Cell walls are rigid and only permeable to very small molecules. As water moves into the cell, the membrane is pushed up against the cell wall, creating hydrostatic, or turgor, pressure. This pressure limits the rate and amount of water that can enter the cell.

Key terms

Since there is more salt on the outside, there must be less water on the outside. Thus the water inside the cell moves to the outside through the pores in the cell membrane to equalise the concentration gradient (which we call osmosis).

Since the particles are generally not easily allowed into or out of a cell, the only transfer is done by the water (a very small molecule). Since the concentration is higher outside of the cell, the water will move out of the cell to try and dilute the concentration.

If you place an animal or a plant cell in a hypertonic solution, the cell shrinks, because it loses water ( water moves from a higher concentration inside the cell to a lower concentration outside ). Hypotonic solutions have more water than a cell. Tapwater and pure water are hypotonic.

The substances like CO2 and water move in and out of a cell by diffusion from the region of high concentration to low concentration. When the concentration outside the cell becomes low and it is high inside the cell, they moves out.

The circulatory system delivers oxygen and nutrients to cells and takes away wastes. The heart pumps oxygenated and deoxygenated blood on different sides. The types of blood vessels include arteries, capillaries and veins.

The circulatory system carries oxygen, nutrients, and hormones to cells, and removes waste products, like carbon dioxide.

The heart is the key organ in the circulatory system. As a hollow, muscular pump, its main function is to propel blood throughout the body.

The circulatory system is extremely important in sustaining life. It’s proper functioning is responsible for the delivery of oxygen and nutrients to all cells, as well as the removal of carbon dioxide, waste products, maintenance of optimum pH, and the mobility of the elements, proteins and cells, of the immune system.

Organ systems work together, too. For example, the respiratory system and the circulatory system work closely together to deliver oxygen to cells and to get rid of the carbon dioxide the cells produce.

If a particular organ stops it’s function, then soon the other organs will also stop functioning and gradually death occur immediately.

Some organs are in more than one system. For example, the nose is in both the respiratory system and also is a sensory organ in the nervous system. The testes and ovary are both part of the reproductive systems and endocrine systems.

Terms in this set (9)

• Pancreas. Digestive and Endocrine.
• Mammary gland. Reproductive and Integumentary.
• Testes. Reproductive and Endocrine.
• Ovaries. Reproductive and Endocrine.
• Thymus. Lymphatic and Endocrine.
• Kidneys. Urinary and Endocrine.
• Pharynx. Respiratory and Digestive.
• Urethra. Reproductive and Urinary.

The integumentary system

Cards

Bye-Bye Skin Cells Though you can’t see it happening, every minute of the day we lose about 30,000 to 40,000 dead skin cells off the surface of our skin. So just in the time it took you to read this far, you’ve probably lost about 40,000 cells. That’s almost 9 pounds (4 kilograms) of cells every year!