The Respiratory System

1. The Respiratory System Chapter 10

2. http://www.youtube.com/watch?v=HiT621PrrO0&feature=related

3. Introduction • Main job of respiratory system is to bring oxygen (O2) into the body and to carry carbon dioxide (CO2) out of body. • Body’s cells need a constant supply of oxygen to burn nutrients to produce energy. • How does this take place in a simple, single celled animal? • How does this differ from a complex animal such as a dog or cat?

4. Two types of Respiration • External Respiration • Occurs in the lungs. • Is the exchange of oxygen and carbon dioxide between the air that is inhaled into the lungs and the blood flowing through the pulmonary capillaries. • Without which, there would be no oxygen in the blood to be transmitted to the system. • Internal Respiration • Takes place between the body’s cells and the blood. • Cells receive oxygen and dispose of their carbon dioxide

5. External Respiration

6. Internal Respiration

7. The Respiratory System • Composed of: • Lungs • Nostrils • Nasal passages • Pharynx • Larynx • Trachea • Bronchi • Bronchioles • Alveolar ducts • Alveoli

8. Functions of the Respiratory System • Primarily: • Oxygen- carbon dioxide exchange. • Secondarily: • Voice production • Body temperature regulation • Acid-base balance regulation • Sense of smell

9. Voice Production • Also called phonation. • Begins in the larynx (voice box). • Two fibrous connective tissue bands called the vocal cords (or vocal folds) stretch across the lumen of the larynx and vibrate as air passes over them. • Other structures such as thorax (chest cavity), nose, mouth, pharynx (throat), and sinuses may contribute resonance and other characteristics to the vocal sounds.

12. Body Temperature Regulation • Cold conditions: • Superficial blood vessels just under the epithelium of the nasal passages helps warm inhaled air before it reaches the lungs. • Keeps chilled air from circulating through the lungs. • What could be the problem with this? • Hot Conditions: • Aids in cooling through panting. • Rapid respiration movements caused during panting cause increased evaporation of fluid from the lining of the respiratory passages and mouth, which helps to cool the blood just under the epithelium.

13. Acid Base Balance • Important homeostatic mechanism in the body. • pH- unit used to measure relative acidity or alkalinity. • Lower the pH, the more acidic the environment • Higher the pH, the more alkaline the environment. • A pH of 7 is neutral, neither acidic or alkaline. • Normal pH of the blood is 7.4 (acceptable range of 7.35-7.45).

14. Acid-Base Balance Continued… • Respiratory system contributes to the process of acid-base control by its ability to influence the amount of CO2 in the blood. • Higher CO2, lower the blood pH, more acidic the blood. • Respiratory system can alter CO2 content in the blood by adjusting how fast air is breathed in and out.

15. Sense of Smell • Also called the olfactory sense. • Receptors are contained in patches of sensory epithelium located up high in the nasal passages.

16. Structure of Respiratory System • Consists of lungs and system of tubes that connects them with the external environment. • Upper Respiratory Tract • All of the respiratory structures outside the lungs. • Lower Respiratory Tract • All of the respiratory structures within the lungs.

17. Upper Respiratory Tract • Includes: (all air that enters and leaves lungs does so through the upper respiratory structures). • Nose • Pharynx (throat) • Larynx (voice box) • Trachea (wind pipe)

18. Nose • Begins with nostrils also known as nares. • Are external openings of the respiratory tube that lead into the nasal passages.

19. Nasal Passages • Located between the nares and the pharynx. • Nasal Septum- a wall that separates the left nasal passage from the right. • Hard and Soft palates- separates the nasal passages from the mouth. • Contain turbinates (nasal conchae)-thin, scroll-like bones covered with nasal epithelium that occupy most of the lumen of the nasal passages.

20. Nasal Turbinates • Two sets are found in each nasal passage. • Dorsal Turbinate • Ventral Turbinate • These divide each nasal passage into 3 main passageways, each called a nasal meatus. • Ventral nasal meatus is located between the ventral turbinate and the floor of the nasal passage • Middle nasal meatus is located between the two turbinates. • Dorsal nasal meatus is located between the dorsal turbinate and the roof of the nasal passage. • Common nasal meatus is located on either side of the nasal septum, is continuous with other 3 meatuses.

22. Lining of the nasal passages • Consists of pseudostratified columnar epithelium with cilia projecting from the cell surfaces up into a layer of mucus that is secreted by many mucous glands and goblet cells. • Cilia project from the cell surfaces up into a layer of mucus • Extensive complex of large blood vessels lies just beneath the nasal epithelium.

24. Functions of the Nasal Passages • Housing receptors for sense of smell. • Condition the inhaled air • Warming • Warmed by blood flowing in blood vessels • Humidifying • By the mucus and other fluids on the epithelial surface • Filtering • Helps to remove particulate matter before it reaches lungs. • Due to twists and turns of turbinates. • Respiratory infections cut down on this filtering. Why?

