Aparato Respiratorio

Scientific concepts, discoveries, and nature phenomena

Overall function and types of respiration

• Respiratory system functions: air intake into the lungs, gas exchange, and expulsion of inhaled air.
• External respiration: gas exchange between inhaled air and blood (presented as anatomical/organ-level respiration).
• Internal (cellular) respiration: oxidative process occurring inside cells.

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Anatomy of the upper respiratory tract (nose and related structures)

• Anatomical components of the respiratory tract (as described):
  • Nose (external nose, nasal cavity, sinuses)
  • Nasopharynx
  • Larynx
  • Trachea → divides into bronchi → ends in lungs

Nose subdivisions/features

• External nose: bridge and tip; tip has species-specific morphology.
• Equines: tip covered by short, soft hairs.
• Other species: hairs reduced/removed and grooves appear; grooves are said to be individual-specific (analogous to human fingerprints).
• Carnivores / small ruminants:
  • nose may be separated from upper lip forming a nasal plane
  • small ruminants have glands in this nasal plane (not in carnivores)

Nostrils / nasal orifice anatomy and position

• Equines: described as medial dorsolateral/ventral positioning differences and reduced cartilaginous base on the lateral part.
• Carnivores: different lateral ala position.

Nasopharyngeal transition structures

• Nasal vestibule: first part of nasal cavity; marked by transitional mucosa/skin changes.
• Support by cartilages (joining nasal structures and limiting/shaping the orifice).

Special equine structure

• Nasal diverticulum: a cutaneous fold forming a cul-de-sac relative to incisors.

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Nasal cavity lining and air conditioning

• Nasal cavity mucosa types:
  • Mostly respiratory mucosa (air passage)
  • Portions of olfactory mucosa (smell)

Conditioning of inspired air (3 phases)

1. Humidification (fluid supply + airflow conditioning)
2. Filtration (dust/heavier particles trapped in mucus)
3. Warming (heat transfer via nasal structures)

Airflow pathways

• Air passes between turbinates, through spaces called meatuses/conchae (named as aligned media).
• Turbinates increase mucosal surface area:
  • Dorsal turbinate
  • Middle turbinate
  • Ventral turbinate
• Origin differences:
  • dorsal/middle turbinates associated with the ethmoid bone
  • ventral turbinate has different origin

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Meatuses and “fractions” of airflow

Air stratifies into fractions linked to function:

• Respiratory fraction: through conchae / medial entry → mainly toward lungs
• Sinus-related fraction: through medial meatus → toward paranasal sinuses
• Olfactory fraction: through dorsal meatus → toward olfactory mucosa

Clinical note (veterinary): The central/common meatus is emphasized as the main route for probe access toward sinuses (due to position and direct route to the pharynx).

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Paranasal sinuses (pneumatic skull spaces)

• Paranasal sinuses: air spaces within pneumatic skull bones, lined by mostly respiratory mucosa (and sometimes olfactory mucosa).
• Species variation: differ in size/topography.

Examples given

• Frontal sinus: very large in cattle, extending into a corneal process (as described).
• Nasal horn: large in pigs.
• Horses: frontal sinus joins conchal sinus (often called the frontal sinus, as described).
• Maxillary sinus:
  • generally large in many species
  • horses: very small
  • carnivores: very small; described as “conchal sinus” rather than maxillary sinus
• Horse sinus arrangement: sinuses described as fused into a single connected region (maxillary, palatine, sphenoid sinuses).
• Lacrimal sinus: present in the horse (listed among paranasal sinuses).

Practical requirement: Knowledge of topography and shape is needed for clinical examination/procedures.

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Pharynx and larynx (respiratory pathway and comparative structure)

• Pharynx:
  • Nasopharynx portion is respiratory and serves as a communication route.
• Larynx:
  • hollow tubular organ formed by articulated cartilages
  • communicates with pharynx; tube supported by the hyoid bone
  • communicates with trachea (airway into thorax)

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Laryngeal cartilages, glottis, and functions

• Four-cartilage description (as presented):
  • Trigeminal cartilage (caudal ring-shaped)
  • Thyroid cartilage (central)
  • Epiglottis / supraglottic cartilage region (cranial)
  • Auricular cartilages (paired dorsal cartilage)

Species variation

• Shapes of cartilages (and glottic/epiglottic features) differ between carnivores, equines, and bovines.

Glottis vs epiglottis/infraglottis

• Glottis: narrowing at the lumen level.
• Areas caudal/cranial to it are named to avoid confusion (as described).

