Biology ch 23

Circulatory system

• Circulatory system deliver nutrients & remove wastes

• Consists of a heart and associated vessels

Hydra

have two layers of cells; circulation sufficed by diffusion

Planaria

have small flattened body; circulation sufficed by diffusion

Open circulatory system

grasshoppers

• Tubular heart pumps hemolymph

• Hemolymph colorless (no Hgb)

• Hemocoel – cavity containing organs

• Ostia – openings in heart wall

• Trachea – bring in O2 & CO2 out

Closed Cardiovascular system

• consists of strong muscular heart & blood vessels

• Blood always contained within vessels

• arteries, veins, and capillaries

• Lymphatic system picks up excess tissue fluid & returns it to the blood

One Circuit

fishes

• Heart has a single atrium & ventricle

• Reduced pressure through system

• Advantage in body receiving O2 rich blood

Two Circuit

• Systemic circuit & Pulmonary circuit

• Amphibians and some reptiles – two atria & only one ventricle

• Some mixing of O2 rich and O2 poor blood

Circulation in Humans

❖ Double pump

• Right side pumps O2 poor blood to lungs

• Left side pumps O2 rich blood to body

• Complete septum separates sides and prevents mixing.

Each side has two chambers

• Atria are upper, thin-walled chambers receiving blood

• Ventricles are lower, thick-walled chambers pumping blood

veins

take blood to the heart

arteries

take blood away from the heart

Valves

keep blood flowing in a single direction

Pulmonary Circuit

flow of blood through the lungs

atrioventricular valve

tricuspid valve

Systemic Circuit

• From lungs→ pulmonary vein (carrying O2-rich blood) →

left atrium

• Left atrium→ left atrioventricular valve (AKA bicuspid

valve) → left ventricle

• Left ventricle → aortic semilunar valve into aorta

Aorta

pumps blood out to the tissues