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Week 1- Cardiovascular System.pdf

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BIOL 271

The Cardiovascular System Why do we need a cardiovascular (circulatory) system? transportation multicellular organisms: need diffusion Transportation: nutrients gases (O2, CO2) metabolic wastes heat biochemicals (hormones) Subdivisions: cardiovascular system a series of tubes (blood vessels) filled with fluid (blood) connected to a pump (heart) lymphatic system Cardiovascular System Blood functions: transportation regulation of: pH (buffers) body temp (constriction/dilation of surface vessels) ICF (intracellular fluid) volume (dissolved ions and proteins) blood affects interstitial fluid, which affects intracellular fluid (Starling's Law) protection (WBC's, antibodies) physical characteristics 5-6 L in adult male, 4-5 L in adult female 8% of total body weight more viscous than water temp~ 38 C pH: 7.35-7.45 components ___% plasma proteins synthesized in liver don't leave bloodstream ___% other substances electrolytes, nutrients, hormones, gases, waste products Plasma Proteins albumin maintains blood globulins (immunoglobulins, antibodies) bind to foreign antigens, form antigen-antibody complexes prothrombin and fibrinogen clotting factors Formed Elements of Blood red blood cells (erythrocytes) platelets (thrombocytes) white blood cells (leukocytes) granulocytes (end in "phil") eosinophil basophil neutrophil agranulocytes monocyte T lymphocyte (T cell) B lymphocyte (B cell) Natural killer (NK cell) hematocrit (PCV) ratio of red blood cell volume to amount of total blood volume discovered through centrifugation normally ≤45% of blood is red blood cells RBC clump together at bottom, then buffy coat of WBC + platelets, then plasma Blood Cell Formation (hematopoiesis, hemopoiesis) continuous process most blood cells live only hours, days, or weeks (some for years) RBC: ~120 days WBC: years cell differentiation totipotent cells (initial cell of sperm and egg) can differentiate into any type of cell depending on signals it receives pluripotent stem cells can differentiate into many different cell types muscle, nerve, bone, other tissues blood stem cells: RBCs, platelets, WBCs site of hematopoiesis in the embryo… yolk sac, liver, spleen, thymus, lymph nodes, red bone marrow in adults… occurs only in red marrow of flat bones [spongy bone] (sternum, ribs, skull, pelvis) and ends of long bones stages of formation pluripotent stem cells (0.1% of red marrow cells) myeloid stem cells: RBC, platelets, granulocytes, monocytes may differentiate to become more specific cells>> progenitor cells (colony-forming units) specialized to form specific cell types (ex: CFU-E >> RBCs) can no longer divide; but can differentiate into more specific cells>> blast cells (with recognizable histological characteristics) may differentiate into more specific cells>> mature (w/in several generations) lymphoid stem cells: agranulocytes (except monocytes) >> blast cells >>mature cell types (w/in several generations) hemopoietic growth factors regulate differentiation, growth of progenitor cells erythropoietin (EPO) hormone produced by kidneys increased RBC precursor cell production thrombopoietin (TPO) hormone produced by liver stimulates platelet formation cytokines produced by some marrow cells colony-stimulating factor (CSF), interleukin stimulate WBC production medical uses produced using recombinant DNA technology reverse decreasing RBC production in end-stage kidney disease (EPO) prevent platelet depletion during chemotherapy (TPO) stimulate WBC formation in cancer patients with bone marrow destruction (CSF) Erythrocytes (RBCs) function: gas transport biconcave disks flexible increased surface area / volume ratio no nucleus or mitochondria 2 million new RBCs enter circulation every second lifespan about 120 ays normal RBC count: 3 male: 5.4 million cells/mm female: 4.8 million cells/mm3 ⅓ of RBC weight is hemoglobin (oxygen-carrying protein that gives red colour to blood) globin protein consists of 4 polypeptide chains one heme pigment attached to each chain each heme contains an iron ion (Fe2+) that can combine reversibly with one oxygen molecule iron + oxygen = red (rust) hemoglobin binds gases iron portion combines with O2 to form oxyhemoglobin globin portion combines with CO2 to form carbaminohemoglobin transport of O2, CO2and NO each Hb (hemoglobin) molecule can carry four O 2olecules from lungs to tissue cells RBC doesn't use O (2o mitochondria) Hb transports 23% of total CO 2rom cells to lungs CO 2ombines with amino acids in globin portion of Hb iron ions in Hb also pick up and transport nitric oxide (vasodilator (blood vessel diameter changer) that helps regulate blood pressure) Erythrocyte life cycle live 120 days wear out from bending to fit through capillaries no repair capability (no organelles) worn out cells removed by macrophages in spleen and liver breakdown products are recycled RBCs phagocytksed by macrophages in spleen, liver, red bone marrow globin breaks down into amino acids (reused for protein synthesis) heme split into biliverdin and Fe3+ biliverdin transformed to lipid-soluble unconjugated (free) bilirubin blood is mostly water; therefore can't dissolve lipid-soluble solution into blood bilirubin transported to liver bound to protein protein is water-soluble; therefore both can travel through blood within hepatocytes, bilirubin becomes conjugated (attaches to/combines with glucouronic acid) conjugated bilirubin is water-soluble, therefore can be excreted in bile bilirubin cannot be excreted; buildup causes jaundice in bowel, bacteria unconjugates bilirubin, convert it to urobilinogen urobilinogen excreted in feces, urine stercobilin: brown pigment b/c of urobilinogen urobilin: yellow pigment in urine Fe3+ binds to transferrin and is transported to the liver cannot float around on it's own b/c of high charge in muscles, liver, spleen, Fe3+ detaches from transferrin, attaches to ferritin, and is stored when released from storage site, Fe3+ reattaches to transferrin and is transported to red bone marrow in red bone marrow, Fe3+ is taken up by RBC precursors, used in erythropoiesis (to make Hb) Components of Heme Iron transported in blood attached to transferrin protein stored in liver, muscle or spleen attached to ferritin used for Hb synthesis in bone marrow deficiency of iron = not able to create as much protein as necessary biliverdin (green) converted to bilirubin (yellow) transported to liver by protein bilirubin secreted to duodenum in bile converted to urobilinogen by bacteria in large intestine (does nothing in small intestine) urobilinog
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