40.1 Overview of the Circulatory System
3 min read•june 14, 2024
The circulatory system is a vital network that transports , nutrients, and waste throughout the body. It comes in two main types: open and closed. Open systems, found in insects and most mollusks, allow blood to flow freely. Closed systems, in vertebrates and some invertebrates, keep blood in vessels.
Vertebrate circulatory systems have evolved from simple to complex. Fish have a two-chambered , while mammals and birds have a four-chambered heart. This progression supports increased metabolic demands and more efficient oxygen delivery, enabling diverse lifestyles and behaviors in different environments.
Circulatory System Overview
Open vs closed circulatory systems
Top images from around the web for Open vs closed circulatory systems
Phylum Platyhelminthes | Biology for Majors II View original
Is this image relevant?
Overview of the Circulatory System | OpenStax: Biology View original
Is this image relevant?
Mollusks and Annelids · Concepts of Biology View original
Is this image relevant?
Phylum Platyhelminthes | Biology for Majors II View original
Is this image relevant?
Overview of the Circulatory System | OpenStax: Biology View original
Is this image relevant?
1 of 3
Top images from around the web for Open vs closed circulatory systems
Phylum Platyhelminthes | Biology for Majors II View original
Is this image relevant?
Overview of the Circulatory System | OpenStax: Biology View original
Is this image relevant?
Mollusks and Annelids · Concepts of Biology View original
Is this image relevant?
Phylum Platyhelminthes | Biology for Majors II View original
Is this image relevant?
Overview of the Circulatory System | OpenStax: Biology View original
Is this image relevant?
1 of 3
- Open circulatory systems
- Found in arthropods (insects, crustaceans) and most mollusks (snails, clams)
- Blood called flows freely through the body cavity bathing organs and tissues directly
- Heart pumps hemolymph into the body cavity but no vessels return it to the heart resulting in less efficient transport of nutrients and waste removal compared to closed systems
- Closed circulatory systems
- Found in annelids (earthworms), cephalopods (octopuses), and vertebrates (fishes, amphibians, reptiles, birds, mammals)
- Blood confined within a network of vessels including , , and separate from the surrounding cells
- Heart pumps blood through vessels which return it to the heart enabling more efficient delivery of oxygen and nutrients to tissues and removal of waste products
Roles of interstitial fluid and hemolymph
- Interstitial fluid
- Found in closed circulatory systems surrounding cells and filling spaces between them
- Composed of water, ions, nutrients, and waste products enabling exchange of substances between blood and cells
- Maintained by the balance of hydrostatic and osmotic pressures in
- Hemolymph
- Found in open circulatory systems directly bathing organs and tissues
- Composed of water, ions, nutrients, waste products, and respiratory pigments () allowing for exchange of substances
- Transports nutrients, waste products, and hormones while also playing a role in immune response and wound healing
Evolution of vertebrate circulatory systems
- Early chordates (lancelets)
- Simple, closed circulatory system with a contractile vessel pumping blood
- No true heart or specialized blood vessels
- Fishes
- Two-chambered heart (one , one )
- Single : blood flows from heart to for oxygenation, then to body, and back to heart adapting to aquatic life as efficiently extract oxygen from water
- Amphibians
- Three-chambered heart (two atria, one ventricle)
- : blood flows from heart to lungs and skin for oxygenation, then back to heart, and finally to body adapting to terrestrial life as lungs and skin provide oxygen uptake in air and water
- Reptiles (except crocodilians)
- Incomplete separation of ventricle leading to mixing of oxygenated and deoxygenated blood
- Adapts to conserve energy and maintain stable body temperature in terrestrial environments
- Birds and mammals (including crocodilians)
- Four-chambered heart (two atria, two ventricles) with complete separation of oxygenated and deoxygenated blood
- Adapts to support high metabolic rates and maintain constant body temperature (endothermy) enabling efficient delivery of oxygen to tissues, supporting active lifestyles and complex behaviors
Components of the Cardiovascular System
- Blood: The fluid that circulates through the heart and blood vessels
- : The liquid component of blood, consisting of water, proteins, and other dissolved substances
- : Specialized cells that carry oxygen throughout the body
- Heart: The muscular organ that pumps blood through the circulatory system
- Blood vessels: The network of tubes that carry blood throughout the body, facilitating circulation
Key Terms to Review (29)
Arcuate arteries: Arcuate arteries are blood vessels in the kidneys that arch over the base of the renal pyramids. They play a crucial role in supplying blood to the renal cortex and medulla for filtration and osmoregulation.
