BIO 7:  Lecture 19 Preview  (Chapters 23 and 27)

Once monomers and gases are inside the organism, they need to get to individual cells.

• Diffusion works quickly enough over small distances
• Larger organisms need transport systems taking nutrients and oxygen to cells and wastes and carbon dioxide from cells
• Nutrients, wastes, gases are carried in fluid
• The heart is a muscular pump to move fluids; valves prevent backflow
• Transport is more efficient if nutrients are not mixed with wastes and oxygen is not mixed with carbon dioxide

Muscular pumps help to move fluid more quickly.

Hearts have specialized cardiac muscle, which contracts without fatiguing.

Open and closed circulatory systems:  Which is more efficient?  Which takes more energy to build?

 Closed systems have 3 kinds of blood vessels and can have hearts with 2, 3 or 4 chambers

What are the functions of

• Arteries

• Veins

• Capillaries

What is an advantage of having 2 chambers serving the lungs and 2 chambers serving the rest of the body?

Lots of capillaries are found where gases, nutrients, and wastes are exchanged between the blood and the cells

 The amount of blood flow for each beat of the heart depends on the diameter of the blood vessels.

 To carry out life activities organisms must move. 

• Animals use muscle tissue to move
• Muscle tissue is specialized by having lots of protein (actin and myosin) that forms fibers able to shorten
• To move the whole organism, muscle is attached to the body wall and/or skeleton

Energy from ATP is used to help actin and myosin slide along each other, so the whole muscle contracts. When the muscle relaxes it lengthens again.

Muscles can only move bones or body parts by contracting.  So muscles (called opposing muscles) work in pairs to move body parts back and forth.

Energy required to move the whole organism depends on the mass of the organism and also how much surface area it has causing drag (air, water, or soil resistance).