Blood contains fluid part
called plasma. Red blood
cells [erythrocytes] have
red pigment hemoglobin which
binds oxygen and transports it to all cells. They are formed in
the red bone marrow and
have a lifetime of 120 days.
They are destroyed in the spleen.
White blood cells [leucocytes] fight against germs that enter the
body. White blood cells is neutrophiles
[destroy foreign bodies]; basophiles
[inflammatory response], eosinophiles
[allergic response], lymphocytes
[immune response] and monocytes
[destroy foreign bodies]. Platelets
[thrombocytes] in blood
are responsible for clotting
Types of Blood Group
Blood cells can have two
antigens A, B, AB [both] or O
[none]. O blood group is
universal donor and AB is universal
vessels are arteries that
carry oxygen rich blood to different body parts. The walls are
thick, elastic as blood flow is rapid and high pressure. Veins carry carbon dioxide
rich blood to the heart. They have thin walls and valves that
allow blood flow in one direction only.
Our muscles release lactic
acid during anaerobic
respiration. This lactic acid causes cramps.
When we are drowsy, we slow down breathing and body doesn’t get
sufficient oxygen so we yawn to take excess air.
Blood Oxidation and Purification
During respiration ribs move
up and diaphragm moves
down, this increases size of chest cavity and air comes in.
During exhaling, ribs move down and in and diaphragm moves back
to position and this reduces chest cavity so air is released.
Respiration is an exothermic
reaction i.e. heat is evolved. Reactions of decomposition
of wastes into compost are also exothermic.Blood capillaries in
the kidneys filter waste material as urine. This is passed into
the urinary bladder through the ureters. The urethra is
connected to the urinary opening through which urine is passed.In
dialysis, blood is
filtered by an artificial
kidney, when the natural kidneys fail.
Pulmonary artery carries CO2 rich blood from heart to
lungs, Pulmonary vein carries oxygen rich blood to heart from
lungs. Arteries divide to form capillaries to reachtissues,
capillaries rejoin to form veins to take blood from tissues to
monoxide reduces oxygen carrying capacity of blood. It combines
with hemoglobin to form
carboxyhaemoglobin and this reduces the oxygen
carrying capacity of blood.
Fig. Human Heart
Heart has four chambers, two atria and two
ventricles. The right atria and ventricle have deoxygenated
blood. The left atria and ventricle have oxygenated blood.
Ventricles have thick walls as they have to pump blood to
that need energy to regulate body temperature need separate
oxygenated and de-oxygenated blood. Others who regulate
temperature of body based on temperature of surroundings can
tolerate mixing of blood.
Hydra and sponges don’t have a circulatory system or
blood. Water that flows through their body carries food and
oxygen to different parts and waste material from parts is
thrown out by it too.
Birds, insects excrete uric acid [least toxic
so doesn’t need water for excretion]. Fishes excrete ammonia
[highly toxic so needs lots of water]. Mode of excretion depends
on availability of water.