GAS EXCHANGE Flashcards
GAS EXCHANGE IN MAMMALS
What is the general structure of the respiratory system in mammals? (4)
Air is taken in through the nose, air passes into their nasal cavity, hairs in this cavity trap dust particles and pathogens, it also warms and moistens the air before it enters the lungs. The air then makes its way down the trachea, the trachea divides into two bronchi, each bronchus carries air into one of the lungs, each bronchus splits forming progressively narrower airways called bronchioles which further lead into alveoli, air sacs. Where gas exchange occurs.
GAS EXCHANGE IN MAMMALS
What are the key adaptions of the trachea? (3)
-walks contain cartilage
-form c-shaped rings
-walls are lined with ciliated epithelial and goblet cells
GAS EXCHANGE IN MAMMALS
Why does trachea walls contain cartilage? (1)
Cartilage prevents the walls of the trachea from collapsing when we inhale.
GAS EXCHANGE IN MAMMALS
Why does the trachea form c-shaped rings? (1)
Form c-shapes instead of rings, the absence of cartilage in the region near the oesophagus allows food to go down the oesophagus easily.
GAS EXCHANGE IN MAMMALS
What is the role of ciliated epithelial cells? (1)
The wafting of the cilia removes the mucus and trapped foreign material from the respiratory system.
GAS EXCHANGE IN MAMMALS
What is the role of mucus in the trachea? (1)
It traps dust, dirt and pathogens before they enter the lungs.
GAS EXCHANGE IN MAMMALS
What is the role of goblet cells? (1)
Secrete my as to trap dust and other foreign particles that may enter the respiratory system.
GAS EXCHANGE IN MAMMALS
What are the features of an effective exchange system? (3)
-short diffusion distance
-steep concentration gradient
-large surface area
GAS EXCHANGE IN MAMMALS
How to mammals achieve an effective exchange system? (3)
-alveoli and capillary cell walls are only one cell thick (short diffusion distance)
-extensive capillary network means that once oxygen diffuses into the blood it is rapidly carried away from the alveoli which ensures that there is always a concentration gradient for oxygen, they same applied to carbon dioxide. This gradient is also maintained by breathing.
-there are millions of alveoli which creates a large surface area for exchange to occur.
GAS EXCHANGE IN MAMMALS
What is the equation for rate of diffusion? (1)
Rate of diffusion = (surface area x difference in concentration) / thickness of exchange surface
GAS EXCHANGE IN MAMMALS
What occurs during an inspiration? (3)
The external intercostal muscles contract and raise the rib cage upwards and outwards, the diaphragm also contracts and flattens. The volume of the thorax increases, lowering the air pressure in the chest cavity to less than that of the atmosphere outside, so air is sucked in.
GAS EXCHANGE IN MAMMALS
What occurs during an expiration? (3)
The external intercostal muscles relax and lower the rib cage and the diaphragm relaxes to become dome shaped. The volume of the thorax decreases, raising the air pressure in the air cavity to above that of the atmosphere outside. A pressure gradient is created between the lungs and the atmosphere, air rushes out via the trachea to equalise the pressure difference.
GAS EXCHANGE IN MAMMALS
When are internal intercostal muscles used? (1)
During exercise.
GAS EXCHANGE IN INSECTS
How do insects achieve an effective exchange system? (3)
-air is taken directly from outside to tissues via the trachea/tracheoles, open circulation system (short diffusion distance)
-air in trachea has high oxygen demand in cells used in respiration (gives low concentration)
-lots of tracheoles, but there is not that much need for it considering ratio (large surface area)
GAS EXCHANGE IN INSECTS
What is the structure of tracheae? (2)
Tracheae are lined with spirals of chitin (a structural polysaccharide) which keeps them open but is also impermeable to gases. They open to the outside environment by pores called spiracles which are opened and closed by sphincters.
