Week of Notes 10/2-10/16
Week of Notes 10/2-10/16 BSC 116
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This 8 page Class Notes was uploaded by Rani Vance on Saturday October 17, 2015. The Class Notes belongs to BSC 116 at University of Alabama - Tuscaloosa taught by a professor in Fall 2015. Since its upload, it has received 5 views. For similar materials see Principles Biology II in Biological Sciences at University of Alabama - Tuscaloosa.
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Date Created: 10/17/15
BSC 116 Week of Notes 10121016 10 1 2 Lecture 2324 Circulation and Gas Exchange circulatory systems facilitate exchange with the environment ALL cells need to be capable of exchange with their environment all reactions in cells depend on resources moving in waste products moving out all cells must have access to this single celled simple multicelled contact with medium diffusion distances are short large multicelled somemost cells isolated from external environment circulatory systems vary in complexity gastrovascular cavities lack specialized circulatory tissue Specialized because low surface area volume ratio Three Basics 1 circulatory uid carries resourceswaste 2 interconnecting tubes thru which uid travels 3 heart muscular pump Open Circulatory System anthropods most mollusks circulatory uid hemolymph direct contact with organs have same interstitial uid advantage lower pressures uid as hydrostatic skeleton body movements help circulate Closed Circulatory System Annelids cephalopods vertebrates circulatory uid separate from interstial uid higher pressure in closed system metabolically expensive provides oxygen and nutrients Cardiovascular System atrium receives blood ventricle pumps away arteries carry blood from heart arterioles small vessels that carry blood to the capillaries where exchange takes place capillary bed nutrient gas exchange network capillaries converge into venules converge into veins carry blood back to the heart arteries and vein distinguished by the DIRECTION of blood ow Single Circulation In fish 2 chambered hearts blood passes thru 2 capillary beds during circuit runs at lower pressure Double circulation Tetrapod with 3 or 4 chambered hearts blood pumps thru 2 separate circuits right side pulmonary circuit to lungs oxygen poor blood to lungs left side systemic circuit to body maintains higher pressurevelocity of blood 11 Steps in ow of blood thru both circuits right ventricle pumps blood to lungs via pulmonary artery blood ows thru capillary bed for left and right lungs blood returns left atrium with pulmonary veins left ventricle pumps out to the rest of the body via the aorta including coronary arteries to the heart one branch leads to capillary beds in head arms another branch leads to capillary beds in abdomen legs deoxygenated blood drains from head arms via superior vena cava 10 deoxygenated blood drains from legs abdomen via inferior vena cava 11 both empty to right atrium right ventricle OOOQONUIPUJNH Cardiac cycle alternates pumping and filling cardiac cycle complex sequence of pumping systole and filling diastole heart rate 70 mL per ventricle in single contraction cardiac output 5Lmin per ventricle increases with activity striated and involuntary muscle 4 valves keep blood from owing in the wrong direction one way aps bigger than the opening they cover atrioventricular valve AV between chambers semilunar between ventriclearteries heart murmurs defective valve leads to back ow Pacemaker auto rhythmic cells of heart contraction based upon own electrical impulses begins at sinoatrial node cause atria to contract empty into ventricles replayed atrioventricular node offer is delayed ventricles contract nervous system can speed up slow down rate with activity level Structure of blood vessels change with their function all vessels capillaries arteries and veins have an open lumen lined endothelium capillaries smallest just larger than blood cells thin walls to facilitate diffusion endotheliumbasal lamina arteries layer of smooth muscle then layer of elastic connective tissue thicker veins muscle can contract to control ow connective tissue can recoil during diastole to keep up pressure veins layer of smooth muscle 1014 Lecture 2324 continued The structure of blood vessels changes with their function pressure highest in the heart and lowest in the capillary Both velocity and pressure drops as blood moves through the capillary bed one way valves keep blood moving forward is due to SURFACE AREA arteries branch total crosssection area increases velocity of blood decreases through capillaries slow velocity facilitates efficient diffusion speeds up again as capillaries coalesce into veins pressure highest during ventricular systole stretches arteries heart beats again before pressure completely dissipated vasconstrictionvasodilation can change pressure during activity stress and thermoregulation Capillaries are sites of exchange between blood and tissue only a small fraction of capillaries have blood owing thru at all times diverted to where it is needed head heart kidneys usually running at capacity blood to skin used to control temperature blood to digestive tract with meals blood to the muscles during exercise Exchange occurs by both pressure amp diffusion oxygen and C02 exchanged by diffusion NO ATP REQUIRED water moves by pressure blood pressure forces water out at arterial end osmotic pressure draws water back at venous end 85 water recovered by capillaries rest returned via lymphatic system network of small vessels that drain excess interstitial uid lymph eventually returned to circulatory system moves by smooth muscle contraction aided by skeletal muscle with series of valves 15 of water goes to lymph and is recovered later in the body Blood composed of various cells and proteins in a liquid matrix open circulatory hemolymph continuous with interstitial uid closed9blood more comples connective tissue cell and cell fragments plasmas plasma90 water with dissolved salts proteins lipid clottinggases and waste Cellular Components erythrocytes red blood cells 5 trillion per 1L leukocytes white blood cells platelets cell fragments involved in clotting Clotting damage plugged with platelets fibrin protein Multipotent