circulatory system

• Circulatory system


  A system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body
• Cardiovascular system


  Cardio means heart, and vascular refers to blood vessels
• Functions of the circulatory system

  • Moves blood throughout the body
  • Transports oxygen and nutrients to muscles, tissues and organs
  • Removes waste from cells and organs
  • Protects the body against disease and infection
  • Hydration and fluid balance
• Three circuits of the circulatory system

  • Pulmonary circuit
  • Systemic circuit
  • Coronary circuit
• Pulmonary circuit


  Carries blood without oxygen from the heart to the lungs, pulmonary veins return oxygenated blood to the heart
• Systemic circuit


  Blood with oxygen, nutrients and hormones travels from the heart to the rest of the body, veins pick up waste products
• Coronary circuit


  Provides the heart muscle with oxygenated blood, returns oxygen-poor blood to the heart's right upper chamber to send to the lungs
• Three main parts of the circulatory system

  • Heart
  • Blood
  • Blood vessels
• Heart


  Muscular organ that pumps blood throughout the body
• Blood


  Has four components: plasma, red blood cell, white blood cell and platelets. Carries oxygen, nutrients and wastes
• Blood vessels


  Has three types: arteries, veins and capillaries. Serve as channels for the blood
• Heart


  • Muscular organ that pumps blood
  • Located in the chest, between the lungs, slightly to the left of centre
• Functions of the heart

  • Generating blood pressure
  • Routing blood
  • Ensuring one-way blood flow
  • Regulating blood supply
• Pulmonary circulation


  Carries blood to the lungs, where carbon dioxide diffuses out and oxygen diffuses in
• Systemic circulation


  Delivers oxygen and nutrients to all the remaining tissues of the body
• Shape of the heart

  • Blunt cone, approximately the size of a closed fist, with an average mass of 250 g in females and 300 g in males
  • The blunt, rounded point is the apex, the larger, flat part is the base
• Location of the heart

  In the mediastinum, a midline partition of the thoracic cavity
• Parts of the heart

  • Pericardium
  • Heart wall (endocardium, myocardium, epicardium)
  • Heart chambers (right atrium, right ventricle, left atrium, left ventricle)
  • Heart valves
  • Blood vessels (arteries, veins, capillaries)
• Pericardium


  The structure that surrounds and protects the heart
• Layers of the heart wall

  • Epicardium (outer layer)
  • Myocardium (middle layer)
  • Endocardium (inner layer)
• Epicardium


  The superficial layer of the heart wall, a thin serous membrane that constitutes the smooth, outer surface of the heart
• Myocardium


  The thick, middle layer of the heart, composed of cardiac muscle cells responsible for the heart's ability to contract
• Endocardium


  The deep layer of the heart wall, consisting of simple squamous epithelium over a layer of connective tissue, forming the smooth, inner surface of the heart chambers and covering the heart valves
• The heart wall is composed of three layers of tissue: epicardium, myocardium, and endocardium
• Blood vessels are the components of the circulatory system that transport blood throughout the human body
• Functions of blood vessels

  • Carry blood
  • Exchange nutrients, waste products, and gases with tissues
  • Transport substances
  • Help regulate blood pressure
  • Direct blood flow to tissues
• Types of blood vessels

  • Artery
  • Capillary
  • Vein
• Artery


  Has the thickest wall, allowing it to withstand the high pressure created by the heart
• Capillary


  Has the thinnest wall to allow substances to pass through, such as oxygen and sugars
• Vein


  Less muscular and stretchy than an artery, so blood moves through it with low pressure. Has valves to help blood flow in one direction
• Layers of blood vessel wall

  • Tunica externa
  • Tunica media
  • Tunica intima
• Tunica externa


  Composed entirely of connective fibers and surrounded by an external elastic lamina which functions to anchor vessels with surrounding tissues
• Tunica media


  Comprised of smooth muscle cells and elastic and connective tissues arranged circularly around the vessel
• Tunica intima


  Formed from a single continuous layer of endothelial cells and supported by a subendothelial layer of connective tissue and supportive cells
• Conditions of blood vessels

  • Aneurysm
  • Stroke
  • Hypertension
  • Moyamoya
  • Atherosclerosis
  • Raynaud's disease
• Aneurysm


  A localized enlargement of arteries, characterized by a balloon-like bulge, resulting from the abnormal weakening of the blood vessel wall
• Stroke


  A serious condition of blood vessel disorder caused by the stop of blood supply to the brain
• Hypertension


  Also known as high blood pressure, a long-term medical condition in which the blood pressure in the arteries is persistently elevated
• Moyamoya


  A rare condition in which the blood vessels (internal carotid arteries) that supply blood to the brain become narrowed, limiting the flow of blood to the brain and putting them at risk for stroke
• Atherosclerosis


  The buildup of plaque (cholesterol, fat and other substances) inside the arteries, which can lead to a heart attack or stroke