1. Lower Respiratory Tract

2. Lower Respiratory Tract
Trachea-branches into to main bronchi at Tracheal bifurcation (Carina)
Bronchial Tree-airways from bronchi to alveoli
Bronchi>Bronchioles>Alveolar Duct>Alveolor Sac (collection of alveoli)

4. Respiratory Tract

5. Airway Control Smooth muscle surrounds passageways Sympathetic tone-
Bronchial smooth muscle relaxes
=Bronchodilation
Parasympathetic tone-
Partial smooth muscle contraction
=Bronchoconstriction

6. Alveoli External Respiration occurs here
Where is internal respiration???
Exchange of oxygen and carbon dioxide between air in lungs and blood
Thin- walled sacs-simple squamous epithelium
surrounded by capillaries- simple squamous epithelium

7. Alveoli Lined with Surfactant-thin fluid layer
Helps reduce surface tension of the fluid
Surface Tension-attraction of water to each other
Helps prevent alveoli from collapsing
Premature infants

8. Asthma Irritants can cause bronchoconstriction
Asthma patients can become overly sensitive to irritants
Cats-
Mild-wheezing, coughing
Severe-dyspnea (difficulty breathing), cyanosis (bluish gum color)
Treatment-bronchodiliators, anti-inflammatory agents
Asthma Cat

9. Asthma
Aerocat inhalers

10. Lungs 2 Lungs Apex-Cranial thorax Base-Caudal thorax
Lies on the cranial surface of diaphragm
Lateral surface-against thorax wall
Space between lungs-mediastinum

11. Mediastinum Contains: Heart, large blood vessels Nerves Trachea
Esophagus
Lymphatic vessels and lymph nodes

12. Lungs Divided into lobes
Defined by major branches of bronchi-not grooves on the outside
Cat, cow, dog, goat, pig, sheep:
Left lobe
Cranial and Caudal
Right lobe
Cranial, middle, caudal and accessory lobe
Horse-left lung, right lung, accessory lobe

13. Lung Anatomy Hilus-medial aspect of lungs
Where air, blood, lymph and nerves enter and exit lungs
“Attachment”

14. Lung Anatomy Pulmonary (Lung) Circulation
Pulmonary Artery-blood enters the lungs
Low Oxygen, high Carbon Dioxide
Comes directly from the right side of the heart
Split to left and right pulmonary arteries, then follow bronchi
Pulmonary Capillaries
Pulmonary Veins-blood exits the lungs
High Oxygen, Low Carbon Dioxide
Returns to the left side of the heart

16. Fetal Lungs Nonfunctional
No air within lungs until first breath after birth
First breath, surfactant covers alveoli to prevent collapse
Stillborn vs. Neonatal Death???

17. Thoracic Cavity Dorsal-thoracic vertebrae
Lateral-ribs, intercostal mm.
Ventral-sternum
Pleura-thin membrane, covers organs and lines thoracic cavity
Visceral Pleura
Parietal Pleura
Pleural Fluid – lubricates surfaces
Smooth sliding during breathing

18. Thoracic Cavity Caudal-Diaphragm Skeletal muscle Relaxed-Dome shaped
Contracted state-flattens
Enlarges thorax
Inspiration

19. Action of the Diaphragm

20. Smokers lungs

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