TOPIC 3: CIRCULATORY

SYSTEM : PART 1Learning outcomes:

1. Compare open and closed circulatory system

2. Identify different circulatory pathways in vertebrates

3. Explain the composition of human circulatory system and its functions

4. Describe capillary exchange in the tissues

5. Explain the human circulation system

6. Describe blood circulation in human heart

7. Describe the composition and functions of blood

8. Explain the function of lymphatic system

9. Explain the roles of immune system

Circulatory system

Simple

Open

Closed

Single looped

Double looped

COMPARE and CONTRAST

Circulatory system

Simple

Open

Closed

Single looped

Double looped

Simple Circulatory Systems

• Nutrients can diffuse directly across the cells into cavity.

• No vessels or blood are required for transportation of nutrients, waste or gases

• Hydra and planarians are so small– diffusion provides for the

movement of fluids, gases, and wastes.

• Nematodes and echinoderms– movement of the organism

provides for the movement of the internal fluids.

Circulatory system

Simple

Open

Closed

Single looped

Double looped

Open Circulatory Systems• More complex organisms• A circulatory system involves a heart that

pumps fluid through the organism. • In an open circulatory system,

1. A tubular heart pumps hemolymph through channels and cavities throughout the body.

2. Heart pumps hemolymph through channels and cavities throughout the body and into the hemocoel.

3. Hemolymph flow from the heart into the hemocoel when the heart contract

4. When heart relax: hemolymph drown though ostia (pore) back into the heart

5. Hemolymph returned to the heart by passive flow.

Circulatory system

Simple

Open

Closed

Single looped

Double looped

Closed Circulatory Systems

• A closed circulatory system, or cardiovascular system, includes a strong heart and blood vessels.

• The heart pumps the blood to the body and receives the blood returned to the heart.

Closed Circulatory Systems

• There are three types of blood vessels.

1. Arteries carry blood away from the heart.

2. Veins return blood to the heart.

3. Capillaries are a fine network of vessels between the arteries and capillaries where fluid, gas, and waste exchange take place.

Circulatory system

Simple

Open

Closed

Single looped

Double looped

Comparison of Circulatory Pathways in Vertebrates

There are two different types of circulatory pathways in vertebrate animals.

In fish, the circulatory pathway is a single loop with a two-chambered heart.

1. Blood entering the heart and collects in

the atrium before entering ventricle

2. Ventricle pumps blood to the gills

3. Gases exchange occurs in gills,

oxygen-rich blood carry in a vessel to

capillary bed

4. Gases exchange occurs in body capillaries, and

oxygen-poor blood returned to the heart

Circulatory system

Simple

Open

Closed

Single looped

Double looped

Comparison of Circulatory Pathways

• All other vertebrates have a double circulatory system.– The systemic circuit includes the blood vessels that carry

blood to the body.

– The pulmonary circuit includes the blood vessels that send blood to the lungs.

• The double circulatory system helps terrestrial organisms breathe air.

Comparison of Circulatory Pathways

The amphibian and reptilian heart has three chambers.

In amphibians, there are two atria and a single ventricle.

In reptiles, the ventricle has a partial dividing wall (septa).

The right circuit delivers oxygen-poor blood from the heart to the lung (also known as pulmonary circuit).

In the left circuit, oxygen-enriched blood leaves the heart into capillary beds in organ and tissues (also known as systemic circuit)

Comparison of Circulatory Pathways

• The hearts of birds and mammals have four chambers.

• The right side pumps to the pulmonary circuit.

• The left side pumps to the systemic circuit.

Transport in Humans

• The mammalian cardiovascular system pumps blood through the arteries to the capillaries.

• After gases, nutrients, and wastes are exchanged in the capillaries, the blood returns to the heart in the veins.

Heart Artery Arterioles capillaries Venules Veins Heart

Blood Vessels: Arteries• Arteries carry blood (oxygenated blood)

away from the heart.

• The blood pressure is a measure of the pressure of arterial blood flow.

• The structure of arteries includes muscle tissue that allows them to expand as the blood pressure changes.

Blood Vessels: ArteriesThis flexible arterial

structure includes smooth muscle and elastic fibers.

The arterioles are small arteries that help regulate blood pressure.

Blood Vessels: Capillaries• Arteries branch

into microscopic vessels called capillaries.

• The capillaries have only a thin layer of epithelial cells to facilitate exchange of substances with the tissues.

Blood Vessels: Venules & Veins

• Venules are vessels that drain blood from the capillaries into veins.

• Veins have a larger diameter than arteries, but have thinner walls and move blood under a lower pressure.

Blood Vessels: Venules & Veins

• The flow of blood through veins is driven by the contraction of skeletal muscle.

• The veins also have valves which prevent backflow of blood.

Capillary Exchange in the Tissues

• Two forces control the movement of fluid through the capillary wall.

– The osmotic pressure drives tissue fluid into the blood.

– The blood pressure drives fluid from blood into the tissues.

Capillary Exchange in the Tissues

A network that distributes lymph fluid throughout the body.

The interstitial fluid bathes the tissues and is taken up by lymphatic capillaries.

The fluid is now called lymph.Lymph eventually enters the

lymph nodes.In lymph nodes, pathogens

present in lymph encounters macrophages and lymphocytes

Human cardiovascular system

• The human cardiovascular system is a double circuit.

The Pulmonary Circuits• The pulmonary circuit circulates

blood to the lungs for gas exchange. – The pulmonary arteries carry

blood from the right side of the heart to the lungs.

– The pulmonary veins returned oxygenated blood to the left side of the heart.

The Systemic Circuits• The systemic circuit distributes

the oxygenated blood to the body.

• Oxygenated blood from the left side of the heart is distributed to the body through the aorta.

• After passing through the arteries, capillaries and veins, the vena cava returns the blood to the right side of the heart.

End part 1

• http://www.bbc.co.uk/education/guides/zhnk7ty/activity