Circulatory System and Blood

• Circulatory system transports:

  • nutrients
  • hormones
  • oxygen
  • other needed substances in the cell.
• ___ : It also moves waste, carbon dioxide and secretory products to their disposal areas / organs

  Excretory
• ___: Aids in fighting off pathogenic microorganism by providing and/or transporting the cells and substances needed for this purpose.

  Protection
• DIVISION OF CIRCULATORY SYSTEM

  • Cardiovascular System (Blood Vascular System)

  • Lymph Vascular System
• COMPONENTS OF THE CARDIOVASCULAR SYSTEM

  1. Heart
  2. Blood Vessels : Artery, Vein, Capillaries
  3. Blood - RBC, WBC, Platelets
• CIRCULATORY SYSTEM

  An inner lining, the tunica intima [innermost layer], comprising a single layer of extremely flattened epithelial cells called endothelial cells supported by a basement membrane and delicate collagenous tissue.
• CIRCULATORY SYSTEM

  An intermediate predominantly muscular layer, the tunica media.

  contains alternating layers of smooth muscle and collagen or elastic lamellae
• CIRCULATORY SYSTEM

  An outer supporting tissue layer called the tunica adventitia contains connective tissue, small vessels and nerves and vasa vasorum
• TISSUES OF THE VASCULAR WALLS

  ENDOTHELIUM

  • Internal surface of all components of cardiovascular and lymphatic system.
  • Simple squamous epithelium
  • maintain a selectively permeable, antithrombogenic (inhibitory to clot formation) barrier
  • they also determine when and where white blood cells leave the circulation for the interstitial space of tissues
  • secrete a variety of paracrine factors - signals vessel dilation, constriction, and growth of adjacent cells.
• TISSUES OF THE VASCULAR WALLS

  SMOOTH MUSCLE

  • occur in the walls of all vessels larger than capillaries and are arranged helically in layers.
  • permit regulated vasoconstriction and vasodilation
• TISSUES OF THE VASCULAR WALLS

  CONNECTIVE TISSUE

  • Collagen: found in subendothelial layer
  • Elastic Fibers: provide resiliency to blood vessel
• Layer that is composed of Connective Tissue is the

  Tunica adventitia
• Heart - is a hollow muscular organ, about a size of a clenched fist, located in the central mediastinum of thoracic cavity
• heart is a modified artery that has a pumping capacity that propels blood to the arteries of both systemic and pulmonary circulations
• Four chambers of heart

  1. right atrium
  2. left atrium
  3. right ventricle
  4. left ventricle
• Systemic circulation - blood brings nutrient and removes waster in tissue throughout the body.

  Oxygenated blood will flow from left atrium to left ventricle and pump into aorta.

  Passes from aorta to the elastic arteries into the muscle arteries before entering the arterioles.

  Blood from arterioles enters the systemic capillaries of trunk and lower limbs and systemic capillaries of head, neck, & upper limbs

  Blood in arterioles enters capillaries for exchange of gases and nutrients
• Systemic circulation

  Deoxygenated blood exits capillary beds into the venules and veins

  Deoxygenated blood conducted to either superior or inferior vena cava; enters right atrium of the heart
• Pulmonary Circulation

  - Blood is oxygenated in both left and right lung

  - Blood flows from right atrium to right ventricle and pumps into the pulmonary trunk and conducts deoxygenated blood into pulmonary arteries of both left and right lung
• Pulmonary Circulation

  - Blood passes to the smaller arteries before entering the pulmonary capillary for gas exchange.

  - oxygenated blood exits the lung via series of progressively larger veins that merge to form pulmonary veins

  - pulmonary veins drain into the left atrium
• Layers of heart: Endocardium, Myocardium, Epicardium/Visceral pericardium
• ENDOCARDIUM/TUNICA INTIMA

  • endothelium and Fibroelastic tissue
  • smooth muscle fibers and modified cardiac muscle fibers
• MYOCARDIUM/TUNICA MEDIA

  • contractile cardiac muscle fibers arranged spirally around each heart chamber.
• EPICARDIUM/TUNICA SEROSA/VISCERAL PERICARDIUM

  • simple squamous mesothelium supported by a layer of loose connective tissue containing blood vessels and nerves
  • corresponds to visceral layer of pericardium - the membrane surrounding the heart.
• Myocardium is thicker than the endocardium
• Myocardium is found on the walls of left ventricle and is thicker since strong force is required to pump blood for circulation
• CARDIAC SKELETON

  • Forms base for all cardiac valves
  • Separates atria from ventricles & provides points of insertion for cardiac muscle in the atria and ventricles
  • Dense Irregular Connective Tissue in composition
  • Helps coordinate the heartbeat by acting as electrical insulation between atria and ventricles
• CARDIAC CONDUCTING SYSTEM

  • is specialized to generate and conduct waves of depolarization which stimulates rhythmic contractions
  • consist of modified cardiac muscle fibers
• Cardiac conducting system composition:

  1. Sinoatrial Node (Pacemaker)
  2. Atrioventricular Node
  3. Atrioventricular Bundle of His
  4. Purkinje Fibers

  - Contractile Bundles

  - Abundant Glycogen

  - Sparse Bundles of Myofibrils
• BLOOD VESSELS Forms closed circuit to and from the heart.

  - walls of all blood vessels except capillaries that contain smooth muscle and connective tissue in addition to endothelial lining.
• Types of Blood Vessels:

  Capillaries

  Arteries

  Veins
• CAPILLARIES

  • Permit and regulate metabolic exchange between blood and surrounding tissues.
• These smallest blood vessels always function in networks called capillary beds
• TYPES OF CAPILLARIES

  1. continuous capillaries
  2. fenestrated capillaries
  3. discontinued capillaries
• CONTINUOUS CAPILLARIES

  • the most common type of capillary
  • found in muscle, connective tissue, lungs, exocrine glands, and nervous tissue.
  • With well-developed occluding junctions
  • allow cellular exchange
• FENESTRATED CAPILLARIES

  • have a sieve-like structure that allows more extensive molecular exchange across the endothelium
  • found in organs with rapid interchange of substances between tissues and the blood, such as the kidneys, intestine, choroid plexus, and endocrine glands.
• DISCONTINUED CAPILLARIES/SINUSOIDS

  • permit maximal exchange of macromolecules as well as allow easier movement of cells between tissues and blood.
  • have highly discontinuous basement membranes and much larger diameters, often 30-40 μm, which slows blood flow.
  • found in the liver, spleen, some endocrine organs, and bone marrow
• VEINS

  • Carry blood back to the heart from microvasculature all over the body
  • Most veins are classified as small or medium veins that are usually located close and parallel to corresponding muscular arteries
• Venules – numerous in the veins of our legs. These valves help keep the flow of our blood directed toward the heart.
• ARTERIES - blood vessels that bring oxygen-rich blood from your heart to all of your body’s cells
• Types of Arteries

  1. Large elastic arteries
  2. Muscular arteries
  3. Small arteries