Laryngeal folds and vocal mechanics

• Folds (including narrated “buccal folds” / “Tyrolean folds”) connect cartilages and can open/close.
• Opening/closing and tension depend on movement between cartilages and laryngeal muscles.
• Vocal ligament and fold tension relate to glottal opening.

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Laryngeal muscles and glottal opening/closing (mechanism)

• Muscles controlling glottis behavior include (as named/described):
  • Thyroarytenoid / vocal muscle region (via vocalis)
  • Vestibulocochlear muscle (parts affecting folds near the glottis)
  • Transverse/internal muscles (described in terms of adduction/abduction-like actions)
  • Additional intrinsic muscle roles described narratively (dorsal/lateral influences on opening vs closing)

Mechanistic concept

• Coordinated intrinsic muscle contractions can cause:
  • widening (opening) of the glottis
  • narrowing/closure of the glottis

External muscle constraint idea

• Thyroid muscle: fixes/attracts larynx cranially via attachment to the hyoid apparatus.
• Epiglottis muscle: draws epiglottis toward the oral side (as described).

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Trachea and bronchial tree (air-conduction system)

• Trachea:
  • tube made of incomplete cartilaginous rings plus muscle support
  • maintained patency (no emphasized resistance to air passage)
  • Rachis muscle mentioned as closing/connecting incomplete rings
• Tracheal division:
  • ends around 4th–5th thoracic vertebrae into two main bronchi
  • Ruminants: characteristic bronchus emission before division (cranial portion of right lung)

Species variation in tracheal muscle coverage

• Carnivores: muscles cover ring ends (as described).
• Other species (e.g., cattle): ends uncovered, producing a grooved appearance.

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Lungs: structure, lobes, pleura, and ventilation mechanics

• Lung shape: roughly pyramidal with base and apex.

Lung surfaces

• Costal surface (ribs)
• Medial surface (mediastinum)
• Diaphragmatic surface (diaphragm curvature)
• Medial surface impressions from nearby organs (aorta, esophagus, heart, caudal vena cava described).

Pleura and pulmonary ligament

• Visceral pleura reflects to form pulmonary ligament.
• Parietal pleura attaches to thoracic walls, forming a cavity/space (mediastinum content described).

Fissures and lobes

• Internal fissures externalize lobe boundaries.
• Lobe ventilation/contact surfaces relate to fissure placement.

Lobe patterns by species (as stated)

• Left lung:
  • cranial and caudal lobes in most species except horse.
• Horse right lung:
  • three lobes: cranial, caudal, accessory.
• Other species:
  • middle lobe present; formerly called cardiac lobe
• Mentions of additional subdivisions (e.g., in snipe/right cranial division).

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Bronchial branching and conducting vs respiratory portions

• Main bronchi → lobular/segmental bronchi → smaller branches → bronchioles
• Conducting system: air passage portion up to true bronchi (described generally).
• Respiratory portion: from respiratory bronchioles onward, including alveolar ducts and alveoli where exchange begins.

Functional concept: a lobe is ventilated by bronchial branches, while gas exchange occurs near alveoli.

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Mechanics of breathing (pressure-balance model)

• Pleural mechanics: inspiration/expiration involve pleural and thoracic volume changes.
• Two key movements:
  • Inspiration: thoracic cavity expands → pleural cavity pressure decreases → lungs expand → air enters
  • Expiration: thoracic cavity reduces; last movement described as expiration using the same pressure-balance concept
• Mediastinum/pleural cavity:
  • pleural movement follows thoracic wall movement
  • pleural space described as closed (air cannot enter)
• Simplified principle:
  • lung expansion occurs as pressures in pleural cavity and lungs equalize through pressure gradients.

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Clinical lung topography and circulation

Clinical localization

• Dorsal lung border: antepenultimate rib (example: 11th rib in dog/cattle)
• Ventral end: around 6th rib or intercostal space
• Horse: dorsal border starts higher (e.g., 17th rib) with two phases/trajectory changes described

“Double circulation” of lungs (functional idea)

• Oxygenation / functional supply:
  • Pulmonary artery from pulmonary trunk (right ventricle) → with bronchi → capillaries → exchange → becomes venous → returns via pulmonary veins
• Nutrient supply:
  • Bronchial (bronchoesophageal) artery/trunk supplies lung tissue
  • two described networks:
    • deeper peribronchial network
    • superficial pleural-surface network
• Venous return:
  • generalized narration describes mixing via pulmonary veins plus return via bronchial veins.

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Researchers or sources featured

• No specific researchers, authors, or named institutions were mentioned in the provided subtitles.