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In the cells lining the proximal convoluted tubule, sodium-potassium pumps present in the membrane in contact with tissue fluid pump sodium ions out of the cells. This lowers the concentration of sodium i...

By definition, diffusion is the movement of particles from a region of high concentration to a region of low concentration. It occurs in liquids and gases where particles can move freely down a concentrat...

A protein is a sequence of many amino acids. All proteins are made of amino acids. Humans have 20 distinguished amino acids that can arrange in thousands of different combinations and this means that they...

P wave: atrial depolarisation and subsequent contraction. QRS complex: Ventricular depolarisation and subsequent contraction. Q wave is negative due to left to right depolarisation of ventricular septum. ...

Firstly, the alveoli walls consist of a one-cell thick layer of squamous epithelium. This means there is a thin barrier to diffusion, and a small distance for oxygen molecules to diffuse across to get to ...