Arteries: Arteries are blood vessels that carry oxygenated blood away from the heart to the tissues of the body, playing a vital role in the circulatory system. These vessels are characterized by their thick, elastic walls, which help maintain blood pressure and accommodate the high velocity of blood flow. The structure and function of arteries are crucial for effective blood circulation and overall cardiovascular health.
Atrium: An atrium is one of the two upper chambers of the heart that receives blood from the body and lungs, playing a crucial role in the circulatory system. The right atrium collects deoxygenated blood from the body through the superior and inferior vena cava, while the left atrium receives oxygenated blood from the lungs via the pulmonary veins. This separation of oxygen-rich and oxygen-poor blood is vital for efficient circulation.
Blood: Blood is a vital fluid that circulates throughout the body, responsible for transporting oxygen, nutrients, hormones, and waste products. It plays a crucial role in maintaining homeostasis, regulating body temperature, and facilitating immune responses. Blood consists of various components, including red blood cells, white blood cells, platelets, and plasma, each performing specific functions essential for overall health.
Capillaries: Capillaries are the smallest blood vessels in the body, connecting arterioles to venules. They facilitate the exchange of oxygen, nutrients, and waste products between blood and tissues.
Capillaries: Capillaries are the smallest blood vessels in the body, connecting arterioles and venules, allowing for the exchange of gases, nutrients, and waste products between blood and surrounding tissues. They play a critical role in the circulatory system by facilitating the delivery of oxygen and nutrients while removing carbon dioxide and other metabolic waste, which is essential for maintaining homeostasis in organisms.
Cardiovascular system: The cardiovascular system is a complex network that facilitates the transport of blood, nutrients, hormones, and gases throughout the body, primarily involving the heart, blood vessels, and blood. This system plays a crucial role in maintaining homeostasis by regulating blood flow and pressure, delivering oxygen and removing carbon dioxide, while also supporting various bodily functions such as immune response and thermoregulation.
Circulation: Circulation refers to the movement of blood throughout the body, which is essential for delivering oxygen and nutrients to tissues and removing waste products. This process is vital for maintaining homeostasis, supporting cellular function, and enabling various physiological processes. In animals, circulation can occur through different systems, such as open and closed circulatory systems, each adapted to the organism's needs.
Coronary veins: Coronary veins are blood vessels that drain deoxygenated blood from the heart muscle (myocardium) and return it to the right atrium. They play a crucial role in the heart's own circulation by ensuring the removal of metabolic wastes.
Double circulation: Double circulation is a type of circulatory system found in some animals, including mammals and birds, where blood passes through the heart twice during one complete circuit through the body. This system consists of two distinct pathways: the pulmonary circuit, which carries deoxygenated blood from the heart to the lungs for oxygenation, and the systemic circuit, which delivers oxygenated blood from the heart to the rest of the body. Double circulation ensures efficient oxygen transport and waste removal, supporting high metabolic rates.
Gill circulation: Gill circulation is the process by which blood flows through the gills of aquatic organisms, facilitating gas exchange. Oxygen is absorbed from water while carbon dioxide is expelled.
Gills: Gills are specialized respiratory organs found in many aquatic organisms that facilitate gas exchange by extracting oxygen from water. They consist of thin filaments rich in blood vessels, maximizing surface area for efficient oxygen uptake and carbon dioxide release.
Gills: Gills are specialized respiratory organs found in many aquatic animals that allow for the exchange of gases, primarily oxygen and carbon dioxide, with the surrounding water. They play a crucial role in the survival of fish and some amphibians, as they facilitate breathing underwater by extracting dissolved oxygen from water as it flows over them.
Heart: The heart is a muscular organ that pumps blood throughout the body, supplying oxygen and nutrients while removing carbon dioxide and waste products. It plays a crucial role in maintaining the circulatory system, ensuring that all cells receive the necessary substances for survival and functioning. The heart's rhythmic contractions are regulated by electrical signals, allowing it to adapt to the body's changing demands, making it essential for overall homeostasis.
