Respiratory System - Lung L18 Flashcards
Overview of the respiratory system
Core function of the respiratory system
Gas exchange - O2 in, CO2 out
What are two main aspects important for efficient gas exchange?
- Diffusion distance between air and blood must be small
- Surface area over which exchange takes place must be large
Types of respiration
External respiration, internal respiration, cellular respiration
External respiration
The process in the lungs by which oxygen is absorbed from the atmosphere into blood within the pulmonary capillaries, and carbon dioxide is excreted. (physical)
Internal respiration
The exchange of gases between blood in systemic capillaries and the tissue fluid and cells which surround them.
Cellular respiration
The process within individual cells through which they gain energy by breaking down molecules such as glucose. Occurs in the mitochondria, consumes oxygen, and generates carbon dioxide.
Pulmonary ventilation (breathing)
The physical/bulk movement of air into and out of the lungs.
What does the ventilatory pump comprise of?
The rib cage with its associated muscles, and the diaphragm
What is the conducting part of the respiratory system?
Series of cavities and thick-walled tubes which conduct air between the nose and the deepest recesses of the lungs, and in doing so warm, humidify and clean it. The conducting airways are the nasal cavities, pharnyx, larnyx, trachea, bronchi and bronchioles.
Respiration
Transport of gases at various stages in the system
Ventilation
The moving of air in and out of the lung tissue - nothing about gas exchange (need muscles + pressure for that to happen)
What does the respiratory part of the system comprise of?
Tiny, thin-walled airways which gases are exchanged between air and blood. The airways are respiratory bronchioles, alveolar ducts and sacs, and the alveoli themselves.
Is the conducting part of the respiratory system part of gas exchange?
No, it is preparing air for gas exchange
How the lung, heart and tissue works together in the pulmonary cardio circuit.
What is required for efficient gas exchange in terms of the nasal cavity?
- Clean - needs to be free of bacteria, dust, pollen, viruses and all sorts of particulates.
- Warm - room temperature of 37 degrees
- Saturated - 100% of H2O. Must be wet as the lining of our airways is exposed to very dry environment, thus the more moisture we can put in the air protects the cellular lining of the airways and helps with a solid utilisation of those gases to be absorbed across the membrane.
Different types of cross-section
Lateral, medial, coronal, transverse, cadaver
Lateral cross section
slice that captures structures on the side, further from the body’s center.
Medial cross section
structures closer to the midline or center of the body.
Coronal Cross Section
A cut made along the coronal (or frontal) plane, dividing the body into anterior (front) and posterior (back) parts.
Cadaver section
cutting or slicing a human cadaver (deceased body) to study its internal structures.
Transverse (Axial) Cross Section
A cut made along the transverse plane, dividing the body into superior (upper) and inferior (lower) parts.
What cells are in the nasal cavity?
Pseudostratified ciliated columnar epithelium with globet cells, basal cells and lined with a mucous membrane
Mucociliary clearance
Responsible for trapping and removing inhaled particles, pathogens, and debris from the airways.
It relies on the coordinated action of two key components:
Mucus Layer: Goblet cells and submucosal glands in the respiratory tract produce mucus, which traps particles such as dust, bacteria, and viruses. The mucus is a sticky substance that captures these unwanted substances to prevent them from reaching the lower airways and lungs.
Cilia: The respiratory epithelial cells are lined with cilia, which are small, hair-like structures. These cilia beat in a coordinated, wave-like motion to propel the mucus (and trapped particles) upward toward the throat, where it can be swallowed or coughed out. This process is known as the mucociliary escalator.
When is the mucociliary clearance most impaired?
- Allergies -> mucus runny (cannot cope with volume)
- Smoking (excess mucus) -> cough
What happens with long-term smoking?
Cilia is paralysed - disappears
Mucus is then lost and risk of infection goes up
-> higher risks of pneumonia, cough and bronchitis
What is the conchae?
Curved, bony structures located inside the nasal cavity. They serve several important functions related to airflow, filtration, and humidification in the respiratory system.
