MHS1102D: Respiratory System 1

Functions of the Respiratory System

• Gas Exchange: Oxygen and carbon dioxide are exchanged between the blood and air.
• Communication: Facilitates speech and vocalizations.
• Olfaction: Enables the sense of smell.
• Acid-Base Balance: Helps regulate body fluid pH by eliminating CO2.
• Blood Pressure Regulation: Participates in synthesizing angiotensin II.
• Blood & Lymph Flow: Breathing creates pressure gradients that enhance lymphatic and blood flow.
• Blood Filtration: Lungs filter small blood clots.
• Abdominal Pressure Regulation: Breath-holding aids urination, defecation, and childbirth (Valsalva manoeuver).

Anatomy of the Respiratory System

• Principal Organs: Include nose, pharynx, larynx, trachea, bronchi, and lungs, where air reaches alveoli for gas exchange.
• Conducting Portion: Consists of passages solely for air transport (nostrils to bronchioles) without gas exchange.
• Respiratory Portion: Includes alveoli and regions where gas exchange occurs.

Upper and Lower Respiratory Tracts

• Upper Respiratory Tract: Extends from the nose to the larynx.
• Lower Respiratory Tract: Comprises organs within the thorax, from the trachea to the lungs.

Anatomy of the Nose

• Functions: Warms, cleanses, and humidifies inhaled air; detects odors; amplifies voice.
• Structure: Comprised of bone and hyaline cartilage; features vibrissae to filter debris.
• Nasal Septum: Divides nasal cavity, formed by bone and cartilage.
• Nasal Conchae: Enhances air contact with mucous membranes for cleaning, warming, and moistening.

Anatomy of the Pharynx

• Muscular Funnel: Extends from nasal choanae to larynx, divided into nasopharynx, oropharynx, and laryngopharynx.
• Nasopharynx: Located above the soft palate; receives auditory tubes and contains pharyngeal tonsils.
• Oropharynx: Space between soft palate and epiglottis, containing palatine tonsils.
• Laryngopharynx: Extends from epiglottis to cricoid cartilage, connecting to the esophagus.

Anatomy of the Larynx

• Structure: Cartilaginous chamber with nine cartilages, acts as a guard for the airway.
• Unpaired Cartilages: Include epiglottis (covers larynx during swallowing), thyroid (Adam’s apple), and cricoid (ring-like connection to trachea).
• Paired Cartilages: Include arytenoid, corniculate, and cuneiform cartilages.

Vocal Cords

• Folds in Larynx: Two sets—superior (vestibular) folds close larynx during swallowing, inferior (vocal) folds produce sound when air passes through.

Gross Anatomy of the Lungs

• Location: Within the thoracic cavity; apex above clavicle, base resting on diaphragm.
• Surfaces: Costal surface in contact with ribcage; mediastinal surface faces the heart.
• Hilum: Region for entry/exit of main bronchus, blood vessels, nerves, and lymphatics.

Muscles of Respiration

• Diaphragm: Primary muscle; contraction increases thoracic volume, facilitating air intake.
• Intercostal Muscles: Internal and external intercostal muscles support diaphragm function and stabilize the thoracic cage.
• Scalene Muscles: Assist in fixing or elevating the first two ribs during respiration.

Accessory Muscles of Respiration

• Participate mainly in forced respiration, further expanding thoracic volume.
• Include erector spinae, sternocleidomastoid, pectoralis major and minor, serratus anterior, and scalene muscles.

Normal and Forced Expiration

• Quiet Expiration: Passive; relies on lung elasticity, allowing thoracic cavity to recoil and push air out.
• Forced Expiration: Involves abdominal muscles and internal intercostals, significantly increasing thoracic pressure to expel air.

This quiz covers the fundamental aspects of the respiratory system, focusing on its functions, anatomy, and the roles of different structures involved in respiration. By completing this quiz, you will reinforce your understanding of the respiratory system's components, including the lungs, pleura, and muscles of respiration.