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

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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.