Circulatory system (animals)

• Transport system in animals

  The joined exertion of the circulatory framework, and the excretory framework
• Transport system in animals

  • Required by any animal that is too large for nutrients to reach all cells by diffusion alone
  • Made up of the heart, blood vessels (i.e. arteries, capillaries and veins) and blood
• Main functions of the transport system

  • Allow the movement of the nutrients, oxygen, carbon dioxide, hormones, antibodies, urea and heat within the blood plasma throughout the body
  • Bring the necessary resources to the cells by way of the capillaries which exchange materials with the interstitial fluid in turn allowing diffusion to occur over short distances
  • Allow the body to maintain a constant internal environment (homeostasis)
• Three components of the human circulatory system

  • Heart
  • Blood vessels
  • Blood
• Heart


  • The primary organ that pumps blood all through the body
  • Located between the lungs in the middle of the chest
  • Pumps blood through the network of arteries and veins known as the cardiovascular system
  • Pushes blood to the body's organs, tissues and cells
• The heart functions as a pump in the circulatory system to provide a continuous flow of blood throughout the body
• Each day, the average human heart beats about 100,000 times, pumping 2,000 gallons of blood through the body
• Route of blood flow through the heart

  1. Blood enters the right side of the heart through the inferior and superior vena cava

  2. Blood flows from the right atrium into the right ventricle through the tricuspid valve

  3. Blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs

  4. Oxygen-rich blood from the lungs enters the left atrium through the pulmonary vein

  5. Blood flows from the left atrium into the left ventricle through the mitral valve

  6. Oxygen-enriched blood leaves the heart through the aortic valve, into the aorta and to the arteries
• Tracing the flow of blood through the pulmonary circulation

  1. Deoxygenated blood from the inferior and superior vena cava enters the right atrium

  2. Blood flows from the right atrium to the right ventricle

  3. Blood is pumped from the right ventricle through the pulmonary valve and pulmonary artery to the lungs

  4. In the lungs, the blood exchanges carbon dioxide for oxygen

  5. Oxygenated blood flows back to the left atrium of the heart through the pulmonary veins
• Tracing the flow of blood through the systemic circulation

  1. Oxygenated blood leaves the left atrium through the mitral valve into the left ventricle

  2. Blood is pumped from the left ventricle through the aortic valve to the aorta

  3. The aorta branches into the brachiocephalic, left common carotid, and left subclavian arteries

  4. The descending aorta leads downward through the diaphragm and splits into the iliac arteries

  5. The iliac arteries continue down into the legs as the femoral arteries
• Arteries


  • Elastic tubes that carry blood in pulsating waves
  • The blood exerts pressure against the walls of the arteries as it passes through
  • The peak pressure occurs during the heart's contraction (systolic pressure)
  • The minimum pressure occurs between contractions when the heart expands and refills (diastolic pressure)
  • The pressure variation within the artery produces a pulse
• Common pulse sites


  • Temporal (side of forehead)
  • Carotid (neck)
  • Brachial (inside the elbow)
  • Radial (thumb side of wrist)
  • Femoral (groin)
  • Popliteal (behind the knee)
  • Dorsalis pedis (upper surface of foot)
• Pulse rate


  • Count the number of beats for 15 seconds x 4 = pulsations per minute
  • Average resting pulse rate is 70 beats per minute
  • During exercise, the pulse rate might increase to between 130 and 140 beats per minute
• Blood pressure


  • Measured in the brachial artery with a sphygmomanometer and stethoscope
  • Expressed as a ratio of systolic over diastolic pressure in millimeters of mercury
  • Average adult systolic pressure ranges from 100 to 140 mm Hg
  • Average adult diastolic pressure ranges from 60 to 90 mm Hg
  • A reading of 140/90 would be considered 'high' blood pressure
• Arterioles


  Act like adjustable nozzles in the circulatory system, having the greatest influence over blood pressure
• Capillaries


  • The smallest blood vessels, with walls so thin that molecules can pass through them
  • Branch out from the arterioles, passing next to organs, intestines, and through cellular tissue
  • Provide the means of exchange, through the process of absorption
• Flow of blood through the capillaries

  1. Capillaries branching from arteries in the abdomen pick up nutrients and water

  2. Capillaries in cellular tissue exchange oxygen, nutrients, and water, and pick up carbon dioxide and other wastes

  3. Capillaries branching from arteries in the lungs absorb oxygen
• Venules


  • Wider vessels that the capillaries merge into, carrying blood with carbon dioxide and cell wastes
  • Empty into veins, which have valves to prevent backflow
• Blood


  • Plasma is the fluid substance that suspends and moves the blood components
  • Plasma makes up 50 to 60 percent of blood by volume
• Blood components


  • Red blood cells (erythrocytes) - transport oxygen
  • White blood cells (leukocytes) - fight against germs and disease
  • Platelets (thrombocytes) - stop bleeding by clumping and forming plugs
• Types of blood vessels

  • Arteries - carry oxygen-rich blood away from the heart
  • Veins - carry carbon dioxide-rich blood toward the heart
  • Capillaries - exchange oxygen, food, carbon dioxide and waste products between blood and body cells
• Transport system in plants

  Plants have two systems for the transportation of substances - the xylem and phloem
• Xylem


  Specialized plant tissue responsible for carrying water and dissolved minerals from the roots
• Phloem


  Structure responsible for the translocation of food from the leaves to different parts of the plant