Circulation
8th grade study guide
By the 8th grade science class.
Movement of materials
• Cardiovascular system- heart, blood vessels,
and blood.
• Cardiovascular system carries needed
substances to cells and carries waste away.
• Disease fighters- white blood cells
Heart
• Heart- is a hollow muscular organ that pumps
blood though out the body.
• The heart beat pushes blood through the
cardiovascular system.
• Atrium- the two upper chambers that receive
blood.
• Ventricle- pumps blood out of the heart and
they are the 2 lower chambers.
• Valve- a flap of tissue that prevents blood
from flowing backwards.
How the heart works
• 2 main phases
• Phase 1- the heart muscle relaxes and the
heart fill with blood.
• Phase 2- the muscle contracts and pumps
blood forward.
Regulation of heartbeat
• Pacemaker- a group of cells in the right atrium
that sends out signals that make heart muscle
contract.
• Oxygen- being detected by the pacemaker and
it tells the heart how fast to pump.
2 loops
• Arteries- carries blood away.
• Capillaries- substances are exchanged between
blood and body cells.
• Veins- carry blood back to heart.
• First loop-blood goes from the heart to lungs and
back to heart
• Second loop-blood goes from heart to the body
and back to the heart
• Aorta-the largest artery in the body
Blood vessels
• Coronary arteries-carries blood to the heart
• Artery structure-3 layers, make it strong and
flexible so they can withstand enormous
pressure
• Pulse-feeling the artery rise and fall
• Regulating blood flow-involuntary muscles
relax and contract to push blood
Blood vessels
• Capillaries-materials like oxygen and glucose
pass through thin walls into body cells
• Diffusion-the process by which molecules go
from high to low concentration
• Veins-after blood moves through capillaries it
enters large blood vessels called veins
Blood Pressure
• Pressure- The force that something exerts
over a given area.
• Blood pressure is caused by the force with
which ventricles contract.
• A sphygmomanometer is used to measure
blood pressure.
Blood and Lymph
• Plasma- The liquid part of the blood.
• 4 parts of blood- red blood cells, white blood
cells, plasma, and platelets.
• Red blood cells- They deliver oxygen to cells.
• Hemoglobin- A protein that bonds chemically
to oxygen molecules.
Blood and Lymph
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White Blood Cells-disease fighters.
Platelets-form blood clots.
Fibrin-chemical that traps blood cells.
Blood Transfusion-moving blood from 1
person to another.
• Marker Molecules determine blood type for
safe transfusions
The lymphatic system
• Lymphatic system- a network of vessels that
return fluid to the blood stream.
• Lymph- fluid inside the lymphatic system.
• Lymph nodes- small knobs of tissue that trap
bacteria and other micro organisms that cause
disease.
Cardiovascular health
• Atherosclerosis- a condition where a artery
wall thickens, because of build of fatty
materials.
• Heart attack- blood flow to part of the heart
muscle is blocked.
• Diet, exercise, medication, not smoking, and
surgery can reduce chances of these diseases.
• Hypertension- blood pressure is always too
high.