Chap22_PPT

Chapter 22: The Respiratory System

22.1 Anatomy of the Respiratory System

• Expected Learning Outcomes:

  • State the functions of the respiratory system.

  • Name and describe the organs of the respiratory system.

  • Trace the flow of air from the nose to the pulmonary alveoli.

  • Relate the function of portions of the respiratory tract to its gross and microscopic anatomy.

Overview of the Respiratory System

• The respiratory system is responsible for intake and expulsion of air, primarily focusing on the ventilation of the lungs (breathing).

Functions of the Respiratory System

• Gas Exchange:

  • Exchange of oxygen (O2) and carbon dioxide (CO2) between blood and air.

• Communication:

  • Involvement in speech and other vocalizations.

• Olfaction:

  • Sense of smell.

• Acid-Base Balance:

  • Influences pH of body fluids by eliminating CO2 from the body.

• Blood Pressure Regulation:

  • Assists in the synthesis of angiotensin II, regulating blood pressure.

• Blood and Lymph Flow:

  • Breathing creates pressure gradients that facilitate the flow of lymph and blood.

• Platelet Production:

  • Majority of platelets are produced by megakaryocytes located in the lungs.

• Blood Filtration:

  • The lungs filter small clots from the bloodstream.

• Expulsion of Abdominal Contents:

  • Breath-holding assists during urination, defecation, and childbirth.

Organization of Respiratory Organs

• Principal Organs:

  • Nose, pharynx, larynx, trachea, bronchi, and lungs.

• Conducting Zone:

  • Air passages that serve solely for airflow, without gas exchange (from nostrils to major bronchioles).

• Respiratory Zone:

  • Regions participating in gas exchange (including alveoli and surrounding structures).

• Upper Respiratory Tract:

  • Airway from the nose to the larynx.

• Lower Respiratory Tract:

  • Regions from the trachea to the lungs.

Structure of the Nose

• Function:

  • Warms, cleanses, humidifies air, detects odors, and amplifies voice.

• Anatomy:

  • Extends from nostrils to posterior nasal apertures.

  • Composed of bone (nasal bones and maxillae) and hyaline cartilage (lateral and alar cartilages).

  • Ala nasi:

    • The flared portion at the lower end of the nose.

• Nasal Septum:

  • Composed of bone and cartilage, divides the nasal cavity into right and left sides.

Detailed Anatomy of the Nose

• Roofs and Floors:

  • Roof formed by ethmoid and sphenoid bones, floor formed by the hard palate.

• Vestibule:

  • Small chamber inside the nostrils, lined with stratified squamous epithelium, containing guard hairs (vibrissae).

• Nasal Conchae:

  • Superior, middle, and inferior conchae: Three folds projecting from lateral walls into nasal cavity, ensuring that air contacts mucous membranes for cleaning, warming, and moistening.

• Nasal Mucosa:

  • Lined with ciliated pseudostratified columnar epithelium containing goblet cells that produce mucus. Cilia propel mucus to be swallowed.

• Olfactory Epithelium:

  • Located at the roof of each nasal fossa, involved in the sense of smell.

• Erectile Tissue:

  • Swells on one side every 30-60 minutes, allowing recovery from drying and alternating airflow between nostrils.

22.1b. The Pharynx

• Structure:

  • Muscular funnel extending from nasal apertures to the larynx, divided into three regions:

    • Nasopharynx: Receives auditory tubes; contains pharyngeal tonsil.

    • Oropharynx: Between soft palate and epiglottis; contains palatine tonsils.

    • Laryngopharynx: Posterior to larynx; leads to esophagus.

• Epithelial Lining:

  • Nasopharynx: pseudostratified columnar epithelium.

  • Oropharynx and laryngopharynx: stratified squamous epithelium, supporting food and drink passage.

22.1c The Larynx

• Role:

  • Primarily keeps food and drink out of the airway; involved in sound production (voice box).

• Components:

  • Epiglottis: Flap that covers larynx during swallowing.

  • Cartilages: Nine total, including larger thyroid cartilage (Adam's apple) and cricoid cartilage connecting to the trachea.

  • Vocal Cords:

    • Produce sound; controlled by intrinsic muscles that adjust tension to alter pitch.

22.1d The Trachea

• Functions:

  • Connects larynx to bronchi; also known as the windpipe.

• Structure:

  • Rigid tube with C-shaped hyaline cartilaginous rings to prevent collapse.

  • Lined by ciliated pseudostratified columnar epithelium with mucus-secreting cells, facilitating debris removal.

22.1e The Lungs

• Anatomy:

  • Each lung has a conical shape, with a broad base resting on the diaphragm and an apex above the clavicle.

  • Bronchial Tree:

    • A branching system from primary bronchi to terminal bronchioles, where gas exchange occurs.

• The left lung is taller and narrower, contains two lobes; the right lung is shorter, with three lobes.

22.2 Pulmonary Ventilation

• Process:

  • Breathing involves inspiration and expiration involving muscle contractions and pressure gradients.

• Primary Muscles:

  • Diaphragm (primary mover) and intercostal muscles.

• Accessory Muscles:

  • Activated during forced respiration include erector spinae, sternocleidomastoid, and scalenes.

• Neural Control:

  • Breathing is regulated by brainstem respiratory centers. Central and peripheral chemoreceptors monitor blood gas levels and pH.