There are three pairs of conchae in each nasal cavity:
Superior nasal conchae: These are the smallest and are located near the top of the nasal cavity.
Middle nasal conchae: Slightly larger, these are found in the middle part of the nasal cavity.
Inferior nasal conchae: The largest of the three, these are located in the lower part of the nasal cavity.
Functions of the Conchae
Airflow regulation: The curved shape of the conchae creates turbulence in the airflow, slowing it down and allowing more time for the air to be filtered, humidified, and warmed before it reaches the lungs.
Filtration: As air passes over the mucosa covering the conchae, particles like dust, pollen, and pathogens get trapped in the mucus, preventing them from entering the lower respiratory tract.
Humidification and warming: The large surface area of the conchae, covered by a mucous membrane, helps humidify and warm the air, which protects the delicate tissues of the lungs from cold, dry air.
Which glands secrete water?
Serous glands and bowman’s glands
What is under the epithelium?
Very rich blood supply - large blood vessels
Properties of the nasal cavity - preparing air for gas exchange
- the nasal cavity is a tall, narrow chamber lined with mucous membrane. The wet membrane
humidifies and warms inspired air. - the medial surface is flat, the lateral surface carries three sloping shelves (conchae) which
increase the surface area of the mucous membrane. - air-filled (paranasal) sinuses open into the cavity. They lighten the face and add resonance to
the voice. - the roof of the cavity carries the olfactory epithelium. Turbulence caused by sniffing carries
air up to the epithelium. Axons of olfactory receptor cells lead towards the brain through
perforations in the overlying bone, the cribriform plate.
Three parts of the pharnyx
Nasopharynx (Upper part)
Location: Behind the nasal cavity, extending from the base of the skull to the soft palate.
Function:
Serves as a passage for air from the nasal cavity to the oropharynx.
Contains the pharyngeal tonsils (adenoids), which play a role in immune defense.
The Eustachian tubes open into the nasopharynx, allowing air pressure to equalize between the middle ear and the atmosphere.
Oropharynx (Middle part)
Location: Behind the oral cavity, extending from the soft palate to the level of the hyoid bone.
Function:
Acts as a common passageway for both air (from the nasal cavity) and food (from the oral cavity).
Contains the palatine tonsils and lingual tonsils, which are involved in the immune response.
Plays a crucial role in swallowing, guiding food and liquids from the mouth to the esophagus.
Laryngopharynx (Lower part)
Location: Extends from the hyoid bone to the esophagus and larynx.
Function:
Serves as a passageway for food and air.
It is where the pathways for food (to the esophagus) and air (to the trachea) separate. During swallowing, the epiglottis covers the trachea to prevent food from entering the airway.
Esophagus
A muscular tube that carries food and liquids from the laryngopharynx to the stomach. It is part of the digestive system.
Trachea
The windpipe that carries air from the larynx to the lungs. It is part of the respiratory system.
`Epiglottis
A flap-like structure that acts as a switch between the trachea and esophagus. During swallowing, it closes over the trachea to prevent food and liquid from entering the airway.
Pharynx
The pharynx is a muscular tube that extends from the base of the skull to the esophagus. It starts behind the nasal cavity and ends at the top of the esophagus and larynx. It is divided into three sections: the nasopharynx, oropharynx, and laryngopharynx.
Larnyx
The larynx, also known as the voice box, is located just below the pharynx and above the trachea. It sits at the top of the windpipe (trachea), just behind the thyroid cartilage (commonly called the Adam’s apple).
Function:
Voice production: The larynx houses the vocal cords, which vibrate to produce sound when air passes through them. This makes the larynx the primary organ responsible for speech and voice modulation.
Airway protection: During swallowing, the epiglottis, a flap in the larynx, closes off the airway (trachea) to prevent food or liquids from entering the lungs, directing them into the esophagus instead.
Breathing: The larynx is part of the respiratory system, providing a passageway for air to flow between the pharynx and the trachea. It helps regulate the airflow to the lungs.
Structure of the nasal cavity
Tall, narrow chamber lined with mucous membrane
What does wet membrane do?
Humidifies and warms inspired air
