Cardiovascular and Respiratory Systems: Key Structures and Functions

Cardiovascular System

Overview

The cardiovascular system is responsible for the circulation of blood throughout the body, delivering oxygen and nutrients to tissues and removing waste products. Understanding the anatomy of the heart and the flow of blood is essential for comprehending its function.

• Blood Flow Through the Heart: Blood enters the heart through the superior and inferior vena cava, passes through the right atrium and ventricle, and is pumped to the lungs via the pulmonary arteries. Oxygenated blood returns to the left atrium, passes into the left ventricle, and is distributed to the body through the aorta.

• Cardiac Cycle: The cardiac cycle consists of systole (contraction) and diastole (relaxation), which coordinate the pumping action of the heart.

Human Heart Anatomy

Key anatomical structures of the human heart include:

• Chambers: Right atrium, right ventricle, left atrium, left ventricle

• Major Vessels: Superior/inferior vena cava, pulmonary trunk, pulmonary veins, aorta, coronary arteries

• Valves: Tricuspid valve, bicuspid (mitral) valve, aortic semilunar valve, pulmonary semilunar valve

• Other Structures: Interventricular septum, chordae tendineae, papillary muscles, ligamentum arteriosum, apex, coronary sinus, SA/AV nodes

Sheep Heart Comparison

The sheep heart shares similar anatomical features with the human heart, making it a useful model for study.

• Right/left atrium and ventricle

• Interventricular septum

• Valves: Tricuspid, bicuspid, aortic and pulmonary semilunar valves

• Chordae tendineae, papillary muscles, trabeculae carneae

Respiratory System

Overview

The respiratory system enables gas exchange between the body and the environment. It consists of structures that conduct air and facilitate oxygen and carbon dioxide exchange.

• Air Passage: Air passes through the nose, pharynx, larynx, trachea, bronchi, and lungs.

• Pseudostratified Ciliated Columnar Epithelium: Lines much of the respiratory tract, helping to trap and move particles out of the airways.

• Larynx: Contains structures that contribute to phonation (voice production).

Alveolar Structures

• Type I Pneumocytes: Thin cells for gas exchange.

• Type II Pneumocytes: Secrete surfactant, which reduces surface tension in alveoli.

• Alveolar Macrophages: Immune cells that remove debris and pathogens.

• Surfactant: Essential for keeping alveoli open and preventing collapse.

Respiratory Muscles

• Inspiratory Muscles: Diaphragm, external intercostals

• Expiratory Muscles: Internal intercostals, abdominal muscles

• Accessory Muscles: Used during forced breathing (e.g., sternocleidomastoid)

Boyle's Law

Boyle's Law describes the inverse relationship between the pressure and volume of a gas at constant temperature:

• Equation: $P_1V_1 = P_2V_2$

• Application: As lung volume increases during inspiration, pressure decreases, allowing air to flow in.

Pulmonary Volumes and Capacities

• Spirometry: Used to measure lung volumes and capacities.

• Tidal Volume: Volume of air inhaled or exhaled in a normal breath.

• Vital Capacity: Maximum amount of air that can be exhaled after a maximal inhalation.

Respiratory Waste Removal

• Carbon Dioxide, Bicarbonate, Hydrogen Ions: CO2 is transported in the blood as dissolved gas, bicarbonate ions, and bound to hemoglobin. Removal is essential for acid-base balance.

Respiratory System Structures

Upper Respiratory System	Larynx & Cartilages	Bronchial Tree & Lungs
Nose, Nasal conchae, Nasopharynx, Oropharynx, Laryngopharynx, Hard/Soft palate	Epiglottis, Hyoid bone, Thyroid cartilage, Cricoid cartilage, Arytenoid cartilage, Vocal folds	Primary, secondary, tertiary bronchi, Lungs, Lobes, Bronchioles, Alveoli

Vital Signs

Overview

Vital signs are measurements of essential physiological functions, including blood pressure, heart rate, respiratory rate, and oxygen saturation.

• Blood Pressure: Measured using a sphygmomanometer. Key values are systolic (pressure during heart contraction) and diastolic (pressure during relaxation).

• Pulse Pressure: Difference between systolic and diastolic pressure. Equation: $\text{Pulse Pressure} = \text{SBP} - \text{DBP}$

• Mean Arterial Pressure (MAP): Average pressure in arteries during one cardiac cycle. Equation: $\text{MAP} = \frac{1}{3}(\text{SBP} - \text{DBP}) + \text{DBP}$

• ECG (Electrocardiogram): Records electrical activity of the heart. Key components: P wave (atrial depolarization), QRS complex (ventricular depolarization), T wave (ventricular repolarization).

• PERRLA: Pupils Equal, Round, Reactive to Light and Accommodation; used to assess neurological function.

• Pulse Oximetry: Measures oxygen saturation (SpO2); normal values are typically 95-100%.

Additional info:

• Understanding the cardiac cycle and respiratory volumes is essential for interpreting clinical measurements and diagnosing disorders.

• Tables above are reconstructed to group anatomical structures logically for study purposes.