Circulation:Getting from

here to There

Introduction to the Circulatory System

As a life function systemTRANSPORT

nutrients

O2/CO2

wastes

hormones

Immune factors

A CLOSED circulatory system has 3 basic parts

1. A pump

(Blood)

2. Some tubes

3. Something to pump

There will be…

(Heart)

(blood Vessels)

An OPEN circulatory system…is missing one of those components.

These are a little more reasonable…

Open vs. Closed (circulation)

Circulatory PlumbingBlood Vessels

No beginning or end, so since we have to start somewhere…

Arteries

• Carry blood AWAY from heart• Thick, elastic, muscular walls• Have a pulse

Gradually become smaller as they get farther away from the heart until they become arterioles

Capillaries

• Tiny, tiny, tiny (only a few blood cells at a time)

• Very thin walls “leaky”• Exchange of material

Blood

Body cells Environment

Capillaries

• Plasma portion of blood is “squeezed out”

• Becomes “Intercellular fluid”

• Some reenters capillaries, a lot is collected by lymphatic system

Veins

• Blood TO heart• Thinner walls (than arteries)• Have valves for one-way flow• No pulse

The LYMPHATIC SystemThe tubes you never hear about

Have their own capillaries and veins

Collect intercellular fluid in their capillaries

ICF returned to circulatory veins by the Lymphatic veins