Respiratory System

1
Respiratory System

• New material for exam 3

2
Respiratory System

• Importance of the respiratory system in the
  athletic horse.
• research provides evidence that the respiratory
  system may be a limiting factor for maximal
  performance.
• Therefore, any pulmonary dysfunction, even
  subclinical or moderate, may significantly impair
  aerobic metabolism.

3
The airways

• Its main function is to
• Carry air from the nose to the gas-exchange
  regions of the lung during inspiration.
• Term inhalation to breath in.
• And the opposite during expiration.
• Term exhalation to breath out.

4
Respiratory System

• Functions of the respiratory system
• Gas exchange is the major function of the lung,
• which insures the transport of O2 from air into
  blood and of CO2 in reverse.
• Also, plays a role in other nonpulmonic
  functions
• humidification, warming, and filtering of inhaled
  air.

5
Respiratory System

• External factors influencing pulmonary function
• quality of the inspired air
• 20.98 O2 78.06 N2
• 0.04 CO2 0.92 other gas
• position of the head and neck
• abdominal mass
• locomotion-respiration coupling
• cardiac function
• equipment used

6
Structural peculiarities and their functional
impact.

• The function of an organ is highly influenced by
  its anatomy and vise versa.

7
The airways

• Nostrils are large and mobile
• structure allows for expansion during
  inspiration.
• muscle activation during inspiration results
• in flaring of the nostrils
• Collapse of the nasal diverticulum (pouch or sac)

8
Nostrils

• 14. Nasal diverticulum
• Lateral wing of nostril
• Nasal opening of
• nasolacrimal duct
• 17. Medial wing of nostril

9
The airways

• Nasal Cavities
• provides a large surface area for heat and water
  exchange.
• Because of large turbinates (concha) and
  important vascularization.
• Both sympathetic and parasympathetic fibers are
  distributed to the nasal cavities.
• They stimulate vasoconstriction and vasodilation
  of the vascular sinuses.
• This can induce a decrease or increase in nasal
  resistance.

10
Nasal Cavity
Dorsal concha
Ethmoturbinates
Dorsal meatus
Soft Palate
Ventral concha
Nasopharynx
Medial meatus
Ventral meatus
Dorsal conchal fold
Alar fold
Nostril
11
Nasal Cavity
Ethmoturbinates
Nasolacrimal duct
Ventral concha
Dorsal concha
Medial meatus
Ventral meatus
Alar fold
Nostril
Nasal Septum
Basal fold
12
The airways

• Pharynx
• The soft palate divides the pharynx into the
  nasopharynx and the oropharynx.
• The most important structural upper airway area
  is the intrapharyngeal ostium.
• Is an opening in the soft palate.
• The corniculate cartilage and the epiglottis,
  articulate with the ostium to form an airtight
  seal when the horse breathes.

13
The airways

• 1. nasal cavity
• 2. nasopharynx
• 3. oropharynx
• 4. soft palate
• 5. intrapharyngeal ostium
• 6. epiglottis
• 7. corniculate cartilage
• 8. larynx
• 9. trachea

14
Dorsal Displacement of Soft Palate

• Is not physiologic.
• except when coughing, swallowing, or whinnying.
• Will result in dyspnea.
• 10. guttural pouch
• 11. frontal sinus
• 12. sphenopalatine sinus
• 13. esophagus
• 14. tongue
• 15. food bolus
• 16. closed larynx

15
The airways

• This may explain why the horse is a primary nasal
  breather.
• Unlike human and canine, the horse is not able to
  switch from nasal to oronasal breathing when the
  nasal resistance to airflow becomes to high.
• Usually during exercise-induced hypernea deep
  rapid breathing.

16
The airways

• Epiglottis - passively covers the laryngeal
  opening during swallowing.
• Larynx
• is a short tube that connects the pharynx and
  trachea.
• It is a complex valvular apparatus that
• regulates the volume of air in respiration,
• prevents aspiration,
• is the main organ of vocalization.

17
Larynx
18
Nasal Cavity
Esophagus
Hyoid bone
Epiglottic cartilage
Cricoid cartilage
Vestibular fold
Laryngeal ventricle
Vomeronasal organ
Vocal fold
19
Nasal Cavity
Nasopharynx
Guttural pouch
Opening to auditory canal
Ethmoidal conchae
Epiglottis
Hyoid bone
Cricoid cartilage
Esophagus
Tracheal rings
Vocal fold
Lateral Medial Laryngeal ventricle
Cricoid cartilage
Trachea
20
The airways

• Trachea
• is a 70 -80 cm long flexible tube consisting of
  48 to 60 cartilaginous rings that are open
  dorsally.
• Despite its cartilaginous structure, the
  extrathoracic trachea is compliant and is
  susceptible to collapse during forced inspiration.

