Thursday 30 April 2020
How is the mammalian heart adapted to its functions?
Heart is enclosed in a pericardial membrane/pericardium;
that produces a fluid; to lubricate it; the membrane also keeps the heart in
position; It is covered in a fatty layer; that acts as a shock absorber; made
up of cardiac muscles; which are interconnected/interacted hence contract and
relax without fatigue or nervous stimulation/myogenic; for continuous pumping
of blood throughout the lifespan of the animal; the muscles are supplied by
nutrients and oxygen; by the coronary arteries; and the coronary veins take
away wastes and carbon (IV) oxide; heart is divided into 4 chambers; for
efficient double circulation/ avoid mixing of oxygenated and deoxygenated
blood/carry large volume of blood; has interventricular septum; to separate
oxygenated and deoxygenated blood; ventricles are thick/muscular; to generate
high pressure to pump blood out of the heart; left ventricle has thick
muscles/more muscular; to pump blood to all body tissues; heart has bicuspid;
and tricuspid valves; to prevent back flow of blood to left auricle; and right
auricle respectively; valves have tendinous cords/valve tendons; to prevent
them from turning inside out; semi lunar valves located at the beginning of
major arteries; prevent backflow of blood into the ventricles; has sino-artrio
node located in the muscles of the right auricle; to initiate heart
beat/contractions of heart muscles/cardiac muscles, rate of heart beat is
controlled by nerves; vagus nerve; slows down heartbeat; while sympathetic
nerve; speeds up the heartbeat; has aorta; to transport oxygenated blood to all
body parts; has pulmonary artery; that transports deoxygenated blood from right
ventricles to lungs for oxygenation; has pulmonary vein; that transports
oxygenated blood from lungs to the left ventricles; for distribution to all
body parts; has the venacava; that
receives deoxygenated blood from all body parts to right ventricles;
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