Respiratory and Circulatory

• The right ventricle pumps deoxygenated blood out of the heart through the pulmonary artery.
• Blood flows from the right atrium into the right ventricle through the tricuspid valve.
• The heart is located between the lungs, behind the sternum (breastbone), and to the left side of the body.
• The heart is divided into four chambers, two atria (right and left) and two ventricles (right and left).
• Blood flows from the right side to the left side of the heart.
• Breathing is essential for life. All the cells in our body, especially our brain cells, require a constant supply of oxygen to undergo cellular respiration. When deprived of oxygen, cells can begin to die within minutes.
• The respiratory system, together with the circulatory system, provides our cells with the oxygen needed for cellular respiration, while disposing of the carbon dioxide produced by this same process.
• Nose

  • Filters, moistens, and warms the air as it enters the respiratory system
  • Hairs lining the entrance of the nasal cavity trap large particles
  • Incoming air is warmed in the inner nasal cavity and sinuses
  • Mucus moistens the air while trapping smaller dust particles
• Pharynx

  A cavity at the back of the mouth that serves as a passageway for both air and food
• Larynx

  • Contains two highly elastic folds of tissue commonly called the vocal cords
  • As muscles pull these tissues together, the air moving between them causes the vocal cords to vibrate and produce sounds
• Trachea


  • A flap of tissue called the epiglottis covers the entrance to the trachea when you swallow food or liquid to help ensure that they go into the esophagus instead
  • Mucus in the trachea continues to trap inhaled particles
  • The cilia that line the trachea sweep the mucus and dust particles back toward the pharynx where they can be swallowed or spit out
• Lungs and Bronchi

  • Air leaves the trachea and moves into two large tubes called bronchi
  • Each bronchus leads to one lung, where the tube divides into smaller bronchi that lead to even smaller passageways called bronchioles
  • The bronchi and bronchioles are surrounded by smooth muscles that contract and relax to regulate the size of the air passageways
• Alveoli

  • The bronchioles continue to divide inside the lungs until they end in millions of tiny air sacs called alveoli
  • These alveoli are grouped into clusters and are surrounded by capillaries of the circulatory system
  • Oxygen that is carried through the respiratory system dissolves across the alveoli's thin epithelium into the surrounding web of capillaries
• Diaphragm

  • A thin sheet of muscle that forms the bottom wall of the chest cavity
  • Contracting and relaxing this muscle helps to increase and decrease the volume of the chest cavity, causing you to inhale and exhale
  • Breathing is an involuntary, unconscious act controlled by the nervous system
• The rib cage and rib muscles are not part of the respiratory system, but they are important to its function. They work with the diaphragm to cause inhalation and exhalation. You can often observe your rib cage expanding and contracting as you breathe.
• Rib cage and rib muscles

  • Not part of the respiratory system
  • Important to the function of the respiratory system
  • Work with the diaphragm to cause inhalation and exhalation
• Circulatory system

  Consists of the heart, blood, and blood vessels
• Functions of the circulatory system

  • Delivers materials throughout the body, such as oxygen and various important nutrients
  • Removes waste from the body, such as carbon dioxide
  • Fights disease and seals cuts to prevent blood loss
• Heart

  • Divided into four chambers
  • Septum separates the right side of the heart from the left
  • Septum is important because it separates oxygenated and deoxygenated blood and prevents it from mixing
  • Each side of the heart has an upper chamber (atria) and a lower chamber (ventricles)
  • Atria receive blood from the body
  • Ventricles pump blood out of the heart
• Major parts of the heart

  • Aorta
  • Pulmonary Vein
  • Left Atrium
  • Left Ventricle
  • Superior Vena Cava
  • Right Atrium
  • Right Ventricle
  • Pulmonary Artery
• Aorta

  Carries oxygenated blood to the body
• Pulmonary Vein

  Carries oxygenated blood from the lungs to the heart
• Left Atrium

  Pumps oxygenated blood to the left ventricle
• Left Ventricle

  Pumps oxygenated blood away from the heart
• Superior Vena Cava

  Carries blood from the upper body back to the heart
• Right Atrium

  Receives deoxygenated blood from the body
• Right Ventricle


  Pumps deoxygenated blood to the lungs, so it can become oxygenated
• Pulmonary Artery

  Carries deoxygenated blood from the heart to lungs
• Pulmonary Circulation

  1. Right side of heart takes in deoxygenated blood from body

  2. In lung capillaries, CO2 diffuses out and O2 diffuses in

  3. Oxygen-rich blood flows into left side of heart
• Systemic Circulation

  1. Oxygenated blood enters left side of heart

  2. Pumped out to rest of body

  3. Cells absorb oxygen, dispose CO2

  4. Deoxygenated blood returns to right side of heart
• Pulmonary Circulation

  Path of circulation between heart and lungs
• Systemic Circulation

  Path of circulation between heart and rest of body
• Blood Vessels

  • Arteries
  • Capillaries
  • Veins
• Arteries

  • Carry blood out from heart to body
  • Have thick flexible walls to withstand pressure
  • Aorta is largest artery, carries oxygenated blood from left ventricle
  • Coronary arteries supply heart muscle
• Capillaries

  • Smallest blood vessels, allow gas exchange
  • Blood cells travel single file
  • Oxygen/nutrients diffuse out, CO2/waste diffuse in
• Veins

  • Return blood to heart
  • Often have valves to ensure one-way flow
  • Muscles squeeze veins to push blood upwards
• Blood Components

  • Plasma
  • Red blood cells
  • White blood cells
  • Platelets
• Plasma

  • Liquid solution with dissolved ions, proteins, other solutes
  • Maintains balance of solute concentrations for pH and homeostasis
  • Transports nutrients and waste
• Red Blood CellsMost abundant, 25 trillion in 5 liters of blood

  • Flattened disks, lack mitochondria, use anaerobic respiration
  • Transport oxygen, high surface area for gas diffusion
  • Formed in bone marrow, contain hemoglobin
• White Blood Cells

  • Help fight infections, ingest bacteria/debris, produce antibodies
  • Produced in bone marrow, spend time in interstitial fluid