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68 Cards in this Set

  • Front
  • Back
Higher vertebrates have developed respiratory systems whereby gas exchange occurs at a single place, known as
The respiratory surface, the lungs
How does air enter the respiratory tract?
Through the external nares or nostrils
After moving through the external nares and being filtered by mucous and nasal hairs, it passes through the pharynx and into a second chamber called what?
The larynx
Does ingested food also pass through the pharynx?
Yes it does, en route to the esophagus
What is the piece of tissue called that covers the glottis and what is the glottis?
The glottis is the opening to the larynx, and the epiglottis covers it
After passing through the larynx, where does air pass?
Through the trachea
What is the trachea primarily composed of?
How many branches does the trachea branch off to?
They divide into two bronchi
Where do they each go?
One goes into the right lung and the other enters the left
What ciliates both the trachea and bronchi?
Epithelial cells
What is their function?
They filter and trap particles inhaled along with the air
After the bronchi branch repeatedly into smaller bronchi, they reach the terminal branches which are called?
What is each bronchiole surrounded by?
Clusters of small air sacs called alveoli
Where does gas exchange between the lungs and the circulatory system occur?
Across the very thin walls of the alveoli
What is each alveolus coated with?
A layer of liquid containing surfactant
And what is each alveolus surrounded by?
An extensive network of capillaries
What does surfactant do?
It lowers the surface tension of the alveoli and facilitates gas exchange across the membranes
How many alveoli provide 100 m2 of moist respiratory surface for gas exchange?
There hundred million alveoli
What is ventilation of the lungs?
When air is inhaled and exhaled
What is the purpose of ventilation?
To take in oxygen from the environment and eliminate carbon dioxide from the body
Pressure changes are dependent on the ventilating mechanism known as what?
The thoracic cavity
What is the thoracic cavity?
The body cavity that contains the heart and lungs
What is the thoracic cavity separated by from the abdominal cavity?
A muscle known as the diaphragm
Where is the diaphragm bounded to on its sides?
By the chest wall
What membranes are the lungs surrounded by?
The visceral pleura and the parietal pleura
What is the space between the two pleura known as?
The intrapleural space
What does it contain?
A thin layer of fluid
What is the pressure differential between the intrapleural space and the lungs responsible for?
It prevents the lungs from collapsing
During inhalation, when the diaphragm contract and flattens, what muscles contract?
The external intercostals muscles
What do they do?
They push the rib cage and chest wall up and out
What does this cause?
The thoracic cavity to increase in volume
What does this volume increase cause?
A reduction in the intrapleural pressure
What does this cause?
The lungs to fill with air
What is this referred to as?
Negative-pressure breathing
Is exhalation an active or passive process?
A passive process
When the diaphragm and external intercostals muscles relax causing the chest wall to push inward, is there an increase or decrease in thoracic cavity volume?
A decrease
What does this cause?
It causes the air pressure in the intrapleural space to increase
What does this do?
It causes the lungs to deflate, forcing air out of the alveoli
During forced exhalation what muscles contract?
The internal intercostals muscles
What does this cause?
It causes the rib cage to move down
What does surfactant reduce?
The high surface tension of the fluid lining the alveoli, preventing collapse during exhalation
Where are the neurons located that regulate ventilation?
In the medulla oblongata
How do they regulate ventilation?
They rhythmically discharge stimulating the intercostals muscles and or the diaphragm to contract
How can these neural signals be modified?
By chemoreceptors in the aorta
Why do the signals change?
The signals change in order to respond to changes in the pH and the partial pressure of CO2 in the blood
When the partial pressure of CO2 rises, does the medulla oblongata stimulate a decrease or increase in the rate of ventilation?
An increase
Can ventilation be controlled at all by the cerebrum?
To some extent
What is the purpose of hyperventilation?
It lowers the partial pressure of CO2 in the blood below normal
In response to this, what do chemoreceptors do?
They sense it and send signals to the respiratory center which temporarily inhibits breathing
What does a spirometer do?
It measures the amount of air normally present in the respiratory system and the rate at which ventilation occurs
What is the vital capacity?
It is the maximum amount of air that can be forcibly inhaled and exhaled from the lungs
What is the amount of air normally inhaled and exhaled with each breath called?
Tidal volume
What is the residual volume?
The air that always remains in the lungs, preventing the alveoli from collapsing
What is the volume of air that can be forcibly exhaled following a normal exhalation?
The expiratory reserve volume
What is total lung capacity?
It is equal to the vital capacity plus the residual volume
What is the dense network of minute blood vessels called that surrounds the alveoli?
The pulmonary capillaries
How does gas exchange occur across these capillary walls and the alveoli?
By diffusion
When blood enters the pulmonary capillaries, is it in an oxygenated or deoxygenated state?
It is in a deoxygenated state
What does this imply?
It implies that it has a lower partial pressure of O2 than does the inhaled air in the alveoli
Once O2 diffuses down its gradient into the capillaries where it binds to hemoglobin, what does it do next?
It returns to the heart via the pulmonary veins
Is the partial pressure of CO2 in the capillaries greater to that of the inhaled alveolar air or smaller?
It is greater
What does imply?
It implies that CO2 will diffuse from greater concentration to smaller concentration from the capillaries into the alveoli, where it is released into the external environment during exhalation
What happens at high altitudes?
The partial pressure of O2 in the atmosphere declines, making it more difficult to get sufficient oxygen to diffuse into the capillaries
What does the body do to compensate?
It increases the rate of ventilation and also increases the production of red blood cells to carry more oxygen
What happens to the affinity of hemoglobin for oxygen?
It decreases to facilitate unloading of oxygen in tissues
Does active transport facilitate gas exchange in the lungs at any point?
The intrapleural space in the lungs is bounded by what?
The visceral pleura and the parietal pleura
The lungs can collapse from what?
It can collapse from insufficient surfactant production and a rupture of the parietal pleura