BIOL 1030 – TOPIC 16 LECTURE NOTESTopic 16: Circulation and Gas Exchange - Circulatory and Respiratory Systems (Ch. 42)I. circulation required for all animals that are more than a few cells thick so that cells can get oxygen and nutrients and get rid of wastesA. two main types of circulatory systems, open and closed1. open systems- no distinction between circulating fluid and extracellular fluid of body (lymph)- hemolymph is the circulating fluid- less efficient for transport (little pressure, slower)- may still have heart(s) for pumping and some vessels- examples: arthropods, mollusks2. closed systems- circulating fluid (blood) distinct from lymph- at least one heart always present- blood vessels – tubular network for blood flow from heart of body and backarteries carry blood away from heartveins return blood to heartcapillaries between arteries and veins are the thinnest vessel and allow exchanges with body tissues- lymph system - when blood reaches capillaries, liquid seeps out of blood, most is mopped up, but much remains behind and needs to be mopped up or an edema (swelling) will form, lymph vessels return liquid to bloodB. vertebrate circulatory systems functions1. transportation of gasses, nutrients, wastes2. regulation of temperature3. transportation of hormones4. protection (immune defense; blood clotting)C. blood plasma1. metabolites, wastes and hormones including carbon dioxide2. ions - mostly sodium, chloride, and bicarbonate, lower total ion concentration than sea water3. proteins - albumin, globulins (carry lipids and steroid hormones and fibrinogen) serum = fluid after fibrinogen clots out4. formed elements – blood cellsD. blood cells1. erythrocytes - red blood cells- cell that carries hemoglobin - mammals - anucleate, donut shaped - humans - 5 million/cm3; 45% of blood (hematocrit)- live 120 days before replacement in humans- formed in bone marrow2. leukocytes - white blood cells- larger, nucleated, can migrate out of capillaries- humans - 1% of cells in blood- granular leukocyte - neutrophils (most common), eosinophils, and basophils- nongranular leukocytes - monocytes and lymphocytes (T and B cells involved in immune response)- neutrophils accumulate at injury and then joined by monocytes that change into macrophages- phagocytosis by neutrophils and macrophages eliminate disease-causing organisms3. platelets- megakaryocytes in marrow break off bits of their cytoplasm to form platelets (actually cell fragments)- accumulate at wound and form a plug by sticking to each other and tissues- plug reinforced by fibrin (formed by fibrinogen in complex chain of events)E. blood vessels1. structure - endothelium then elastic fibers then smooth muscle layer then connective tissue (except capillaries)2. arteries- large ones - very elastic to absorb force of heart- small ones (arterioles) - more muscular - to control blood flow (vasoconstriction and vasodilation)3. capillaries- only endothelial lining (one-cell thick)- about one red blood cell wide- all exchange occurs here- little blood pressure after exit4. veins and venules (smaller veins, just after capillaries)1 of 4BIOL 1030 – TOPIC 16 LECTURE NOTES- less muscular than arteries- blood pressure greatly reduced in venous system - possibility for retrograde (back) flow- valves - present in ascending veins to halt retrograde flow- descending veins - no valves, gravity helps- skeletal muscles help move blood - contract leg muscles to avoid fainting, which is typically caused by blood pooling in the legsF. the mammal heart1. 4 chambers2. right side - atrium receives blood from body, pumps to ventricle, which pumps to lungs3. left side - atrium receives blood from lungs, pumps to ventricle, which pumps to body4. atria both pump at the same time, then after about 100 ms delay both ventricles pump; both sides must pump the same volume, but the left pumps at greater pressure because it is going through greater resistance5. valves prevent backflow6. sinoatrial node (SA node) - pacemaker - starts impulse at atria and sends impulse to atrioventricular (AV) node7. AV node shunts impulse to the apex (bottom) of the heart through Purkinje fibers - modified cardiac muscle cells that look like neurons (unique to mammals)8. shunted impulse squeezes the heart from the bottom up - more efficient just like squeezing the toothpaste from the bottom of the tube is more efficient9. heart rate increases under exercise to get enough oxygen to musclesII. respiration – general term for use of oxygen and production of carbon dioxide; cellular respiration – direct biochemical use to break down simple sugars for energybody respiration (respiratory system) – exchange with environmentA. components of respiratory systems in vertebrates1. air exchange surface – gills and lungs, sometimes skin2. transporting system – hemoglobin, red blood cells, and blood plasmaB. air exchange surfaces1. mechanical issues (diffusion)- net movement of molecules is diffusion; parameters involved covered by Fick's Law of Diffusion, which includes that the rate of diffusion:is proportional to surface areais proportional to the partial pressure differenceis inversely proportional to travel distance- consequencesair exchange organs have very large surface areasefficient air exchange mechanics tend to maximize partial pressure differenceair exchange organs and capillaries are thin (1-2 cells thick)2. gills- mainly epithelial tissues coated with capillaries for gas exchange- gill arches help spread the tissue- countercurrent flow of blood to water maximizes oxygenation- gills do not work in terrestrial environmentscollapse without water to keep them open, greatly reducing surface area for exchangeallow too much water loss – need some sort of enclosure for exchange, or limited to water or moist areas3. lungs- primitive versions apparent in early jawed vertebrate fossils; original use for buoyancy in water (swim bladder in modern bony fishes)- air has more oxygen than water, and is easier to get and easier to move than water; however, all exchange surfaces must remain moist- internal placement limits water loss (stays humid inside)- typically has two-way flow, modified in birds to a one-way flowtwo-way flow: air enters and exits through same tube systemresidual volume of air retained in lung after each breathdiffusion surfaces exposed to mix of fresh and residual airpartial pressure difference far from maximalless