Human cells contain 23 pairs of chromosomes for a total of 46. There are 22 pairs of autosomes and one pair of sex chromosomes. The sex chromosomes are the X chromosome and the Y chromosome.Sex Chromosomes: In human sexual reproduction, two distinct gametes fuse to form a zygote.f an X sperm cell fertilizes an egg, the resulting zygote will be XX or female. If a sperm cell containing no sex chromosome fertilizes an egg, the resulting zygote will be XO or male. Sex Chromosomes Z-W: Birds, insects like butterflies, frogs and some species of fish have a different system for determining gender.
It is the abnormal leaking of blood backwards from the left ventricle, through the mitral valve, into the left atrium, when the left ventricle contracts, i.e. there is regurgitation of blood back into the left atrium. MI is the most common form of valvular heart disease.t is the abnormal leaking of blood backwards from the left ventricle, through the mitral valve, into the left atrium, when the left ventricle contracts, i.e. there is regurgitation of blood back into the left atrium. MI is the most common form of valvular heart disease.
In mitral valve disease, the mitral valve, which is located between your left heart chambers (left atrium and left ventricle), doesn't work properly. Types of mitral valve disease include:Mitral valve regurgitation. In this condition, the flaps (leaflets) of the mitral valve don't close tightly, causing blood to leak backward into the left atrium of your heart. If not treated, it can result in heart muscle damage.The most common cause of blood leakage is mitral valve prolapse, in which the leaflets bulge back into the left atrium as your heart contracts. 1  Mitral valve stenosis. 2  In this condition, the flaps of the mitral valve become thick or stiff, and they may fuse together. Mitral valve stenosis. 2  In this condition, the flaps of the mitral valve become thick or stiff, and they may fuse together. 3  This results in a narrowed valve opening and reduced blood flow from the left atrium to the left ventricle.