24.1: Diversity of Animal Circulatory system

Muscular Pump

Muscular pump that provides the force to drive the flow of a circulating fluid.

Circulating Fluid

Fluid that moves through a system of open-ended or closed tubular vessels in the circulatory system.

Hemolymph

Circulating fluid in an open circulatory system that is the same as the fluid in the body cavity.

Blood Plasma

Circulatory fluid contained within a network of vessels, separate from interstitial fluid - in closed systems.

Ostia

Little holes that allows for hemolymph to directly renter the heart.

Arteries

Vessels carrying blood away from the heart.

Veins

Vessels returning blood to the heart.

Capillaries

Tiny vessels that go through the gas exchange organ and the body for nutrient and gas exchange.

Pulmonary Circuit

Circuit that goes from the heart to the gas exchange organ (e.g., lungs or gills) and back again to the heart.

Systemic Circuit

Circuit that goes from the heart to the body and back again to the heart.

all animal circulatory systems include

muscular pump, circulating fluid and system of tubular vessels that forms circuit

2 types of circulatory system

open and closed

features of an open circulatory system

hemolymph travels through vessels and empties int body cavities to directly surround tissues and organs before flowing back to heart or vessels

features of closed circulatory system

blood plasma is contained and remains within a network of vessels

why do some organisms lack circulatory sysmtes

their needs can be meet by direct exchange with external environment due to all cells being short distance away from environment = animals that are very small, thin, hollow or porous

• e.g flatworms, coral and jellyfish

circulatory system of fish

most primitive - closed system where blood flows from heart to gills and then to body in single circuit. Single circuit means relatively low pressure in large dorsal artery

amphibian circulatory system

2 circuits - pulmonary and systemic = allows for good pressure going through both systems. Characteristics:

• 3-chambered heart

• gas exchange with air

• partial double circuit

• pulmonary and systemic partially separated = sometimes mixing of blood = less efficient oxygen transport

bird and mammal circulatory system

complete separation between pulmonary and systemic due to 4-chambered heart = allows circuits to have different pressures.

• high amount of blood vessels to meet needs = higher pressure from heart allows blood to be pushed through highly branched network

• fewer vessels in lungs as pulmonary circuit functions at lower pressure