• The heart is the pump of the circulatory system.
• It is made of cardiac muscle which does not tire.
• Cardiac muscle receives its own blood supply through the coronary arteries and veins.
• The septum divides the heart into right and left sides.
• The heart has four chambers; right atrium, right ventricle, left atrium, left ventricle.

Blood Flow Through the Heart

1. The blood flows into the vena cava into the right atrium. It is deoxygenated blood.
2. The valves open and allow the blood flow into the right ventricle. The valves close.
3. The right ventricle contracts, valves open and blood is pushed... (More)

Animal cell.

• Cell membranes - is made up of mostly of fat. It does not allow everything through it generally it allows small substances through , for example water , but not large substances , for example protein.
• Cytoplasm - is made up of mostly water with salts glucose and other food materials in it.
• Nucleus cparties chromosome, which are made up of Genes that control the working of the cell. Genes are made of DNA.
• Mitochondrian - known as the power house of the cell , is where food reacts with oxygen to release energy. This process is called... (More)

• Cells are the building blocks of an organism.
• Unicellular organisms are made up of only one cell, for example bacteria.
• Multicellular organisms are made up of lots of cells, for example a human.

Cell Structure

• Cells may look different but they have the same basic structure.
• Most cells have the following structures: cell membrane, cytoplasm, nucleus, small vacuole and mitochondrion.
• Plant cells have extra structures: chloroplasts, cell wall and large vacuole.

Functions of the Cell Organelles

Cell membrane: holds the cells together and controls what can enter and leave the cell.

Cytoplasm: watery fluid that holds the organelles in place.... (More)

All cells have the same basic structure but different types of cells have special features that are suited to the functions that they carry out.

Red Blood Cells

• Contains a chemical called haemoglobin which can bond to oxygen. Red blood cells carry oxygen around the body.
• Their shape allows them to bend to fit through small blood vessels.
• Do not contain a nucleus.

Muscle Cells

• Lots of mitochondria for energy
• Can contract and relax to enable movement

Sperm Cell

• Tail for swimming
• Lots of Mitochondria for energy

Nerve cells

• Can carry electrical messages
• Can pass a message onto another nerve... (More)