foundations of the cardiac and respiratory systems

• circulatory routes

  • System of double circulation:
  • Pulmonary circulation – through the lungs) to oxygenate blood
  • Peripheral circulation – via the arteries to deliver oxygen & other nutrients to the tissues; and to collect waste metabolites via the veins
• What is the outermost layer of vessel walls called?

  Tunica externa (or adventitia)
• What type of tissue makes up the tunica externa?

  Loose connective tissue
• What is the middle layer of vessel walls known as?

  Tunica media
• What components make up the tunica media?

  Smooth muscle, collagen, and some elastic tissue
• What is the innermost layer of vessel walls called?

  Tunica intima (interna)
• What is the function of the tunica intima?

  To act as a selectively permeable barrier that usually repels blood cells and platelets
• What is the primary function of arteries?

  To distribute blood around the body
• How do arteries differ from veins in terms of blood flow direction?

  Arteries carry blood away from the heart
• What structural feature do arteries have in their tunica media?

  A thick layer of smooth muscle
• How do arteries appear in cross-section?

  They look quite round
• What is the primary function of veins?

  To convey blood back to the heart
• How do the walls of veins compare to those of arteries?

  Veins have thinner walls than arteries
• What do veins depend on to assist in blood flow?

  Skeletal muscles and visceral action
• What is the role of valves in veins?

  To maintain one-way flow despite low pressure
• What are capillaries primarily known as?

  Exchange vessels
• What substances do capillaries exchange via diffusion?

  Oxygen, nutrients, and wastes
• What facilitates the exchange process in capillaries?

  Very thin walls consisting of endothelium and base membrane only
• Approximately how many capillaries are there in the body?

  ~ billion capillaries
• lymphatic system

  • Network of vessels with collection of tissues & organs with a role in immunity
  • Removes fluid, large proteins and other large molecules from interstitial spaces and back into the venous system
  • Lymph nodes filter fluid to remove pathogens & foreign bodies
• What is the cardiac cycle?

  It is the complete cycle of contraction and relaxation of all four chambers of the heart.
• What does the cardiac cycle NOT represent?

  It does NOT represent the passage of blood as it flows around the heart, lungs, and periphery.
• What are the main events in the cardiac cycle?

  • Ventricular filling
  • Heart contraction
  • Ejection of blood from ventricle into circulation
  • Heart relaxation
  • The cycle continues
• What is systole in the context of the heart?

  Systole is the phase when the heart is contracting.
• What happens to blood flow when the atria are relaxed?

  Blood flows from the great veins into the atria and then into the ventricles.
• What role does atrial contraction play in the cardiac cycle?

  Atrial contraction acts as a primer pump to add extra filling to the ventricles.
• What occurs during ventricular contraction?

  Ventricular contraction creates pressures to overcome aortic and pulmonary pressures and ejects blood into circulation.
• What is the term for the heart's relaxation phase?

  The relaxation phase is called diastole.
• What is the function of the atrioventricular valves?

  • Prevent backflow of blood from ventricles into the atria
  • They close and open passively
• What is the function of the aortic and pulmonary artery valves?

  • They are semi-lunar valves
  • Snap shut at the end of systole to prevent backflow of blood
• What are the two main divisions of the respiratory tract?

  Upper respiratory tract and lower respiratory tract
• What structures are included in the upper respiratory tract?

  Nose, pharynx, and larynx
• What structures are included in the lower respiratory tract?

  Trachea, bronchi, and bronchioles
• What is the function of the nasal conchae?

  To increase turbulence in the nasal cavity for warming, humidification, and filtering of air
• How do sensory nerve endings in the nose contribute to respiratory health?

  They trigger a sneeze reflex when inhaling particles
• What role does the epiglottis play in the larynx?

  It protects the larynx from food by closing over it during swallowing
• What is contained within the larynx?

  The vocal cords
• Why are vocal cords essential for an effective cough?

  They help to produce the sound and force needed for coughing
• What is the trachea commonly referred to as?

  The windpipe
• Where does the trachea descend from?

  From the larynx into the thorax