BIOL 410: Cardiovascular System

Comparative Anatomy of the Circulatory System

Review

Fish

Amphibians

Reptiles

Birds & Mammals

Let's Review

Cardiovascular System

Cardiovascular System

Cardiovascular System consists of:

• Blood
• Heart
• Arteries, Veins, and Capillaries

Cardiovascular System Review

Blood

Purpose

Heart

transport gases, nutrients, waste products, hormones, heat, & various other materials

Liquidus transport medium comprised of plasma & formed elements.

Muscular pump comprised of cardiac tissue.

Comparing Heart Structure

Cartilaginous fish

Cartilaginous & Teleost Fishes

• Single circuit heart structure with two simplified pumping "chambers"- atrium & ventricle.
• Tehnically have four chambers of heart (see below).
• Cartilaginous fish:
• sinus venosus, atrium, ventricle, & conus arteriosus

Bony Fish

• Bony fish:
• sinus venosus, atrium, ventricle, & bulbus arteriosus

Circulatory System in Fish

Patterns of flow

Gill Circulation

• atrium collects blood that has returned from the body
• ventricle pumps the blood to the gills

Systemic Circulation

• unidirectional flow of blood produces a gradient of oxygenated to deoxygenated blood
• limits the metabolic rate due to oxygen capacity

Amphibian Heart

• Modified due to the prescence of lungs.
• 3-chambered system.
• Right & left atrium, one ventricle.
• Can result in mixing of blood, but not a major issue since amphibians can also acquire oxygen from skin.

Amphibian Circulation

Double circulatory pattern- first to lungs, then back to heart, then systemic.Pulmoncutaneous

• Oxygen recevied from lungs and skin

Systemic

• Shortening of ventral aorta, which helps:
• Ensure that the oxygenated & unoxygenated blood is kept separate in the heart.
• Moves blood directly into the appropriate vessels.

Reptile Heart

• Most reptiles also have a three-chambered heart similar to the amphibian heart.
• Ventricle is divided more effectively by a partial septum, which results in less mixing of oxygenated and deoxygenated blood.
• EXCEPTION: Alligators and crocodiles are the most primitive animals to exhibit a four-chambered heart.

Unique Feature of Reptilian Heart

Shunting of Blood

• Crocodilians - ventricular septum is complete but a narrow channel called the Foramen of Panizza
• Connects the base of the right & left systemic trunks
• Permits bypass of the pulmonary circuit when submerged or when "resting and digesting".
• Stabilizes blood oxygen levels when submerged.

Bird Heart

• Heart is divided into four chambers: two atria and two ventricles.
• Septum completely closes chambers to prevent mixing of blood.
• Improves efficiency of circulatory system.

Mammalian Heart

• Very similar to the structure of the bird heart.
• Four separate chambers to prevent mixing of blood.
• Pulmonary & Systemic circuits.