Transport Systems
Transport Systems Essay
In single celled organisms, nutrients, water and various substances that are need for basic cellular processes can easily be transported in and out through the cell membrane. This is an effective transport system for microscopic organisms, but multicellular organisms require a more complex transport system to sustain itself. Take humans for example; unlike a cell, only the outer layer of skin is in contact with the body’s outside environment. It’s not possible for substances to diffuse all the way through every layer of cells in the human body and reach an organ deep within it, like the heart. The movement of waste from inside the body to outside the body is also not possible without a transport system. For this very reason, large multicellular organisms such as plants and mammals must have multiple specialised transport systems.
Many large multicellular organisms contain complex transport systems. In mammals, a circulatory system containing the heart, arteries, veins, blood and lungs allow cells in the organism to gain oxygen from red blood cells, release carbon dioxide and dissolved nutrients from the plasma in blood. Hormones, proteins and white blood cells from the immune system are other substances that can be found in blood. This system is known as a “circulatory” system because fluids containing the nutrients (blood) travel around it in a closed circuit around the body. An organ called the heart, which is a large muscle, continuously pumps blood through the circuit. The vessels that make up the circuit are thick veins and arteries, or thin one-cell thick capillaries. Dissolved nutrients and oxygen are contained in the blood, which travel around arteries and into the smaller capillaries. As the capillaries are only one cell thick, it is possible for the oxygen and the nutrients to diffuse through to the cells in need. After the oxygen diffuses through, the blood becomes deoxygenated and travels through veins, back into the heart
In single celled organisms, nutrients, water and various substances that are need for basic cellular processes can easily be transported in and out through the cell membrane. This is an effective transport system for microscopic organisms, but multicellular organisms require a more complex transport system to sustain itself. Take humans for example; unlike a cell, only the outer layer of skin is in contact with the body’s outside environment. It’s not possible for substances to diffuse all the way through every layer of cells in the human body and reach an organ deep within it, like the heart. The movement of waste from inside the body to outside the body is also not possible without a transport system. For this very reason, large multicellular organisms such as plants and mammals must have multiple specialised transport systems.
Many large multicellular organisms contain complex transport systems. In mammals, a circulatory system containing the heart, arteries, veins, blood and lungs allow cells in the organism to gain oxygen from red blood cells, release carbon dioxide and dissolved nutrients from the plasma in blood. Hormones, proteins and white blood cells from the immune system are other substances that can be found in blood. This system is known as a “circulatory” system because fluids containing the nutrients (blood) travel around it in a closed circuit around the body. An organ called the heart, which is a large muscle, continuously pumps blood through the circuit. The vessels that make up the circuit are thick veins and arteries, or thin one-cell thick capillaries. Dissolved nutrients and oxygen are contained in the blood, which travel around arteries and into the smaller capillaries. As the capillaries are only one cell thick, it is possible for the oxygen and the nutrients to diffuse through to the cells in need. After the oxygen diffuses through, the blood becomes deoxygenated and travels through veins, back into the heart
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