7.4 Comparative cardiovascular systems in animals
3 min read•august 7, 2024
Cardiovascular systems in animals come in various forms, from open to closed systems. The 's structure ranges from two to four chambers, each adapted to the animal's specific needs and environment. These differences impact how blood flows and oxygen is delivered throughout the body.
Circulation pathways vary among species, with in aquatic animals and in air-breathers. Some animals have developed specialized adaptations, like marine mammals' ability to dive deep for extended periods, showcasing the incredible diversity of cardiovascular systems in the animal kingdom.
Circulatory System Types
Open vs Closed Circulatory Systems
Top images from around the web for Open vs Closed Circulatory Systems
evolution - How did the double circulatory system evolve from the single circulatory system ... View original
Is this image relevant?
Overview of the Circulatory System | OpenStax Biology 2e View original
Is this image relevant?
Frontiers | Subjectivity “Demystified”: Neurobiology, Evolution, and the Explanatory Gap ... View original
Is this image relevant?
evolution - How did the double circulatory system evolve from the single circulatory system ... View original
Is this image relevant?
Overview of the Circulatory System | OpenStax Biology 2e View original
Is this image relevant?
1 of 3
Top images from around the web for Open vs Closed Circulatory Systems
evolution - How did the double circulatory system evolve from the single circulatory system ... View original
Is this image relevant?
Overview of the Circulatory System | OpenStax Biology 2e View original
Is this image relevant?
Frontiers | Subjectivity “Demystified”: Neurobiology, Evolution, and the Explanatory Gap ... View original
Is this image relevant?
evolution - How did the double circulatory system evolve from the single circulatory system ... View original
Is this image relevant?
Overview of the Circulatory System | OpenStax Biology 2e View original
Is this image relevant?
1 of 3
- pumps blood into body cavities (hemocoel) allowing direct contact with tissues and organs
- Found in arthropods (insects, spiders) and most mollusks (snails, clams)
- pumps blood through a network of vessels that transport blood to tissues without direct contact
- Blood remains separate from interstitial fluid surrounding cells
- Found in annelids (earthworms), cephalopod mollusks (octopus, squid), and all vertebrates
Variations in Heart Structure
- has one atrium and one ventricle
- Found in fish
- Blood flows in single loop, first to gills for oxygenation then to rest of body
- has two atria and one ventricle
- Found in amphibians and most reptiles
- Oxygenated and deoxygenated blood mix in the single ventricle
- has two atria and two ventricles
- Found in birds, mammals, and crocodilians
- Oxygenated and deoxygenated blood remain completely separated
- Allows for higher blood pressure and more efficient to tissues
Circulation Pathways
Gill and Pulmonary Circulation
- Gill circulation in fish and some amphibian larvae
- Heart pumps deoxygenated blood to gills where occurs
- Oxygenated blood then flows to rest of body
- Pulmonary circulation in air-breathing animals
- Heart pumps deoxygenated blood to lungs
- Gas exchange occurs in lungs, oxygenating the blood
- Oxygenated blood returns to heart to be pumped to body
Systemic Circulation
- delivers oxygenated blood from heart to body tissues
- In fish, blood flows from gills directly to systemic circulation
- In animals with pulmonary circulation, oxygenated blood returns to heart first
- Deoxygenated blood from tissues returns to heart to be re-oxygenated
Countercurrent Exchange
- is a mechanism for efficient transfer of heat or gases between fluids flowing in opposite directions
- Examples include heat exchange in limbs of marine mammals and oxygen uptake in fish gills
- In fish gills, water and blood flow in opposite directions over gill filaments
- Maintains a constant diffusion gradient for efficient oxygen uptake from water into blood
Specialized Adaptations
Diving Adaptations in Marine Mammals
- Marine mammals like whales and seals have adaptations for prolonged deep dives
- Increased in blood and muscle
- High levels of in blood and in muscles
- Reduced heart rate () and restricted blood flow to non-essential organs during dives
- Maintains blood flow to heart, lungs and brain
- Collapse of lungs at depth to avoid nitrogen absorption and decompression sickness
- Efficient oxygen extraction allows some whales to dive for over 2 hours on a single breath
Key Terms to Review (20)
Aquatic adaptation: Aquatic adaptation refers to the specialized traits and physiological changes that organisms develop to thrive in aquatic environments. These adaptations can include modifications in morphology, behavior, and physiology, enabling species to efficiently navigate, feed, reproduce, and survive in water. The study of these adaptations helps us understand how different organisms optimize their cardiovascular systems to function effectively under varying aquatic conditions.
Bradycardia: Bradycardia is a medical term that refers to a slower than normal heart rate, typically defined as fewer than 60 beats per minute. This condition can impact the cardiovascular efficiency and overall oxygen delivery to tissues, particularly in various animal species, and can be linked to specific respiratory adaptations in response to environmental conditions.
Cardiac output: Cardiac output is the volume of blood pumped by the heart per minute, a crucial measure of cardiovascular efficiency and health. It reflects the ability of the heart to supply oxygen and nutrients to tissues while removing waste products. Understanding cardiac output helps in examining blood composition, hemodynamics, and how the body regulates blood flow during different physiological states, including exercise and rest.
Closed circulatory system: A closed circulatory system is a type of cardiovascular system where blood circulates within a network of vessels, separating it from the interstitial fluid. This system allows for more efficient transport of oxygen, nutrients, and waste products throughout the body compared to open systems. It is found in more complex organisms, supporting higher metabolic demands and providing better regulation of blood flow and pressure.
Countercurrent exchange: Countercurrent exchange is a biological mechanism where two fluids flow in opposite directions, allowing for efficient transfer of heat, gases, or solutes between them. This strategy is crucial in maintaining homeostasis in various physiological processes, enhancing efficiency in gas exchange, thermoregulation, and osmoregulation across different animal species.
