Circulatory system

Linking Respiration with Body Cells

O2 and CO2 move between cells and surroundings via diffusionDiffusion time proportional to distance traveled

Diffusion time proportional to distance traveled

Works for single-celled organisms

Those with gastrovascular cavity

Animals with complex body plan circulatory system for efficient exchange

Circulatory system basics

Circulatory fluid (blood or hemolymph)

Interconnecting vessels

Muscular pump (heart)

Open - Circulatory fluid (hemolymph) bathes the organs directlyArthropods, some molluscs

Closed - Circulatory fluid (blood) confined to vesselsHeart pumps blood through vessels

Annelids, cephalopods, vertebrates

Vertebrate Circulatory System

Cardiovascular- Heart & blood vessels

Arteries: carry blood away from heart

Mostly oxygenated

Branch into arterioles before meeting capillaries

Capilaries : direct contact with tissue cellsSite of chemical exchange

Converge into venules

Veins : carry blood toward heartMostly deoxygenated

What is in the single circulation

From the heart, blood passes through two capillary beds before returning to heart

Two-chambered heart (atrium & ventricle)

Sharks, rays, and bony fish

accelerates circulation

What is in the double ciruclation

Two circuit of blood flow
Systemic - Heart and body tissues 

Pulmonary - Heart to lungs 

Amphibians, reptiles, & mammals 
Oxygen-poor and oxygen-rich blood are pumped separately from right and left sides of the heart 

Maintains higher blood pressure in organs 

What is in the mamalian heart

We have 4 chambers

2 atria - receiving chambers

2 ventricles - pumping chambers

Valves prevent backflow