I. Basics of Circulatory System

A. Types of Circulatory System B. Vertebrate Circulation C. Comparison of Vertebrate Circulation

Circulatory System

• A vital network that transports oxygen, nutrients, and hormones to cells while removing waste products like carbon dioxide 

• Some animals do NOT have a circulatory system ex. Sponges, portifera

Three basic components

• Fluid (need for gas exchange)

• Interconnecting vessels 

• Pump (heart) 

1. Open Circulatory System

• Fluid = hemolymph= intestinal fluid

• Heart contractions: hemolymph-> cavities -> interconnected sinuses 

• Heart relaxes: draws hemolymph back into heart 

• Seen in tracheal systems, small insects, low pressure, low energy, low efficiency 

• Arthropods and mollusks 

2. Closed Circulatory System

• Blood: circulatory fluid confined to vessels

• Heart pumps blood through branched vessels 

• Higher pressure, more efficient, requires more E

• Annelids, cephalopods, vertebrates

Cardiovascular system

• Involves

  • Heart: pumps blood

  • Vessels: carry blood

  • Exchange at capillaries (smallest branch)

• Blood Vessels (3 types)

• Arteries: away from heart

• Capillaries

• Veins (bring blood back to heart)

• Arteries -> arterioles-> capillaries -> tissues -> venules -> veins

• Fish- single circulation

• heart - two chambers

• 1 atrium: blood from tissues

• 1 ventricle: pump to arteries

• Heart -> gills -> body -> heart

• Slow metabolic rate: not very efficient (looses pressure when moves, doesn't go back to heart)

Amphibians- double circulation

•  low metabolic rate, slow system

• Three chambered heart

• 2 atria, 1 ventricle

• Pulmocutaneous circuit

  • O2 picked up from skin

  • Systemic circuit -> to body -> returns to right atrium 

  • In single ventricle both blood combine and are sent out to body

Mammals and Birds- more rigorous double circulation

• Endotherms

• Double circulation: more rigorous blood flow

• Four chambered heart

• 2 atria, 2 ventricle

• Systemic and pulmonary

• Circuits completely separate (blood, w or without o2, that enters and leaves has separate ventricle )