21
Trachea
Tracheal m.
Apex
Trachea
Tracheal ring
Mucous membrane
Rt. Cranial (apical) lobe
22
The airways

• The airways can be divided into 3 groups
• Conducting airways which no gas exchange occurs
• Transitional airways
• Respiratory airways gas exchange airways

23
Airways which no gas exchange occurs

• Conducting airways
• Nasal cavity
• Nasopharynx
• Larynx
• Trachea
• Primary bronchi
• Segmental bronchi
• Subsegmental bronchi
• Bronchioles (BL)
• Terminal bronchioles (TBL)

24
The airways

• The lungs
• are covered by a thick pleura
• right and left lung are about the same length,
  but the thickness of the right lung is greater
  than the left.
• the two lungs are divided into lobes, which are
  divided into lobules.
• left lung is composed of the apical and
  diaphragmatic lobe
• right lung has the same arrangement w/ accessory
  lobe in addition.

25
Pleural Membrane
Pleural cavity
Diaphragm
Parietal pleura
Visceral pleura
Pericardium
Pericardial cavity
Left Lung
Heart
Pericardial pleura
26
The airways
Lung
Trachea
Apex
Basal border
Cardiac Notch
27
Lung
Apex
Trachea
Rt. Cranial (apical) lobe
Rt. Cardiac notch
Tracheobronchial lymph nodes
Rt. Principal bronchus
Rt. Caudal (diaphragmatic lobe)
Accessory lobe
28
Lung
Apex
Trachea
Lt. Cranial (apical) lobe
Rt. Cranial (apical) lobe
Rt. Main bronchus
Lt. Main bronchus
Lt.Caudal Lobe
Rt.Caudal Lobe
Accessory lobe
Base
29
Transitional airways

• Or known as respiratory bronchioles (RBL)
• They are interposed between conduction airways
  and respiratory airways.

30
The airways

• Bronchi
• After the bifurcation of the trachea into right
  and left principal bronchi, the bronchi tree
  branches many times to the periphery of the lung
  via the primary bronchi (5), segmental bronchi
  (9), the bronchioles(7 8), and the terminal
  bronchioles.

31
Bifurcation
32
Respiratory or gas exchange airways

• Consist of alveolar ducts (AD) and alveolar sacs
  (AV).

33
Alveoli
Pulmonary artery
Pulmonary arteriole
Terminal Bronchiole
Pulmonary Vein
Respiratory Bronchiole
Alveolar sac
Pulmonary Vein
Alveolus
Respiratory Bronchiole
Capillaries in The walls of alveoli
34
Respiratory System

• Blood Supply
• The lung receives blood from two circulation's
• 1. Pulmonary circulation
• receives the total cardiac output from the right
  side of the heart.
• branches of the pulmonary artery carry venous
  blood to the lung, accompany the bronchi.
• form rich capillary plexuses on the walls of the
  alveoli.

35
Alveoli
Pulmonary artery
Pulmonary arteriole
Terminal Bronchiole
Pulmonary Vein
Respiratory Bronchiole
Alveolar sac
Pulmonary Vein
Alveolus
Respiratory Bronchiole
Capillaries in The walls of alveoli
36
Respiratory System

• The blood is then arterialized and returned to
  the left side of the heart by pulmonary veins.
• Equine pulmonary arteries adjacent to the
  bronchioles and the alveolar ducts are muscular
  and have a thick medial smooth-muscle layer.
• This amt. of smooth muscle determines reactivity
  of the vessels to hypoxia.
• Consequently explains why a horse may present a
  pulmonary hypertension due to a hypoxic
  vasoconstriction.

37
Respiratory System

• 2. Bronchial circulation
• is a branch of the systemic circulation
• carries arterial blood for the nutrition of the
  airways and other lung structures.
• originates from two arteries
• bronchoesphageal artery supplying the airways
  and interlobular septa of most of the lung.
• right apical bronchial artery supplying the
  airways of the right apical lobe.

38
Respiratory System

• Bronchial arteries form a circulation plexus in
  the connective tissues along the airways.
• Branches from the plexus penetrate the bronchial
  walls to form subepithelial vascular plexus.
• The role is probable to ensure some heat
  dissipation.

39
Respiratory System

• Thoracic Cavity
• roughly triangular
• caudal base formed by diaphragm
• roof formed by thoracic vertebrae and the
  ligaments and muscle that connect them.
• lateral walls are formed by 18 ribs and the
  intercostal muscles
• floor is formed by the sternum

40
The airways
Lung
Trachea
Apex
Basal border
Cardiac Notch
41
Respiratory System

• Inspiratory Muscle
• the diaphragm is the main inspiratory muscle.
• other inspiratory muscle include those
  connecting the sternum or the ribs.
• when they contract, they pull the sternum or the
  ribs forward and participate consequently in
  enlargement of the thorax.

42
Respiratory System

• Expiratory Muscle
• The abdominal muscles
• external and oblique abdominis
• transverse and rectus abdominis
• transverse thoracis
• and the internal intercostal muscles are
  expiratory muscles.
• when they contract, they increase the abdominal
  pressure, forcing the relaxed diaphragm forward
  and reducing the thoracic volume.