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BLOOD & CIRCULATION (page 70 - 80) - Coggle Diagram
BLOOD & CIRCULATION (page 70 - 80)
Blood is pumped around a closed circuit made up of the heart and blood vessels
As blood travels around the body, it collects materials from some places and unloads materials in others
in mammals, blood transports:
oxygen from lungs to other parts of the body
carbon dioxide from other parts of body to lungs
nutrients from the gut to all parts of the body
urea from the liver to kidneys
Hormones, antibodies, and other substances are also transported by blood
Single-celled organisms don't have circulatory systems
BECAUSE there's no circulatory system to carry materials around the small bodies of the single-celled organisms
Materials can move easily around the cell without a special system
no need for lungs or gills to obtain oxygen from the environment
they obtain oxygen by diffusion through the surface membrane of the cell
area of cell's surface determines how much oxygen the organism can get the supply rate
volume of cell determines how much oxygen the organism use
single-celled organisms have a high surface area to volume ratio
their cell surface membrane has a large enough area to supply all the oxygen that their volume demands
large animals' surface area to volume ratio is lower
large animals' can't get all the oxygen they need to through their surface because there isn't enough s ur face to supply all the volume
thus large organisms have volved special gas exchange organs and circulatory systems
a circulatory system carries oxygen to all parts of the body
the gut obtains nutrients from food and the circulatory system distributes the nutrients around the body
main functions of a circulatory system = transport oxygen
blood is pumped to a gas exchange organs to load oxygen
single circulatory system
BLOOD IS PUMPED FROM HEART -> GAS EXCHANGE ORGAN -> OTHER PARTS OF THE BODY
double circulatory system
BLOOD IS PUMPED FROM HEART -> GAS EXCHNGE ORGAN -> HEART -> OTHER PARTS OF THE BODY
HAS 2 PARTS
PULMONARY CIRCULATION
deoxygenated blood leaves heart through pulmonary arteries, and is circulated through the lungs, where it becomes oxygenated
then oxygenated blood returns to the heart through pulmonary veins
SYSTEMIC CIRCULATION
oxygenated blood leaves heart through aorta, and is circulated through other parts of the body, where it unloads its oxygen
deoxygenated blood returns to the heart through vena cava
more efficient than a single circulatory system
BECAUSE..
heart pumps blood TWICE, so higher pressures can be maintained
blood travels faster to organs
compared to single circulatory system of a fish, blood lose pressure as it pass through the gills, then travel slower to other organs
human circulatory system comprises..
heart
a pump
blood vessels
carry blood around the body
arteries carry blood away from heart and towards other organs
veins carry blood towards heart and away from other organs
capillaries carry blood through organs, linking arteries and veins
STRUCTURE AND FUNCTION OF HUMAN HEART
heart is pump
it pumps blood around the body at different speeds and at different pressures according to body's needs
blood is moved through heart by contractions and relaxations of muscle in the walls of 4 chambers.
these events form
CARDIAC CYCLE
STEP 1
blood enters atria. it can't pass to ventricles because bicuspid and tricuspid valves are closed
STEP 2
walls of atria contract, raising pressure of blood in the atria which forces open bicuspid and tricuspid valves. blood passes through these valves to ventricles
STEP 3
when ventricles are full, they contract. this increase pressure of blood in the ventricles which closes the bicuspid and tricuspid valves again. blood can't return to atria.
STEP 4
ventricles continue to contract and pressure increase
which forcely open the semi-lunar valves at base of aorta and pulmonary artery
blood is ejected into the 2 arteries
pulmonary artery carries blood to lungs