Anatomy of the Respiratory System

Cardio-pulmonary System

• The cardio-pulmonary system includes the cardiovascular system and respiratory system
• Cardiovascular system comprises the heart and blood vessels
• Respiratory system includes the nasal cavity, oral cavity, pharynx, larynx, trachea, bronchi, bronchioles, and lungs
• The heart is a hollow muscular organ, it propels blood throughout the body via blood vessels
• The heart is located in the thoracic cavity, positioned between the lungs with 60% of it to the left of the median plane

Heart Coverings

• The heart is enclosed in a double-walled sac called pericardium
• It consists of two layers: fibrous pericardium and serous pericardium
• Fibrous pericardium is a tough, dense connective tissue layer that anchors the heart to surrounding structures, providing protection
• Serous pericardium is a thin, slippery, two-layered serous membrane
• The parietal layer lines the internal surface of the fibrous pericardium
• The visceral layer covers the outer surface of the heart
• Between the parietal and visceral layers is a slit-like pericardial cavity, filled with pericardial fluid

Heart Wall Structures

• The heart wall is composed of three distinctive layers: epicardium, myocardium, and endocardium
• Epicardium is the outermost layer, forming the visceral layer of the serous pericardium
• Myocardium is the middle layer, primarily composed of cardiac muscle, forming the bulk of the heart
• Endocardium is the innermost layer, a glistening white sheet of endothelium

Heart Chambers

• The heart has four chambers: two atria (superior) and two ventricles (inferior)
• Atria are receiving chambers, positioned superiorly to the ventricles
• Ventricles are discharging chambers, positioned inferior to the atria
• The atria are separated from each other by the interatrial septum
• The ventricles are separated from each other by the interventricular septum

Right Atrium

• Separated from the left atrium by the interatrial septum
• Receives blood from the superior vena cava, inferior vena cava, and coronary sinus
• Communicates with the right ventricle via the right atrioventricular orifice, guarded by the tricuspid valve

Left Atrium

• Forms the greater part of the heart's base
• Contains four pulmonary veins, which convey oxygenated blood from the lungs to the heart
• Connects to the left ventricle via the mitral (bicuspid) valve, guarded by two cusps

Right Ventricle

• Separated from the left ventricle by the interventricular septum
• Its wall is thinner compared to the left ventricle
• The pulmonary trunk arises from the right ventricle, dividing into two pulmonary arteries, one for each lung

Left Ventricle

• Forms the apex of the heart
• Its wall is significantly thicker than the right ventricle
• The ascending aorta arises from the left ventricle

Blood Supply of the Heart

• Arterial supply is provided by the right and left coronary arteries, which originate from the ascending aorta
• Venous drainage is primarily by coronary veins, which empty into the coronary sinus and then the right atrium

Blood Vessels

• Arteries carry oxygenated blood away from the heart, characterized by high pressure and lacking valves
• Veins carry deoxygenated blood towards the heart, characterized by low pressure and possessing valves
• Capillaries are microscopic vessels facilitating the exchange of substances between blood and surrounding tissues. They are single-cell thick, linking arterial and venous systems with significantly slower blood flow

Respiratory System

• The respiratory system consists of the upper, conducting, and lower parts
• Upper part comprises nasal cavities, pharynx, and larynx
• Conducting part includes the trachea, bronchi, and bronchioles
• Lower part contains the lungs and pleurae

Nasal Cavity

• Situated posterior and inferior to the external nose
• Contains a midline nasal septum that divides it into right and left nasal cavities
• Continuous with the nasal portion of the pharynx posteriorly
• Nasal conchae project inward from the lateral walls, each with a nasal meatus beneath

Pharynx

• A fibromuscular tube (12-15cm) located behind the nasal, oral, and laryngeal cavities
• Connects the nasal cavities to the esophagus
• The nasopharynx is a posterior extension of the nasal cavities

Larynx

• Also known as the voice box, it's located at the lower part of the pharynx and connected to the trachea
• Supported by hyaline and elastic cartilages, connected by membranes
• Larynx is lined with a mucous membrane internally and is covered by muscles externally

Trachea

• A fibrocartilaginous tube approximately 10cm long
• Connected to the larynx superiorly and divides into two bronchi inferiorly
• Contains C-shaped cartilaginous rings (20) that keep it open, in a U-shape, posteriorly

Bronchi

• Bronchial structure similar to that of the trachea
• Each bronchus enters a lung at the hilum and then descends toward the lung base
• Each bronchus branches repeatedly to form a bronchial tree (bronchioles)
• Bronchioles eventually divide into alveolar ductules with sacs for gas exchange (alveolar sacs)

Lungs

• Two cone-shaped lungs fill the thoracic cavity except for the mediastinum
• Each lung has an apex, base, costal, and mediastinal surfaces
• The lung's root, on the medial surface, contains the bronchus, pulmonary artery, and pulmonary veins
• The right lung is divided into three lobes by two fissures
• The left lung is divided into two lobes by one fissure

Pleurae(Pleura)

• A serous sac composed of a double-walled membrane (parietal and visceral)
• The space between the layers is the pleural cavity, containing pleural fluid
• Parietal pleura covers the thoracic surface of the diaphragm, lateral aspect of the mediastinum, and supra-pleural membrane
• Visceral pleura covers the lung's surface and extends into fissures
• Pulmonary ligament connects the visceral and parietal pleura at the lung root, accommodating expansion/movement of vessels

Test your knowledge on the anatomy of the respiratory system with this quiz. Questions cover cartilage structures, gas exchange functions, and airway protection. Perfect for students studying anatomy or related health sciences.