Lobes of the Lungs - PowerPoint PPT Presentation

• Lungs are divided into _______ (in most species)
• Pattern varies with species
• Dogs, cats, cattle, pigs, goats, sheep → deeply fissured into lobes
• L: Cranial and Caudal
• R: Cranial, Middle, Caudal, Accessory
• Horses → least subdivided
• L: All one lobe
• R: All one lobe + accessory
• Lobes are distinguished by the major branches of the bronchi

• __________- small, well-defined area on medial side of the lung
• Location of air, blood, lymph, and nerves entering and leaving the lung.

• ______________ blood enters the lungs from ______ ventricle of heart through the pulmonary ______.
• Pulmonary artery 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.

• 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

• 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 (_______________)

• 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

• 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 passively as movements of thoracic wall and diaphragm alternately enlarge and reduce volume of thorax
• Negative intrathoracic pressure helps draw blood through ________ in the mediastinum and into atria

Leakage of air into thorax → Loss of negative pressure in lungs

(causes “collapsed lung”)

• Causes (many: basically 1 of 2 things happens)
• Penetrating wound of chest
• Rupture of alveoli
• Rx
• Remedy cause
• Remove air from thorax
• Needle/syringe (aka ________________)
• Chest tube

• 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)
• 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.

• 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

• 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, therefore the muscles are considered “voluntary”

• __________ 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

• 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 are usually linked
• __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
• 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