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BIOL 252 Exam 4 Respiratory System Questions and Answers with
Complete Solutions UPDATED!!!!
Alveolar macrophages - ANSWER o Macrophages that patrol the
alveolar surface for pathogens
o Keep the alveoli free of debris by phagocytizing dust particles
that escape entrapment by mucus in the higher parts of the
respiratory tract
Alveoli - ANSWER o 300 million alveoli inside alveolar sacs
o Account for most of the lung's volume
o Provide tremendous surface area for gas exchange
• Gas exchange of air from alveoli and into capillaries
• Carbon dioxide from capillaries and into the sac→ back into
the air
o External surfaces of the alveoli are densely covered with a
"cobweb" of pulmonary capillaries
o Elastic fibers allow alveoli to stretch
Diaphragm - ANSWER o Contraction of diaphragm=flattening
out
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• Helps in inspiration to increase the volume of the thoracic
cavity
o Passive relaxation of the diaphragm=folds in
• Helps in expiration to reduce the volume of the thoracic cavity
DRG - ANSWER o Dorsal respiratory group
o Found in the medulla oblongata
o Neurons that control breathing
o Primary group for setting the pace of breathing
o Act through inspiratory neurons and expiratory neurons
• Inspiratory neurons receive inputs from chemoreceptors and
fire action potentials- stimulate muscles to contract and
breathe
• Expiratory neurons inhibit inspiratory signals
Expiration - ANSWER o Exhaling
o Pressure changes drive air flow
o Decrease the volume of the alveoli→ Increases the pressure
in the alveoli→ Pressure in alveoli is higher than atmospheric
pressure→ Air flows out of the lungs
BIOL 252 Exam 4 Respiratory System Questions and Answers with
Complete Solutions UPDATED!!!!
Alveolar macrophages - ANSWER o Macrophages that patrol the
alveolar surface for pathogens
o Keep the alveoli free of debris by phagocytizing dust particles
that escape entrapment by mucus in the higher parts of the
respiratory tract
Alveoli - ANSWER o 300 million alveoli inside alveolar sacs
o Account for most of the lung's volume
o Provide tremendous surface area for gas exchange
• Gas exchange of air from alveoli and into capillaries
• Carbon dioxide from capillaries and into the sac→ back into
the air
o External surfaces of the alveoli are densely covered with a
"cobweb" of pulmonary capillaries
o Elastic fibers allow alveoli to stretch
Diaphragm - ANSWER o Contraction of diaphragm=flattening
out
, 2|Page
• Helps in inspiration to increase the volume of the thoracic
cavity
o Passive relaxation of the diaphragm=folds in
• Helps in expiration to reduce the volume of the thoracic cavity
DRG - ANSWER o Dorsal respiratory group
o Found in the medulla oblongata
o Neurons that control breathing
o Primary group for setting the pace of breathing
o Act through inspiratory neurons and expiratory neurons
• Inspiratory neurons receive inputs from chemoreceptors and
fire action potentials- stimulate muscles to contract and
breathe
• Expiratory neurons inhibit inspiratory signals
Expiration - ANSWER o Exhaling
o Pressure changes drive air flow
o Decrease the volume of the alveoli→ Increases the pressure
in the alveoli→ Pressure in alveoli is higher than atmospheric
pressure→ Air flows out of the lungs