Hemocyanin: Hemocyanin is a copper-containing protein found in the blood of many arthropods and mollusks that serves as a respiratory pigment, facilitating the transport of oxygen. This protein binds oxygen more efficiently in cold and low-oxygen environments, making it crucial for the survival of organisms in such conditions. Hemocyanin acts similarly to hemoglobin, but instead of iron, it utilizes copper to bind oxygen molecules.
Hemolymph: Hemolymph is a fluid that circulates in the bodies of arthropods, functioning similarly to blood in vertebrates. It plays a crucial role in transporting nutrients, hormones, and waste products throughout the organism, while also participating in immune responses. Hemolymph is an essential component of the open circulatory system found in arthropods, helping to maintain internal homeostasis and support vital physiological processes.
Hydrostatic Pressure: Hydrostatic pressure is the pressure exerted by a fluid at equilibrium due to the force of gravity acting on it. In the circulatory system, it plays a crucial role in driving blood flow and influencing the exchange of fluids and nutrients between blood and tissues. The balance of hydrostatic pressure with osmotic pressure helps regulate the movement of fluids across capillary walls, maintaining proper circulation and tissue hydration.
Interstitial fluid: Interstitial fluid is the liquid found between cells in tissues, providing a medium for nutrients and waste to be exchanged. It plays a crucial role in maintaining the internal environment of tissues.
Osmotic pressure: Osmotic pressure is the pressure required to prevent the flow of water across a semipermeable membrane due to osmosis. It is a crucial factor in maintaining cellular and systemic fluid balance.
Osmotic Pressure: Osmotic pressure is the pressure required to prevent the flow of water across a semipermeable membrane, resulting from the difference in solute concentrations on either side of the membrane. It plays a crucial role in maintaining fluid balance within biological systems, particularly in relation to blood circulation and the regulation of body fluids.
Plasma: Plasma is the yellowish, liquid component of blood that makes up about 55% of its volume. It serves as a medium for transporting nutrients, hormones, and waste products throughout the body.
Plasma: Plasma is the liquid component of blood, making up about 55% of its total volume. It serves as a medium for transporting nutrients, hormones, proteins, and waste products throughout the body, playing a crucial role in maintaining homeostasis and supporting cellular functions.
Pulmocutaneous circulation: Pulmocutaneous circulation is a circulatory pathway in amphibians where blood flows from the heart to the lungs and skin for gas exchange. This system allows amphibians to utilize both lungs and skin for respiration.
Pulmonary circulation: Pulmonary circulation is the part of the circulatory system that carries deoxygenated blood from the right ventricle of the heart to the lungs and returns oxygenated blood to the left atrium. It is essential for gas exchange, where carbon dioxide is expelled, and oxygen is absorbed.
Red blood cells: Red blood cells, also known as erythrocytes, are specialized cells in the bloodstream responsible for transporting oxygen from the lungs to the body's tissues and returning carbon dioxide from the tissues back to the lungs. They contain hemoglobin, a protein that binds oxygen, making them crucial for cellular respiration and overall metabolism. The efficient functioning of red blood cells is vital for maintaining the body's energy levels and sustaining life.
Systemic circulation: Systemic circulation is the part of the circulatory system that carries oxygenated blood from the heart to the body and returns deoxygenated blood back to the heart. It is essential for delivering nutrients and removing waste products from tissues.
Unidirectionally: Unidirectionally describes a process that occurs in a single direction. In biological systems, it often refers to the one-way flow of substances like blood or other fluids.
Veins: Veins are blood vessels that carry deoxygenated blood back to the heart, playing a crucial role in the circulatory system. They are equipped with one-way valves that prevent the backflow of blood and rely on the contraction of surrounding muscles to assist in the movement of blood, particularly from the extremities. This function is vital for maintaining proper circulation and ensuring that oxygenated blood can efficiently reach all body tissues.
Ventricle: A ventricle is a chamber within the heart that plays a critical role in pumping blood to different parts of the body. Each heart has two ventricles: the right ventricle, which pumps deoxygenated blood to the lungs for oxygenation, and the left ventricle, which pumps oxygenated blood to the rest of the body. The structure and function of ventricles are essential to understanding how blood circulation operates and maintains homeostasis in the organism.