Pulmonary Circulation- THIS IS A REVIEW!!!!
• ______________ blood enters
the lungs from ______ ventricle
of heart through the pulmonary
______.
• Pulmonary trunk splits into left
and right pulmonary arteries that
enter the two lungs
• Pulmonary arterioles enter
capillary networks around the
alveoli
• Oxygenated blood returns to the
left atrium in the pulmonary
veins.
Thoracic Cavity
• Bound by __________ vertebrae dorsally, ______ &
_____________ muscles laterally, the __________ ventrally,
and the _____________caudally.
• Mediastinum – area between lungs REVIEW!!!
• Contains heart, trachea, esophagus, blood vessels, nerves,
lymphatic structures, thymus
Pleura- REVIEW!!!
• Serous membrane that lines thoracic cavity and
covers organs and structures in thorax
• __________ layer covers thoracic organs and structures
• __________ layer lines the cavity
• Space between the two pleural layers is filled with a small
amount of pleural _________ (same in abdomen, pericardium)
• Helps ensure that surfaces of organs slide smoothly along lining of
thorax during breathing (_______________)
Diaphragm
• Thin, dome-shaped sheet of skeletal
muscle
• Forms caudal boundary of thorax
• Base of lungs lie directly on the
cranial surface and the liver lies
on the caudal surface
• Important respiratory muscle
• Dome-shaped when ___________
• Flattens when it __________
• Enlarges volume of thorax and
aids inspiration
Process of Respiration
• Requires effective movement of air into and out of lungs
at an appropriate rate and in sufficient volume to meet
the body’s needs at any particular time.
•Pressure within the thorax is ____________ with respect
to atmospheric pressure.
• Pulls lungs tight against the thoracic wall
• Flexible nature of lungs allows them to conform with shape
of the thoracic wall.
• Pleural fluid provides __________.
• Lungs follow movements of thoracic wall
• Negative intrathoracic pressure helps draw blood through
________ in the mediastinum and into atria
Pneumothorax
Leakage of air into thorax → Loss of
negative pressure in lungs
(causes “collapsed lung”)
• Causes:
• Penetrating wound of chest
• Rupture of alveoli
• Rx
• Remedy cause
• Remove air from thorax
• Needle/syringe (aka
____________________)
• Chest tube
Inspiration
• Process of drawing air into lungs
(inhalation)
• Results from increasing volume of
thoracic cavity by inspiratory muscles
• Main inspiratory muscles: ___________
and ____________ intercostal muscles
• External intercostals located in external
portion of intercostal spaces (between
ribs)
• Diaphragm enlarges the thoracic cavity
by flattening out.
• Process of pushing air out of lungs
(exhalation)
Expiration
• Results from decrease in size of thoracic
cavity
• Main expiratory muscles: ___________
intercostal muscles and ____________
muscles
• Internal intercostal muscles located
between the ribs, deep to the external
intercostal muscles
• Contraction of abdominal muscles pushes
abdominal organs against the diaphragm
and pushes diaphragm back into its full
dome shape.
• ___________ volume – volume of air inspired and expired during
one breath.
• Varies according to body’s needs.
• Smaller when animal is at rest and larger when excited and active.
• __________ volume – volume of air inspired and expired during one
minute.
• Calculated by multiplying the tidal volume by breaths per minute.
• Measured in mL or Liters
• __________ volume – volume of air remaining in the lungs after
maximum expiration.
• Residual volume always remains, lungs will never be completely emptied
of air.
Respiratory Volumes
Alveolar Gas
Exchange- REVIEW!!
• Simple _________ of gas
molecules from areas of _____
concentration to areas of
_____ concentration.
• _____ diffuses from the
alveolar air into the blood of
the alveolar capillary
• _____diffuses from the blood
into the alveolus
Respiratory
Center
• Even though all of the inspiratory
and expiratory muscles are
skeletal muscles under voluntary
control, breathing does not
require a conscious effort.
• Breathing is controlled by an area in
the _________ ___________ of the
brain stem known as the
Respiratory Center.
• Directs timing and strength of
contraction
• Can be consciously controlled for brief
periods.
Mechanical
Control
System
• __________ receptors in the
lungs set limits on routine resting
inspiration and expiration.
• Respiratory center sends out
nerve impulses when lungs
inflate to a certain point
• Stops muscle contractions that
produce inspiration and starts
contractions to produce
expiration
• Another set of nerve impulses
sent when lungs deflate
sufficiently
• Stops expiration and starts the
process of inspiration again
Chemical Control System
• Adjusts normal rhythmic
breathing pattern produced by
mechanical control system
• Chemical (peripheral) receptors
in carotid artery and aorta
monitor blood _____, ____, and
____.
• Central chemical receptors
are located in the medulla
oblongata.
• Blood level of CO2 and blood pH linked
Chemical
Control
System
• __CO2 in blood and __blood pH triggers
respiratory center to increase rate and
depth of respiration
• __CO2 in blood and __blood pH triggers
respiratory center to decrease rate and
depth of respiration
• _______ - decrease in blood O2 level
Chemical
Control
System
• Slight hypoxia triggers respiratory center to
increase the rate and depth of breathing
• Severe hypoxia - neurons of the
respiratory center can become so
depressed that adequate nerve impulses
cannot be sent to the respiratory muscles
•
• Can cause breathing to decrease or stop
completely