Comparative Vertebrate Anatomy and Physiology

Cardiovascular System Heart (4 parts): Sinus venosus, Atrium, Ventricle, Conus arteriosus Vessels: Arteries, Veins, Capillaries

The HEART: Where is the blood going and is it oxygen rich or poor?

Part 1: Sinus Venosus Thin walls, fibrous tissue, little muscle Contains Sinoatrial Node = “Pacemaker” Receives Common Cardinal Veins, Hepatic Veins and Jugular Passive collector – blood “sucked” in via aspiration as Sinus Venosus expands

Part 2, Chamber 1: Atrium Large chamber Thin walls, but muscular Separated from Sinus Venosus by Sinoatrial Valve Valve opens via blood pressure Relaxed Atrium fills Atrium has the ability to contract Dorsal position allows gravity to assist contraction in moving blood

Part 3, Chamber 2: Ventricle Thick walls with cardiac muscle Separated from Atrium via Atrioventricular Valve Valve opens when Atrium contracts Ventricle fills & produces primary heart contraction Contraction increases space in rigid Pericardial Cavity Atrium & Sinus Venosus fill via aspiration

Part 4: Conus arteriosus (Ventral aorta) Small diameter tube Thick walls with smooth muscle Flow back into Ventricle prevented via series of Conal, Semilunar Valves Serves as auxiliary pump Contracts as Ventricle relaxes Assures steady pressure as blood enters Ventral Aorta & gills

The VESSELS: Compare and Contrast Thick walled Capable of contractions Oxygen level high, CO 2 level low. High pressure Take blood away from heart.

The VESSELS: Compare and Contrast Thinner walled Incapable of contractions Oxygen level low, CO 2 level high. Low pressure, valves needed. Take blood to heart.

The VESSELS: Compare and Contrast VERY thin walled Incapable of contractions Oxygen and CO 2 level similar. low pressure Blood direction both ways.

The VESSELS: Where is the blood going and is it oxygen rich or poor?