Circulatory Systems Overview

Open Circulatory System
- Found in arthropods and most mollusks.
- Blood (hemolymph) is not confined to vessels; it bathes organs directly.
- Hemolymph is circulated by a heart and movements of the body.
Closed Circulatory System
- Found in annelids, vertebrates, and some mollusks.
- Blood is contained within vessels, allowing for more efficient transport.
- Typically has a heart that pumps blood through a network of arteries, veins, and capillaries.

Heart
- Muscular organ responsible for pumping blood.
- Can be single or multi-chambered (e.g., two-chambered in fish, four-chambered in mammals).
Blood Vessels
- Arteries: Carry oxygenated blood away from the heart (except in pulmonary circulation).
- Veins: Carry deoxygenated blood back to the heart (except in pulmonary circulation).
- Capillaries: Microscopic vessels where gas and nutrient exchange occurs.
Blood
- Composed of red blood cells (for oxygen transport), white blood cells (for immune response), platelets (for clotting), and plasma (liquid component).

Transport of oxygen from respiratory organs to tissues.
Removal of carbon dioxide and metabolic wastes from tissues to excretory organs.
Distribution of nutrients and hormones throughout the body.
Regulation of body temperature and pH levels.
Protection against disease via immune cells in the bloodstream.

Fish: Single circuit with a two-chambered heart; efficient for aquatic respiration.
Amphibians: Double circuit with a three-chambered heart; allows for both oxygenated and deoxygenated blood mixing.
Reptiles: Generally three-chambered hearts; some have partial separation of oxygenated and deoxygenated blood.
Mammals and Birds: Four-chambered hearts; completely separate pulmonary and systemic circuits for efficient oxygen transport.

Adaptations in circulatory systems reflect environmental demands (e.g., oxygen availability).
Evolution of multi-chambered hearts allows for more effective separation of oxygenated and deoxygenated blood, enhancing metabolic efficiency.

Essential for maintaining homeostasis in animals.
Supports higher metabolic rates and larger body sizes in vertebrates.
Critical for survival, facilitating interactions with the environment and other organisms.

Open circulatory systems are present in arthropods and most mollusks, where hemolymph bathes organs directly without being confined to vessels.
Closed circulatory systems, found in annelids, vertebrates, and some mollusks, have blood contained within vessels, allowing for efficient transport through a network of arteries, veins, and capillaries.

The heart is a muscular organ that pumps blood and can be single or multi-chambered, with fish having two chambers and mammals having four.
Blood vessels include arteries (oxygenated blood away from the heart), veins (deoxygenated blood towards the heart), and capillaries (sites of gas and nutrient exchange).
Blood comprises red blood cells for oxygen transport, white blood cells for immune defense, platelets for clotting, and plasma as the liquid component.

Responsible for oxygen transport from respiratory organs to tissues.
Facilitates removal of carbon dioxide and metabolic wastes from tissues to excretory organs.
Distributes nutrients and hormones throughout the body.
Regulates body temperature and pH levels.
Provides protection against disease through immune cells present in the bloodstream.

Fish possess a single circuit with a two-chambered heart, optimizing oxygen uptake in aquatic environments.
Amphibians have a double circuit with a three-chambered heart, allowing for mixing of oxygenated and deoxygenated blood.
Reptiles typically have three-chambered hearts, with some displaying partial separation between blood types.
Mammals and birds feature four-chambered hearts, ensuring complete separation of pulmonary and systemic circulation for maximum oxygen transport efficiency.

Circulatory systems have evolved in response to environmental factors like oxygen availability, enhancing survival.
Multi-chambered hearts have developed to improve the separation of oxygenated and deoxygenated blood, leading to increased metabolic efficiency.

Circulatory systems play a crucial role in maintaining homeostasis across animal species.
Support higher metabolic rates and facilitate larger body sizes, particularly in vertebrates.
Critical for survival, they enable interactions with various environments and organisms.