Final answer:
The systemic circuit of mammals includes three main types of blood vessels: arteries, which carry oxygenated blood away from the heart; veins, which bring deoxygenated blood back to the heart; and capillaries, where the exchange of oxygen and nutrients occurs.
Step-by-step explanation:
Major Types of Blood Vessels and Their Functions
The systemic circuit of a mammal contains three major types of blood vessels, each with distinct functions:
- Arteries: These vessels carry oxygenated blood away from the heart to the body's tissues. The largest artery is the aorta.
- Veins: Veins return deoxygenated blood back to the heart. The two largest veins are the superior and inferior vena cava.
- Capillaries: These are small thin-walled vessels where oxygen and nutrient exchange occurs between the blood and tissues.
Arteries, designed to manage high pressure as blood is pumped from the heart, have thick elastic walls. In contrast, veins have thinner walls and contain valves to help maintain one-way blood flow. Capillaries, being the site of exchange, have walls that are only one cell thick to facilitate the diffusion of oxygen, nutrients, and waste products.
Blood pressure is the force of blood against vessel walls, usually measured in mmHg, with normal levels being around 120/80 mmHg. Blood vessels maintain homeostasis by working in conjunction with neural and endocrine systems, and they interact closely with other body systems.