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Human Physiology Osmosis.

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Human Physiology Osmosis Osmosis is a special type of diffusion that includes only moving water molecules in the presence of a selectively permeable membrane. It can be defined as: ' The movement of water molecules from a region of high concentration to a region of low concentration through a selectively permeable membrane ' A selectively permeable membrane is a thin sheet that allows certain small molecules to pass through but not larger molecules. In a living body there are many types of selectively permeable membranes such as: * The plural * The peritoneum However, the most selectively permeable membrane you will hear about is a cell membrane around every living cell. In the laboratory we can mimic the cell membrane by using a product known as Visking Tubing that was developed for use in kidney machines for renal dialysis. Active Transport There are many examples of materials passing through living cell membranes against a concentration gradient, i.e. ...read more.


The 'extra' water that passes through the membrane exerts a pressure called osmosis pressure and osmosis potential is the power of a solution to gain or lose water molecules through a membrane. Cells that are surrounded by tissue fluid of the correct strength are said to be isotonic with their surroundings. When the potato tissue was bathed in the hypotonic solution the cell swelled up and nearly burst. When the potato tissue was put into the hypertonic solution the water left the cell and the cell shrunk. Cells that more bathed by more dilute fluid are in a hypotonic environment and those in more concentrated medium are in a hypertonic environment. Hypertonic and hypotonic environments will disturb the metabolism of cells and can even cause their deaths. Water, glucose and salts affect the tonicity of fluids. Osmoregulation Osmoregulation refers to the regulation of the water content of the body. ...read more.


The only difference between males and females is that the urethra in the male is longer and also serves as part of the reproductive system as it is used to convey semen during copulation. Sexual Reproduction The cells of the human body contain nuclei with 46 or 23 pairs of chromosomes that contain units of heredity or genes. The number of chromosomes is very important in a species because any deviation from this number produces abnormalities in human life. When humans reproduce they do so, sexually. A female cell nucleus unites with a male cell nucleus. The male and female cells are known as, gametes. Male gametes are spermatozoa. Female gametes or ova are usually produced singly every four weeks by the ovary. The ovum enters the oviducts and travels slowly towards the uterus or womb. It may not become fertilized during this journey, depending on whether insemination or sexual intercourse occurs at the right time. When fertilization has taken place the resulting cell known as a zygote undergoes many cell divisions to form an embryo. Human Physiology Claire McNeill ...read more.

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