AQUATEXT - The Free Online Aquaculture Dictionary

H

Haematoma

Tumour like pocket where blood escapes the blood vessels (usually as a result of physical damage) and collects. Has the appearance of a fluid filled sac which may be floppy or quite hard, depending on the state of the damage and internal healing that has taken place.

Haematopoietic tissue

Area where blood and blood cells are formed. In fish this is mainly in the anterior end of the kidney.

Haemoglobin

A protein in the red blood cells which carries the oxygen and carbon dioxide in the bloodstream. The protein has four "haem" groups, each of which can bind one oxygen or carbon dioxide molecule. When the haemoglobin is rich in oxygen it is sometimes called oxyhaemoglobin. At the tissue site where oxygen is absorbed for respiration, carbon dioxide takes the place of the oxygen molecule. High ambient carbon dioxide concentrations in the environment, can lead to an inability for the haemoglobin to release all it's carbon dioxide across the gills. This in turn leads to a lower take up of oxygen in the blood as one or more of the haem sites is occupied by carbon dioxide, preventing the oxygen from binding. See also Bohr effect.