⇦ Back to Human physiology

Human physiology is the study of how the human body functions. It encompasses all aspects of the body, from the smallest cells to the largest organs. In this lesson, we will focus on the cardiovascular system, which is responsible for transporting blood and nutrients throughout the body.

The Structure and Function of the Heart and Blood Vessels

The heart is a muscular organ that pumps blood throughout the body. It is divided into four chambers: the right atrium, the right ventricle, the left atrium, and the left ventricle. The blood vessels that carry blood away from the heart are called arteries, while the vessels that carry blood back to the heart are called veins. Capillaries are the smallest blood vessels and are responsible for exchanging nutrients and waste products between the blood and the tissues.

The Regulation of Blood Pressure and Blood Flow

Blood pressure is the force that blood exerts on the walls of the blood vessels. It is regulated by a complex system involving hormones, the nervous system, and the cardiovascular system. Blood flow is the movement of blood through the blood vessels. It is also regulated by the same system that regulates blood pressure.

The Mechanisms of Gas Exchange in the Lungs and Tissues

The respiratory system is responsible for the exchange of gases between the body and the environment. Oxygen is taken in through the lungs and transported to the tissues, where it is used for cellular respiration. Carbon dioxide, a waste product of cellular respiration, is transported back to the lungs and exhaled.

The Role of the Cardiovascular System in Maintaining Homeostasis

Homeostasis is the maintenance of a stable internal environment in the body. The cardiovascular system plays a crucial role in maintaining homeostasis by regulating blood pressure, blood flow, and the delivery of nutrients and oxygen to the tissues.

The Response of the Cardiovascular System to Stress

The cardiovascular system responds to stress by increasing heart rate and blood pressure. This response is mediated by the sympathetic nervous system and is designed to prepare the body for fight or flight.


The cardiovascular system is a complex system that is responsible for maintaining the health and well-being of the body. By understanding the structure and function of the heart and blood vessels, the regulation of blood pressure and blood flow, the mechanisms of gas exchange in the lungs and tissues, the role of the cardiovascular system in maintaining homeostasis, and the response of the cardiovascular system to stress, we can better appreciate the importance of this system in our daily lives.

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⇦ 4. The Endocrine System 6. The Digestive System ⇨