Circulation and Blood Vessels Class 5 PDF

TRANSPORT - CirculatION Objectives: Types of systems Cardiac cycle Heart rhythm Blood pressure Richard Ellis/Science Source.  Cnidarians Mouth Radi...

TRANSPORT - CirculatION Objectives: Types of systems Cardiac cycle Heart rhythm Blood pressure Richard Ellis/Science Source.  Cnidarians Mouth Radial canals Circular canal 2.5 cm Anemones, jellyfish, and hydroids lack a circulatory system and instead circulate nutrients and gases through a simple gastrovascular cavity.   Types of circulatory systems  Features -  circulatory fluid, vasculature and a pump  nutrition & waste removal  Open circulatory system  Incomplete vasculature, circulatory fluid leaves vessels, supplies the cells and returns to the heart  Closed circulatory system  Circuit of vessels attached to the heart allowing circulatory fluid to pass through  Open vs closed circulatory systems (a) An open circulatory system (b) A closed circulatory system Heart Heart Interstitial fluid Hemolymph in sinuses Blood Small branch vessels in each organ Pores Dorsal vessel Auxiliary (main heart) hearts Tubular heart Ventral vessels The heart pumps hemolymph through valves into a hemocoel, where the body tissues and organs are bathed.  Closed circulatory systems (a) Single circulation: (b) Double circulation: (c) Double circulation: fish amphibian mammal Gill capillaries Pulmocutaneous circuit Pulmonary circuit Lung Lung and skin capillaries capillaries Artery Atrium Atrium (A) (A) Heart: Atrium (A) A A Ventricle (V) V V Right Left Right Left Vein Ventricle (V) Systemic Systemic capillaries capillaries Body Oxygen-rich blood capillaries Systemic circuit Systemic circuit Oxygen-poor blood Can have single or double circulatory circuits. In double circulatory systems, one system is involved in gas exchange, while the other distributes oxygen and nutrients throughout the body. In amphibians pulmonary-cutaneous circuit prevails. Evolutionary variation in double circulation Intermittent breathers: amphibians and reptiles have 3 chambered heart & can use skin. Amphibians have 3 chambered heart (2 atria and 1 ventricle) and use skin when underwater shutting off blood flow to lungs Turtles, lizards and snakes have incomplete septum that divides ventricle into 2 chambers Alligators & crocodiles have ventricles divided by a complete septum but pulmonary and systemic circuits connect Birds & mammals are continuous breathers and have 4 chambered hearts.  Superior Capillaries of Mammalian vena cava 7 head and forelimbs Cardiovascular system Pulmonary Pulmonary artery artery Capillaries 9 Aorta Capillaries of right lung of left lung 6 Composed of the pulmonary and systemic circuits, which carry blood 2 3 3 to and from the lungs and the body, 11 4 respectively. Pulmonary 5 Pulmonary vein 1 vein Right atrium 10 Left atrium Right ventricle Left ventricle Inferior Aorta vena cava Capillaries of 8 abdominal organs 3D4Medical/Science Source. and hind limbs  Human Pulmonary artery Aorta heart Pulmonary structure Right artery atrium Left The valves in the heart are designed atrium such that blood can only flow in one direction. The tricuspid valve and the mitral valve allow blood to enter the ventricles but keep blood from flowing back into the atria during a Semilunar Semilunar ventricular contraction. valve valve The aortic and pulmonary valves allow blood to flow out of the heart Atrioventricular Atrioventricular during ventricular contraction but (AV) valve (AV) valve prevent blood from flowing back in during relaxation. Heart murmur Right Left ventricle ventricle   The cardiac cycle  Blood is pumped by alternate contraction (systole) and relaxation (diastole) of the atria and ventricles of the heart.  An electrocardiogram (ECG) is used to detect the electrical impulses that drive heart contractions.  