The Circulatory System Melissa Zelaya Spring 2010 Senior Seminar The circulatory system distributes materials such as oxygen and nutrients throughout the body. The Circulatory System The heart muscular pump System of vessels -Arteries -Veins -Capillaries 1
Open vs. Closed Systems Vertebrates closed circulatory systems Some invertebrates open systems -less efficient -slower circulatory time The Human Heart Four-chambered structure located in the chest comprised of: 2 ventricles 2 atria Sinoatrial node (SA node) Atrioventricular (AV) heart valves -Tricuspid valve -Bicuspid valve Semilunar valves Coronary Arteries Supply the heart with blood Can become clogged or blocked Blocked coronary artery = heart attack Heart attack is the common cause of death in middle-aged men in the U.S. 2
Cardiac Output CO= stroke volume x heart rate Under resting conditions average CO is 5 liter per minute Cardiac Muscle The more its stretched, the greater its strength of contraction Capable of conducting an electrical pulse Internal signals arise within the heart and spread from heart fiber to heart fiber Pacemaker = SA node Fibrillations cause stroke or heart failure Heartbeat Cardioaccelerator releases norepinephrine which speeds up the heart rate Vagus nerve releases acetylcholine which slows down the heart rate Strong vagal stimulation Hypervagal response 3
Carry oxygenated blood Innermost layer = tunica intima Middle layer = tunica media Outermost layer = tunica externa Arteries Veins Similar to arteries Thinner walls Lack pumping pressure Dilated by blood moving through them Blood Pressure Force exerted in the blood vessels by the blood contained within them Produced by 2 primary event Not uniform Normal blood pressure is 120 mm Hg/ 80 mm Hg Systolic blood pressure/diastolic blood pressure 4
Pulse is simply alternate contractions and dilations during the passage of blood from the ventricle into the aorta. Hypertension High blood pressure Systolic pressure above 150 mmhg Diastolic pressure above 95 mmhg Norepinephrine and epinphrine naturally increase blood pressure Increase cardiac output, stroke volume, heart rate Treatment= antihypertensive drugs and diuretics Hardening or thickening of the artery wall Pulse pressure High pulse pressure may be a high-risk factor for stroke Atherosclerosis 5
Fluid made up of 55% liquid plasma Plasma is made up of water and 45% floating cells - contains dissolved proteins, lipids, and carbohydrates Lymph is similar to plasma just less concentrated Blood Blood, lymph, and fluids bathing the tissues makes up 1/5 of the total body weight Blood alone comprises 1/12 of the body weight, just under 5 liters in volume Blood Constituents Red blood cells (erythrocytes) White blood cells (leukocytes) Platelets (thrombocytes) Highly viscous (resistance to flow) 6
Red Blood Cells Carry oxygen Relatively small When mature they lack a nucleus and other organelles Bulk of the RBC is taken up by the conjugated protein hemoglobin Erythropoietin White Blood Cells Involved in guarding against invading organisms Divided into 2 large groups: -granulocytes -agranulocytes Neutrophils Eosinophils Basophils Granulocytes 7
Blood ph ph of blood is always maintained within the range of 7.3 and 7.5 ph maintained through buffer systems Less than 7.3 acidosis Higher than 7.5 alkalosis Both severely life threatening The Immune System Definitions Immunology refers to all of the defense mechanisms that the body can use to fight the threat of foreign invasions Pathogens disease-causing organisms Natural Flora consisting of indigenous bacteria that keep each other s populations in check (act as barriers) 8
Components Defenses are highly specific in their action Skin Glands (sweat) Mucous membranes Secretions Lymph vessels and nodes WBC s Bone marrow Thymus Immune Response Mediated by two types of lymphocytes: - B lymphocyte - T lymphocyte Both arise from lymphocytic cells in bone marrow Reside in the lymph tissues Involved in formation of antibodies Humoral response B-Lymphocytes 9
T-Lymphocytes Cell mediated response Initiate attack by various cell types Antigens Invading entity or organism Each contains unique chemical compounds not found in other entities Usually consist of proteins, large polysaccharides, or large lipoproteins Frequently found on surfaces of unicellular organisms ~A A specific antibody exists for every anitgen Humoral Response 10
Antibodies Globular proteins coded for by specific genes Made up of 4 polypeptide chains: -2 Heavy chains -2 Light chains Bound by S-S bonds Constant region specific to class Variable region specific to antigen Mote than 1 million kinds of antigens are encountered during a person s s lifetime!! Antibody-Antigen Reaction Antibody has 2 binding sites Also has unique conformations for antigen specificity Antigenic determinant (small portion of antigen) fits into cleft of antibody Antibody-antigen reaction initiates proliferation of lymphocytes 11
Types of Antibodies 5 types -IgG (most common) -IgM (first group found during infection) -IgA (tears, saliva, breast milk) -IgD (function not yet known) -IgE (releases histamine, fights parasites and allergic reactions) Antibodies (mini conclusion) Primary weapon of the humoral response Attacks antigen directly or activates related systems which will attack invader Mode of Direct Attack Agglutination involves involves clumping of antigens into an antigen-antibody complex Network of interconnected Ab and Ag Complexes reduce mobility of Ag Makes them susceptible to phagocytosis -leukocytes engulf and ingest invader 12
Other forms of Attack Certain Ab can lyse cells they attack Others bind to toxic sites of the Ag and neutralize them Activate the complement system Complement System Activated enzymes eat into cell membrane of Ag and eventually causes them to rupture Makes cell surfaces more susceptible to phagocytosis Produces a chemotaxic effect Elicits a local inflammatory response Inflammatory Response Nonspecific response to injury of cells Mediated by release of histamine Involves -Increase in blood flow (vasodilatation) -Local swelling -Increase in temp. -systemic fever-caused by pyrogenes 13
Cell Mediated Response Sensitized by T lymphocytes Attacks eukaryotic cells: -Invader cells -Host cells different from self cells -Cells invaded by viruses -Transplanted organs and tissues Destruction of Invader Specialized T-cells cytotoxic cytotoxic T cells attacks directly Like Ab s of the humoral response Attacks specific Ag Releases cytotoxic and digestive enzymes Attracts macrophages 14
AIDS Disease caused by the retrovirus HTLV-III RNA virus is known as HIV Virulence ability to attack a group of T lymphocytes Destruction of cells causes cancers opportunistic infections Blood Types Antigen present on RBC determines blood type 2 types of antigens A A and B Type of Blood: -Type A -Type B -Type AB (universal donor0 -Type O (rare type) Fried, G., Hademenos,, G. 2009. Schaums Outlines Biology.. 3 rd Editon 15