25. Paranasal Sinuses • Usually just called sinuses • Outpouchings of the nasal passages that are contained within spaces in certain skull bones. • Each sinus is named after the skull bone that houses it. • Most animals have two frontal sinuses and maxillary sinuses. • Some animals (including humans) have two more. • Sinuses have same ciliated lining as the nasal passages. Cilia keep fluid and debris from accumulating in sinuses and obstructing the openings of the nasal passages.

29. Sinusitis • Inflammation of the sinuses. Due to infection, tumors, etc. • Build up of pressure can be very uncomfortable for the animal. • Can be treated with medication but if ineffective, hole may need to be drilled into the sinus to allow drainage.

30. Pharynx (Throat) • Common passageway for both respiratory and digestive systems. • Rostral end is divided into: • Nasopharynx (respiratory passageway) • Oropharynx (digestive passageway) • Caudal end is divided into: • Esophagus (digestive passageway) • Larynx (respiratory passageway)

32. Breathing and Swallowing • Pharynx has to stay open to allow airflow. • Larynx and pharynx work together to prevent swallowing from interfering with breathing and vice versa. • Swallowing requires: • stopping the process of breathing, • covering the opening of the larynx, • moving material to rear of pharynx, • open the esophagus, • move material into it, • open covering to larynx, • breathing resumes.

33. G=Oropharynx H=Larynx J=Nasopharynx K=Esophagus I=Trachea

34. Larynx • Commonly called the “voice box” . • Short, irregular tube that connects the pharynx with the trachea. • Made of segments of cartilage that are connected to each other and the surrounding tissues by muscles. • Supported in place by the hyoid bone.

35. Cartilage components of the Larynx • Epiglottis • single, leaf-shaped; projects forward from the ventral portion of the larynx • During swallowing, the epiglottis is pulled back to cover the opening of the larynx • Arytenoid cartilages • paired; attachment site of the vocal cords • Muscles adjust the tension of the vocal cords by moving the cartilages. • Arytenoid cartilages and the vocal cords form the boundaries of the glottis-the opening into the larynx. • Thyroid cartilages • Shaped as a V that forms and supports the ventral portion of the larynx. • Cricoid cartilage • Ring-shaped, helps from and support the caudal portion of the larynx.

38. Larynx continued • Vestibular folds (false vocal cords) - are found in nonruminant animals. Are a second set of connective tissue bands. • Not involved in voice production. • Each side of larynx, blind pouches called lateral ventricles project laterally into the space between the vocal cords and the vestibular folds. • These lateral ventricles are often involved in the treatment of a condition in horses called roaring (laryngeal hemiplegia).

39. Occurs when muscles that tighten cartilage are paralyzed. At rest usually does not cause a problem When animal exercises , may result in obstruction of the glottis. Surgery may remove ventricle to allow scar tissue to tighten cartilage. Laryngeal Hemiplegia (Roaring) or Laryngeal paralysis

40. Laryngeal Intubation • Process in which an endotracheal tube is placed through the glottis to the trachea. • May be helped by the use of a laryngoscope- an instrument that helps to hold down epiglottis. • Laryngospasms –sometimes seen in cats, when glottis is touched, larynx slams shut. Is reflex.

42. Aspiration Pneumonia • Inflammation of the lungs produced by inhalation of a foreign material. • Use caution when administering liquids to animals (remember the swallowing process). • May see during anesthesia. • May potentially be fatal.

43. Laryngeal Functions • 1. Voice Production • Originates at vocal cords in the larynx. • Vocal cords are attached to arytenoid cartilages and stretch across the lumen of the larynx. • As air passes over vocal cords, they vibrate and produce sounds. • Muscles attached to arytenoid cartilages control the tension of the vocal cords. • Lessening tension of the vocal cords allows for lower pitched sounds. • Tightening of the vocal cords allows for higher pitched sounds.

45. Laryngeal Functions • 2. Prevention of Foreign material being inhaled. • Accomplished by trapdoor action of the epiglottis. • The moving up and down of the adam’s apple is part of this process. • 3. Control of airflow to and from lungs. • Partially through epiglottis action when swallowing occurs but also through adjustments in the size of the glottis. • Adjustments in the size of the glottis. • May even be helpful in straining.

46. Coughing • Cough is generated behind a closed glottis. • Breathing muscles contract, compressing the thorax. • Builds pressure behind the closed glottis. • When glottis suddenly opens, the forceful release of air results in a cough. • Purpose of coughing is to clear mucus and other matter from lower respiratory passages.

47. Trachea • Windpipe- short, wide tube that extends from the larynx down through the neck region into the thorax. • Lined with ciliated epithelium. • Bifurcation of the Trachea- occurs at about the level of the heart.

48. Trachea • Structurally, trachea is a tube of fibrous tissue and smooth muscle held open by hyaline cartilage rings and lined by the same ciliated epithelium that is present in the nasal passages. • Hyaline cartilage rings are C shaped.

49. Trachea continued • Ciliated lining of the trachea is similar to the nasal passages. • The mucous layer on its surface traps tiny particles of debris that have made it down this far into the respiratory tube. • Eventually reaches pharynx and is swallowed.

50. Collapsing Trachea • Pushing down of the cartilage area, obstructs air flow. • Causes dry, honking cough.