(unit a) biology

• circulatory functions

  • carries nutrients (O2, glucose) to cells, wastes (co2, and urea) away from cells
  • carries chemical messengers (harmonies) from cells in one part of the body to distant target tissues
  • distributes heat throughout the body
  • along with the kidneys, maintains levels of body fluids
  • defense against invading organisms
• types blood vessels

  • arteries ~ thickest
  • veins ~ in between
  • capillaries ~ thinnest
• Artery


  Carry blood from the heart
• Arteries


  • Thick walls
  • Stretch to control blood flow to different tissues
• Arterioles


  Smaller arteries that control blood flow to tissues
• Capillaries


  Smallest blood vessels, site of exchange of nutrients/oxygen and waste
• Capillaries


  • One cell layer thick wall
  • Movement of materials by diffusion and osmosis
• Veins


  Carry blood back to the heart
• Veins


  • Thin walls
  • One-way valves to prevent backflow
  • Skeletal muscles help pump blood back to the heart
• The human heart lies just behind the breastbone and is about the size of a person's fist
• Heart structure


  • Made of muscle tissue
  • Acts like 2 pumps, left and right
  • Both sides separated by a wall of muscle called the septum
  • Both sides pump at the same time
• Right Atrium


  • Receives blood from the superior and inferior
  • Pumps blood to the ventricles
• Left Atrium


  • Receives blood from the lungs
  • Pumps blood to the left ventricle
• Right Ventricle


  Pumps blood to the lungs
• Left Ventricle


  Pumps blood to the body
• A human heart has the following structure: right atrium, right ventricle, left atrium, left ventricle, aortic valve, pulmonary arteries, chordae tendineae, interventricular septum
• Why is the left ventricle more muscular than the right ventricle?

  It must have to pump blood to the entire body, not just to the lungs
• Valves of the heart

  Located between the atria and ventricles, and ventricles and arteries
• Function of heart valves

  • Provide the one-way flow of blood
• A human heart has valves
• The heart has pulmonary arteries
• The heart has a right ventricle and a septum
• Blood vessels leading towards and away from the heart

  • Vena cava
  • Pulmonary artery
  • Pulmonary veins
  • Aorta
• Vena cava


  Carries deoxygenated blood from the body
• Pulmonary artery


  Carries deoxygenated blood to the lungs
• Pulmonary veins


  Carry oxygenated blood from the lungs
• Aorta


  Carries oxygenated blood to the body
• The cardiac cycle


  1. Heart relaxed

  2. Atria contract

  3. Ventricles contract
• Systole


  Ventricles contract
• Diastole


  Ventricles relax and fill with blood
• Circulatory pathways


  • Pulmonary (lungs)
  • Systemic (body)
  • Coronary (heart)
• Pulmonary circulation


  Carries deoxygenated blood to the lungs, picks up oxygen, and returns oxygenated blood to the heart
• Systemic circulation


  Carries oxygenated blood to the body
• Coronary circulation


  Supplies blood to the heart muscle
• Blood pressure


  Measure of the pressure of blood in the vessels, expressed as two numbers
• Blood pressure measurement


  Increasing pressure in a cuff blocks blood flow, then the cuff is slowly deflated until a sound is heard, representing systolic and diastolic pressure
• Blood pressure


  Highest in arteries, lowest in veins
• Blood pressure


  Decreases further away from the heart
• Blood flows fastest in arteries, slowest in capillaries, but capillaries have the greatest surface area
• Factors that increase blood pressure

  • Increased blood volume
  • Hardening of arteries
  • Eating salty food
  • High cholesterol