Circulation and Gas Exchange

In double circulation, blood flows through the heart twice in one complete circuit. It ensures efficient oxygen delivery and high blood pressure in the systemic circuit, which carries oxygenated blood to the body.

The pulmocutaneous circuit in amphibians is responsible for transporting deoxygenated blood from the heart to the lungs and skin for gas exchange.

Amphibians have a three-chambered heart with two atria and one ventricle. The incomplete septum within the ventricle partially separates oxygenated and deoxygenated blood, leading to some mixing.

Reptiles have a three-chambered heart similar to amphibians, with a partial septum in the ventricle. While this allows for some separation, it's still less efficient than the fully divided ventricle in mammals.

Mammals and birds have evolved a four-chambered heart with a completely divided ventricle. This ensures complete separation of oxygenated and deoxygenated blood, maximizing oxygen delivery to the body.

The systemic circuit carries oxygenated blood from the heart to the rest of the body, delivering oxygen to all cells and tissues. It operates at high blood pressure to ensure efficient delivery.

The pulmonary circuit carries deoxygenated blood from the heart to the lungs, where it picks up oxygen. It operates at lower blood pressure relative to the systemic circuit.

Convergent evolution is when two or more species evolve similar traits independently, due to similar environmental pressures. This applies to the evolution of a four-chambered heart in both mammals and birds.

The movement of fluids throughout a body, transporting necessary substances (e.g., oxygen, nutrients) and removing waste products.

A circulatory system where the circulatory fluid (hemolymph) directly bathes the organs.

A circulatory system where the circulatory fluid (blood) is confined to vessels.

The benefit of a closed circulatory system is the ability to maintain higher blood pressure, allowing for efficient oxygen delivery and nutrient transport in larger and more active animals.

Blood vessels that carry blood away from the heart.

Blood vessels that carry blood back to the heart.

Tiny blood vessels connecting arteries and veins, where the exchange of gases, nutrients, and waste takes place.

A circulatory system with a single circuit, where blood passes through the heart only once per complete circulation.

The phase of the cardiac cycle when the heart muscle relaxes and fills with blood.

The phase of the cardiac cycle when the heart muscle contracts and pumps blood out.

The medium used for gas exchange in animal respiration, which can be air, water, or even soil.

A specialized gas exchange mechanism in fish where blood flows in the opposite direction of water, maximizing oxygen uptake.

The process of moving air in and out of the lungs, facilitated by the contraction and relaxation of the diaphragm and intercostal muscles.

A highly efficient ventilation system in birds, where air flows through the lungs in a single direction, maximizing oxygen uptake by the lungs.

The heart's rhythmic cycle of contraction (systole) and relaxation (diastole).

The force exerted by blood on the walls of arteries, measured during systole and diastole.

The pressure in arteries during ventricular systole, when blood is pushed out.

The pressure in arteries during diastole, when blood is filling the chambers.

The rhythmic bulging of artery walls due to the heart's contractions.

The movement of a respiratory medium (air or water) over a respiratory surface.

A specialized gas exchange system in aquatic animals for extracting oxygen from water and releasing carbon dioxide.

A mechanism in fish gills where blood flows in the opposite direction of water, maximizing oxygen uptake.

A network of branching tubes in insects that directly deliver oxygen to body cells.

Organs for gas exchange in vertebrates, consisting of infoldings of the body surface.

Tiny air sacs in the lungs where gas exchange takes place.

A type of breathing in amphibians where air is forced into the lungs using a buccal pump.

A type of breathing in mammals where air is pulled into the lungs by expanding the chest cavity.

A dome-shaped muscle that plays a key role in breathing by contracting during inhalation, pulling air into the lungs, and relaxing during exhalation, pushing air out.

When the diaphragm contracts, it moves downward, increasing the volume of the chest cavity, creating a lower pressure inside the lungs, and causing air to rush in.

When the diaphragm relaxes, it moves upward, decreasing the volume of the chest cavity, increasing the pressure inside the lungs, and forcing air out.

The ability of an organism to breathe efficiently in an underwater environment.

Organisms that have adapted to survive underwater for extended periods, often employing strategies like storing oxygen in muscles or slowing their heart rate.