Respiratory System medium

The Respiratory System

• The respiratory system is responsible for the exchange of oxygen and carbon dioxide between the atmosphere and the body cells, including inhalation and exhalation.
• The respiratory system is comprised of two primary parts: the upper respiratory system and the lower respiratory system.
• The upper respiratory system is made up of structures that filter and warm the air that we breathe including the nose and nasal cavity, pharynx, larynx, and trachea.
• The lower respiratory system is comprised of structures that are essential for gas exchange and includes the bronchi, bronchioles, lungs, pleura, diaphragm, ribs, and intercostal muscles.

The Nose and Nasal Cavity

• The nose is the only externally visible portion of the respiratory system.
• The nose provides the primary route for air entry into the respiratory system.
• The nasal cavity is divided into two sections by the nasal septum which is composed of hyaline cartilage.
• The function of the nose and nasal hairs is to trap particles such as dust, and to warm, moisten, and filter incoming air.
• The moist mucosa inside the nasal cavity is responsible for warming and humidifying incoming air to within 1 degree of body temperature.
• The nose also houses the olfactory nerve responsible for smell and plays a role in taste sensation.

The Palate

• The palate is the dividing structure that separates the nasal cavity from the oral cavity.
• The hard palate forms the floor of the nasal cavity
• The soft palate is situated posterior to the hard palate and divided into superior nasopharynx and lower pharynx.

The Pharynx

• The pharynx is the portion of the throat located immediately behind the nasal cavity.
• The pharynx serves to transfer food from the mouth to the esophagus and functions to warm, moisten, and filter air that it receives from the nasal passages.
• The pharynx is part of both the digestive and respiratory systems.

The Nasopharynx

• The nasopharynx is situated at the back of the nose and connects the nose to the mouth.
• The nasopharynx contains adenoid tissue which helps to fight infection, and the openings to the Eustachian tubes which lead to the ears.
• The nasopharynx acts as a primary drainage path for lymphatic fluids.

The Oropharynx

• The oropharynx receives air from the nasopharynx and passes it to the laryngopharynx.
• The oropharynx serves to prevent food or liquids from entering the lungs.

The Laryngopharynx

• The laryngopharynx is the final section of the pharynx and connects to the trachea and esophagus.

The Larynx

• The Larynx is the voice box responsible for producing sound.
• It is located at the top of the trachea and is made of a series of cartilages and muscles.

The Trachea

• The trachea is the windpipe and serves as the passageway for air to travel from the larynx to the lungs.
• The trachea is composed of C-shaped hyaline cartilage rings that keep it open and provide structural support.

The Bronchi

• The trachea divides into two main bronchi; the right bronchus and the left bronchus.
• The bronchi further divide into smaller bronchioles which are lined with smooth muscle and cilia.
• The bronchioles control airflow in the lungs.

The Lungs

• The lungs are the primary organs of respiration.
• The lungs are housed within the thoracic cavity and are covered by the pleura.
• The left lung has two lobes, the superior lobe and the inferior lobe.
• The right lung has three lobes: the superior lobe, middle lobe, and inferior lobe.
• The lungs are comprised of a network of branching airways (bronchi and bronchioles) and tiny air sacs called alveoli.
• The alveoli are the site of gas exchange in the lungs.

The Pleura

• The pleura is a thin membrane that surrounds the lungs.
• The pleura is composed of two layers: the visceral pleura and the parietal pleura.
• The visceral pleura is the innermost layer and covers the lungs.
• The parietal pleura is the outermost layer and lines the chest wall.
• The space between the visceral pleura and the parietal pleura is called the pleural cavity.
• The pleural cavity contains pleural fluid which helps to reduce friction between the lungs and the chest wall, and lubricates the lungs during breathing.

The Diaphragm

• The diaphragm is a dome-shaped muscle that separates the thoracic cavity from the abdominal cavity.
• The diaphragm is the primary muscle of respiration.
• The diaphragm contracts during inhalation, which helps to increase the volume of the thoracic cavity.
• The diaphragm relaxes during exhalation, which helps to decrease the volume of the thoracic cavity.

The Ribs and Intercostal Muscles

• The ribs form the bony cage that protects the lungs.
• The intercostal muscles are located between the ribs.
• The external intercostal muscles help inhale by expanding the chest cavity.
• The internal intercostal muscles help exhale by contracting the chest cavity.

The Respiratory Membrane

• The respiratory membrane is the thin barrier that separates the air in the alveoli from the blood in the capillaries.
• The respiratory membrane is composed of the alveolar wall, the capillary wall, and the basement membranes between them.
• The respiratory membrane facilitates the exchange of gases between the air and the blood.

Gas Exchange

• Oxygen diffuses from the alveoli into the capillaries, and carbon dioxide diffuses from the capillaries into the alveoli.
• This exchange of oxygen and carbon dioxide is driven by the difference in partial pressures of these gases between the alveoli and the capillaries.

Blood Supply to the Lungs

• The pulmonary arteries carry deoxygenated blood from the heart to the lungs.
• The pulmonary veins carry oxygenated blood back to the heart.
• The pulmonary circulation is a low-pressure system, which makes it easier for gas exchange to occur at the alveoli.

Innervation of the Lungs

• The lungs are innervated by the parasympathetic and sympathetic nervous systems.
• The parasympathetic nervous system causes bronchoconstriction, which reduces airflow to the lungs.
• The sympathetic nervous system causes bronchodilation, which increases airflow to the lungs.

Inhalation

• During inhalation, the diaphragm contracts and moves downward.
• The external intercostal muscles contract, pulling the ribs upward and outward.
• The increased volume of the thoracic cavity creates a negative pressure that draws air into the lungs.

Exhalation

• During exhalation, the diaphragm relaxes and moves upward.
• The external intercostal muscles relax, allowing the ribs to move downward and inward.
• The decreased volume of the thoracic cavity creates a positive pressure that forces air out of the lungs.

Accessory Muscles of Respiration

• The sternocleidomastoid and scalene muscles are examples of accessory muscles of respiration that aid in respiration.
• These muscles support the rib cage during forced breathing.

Breathing Processes

• The act of breathing is controlled by the medulla oblongata, which is located in the brainstem.
• The medulla oblongata sends signals to the diaphragm and intercostal muscles that tell them to contract and relax.

This quiz explores the essential components and functions of the respiratory system. It covers the distinctions between the upper and lower respiratory systems, as well as the role of the nose and nasal cavity in air intake and filtration. Test your knowledge on how our body exchanges gases vital for life.