THE CARDIOVASCULAR SYSTEM

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  • heart- triangular organ located in mediastinum two thirds of the mass to the left body midline and one third to the right; the apex in the diaphram; shape and size of a closed fists.
  • HEART CHAMBERS
    1. two upper chambers called atria( receiving chambers)- right and left atria.
    2. two lower chambers called ventricles ( discharging chambers)- right and left ventricles.
    3. wall of each heart chamber is composed of cardiac muscle tissue called myocardium
    4. Endocardium- smooth lining of heart chambers- inflammation of endocardium called endocarditis.
  • What is the contraction of the heart called?

    Systole
  • What is the relaxation of the heart called?

    Diastole
  • What is the function of heart valves?
    • Keeps blood flowing through the heart
    • Prevents backflow
  • How many types of heart valves are there?

    • Two atrioventricular valves
    • Two semilunar valves
  • What is the function of the tricuspid valve?

    It is the opening of the right atrium into the ventricle
  • What is the function of the bicuspid valve?
    It is the opening of the left atrium into the ventricle
  • What does the pulmonary semilunar valve do?
    It is the beginning of the pulmonary artery
  • What does the aortic semilunar valve do?
    It is the beginning of the aorta
  • What are the two distinct heart sounds in every heartbeat called?
    • "Lub" (first sound)
    • "Dup" (second sound)
  • What causes the first heart sound (lub)?
    It is caused by the vibration and closure of AV valves during contraction of the ventricles
  • What causes the second heart sound (dup)?
    It is caused by the closure of the semilunar valves during relaxation of the ventricles
  • How does the heart function in terms of pumping blood?
    • Acts as two separate pumps
    • Right atrium and right ventricle perform different functions from left atrium and left ventricle
  • What is a complete heartbeat called?
    Cardiac cycle
  • What is the average heart rate in beats per minute?
    About 72 beats per minute
  • What is the duration of each cardiac cycle?
    • Each cycle is about 0.8 seconds long
    • Subdivided into systole and diastole
  • COVERING SAC, OR PERICARDIUM
    1. pericardium is a two layered fibrous sac with a lubricated space between the two layers
    2. inner layer called visceral pericardium or epicardium
    3. outer layer called parietal pericardium
  • What is the primary function of arteries?

    To carry blood away from the heart and toward capillaries
  • What is the primary function of veins?
    To carry blood toward the heart and away from capillaries
  • What is the primary function of capillaries?

    To carry blood from arterioles to venules
  • What are the three main types of blood vessels and their functions?
    • Arteries: Carry blood away from the heart to capillaries
    • Veins: Carry blood toward the heart from capillaries
    • Capillaries: Connect arterioles to venules
  • What is the tunica intima in arteries?
    It is the inner layer of arteries
  • What is the function of valves in the tunica intima of arteries and veins?

    To prevent retrograde movement of blood
  • What is the tunica media in arteries composed of?
    Smooth muscle with some elastic tissue
  • Why is the tunica media important in arteries?
    It is important in blood pressure regulation
  • What is the tunica externa in arteries?
    A thin layer of fibrous elastic connective tissue
  • What characterizes capillaries in terms of structure?
    They are microscopic vessels with only one layer, the tunica intima
  • What is the tunica intima in veins?
    It is the inner layer of veins
  • How does the tunica media in veins compare to that in arteries?
    It is similar, consisting of smooth muscle with some elastic tissue
  • What is the tunica externa in veins?
    A heavy layer of fibrous connective tissue in many veins
  • What are the structural differences between arteries, veins, and capillaries?
    • Arteries:
    • Tunica intima: inner layer
    • Tunica media: thick, smooth muscle with elastic tissue
    • Tunica externa: thin fibrous elastic connective tissue
    • Veins:
    • Tunica intima: inner layer with valves
    • Tunica media: smooth muscle with elastic tissue
    • Tunica externa: heavy fibrous connective tissue
    • Capillaries:
    • Only one layer: tunica intima
  • FUNCTIONS
    Arteries- distribution of nutrients gasses etc. with movement of blood under high pressure; assist in maintaining the arterial blood pressure
    Capillaries- serve as exchange vessels for nutrients, wastes and fluids
    Veins- collect blood for return to the heart; low pressure vessels
  • What does blood circulation refer to?
    The flow of blood through vessels forming a complete circuit or circular pattern
  • What is systemic circulation?
    • Carries blood throughout the body
    • Path: left ventricle → aorta → smaller arteries → arterioles → capillaries
  • What is pulmonary circulation?
    • Carries blood to and from the lungs
    • Arteries deliver deoxygenated blood to the lungs for gas exchange
    • Path: right ventricle → pulmonary arteries → lungs → pulmonary veins → left atrium
  • What is blood pressure?
    The push or force of blood in the blood vessels
  • What factors influence blood pressure?
    • Blood volume: larger volume increases pressure
    • Strength of heart contractions: stronger contractions increase pressure
    • Heart rate: increased rate increases pressure
    • Blood viscosity: less viscosity decreases pressure, more viscosity increases pressure
    • Resistance to blood flow
  • How does blood volume affect blood pressure?
    A larger blood volume exerts more pressure on vessel walls