway and change airflow.
- Elastic tissue contains elastic fibres with elastin that allows stretching and recoiling.
- Lined with ciliated epithelial cells and goblet cells.
Strructure and Adaptations of the Trachea:
- large tube in which it carries air from the throat down to the lungs
Adaptations:
1. Rings of cartilage to keep the airway open
1. Smooth muscle can contract or relac to constrict or dilate the airway and change airflow
1. Elastic tissue contain elastic fibres with elastin that allows stretching and recoiling
1. Lined with ciliated epithelial cells and goblet cells
What do ciliated epithelium contain and what do they do (2):
- Goblet cells - produce and secrete mucus that traps dust and microbes
- Cilia on ciliated epithelial cells - waft the mucus upward to the mouth so it can be swallowed
Pathway of air in the human body (4):
- Air first enters the trachea
- Air travels into the 2 bronchi, with one bronchus going to each lung
- Air travels into smaller airways called bronchioles
- Air travels into cluster of air sacs called alveoli at the end of the bronchioles
Human gas exchange system is inside the body due to what reason? (2):
- air is not dense enough to support and protect these delicate structures
- body would otherwise lose water and dry out