Stroke volume  Cardiac output   Heart rhythm control 1 Signals (yellow) 2 Signals are 3 Bundle branches 4 Signals from SA node delayed at AV pass signals to spread spread through node. heart apex. throughout atria. ventricles.  P – atrial depolarization  QRS – Ventricular depolarization  T wave – ventricular AV SA node repolarization (pacemaker) node Bundle branches Heart Purkinje apex fibers ECG  Blood Vessels Artery Vein LM Structure Red blood cells 100 µm Basal lamina Valve Endothelium Endothelium Smooth Smooth muscle muscle Connective Connective Capillary tissue tissue Arteriole Venule Capillary bed 15 µm Red blood cells in capillary LM  Blood flow, velocity & pressure  Velocity of blood flow is slowest in the capillary 5,000 beds (for exchange of materials)as a result of the Area (cm2) 4,000 high resistance and large total cross-sectional 3,000 2,000 area 1,000  Blood flows from areas of higher pressure to 0 50 areas of lower pressure (cm/sec) 40 Velocity 30  Resistance to flow determines blood pressure 20  Systolic pressure – high in arteries 10 0  Diastolic pressure Systolic pressure 120  Pulse - bulging of artery walls with each 100 Pressure (mm Hg) 80 heartbeat 60 Diastolic Mean 40 pressure pressure  Blood pressure regulation – vasoconstriction 20 0 (endothelin) & vasodilation (nitric oxide) Arteries Aorta Arterioles Capillaries cavae Veins Venae Venules  Measurement of blood pressure Pressure in cuff Pressure in cuff Pressure in greater than drops below cuff below 120 mm Hg 120 mm Hg 70 mm Hg Cuff inflated 120 120 with air 70 Artery Sounds Sounds closed audible in stop 1 2 stethoscope 3  Blood flow in Veins o Fainting is caused by inadequate blood flow to the head o Animals with long necks require a very high systolic pressure to pump blood a great distance against gravity o Because blood pressure is low in veins, one- way valves in veins prevent backflow of blood o Return of blood is also enhanced by contraction of smooth muscle in venule walls and skeletal muscle contraction Capillary dynamics  Blood and lymph  Capillaries carry gases and nutrients to cells in the tissues. Blood pressure pushes excess fluid from the capillaries into the extracellular space. This fluid drains into lymphatic capillaries.  Types of cholesterol: LDL & HDL  Atherosclerosis  Cholesterol deposits in the vessel wall lead to chronic inflammation, thrombus (clot) formation, and development of calcified plaques that narrow the vessel.  Cross-section of a blood vessel. The colored region indicates accumulation of cholesterol-containing plaques that narrow the vessel. Inserting a Stent to Widen an Obstructed Artery Deep vein thrombosis During extended periods of inactivity such as sitting in an airplane without sufficient movement, a thrombus can form in the legs, which can break off to form an embolus that is circulated in the blood and can become lodged in the pulmonary vessels, disrupting gas exchange.  Blood   Blood Plasma 55% Cellular elements 45% Constituent Major functions Number per Cell type Functions µL (mm3) of blood Water Solvent Leukocytes (white blood cells) 5,000–10,000 Defense and Separated immunity Ions (blood Osmotic balance, blood electrolytes) pH buffering, elements Sodium and regulation Lymphocytes Basophils Potassium of membrane Calcium permeability Magnesium Chloride Eosinophils Bicarbonate Plasma proteins Albumin Osmotic balance, Monocytes Neutrophils pH buffering Immunoglobulins Defense Platelets 250,000–400,000 Blood clotting (antibodies) Apolipoproteins Lipid transport Fibrinogen Clotting Erythrocytes (red blood cells) 5,000,000–6,000,000 Transport of O2 and some CO2 Substances transported by blood Nutrients (such as glucose, fatty acids, vitamins), waste products of metabolism, respiratory gases (O2 and CO2), and hormones Blood Clotting Sickle-cell anemia A mutation in hemoglobin causes it to aggregate abnormally in red blood cells, giving them a sickle shape. These abnormal cells move poorly through the capillaries, causing pain and ischemia (tissue damage from lack of oxygen).