Post on 27-Dec-2015
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Circulatory ( or cArdiovascular) System
Blood CompositionPlasma (55%): Fluid portion of bloodRed blood cells (44%): Carry oxygenWhite blood cells: Defend against
pathogensPlatelets: Cell fragments, form blood
clots
Red Blood Cells Hemoglobin: Iron-containing molecule Loosely binds O2 in lungs (high concentration)
Releases O2 in body tissue (low concentration) Shape of RBC’s allows them to travel through
narrow capillaries more easily
Red Blood Cell Lifespan
Produced in the marrow Only type of body cell without a nucleus Old RBC destroyed in liver, spleen Average lifespan 120 days
Blood Types
RBC Marker ProteinsA- A proteinB- B proteinAB- both A and B proteinsO – neither A nor B proteins
Another marker protein is Rh factor. Rh +: has Rh factor; Rh - : no Rh factor
Immune system produces antibodies against foreign antigens (any protein etc. not produced in the body)
AB + is the universal receipientO – is the universal donor
Blood VesselsArteries Arterioles (thinner arteries) Capillaries Venules (thinner veins) Veins
Arteries Carry blood away from the heart Most arteries contain oxygenated blood Blood is under greater pressure (most arteries
protected deeper within body) Thick walled vessels Muscular walls expand/ contract to help move blood
Capillaries: Site of Gas/Nutrient Exchange
Microscopic blood vessels Lining is 1 cell thick Allows oxygen and nutrients to diffuse into
body cells Waste from cells diffuses into blood
Veins Carry blood back to the heart Most veins carry deoxygenated blood Since many veins travel against gravity, equipped with one-way valves to prevent
back-ups
Artery: Thicker layer of smooth muscle
Vein: One way valves
Heart
Mainly cardiac muscle Cells have numerous mitochondria Mammalian hearts have 4 chambers
• 2 Upper Chambers: Atria Receiving chambers
• 2 Lower Chambers: Ventricles Pump blood out of heart
Left and right sides separated by solid wall (septum) to create two pumps
Video on Flow of Blood in the Heart: click once to start video
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Pathway of Blood
Oxygen poor blood returning from body enters right atrium
Right atrium right ventricle
pulmonary artery lungs
pulmonary vein left atrium
left ventricle aorta arteries
capillaries veins
vena cavae
Amphibians and reptiles have a 3 chambered heart rather than four chambered heart, which allows mixing of oxygenated and deoxygenated blood.
Mammals and birds have a four chambered heart which keeps oxygenated and deoxygenated blood separated and allows for more efficient transport of oxygen.
Discuss with your table partner why amphibians (such as frogs) and reptiles (such as crocodiles) do not require as efficient a heart as mammals and birds.
Mammals and birds are warm-blooded (endotherms.)
A large expenditure of energy (ATP) is used to keep the body warm. This ATP is provided by cellular respiration, which requires both food and oxygen. Endotherms require a larger amount of both food and oxygen.
Amphibians and frogs are cold-blooded (ectotherms). Their body temperature changes with the outside temperature, and they do not require energy for heating.
Heartbeat regulation
Region of heart called the sinoatrial node acts as pacemaker, regulating the heart rate through electrical impulses that spread through the heart.
Medulla oblongata regulates the pacemaker, speeding or slowing the heart rate as necessary.
Systolic and Diastolic Pressure
Systolic pressure is the pressure exerted when the heart beats.
Diastolic pressure is the lowest pressure, when your heart relaxes between beats.