stem cells located in bone marrow procedure new blood cells lymphoid differentiate B cells and T cells myloid differentiate 5 type white blood cells or red blood cells Gas Exchange occurs across respiratory surfaces Gas has pressures rather than concentrations partial pressure of 02 is the fraction of total pressure exerted by air 02 21 by volume pressure of C02 029 mm Hg partial pressure of dissolved gas equals partial pressure in the air but concentration depends on temperature salinity gas diffuses high pressure to low pressure 02 more available than water 21 of air easier to move around 40 x less 02 in same volume water warmer saltier holds less All 02 must be exchanged through water cell membranes need moist membrane entirely by diffusion rate proportional to surface area inversely proportional Aquatic organisms have more efficient gas exchange surfaces less 02 available so less wasted various respiratory surfaces among invertebrates fish have gills delicate out foldings of body surface surface area much greater than that of the body counter current exchange of respiratory medium maintained by ventilation more surface through medium capillaries ow in the opposite direction P02 in blood always less than in medium very efficient removes 80 of dissolved 02 won t work on land Two common terrestrial adaptations for breathing air most common tracheal system series of air tubes that branch throughout the body gas exchange does not involve circulatory system Most familiar lungs vertebrates large infoldings of the body subdivided to increase surface area air in thru nostrils filtered and warm to larynx via pharynx held open by cartilage opens to trachea trachea branches into two bronchi bronchioles surface covered by cilia Ventilation of exchange surfaces achieved by breathing Amphibians positive pressure breathing push air in by shrinking oral cavity Mammals negative pressure breathing pull air in by expanding thoracic cavity with muscles and diaphragm controlled by breathing control centers in brain by negative feedback C02 determined by pH coordinated with circulatory system birds are more efficient and complex use posterior and anterior air sacs to regulate oneway amp low air no mixing of old and new Hemoglobin is necessary because 02 has low solubility in water during exercise you need 2 L 02 per minutes under normal conditions 1 L of water has 0045 L 02 02 transported attached to respiratory pigment hemoglobin reduces necessary cardiac output to 125 L per minute in erythrocytes 4 protein subunits each with Fe atom reversibly binds 02 subunits cooperative affinity varies as P 02 varies Bohr shift 1016 Immune systems are necessary for multicellular animals internal environment for pathogens foreign invaders that try to coopt organismal resources cause disease Among vertebrates there are two levels of immunity 1 Innate active all the time not dependent on infection found in all animals inhibit detect broad range of pathogens invertebrate only line of defense 1 line of defense is the skin 2rld is phagocytosis 2 Acquired adapted immunity response enhanced by previous infection highly specific only vertebrates have this Innate immunity proved general protection from pathogens Invertebrates eg insects barrier waxy chitin low pH and lysozom digest bacteria cell walls of microbes Hemocytes in hemolymph phagocytosis and various chemical protections ID tags fungi unique cell wall with polysaccharides bacteria cell wall contains polymer with sugar and amino acids Antimicrobial peptides disrupt pathogen plasma membranes of fungi and bacteria elicit specific chemical responses Vertebrates 1st barrier skin mucus coverings over exchange surfaces lysosome in saliva mucus tears sweat lowers skin pH low stomach pH 2nd barrier tolllike receptor TLR that recognize pathogen bits ID bits as noncell activation triggers innate immune response Phagocytic cells engult and digest microbes 4 types 1 neutrophils circulate in blood 2 microphages circulate around the body 3 demdritic found on skin 4 eosinophils mucus surface Antimicrobial Proteins interferins produced by cells infected with viruses signal other cells to produce anti viral compounds complement system proteins in blood plasma activated by lyse in ammation lymph nodes filled with microphages Lymphatic system organs to trap foreign particles tonsils spleen appendix In ammatory response and actions of natural kill cells in ammatory response release of signaling molecules following infectioninjury most cells release histamine a signaling molecule vessels dilate become permeable activate macrophages also release signaling molecules cytokines promote blood ow blood to site warmth swelling antimicrobial proteins formation of pus concentration of white blood cells Systemic vs local in ammatory responses increase production of white blood cells macrophages and lymphocytes fever accelerate repair kill invaders natural killer cells can recognize and chemically destroy diseased cells normal body cells produce class 1 MHC surface proteins infected or cancerous do not NK cells look for such cells and kill them Vertebrates Acquired immunity involves immunological memory same white blood cells lymphocytes have an enhanced response to infections the body has previously encountered immunological memory two lymphocytes originate from stem cells in bone marrow B cells mature in bone marrow T cells mature in thymus Each lymphocyte has receptors for only a single foreign molecule an antigen lymphocytes activated by binding to specific antigens displayed on cell surfaces using antigen receptors B cells secrete antigen receptors that bind to foreign molecules some T cells detect and kill infected cells Need to know how antigens function Antigens typically proteins or polysaccharides surface of pathogen TampB lymphocytes have antigen receptors in plasma membrane 100000 per cell differ in morphology across B and T cells exact same binding sites Epitope small part of antigen that is recognized and bound to antigen reception ALL antigen receptors on a single lymphocyte are the same 1 a lymphocyte B cell antigen receptors and antibodies some B lymphocytes produce antigen receptors antibodies immunoglobulin
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