Download Chapter 7: Circulation and Blood

Chapter 7: Circulation and Blood
The Importance of the Circulatory System
The circulatory system carries:
 nutrients and oxygen to cells
 waste away from the cell
 chemical messages fro cells in one part of the body to
distant target tissues
 distributes heat through the body
 along with kidneys, maintains acceptable levels of body
fluid
 helps defend against invading organisms
 permits the transport of immune cells throughout the
body
 transports waste
The Circulatory system consists of:
 The heart
 The blood vessels: arteries, veins, and capillaries
 Blood: red, white, and platelets
There are two types of circulatory systems:
1. Open Circulatory system
2. Closed Circulatory System
The Open Circulatory System (p. 243)
 Found in snails, insects, and crustaceans
 There is no distinction between the blood and the
interstitial fluid system
 Blood carrying oxygen and nutrients is pumped into
body cavities where it bathes the cells directly.
The Closed Circulatory System
 Found in earthworms, squids, octopuses, and
vertebrates.
 The blood is contained within blood vessels
Components of Blood
 45% of blood is composed of blood cells
 55% of blood is composed plasma, which is the fluid
part.
 90% of the plasma is water
The plasma contains: proteins, glucose, vitamins, minerals,
dissolved gases, and waste products. The large plasma
proteins help maintain homeostasis and these are:
1. Albumins: maintain body fluid levels by regulating
osmotic balance
2. Globulins: provide protection against invading
microbes
3. Fibrinogens: important in blood clotting
Components of Blood
The red, the white, the platelets are produced by stem
cells found in the bone marrow. 60% of the stem cells
become red blood cells, 30% become white blood cells, 5%
become platelets, and the rest 5% are indiscernible.
1. Red Blood Cells or Erythrocytes
 The primary function of red blood cells id to transport
oxygen
 The red blood cells carry oxygen with the help of an
iron containing protein called hemoglobin.
 The presence of hemoglobin increases the ability of
blood to carry oxygen by a facto of 70.
 An estimated 280 million hemoglobin molecules are
found in a single red blood cell.
 Four iron atoms attach to the folded protein structure
and bind with oxygen molecules.
 The oxyhemoglobin gives blood its red color.
 The deoxhemoglobin makes blood appear blue because
of the change in shape of the hemoglobin.
 Red blood cells live only about 120 days
 At least 5 million red blood cells are produced every
minute.
 Red blood cells lose their nucleus as they enter the
blood stream. Enucleation helps red blood cells
accommodate as many hemoglobins as they can so that
they transport oxygen more efficiently.
2. White Blood Cells or Leukocytes
 There is one white blood cell for every 700 red blood
cells.
 Their main functions are defending against foreign
invaders, cleaning up dead cells, and foreign matter at
injury cites.
 All white blood cells are colourless and are larger than
red blood cells.
 All white blood cells have district nuclei.
 There are 5 different types of white blood cells:
1. Neutrophil: when pneumonia is present their count
increases by 25%
2. Eosinophil: play major role in allergic reactions
3. Basophil: their numbers increase when Leukemia is
present
4. Monocyte: when tuberculosis is present their count
increases by 500%.
5. Lymphocytes (T and B cells): produce custom made
antibodies to destroy foreign substances such as protein
coats of viruses.
3. Platelets
 Platelets are small fragments of larger cells found in
bone marrow.
 Platelets do not contain nucleus.
 There is 1 platelet for every 20 red blood cells
 Platelets initiate blood clotting
 The rupturing of platelets membranes during an injury
releases a substance that reacts with the plasma proteins
such as fibrinogen to form a mesh of fibers.