human anatomy

• Lymphatic System


  A vast collection of cells and biochemicals that travel in lymphatic vessels, and the organs and glands that produce them
• Lymphatic System


  • Part of the circulatory system and the immune system
  • Made up of a large network of lymphatic vessels and lymphatic or lymphoid organs and tissues
• Lymphatic System


  A network of tissues and organs that help rid the body of toxins, waste and other unwanted materials
• Primary function of the lymphatic system

  To transport lymph, a fluid containing infection-fighting white blood cells, throughout the body
• Lymphatic Vessels


  • Similar to veins and capillaries of the circulatory system
  • Connected to lymph nodes, where the lymph is filtered
  • The tonsils, adenoids, spleen and thymus are all part of the lymphatic system
• There are hundreds of lymph nodes in the human body
• Lymphatic Vessels


  • Similar to blood capillaries but are extremely permeable
  • The endothelial cells forming the walls of lymphatic capillaries are not tightly joined, adjacent edges overlap loosely
  • Collagen filaments anchor the endothelial cells to surrounding structures, any increase in interstitial fluid volume opens the mini-valves
• Lymphatic Vessel Function


  1. When fluid pressure in interstitial space is greater than the pressure in the lymphatic capillary, the mini flaps gape open allowing fluid to enter

  2. When pressure is greater inside the lymphatic capillary, endothelial mini-valves flap are forced closed preventing lymph from leaking back out as the pressure moves it along the vessel
• Proteins in interstitial space

  Unable to enter blood capillaries but enter lymphatic capillaries easily
• Inflamed tissues


  Lymphatic capillaries develop openings that permit uptake of large debris and cancer cells, pathogens
• Pathogens in lymph


  Travel in lymph as it detours to lymph nodes and cleansed by cells of the immune system
• Spleen


  • The largest lymphatic organ, located on the left side of the body just above the kidney
  • Acts as a blood filter, controls the amount of red blood cells and blood storage in the body, and helps to fight infection
• Lacteal


  Highly specialized lymphatic capillaries in the fingerlike villi of the intestinal mucosa
• Lymph from digestive viscera

  Milky white, since it plays a major role in fat absorption, referred to as fatty lymph or chyle
• Sometimes lymph nodes are overwhelmed by the agents they are trying to destroy
• Cardiovascular System


  Consists of three interrelated components: the heart, the blood vessels and the blood and lymphatic system
• Heart


  Circulatory pump that constantly delivers blood through blood vessels to all body cells and tissues
• The average adult heart beats about 100,000 times each day
• Purpose of the heart


  Transport system pump that sends blood through hollow blood vessels to the cells of the body
• Location of the heart

  • About the size of the owner's fist
  • Hollow cone-shaped mass of about 250-350 grams
  • Lies within the mediastinum, the medial cavity of the thorax
  • Extends from the 2nd to 5th intercostal space
  • 2/3 of mass lies to the left, 1/3 lies to the right
• Heart's broad flat base or posterior surface

  • 9 cm (3.5 in) wide
  • Directed towards the right shoulder
• Heart's apex


  • Points below towards the left hip
• Apical impulse


  • Caused by the beating heart in contact with chest wall
  • Can be felt between the 5th and 6th rib below the left nipple
• Pericardium


  Double-walled sac that encloses the heart
• Fibrous pericardium


  Tough, dense connective tissue layer that protects the heart, anchors it to surrounding structures, and prevents overfilling of the heart with blood
• Serous pericardium


  • Thin, slippery, two-layer serous membrane
  • Parietal layer lines the internal surface of the fibrous pericardium
  • Visceral layer (epicardium) covers the external heart surface
• Pericardial cavity


  Slit-like space between the parietal and visceral layers, containing serous fluid
• Pericarditis is inflammation of the pericardium
• Pericardial friction rub is the creaking sound heard with a stethoscope as the beating heart rubs against its pericardial sac
• Cardiac tamponade is excess fluid compressing the heart, limiting its ability to pump blood
• Epicardium


  Outer layer of the heart wall, the visceral layer of the serous pericardium
• Myocardium


  Middle and muscular layer of the heart wall, composed mainly of cardiac muscles
• Endocardium


  Inner layer of the heart wall, a glistening white sheet of endothelium resting on a thin connective tissue layer
• Chambers of the heart

  • 2 superior atria, 2 inferior ventricles
  • Interatrial septum divides the atria
  • Interventricular septum divides the ventricles
  • Right ventricle forms most of the anterior surface, left ventricle dominates the inferoposterior aspect and forms the apex
• Atria


  Receive the blood returning to the heart from the circulation, are relatively small and thin-walled as they only contract a little to push blood into the ventricles
• Tricuspid valve


  Separates the right atrium and ventricle
• Bicuspid (mitral) valve


  Separates the left atrium and ventricle
• Pathway of blood to the heart

  1. Deoxygenated blood returns from the body via the superior and inferior vena cavae into the right atrium

  2. Right atrium contracts and pushes blood through the tricuspid valve into the right ventricle

  3. Right ventricle contracts and sends blood through the semilunar valve to the pulmonary trunk and lungs

  4. Oxygenated blood returns from the lungs via the pulmonary veins to the left atrium

  5. Left atrium contracts and pushes blood through the bicuspid valve into the left ventricle

  6. Left ventricle contracts and sends blood through the semilunar aortic valve to the aorta and systemic circulation
• Equal volumes of blood are pumped into the pulmonary and systemic circuits at any moment, but the two ventricles have very unequal workloads
• Coronary circulation


  • Functional blood supply to the heart, the shortest in the body
  • Arterial supply is by the right and left coronary arteries, arising from the base of the aorta and encircling the heart
  • Left coronary artery divides into the anterior interventricular artery and circumflex artery
  • Right coronary artery branches into the right marginal artery and posterior interventricular artery