CIRCULATORY SYSTEM

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CIRCULATORY SYSTEM
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Circulatory System

• Circulatory system
• Efficient distribution system
• Network of 100,000 km of blood vessels
• Supplies cells with nutrients and oxygen and
  removes carbon dioxide and waste products
• Transports hormones
• Plays an important role repairing tissues and
  protecting the body from infection

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Organs of the Circulatory System

• Blood Type of connective tissue (cells
  liquid)
• Heart Multi-chambered, muscular organ
• Overall flow of blood via blood vessels ? from
  the heart to the tissues
• throughout the body back to the
• heart
• - Body contains 5 L of blood

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3 Types of Blood Vessels

• Capillaries
• Microscopic blood vessels- make contact with all
  cells of the body
• Walls of capillaries consist of a thin layer of
  epithelial tissue ? enables diffusion of
  nutrients and oxygen out of the blood the
  diffusion of waste products into the blood
• Arteries
• Blood flows from the heart to the capillaries
  through thick walled blood vessels arteries
• Walls of arteries epithelial tissue wrapped in
  layers of smooth muscle and connective tissue
• Muscle tissue enables arteries to constrict
  dilate Blood in arteries is under pressure due
  to the hearts pumping action

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3 Types of Blood Vessels

• 3. Veins
• Blood returns from the capillaries to the heart
  through vessels veins
• Walls of veins consist of epithelial tissue
  surrounded by smooth muscle connective tissue
  but muscle layer is thinner than that in arteries
• Blood is under little pressure
• Contracting skeletal muscles squeezes the
• veins and forces blood back to the heart

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Chemical Exchange between Blood Body Tissues

• Most cells are no further than 10 micrometers
  from a capillary and the blood inside
• Capillary network
• Critical to accomplishing the main functions of
  the circulatory system
• Distribution of oxygen nutrients, and removal
  of waste products
• Cells in body tissues ? surrounded by
  interstitial fluid

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Chemical Exchange between Blood Body Tissues

• Substances in capillaries do not enter tissue
  cells directly
• First Substances in capillaries enter the
  interstitial fluid
• Second Substances in the interstitial fluid then
  enter the cells

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Chemical Exchange between Blood Body Tissues

• Exchange of substances between blood
  interstitial fluid occurs in several ways
• Small molecules (oxygen, carbon dioxide) ?
  diffuse across the membrane or pass through gaps
  between the epithelial cells of the capillary
  wall
• Oxygen nutrients move from the blood into the
  interstitial fluid
• Carbon dioxide other small waste products move
  from the interstitial fluid into the blood
• Larger molecules move across the membranes by
  exocytosis and endocytosis

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Chemical Exchange between Blood Body Tissues

• Exchange of substances between blood
  interstitial fluid occurs in several ways
• Blood pressure ? forces fluid through the
  capillary wall
• ? At the artery end of a capillary ? blood
  pressure forces water, small solutes, and some
  dissolved proteins through the gaps between the
  cells However, blood cells larger proteins are
  too large to pass easily through the openings ?
  remain in the capillary
• ? Result Vein end of the capillary in hypertonic
  compared to the surrounding interstitial fluid ?
  Thus, water reenters the vein end of the
  capillary via osmosis Blood pressure is very low
  at the vein end of the capillary, so it does not
  oppose the flow of fluid back into the capillary

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Blood consists of Cells suspended in Plasma

• Blood
• Highly specialized tissue
• Part liquid, part cellular material
• Plasma
• Composes 55 of the volume of blood
• Plasma 90 water Other 10 dissolved salts,
  proteins, transport substances

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Blood consists of Cells suspended in Plasma

• Red blood cells (Erythrocytes)
• Constitutes the remaining 45 of the blood volume
• Carry oxygen from the lungs to all the tissues in
  your body
• Each RBC ? contains 250 million molecules of
  hemoglobin (Protein that temporarily stores
  oxygen for delivery to cells)
• Hemoglobin ? Contains iron ? Oxygen molecules
  bind to the iron portion (heme group) of the
  hemoglobin molecule

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Red Blood Cells

• Red blood cells (Erythrocytes)
• Produced in the bone marrow
• Distinctive shape due to the loss of their nuclei
  and mitochondria ? shape flat disk, curves
  inward in the middle ? structure provides
  increased surface area for oxygen transport
• Life span of a RBC 100-120 days

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Blood consists of Cells suspended in Plasma

• White blood cells (Leukocytes)
• Responsible for fighting infection and preventing
  the growth of cancer
• When an infection invades your body ? of WBCs
  increases
• Most of the action of the WBC takes place outside
  the blood vessels in the interstitial fluid

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3 Functions of Blood

• Blood
• Carries oxygen, nutrients, and hormones
• Removes waste (carbon dioxide)
• Fights infection

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Blood consists of cells suspended in plasma

• Blood
• Connective tissue
• Flows through blood vessels
• Five liters of blood
• Takes 1 minute to make a complete circuit
• Composed of
• 55 Plasma
• 45 RBCs

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Blood consists of cells suspended in plasma

• Plasma (45)
• 90 water
• 10 dissolved salts, proteins, and other
  substances
• RBCs
• Erythrocytes
• Most numerous cells in blood
• 5 million RBCs in 1 drop of blood
• Contains hemoglobin
• Produced in the bone marrow (2 million per
  second)
• Replaced every 120 days

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Blood consists of cells suspended in plasma

• Hemoglobin
• Protein that binds with oxygen for transport to
  cells
• Contains iron which contains a high affinity for
  oxygen

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Blood consists of cells suspended in plasma

• WBCs
• Leukocytes
• Fight infection and prevents growth of cancer
• 4,000-11,000 WBCs in 1 drop of blood
• Infection increases the number of WBCs
• Most action takes place in the interstitial fluid

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Blood consists of cells suspended in plasma

• Blood clotting
• Platelets help with blood clotting
• Originate from the bone marrow
• 250,000 500,000 in a drop of blood
• Stick to damaged site
• Release clotting factors
• Fibrin produced (Protein)
• Patch forms and dries into a scab