Four-chambered heart: A four-chambered heart is a type of circulatory system structure that consists of two atria and two ventricles, allowing for the separation of oxygenated and deoxygenated blood. This design enables more efficient oxygen delivery to the body, which is essential for sustaining high metabolic rates. The four-chambered heart is characteristic of mammals and birds, providing a significant advantage in terms of maintaining homeostasis and supporting active lifestyles.
Gas exchange: Gas exchange is the biological process by which oxygen is acquired from the environment and carbon dioxide is released, enabling cellular respiration. This process occurs in specialized structures, such as lungs or gills, and is essential for maintaining the metabolic functions of animals. The efficiency and mechanisms of gas exchange can vary greatly across different species, reflecting adaptations to their environments and lifestyle needs.
Gill circulation: Gill circulation refers to the specialized blood flow through the gills of aquatic animals, facilitating gas exchange by delivering oxygen-rich water to gill surfaces while removing carbon dioxide. This process is vital for the respiratory efficiency of fish and other gill-breathing organisms, connecting their circulatory and respiratory systems to maximize oxygen uptake in water environments.
Heart: The heart is a muscular organ responsible for pumping blood throughout the body, maintaining circulation and supplying oxygen and nutrients to tissues while removing carbon dioxide and waste products. It plays a critical role in the cardiovascular system, which varies significantly across different animal species, affecting how they adapt to their environments and meet their metabolic needs.
Hemoglobin: Hemoglobin is a complex protein found in red blood cells responsible for transporting oxygen from the lungs to the body's tissues and facilitating the return transport of carbon dioxide from the tissues back to the lungs. This protein's ability to bind oxygen depends on its structure and the presence of heme groups, which contain iron, allowing for efficient gas exchange and contributing to overall blood composition and hemodynamics.
High-altitude adaptation: High-altitude adaptation refers to the physiological changes and adjustments that organisms undergo to survive and thrive in environments with low oxygen levels and reduced atmospheric pressure, typically found at elevations above 2,500 meters (8,200 feet). These adaptations involve modifications in the cardiovascular, respiratory, and cellular systems to optimize oxygen uptake and utilization, which is crucial for maintaining metabolic functions in challenging conditions.
Myoglobin: Myoglobin is a globular protein found in muscle tissues, primarily responsible for the storage and transport of oxygen within muscle cells. Its structure allows it to bind oxygen more effectively than hemoglobin, making it essential for sustaining muscular activity during periods of intense exercise. Myoglobin plays a crucial role in facilitating aerobic respiration, especially in animals that engage in sustained physical exertion or occupy environments with varying oxygen availability.
Open circulatory system: An open circulatory system is a type of circulatory system where blood is not always contained within blood vessels but instead flows freely through cavities in the body, bathing the organs directly. This system is common in many invertebrates, such as arthropods and mollusks, and is characterized by the presence of hemolymph, a fluid that serves both as blood and interstitial fluid. The efficiency of this system varies among different species, depending on their size and metabolic demands.
Oxygen delivery: Oxygen delivery refers to the process by which oxygen is transported from the respiratory system to the tissues of the body, ensuring that cells receive the necessary oxygen for metabolism. This process is crucial for maintaining cellular respiration and energy production in animals. Different cardiovascular systems have evolved various adaptations to optimize oxygen delivery, influenced by factors such as metabolic needs, habitat, and evolutionary lineage.
Oxygen storage: Oxygen storage refers to the mechanisms and capacities in animals for retaining oxygen in tissues and blood, enabling sustained aerobic metabolism during periods of low oxygen availability or high energy demand. This process is crucial for many species, especially those with high metabolic rates or that engage in prolonged physical activities, allowing them to maintain performance even when environmental oxygen levels fluctuate.
Pulmonary circulation: Pulmonary circulation is the part of the cardiovascular system responsible for transporting deoxygenated blood from the right ventricle of the heart to the lungs and returning oxygenated blood back to the left atrium. This process is crucial for gas exchange, allowing carbon dioxide to be expelled and oxygen to be absorbed in the lungs, which plays a vital role in maintaining homeostasis in animals with varying cardiovascular systems.
Red Blood Cells: Red blood cells (RBCs), also known as erythrocytes, are specialized cells in the blood responsible for transporting oxygen from the lungs to the body's tissues and returning carbon dioxide from the tissues back to the lungs. These biconcave, disc-shaped cells contain hemoglobin, a protein that binds oxygen, making them essential for cellular respiration and overall metabolic processes in various animal species.
Systemic circulation: Systemic circulation is the part of the cardiovascular system responsible for transporting oxygenated blood from the heart to the rest of the body and returning deoxygenated blood back to the heart. This process is crucial for delivering essential nutrients and oxygen to tissues while removing carbon dioxide and waste products. In the context of different animal cardiovascular systems, systemic circulation showcases various adaptations that help meet the metabolic demands of diverse organisms.
Three-chambered heart: A three-chambered heart consists of two atria and one ventricle, allowing for a mix of oxygenated and deoxygenated blood. This type of heart is found in amphibians and some reptiles, providing a transitional system that supports both aquatic and terrestrial lifestyles. The unique structure helps organisms efficiently manage their circulatory needs as they move between environments, impacting their overall physiology and adaptation.
Two-chambered heart: A two-chambered heart is a simple cardiac structure consisting of one atrium and one ventricle, primarily found in fish and some amphibian larvae. This basic arrangement facilitates the circulation of blood, allowing it to flow in a single circuit from the heart to the gills (or skin in some amphibians) for oxygenation and then to the rest of the body. Despite its simplicity, this heart structure is efficient for the metabolic demands of organisms that possess it.