Dr O'Quin Notes 4/18, 4/20, 4/22
Dr O'Quin Notes 4/18, 4/20, 4/22 Bio 152
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This 10 page Class Notes was uploaded by Alena Comley on Monday May 2, 2016. The Class Notes belongs to Bio 152 at University of Kentucky taught by Dr. O'Quin in Spring 2016. Since its upload, it has received 10 views. For similar materials see Introductory Biology II in Biology at University of Kentucky.
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Date Created: 05/02/16
Homeostatic Control ATP production is dependent on maintaining appropriate blood oxygen levels Under normal conditions, the rate of breathing is established by the medullary respiratory center During exercise, the partial pressure of oxygen in the blood drops due to it being used up quickly by muscle tissue The partial pressure of CO 2ises, with this gas being released by the muscles CO 2eacts with water in blood to form carbonic acid, which lowers blood pH (increased acidity) o This drop in pH by special neurons located near large arteries or by pH detectors in the medullary center o This cases the rate and depth of ventilation to increase in order to restore the correct partial pressures of O2and CO 2 CLICKER #1 What forms in the blood that causes a drop in pH? A Hydrochloric acid B Carbonic acid C Biocarbonate ions D Ammonia ANSWER: B- Carbonic Acid Blood Gases Blood functions o Carries oxygen and carbon dioxide between the cells and lungs o Transports nutrients from digestive tract to the rest of the body o Moves waste products to kidney and liver for processing o Carries hormones to target tissues o Delivers immune system cells to infection sites o Distributes heat throughout the body Blood components o Most of your blood volume comes from the extracellular matrix known as plasma o Blood is also composed of formed elements which include Platelets Cell fragments that act to minimize blood loss from ruptured blood vessels White blood cells Part of the immune system and fight infection Red blood cells Transport oxygen from the lungs to the tissues throughout the body oThe formed elements develop from stem cells in the bone marrow CLICKER #2 Which component of blood is the extracellular matrix of this connective tissue? A Plasma B Platelets C Red blood cells D White blood cells ANSWER: A- Plasma The red blood cells of mammals do not contain nuclei or most other organelles Instead, they carry millions of copies of the oxygen carrying molecule hemoglobin oHemoglobin has four polypeptide chains, with each containing a non- protein group called heme Each heme molecule contains an iron that can bind to an oxygen molecule CLICKER #3 So, based on the previous information, how many oxygen molecules should hemoglobin be able to bind? A 1 B 2 C 3 D 4 E 5 ANSWER: D- 4 As a result, each hemoglobin molecule can bind four oxygen molecules Cooperative binding oBlood leaving the human lungs has a PO (2artial pressure of oxygen) of about 100 mm Hg, while at rest, the muscles and other tissues have a PO 2f about 40 mm Hg These differences facilitate movement of oxygen into the tissues oLet's look at the dynamics of oxygen unloading in different tissues When in oxygen poor tissues, oxygen unbinds from all subunits The shape of this curve is the result of what is known as cooperative binding Cooperative binding occurs because the binding of each successive oxygen molecule to hemoglobin causes a conformational change that makes the remaining subunits more likely to bind oxygen Same thing happens with unbinding of oxygen o Let's talk about why this cooperative binding is important Tissues at rest have a PO o2 about 40 Tracing on the curve shows hemoglobin unloads half of oxygen at rest Tissues that are exercising have a PO of 2bout 30 Tracing on the curve shows hemoglobin unloads 785 of its oxygen A relatively small change in tissue PO re2ults in a relatively large change in the percentage of hemoglobin saturation Without cooperative binding, the amount of oxygen saturation only displays a small change compared to cooperative binding (16% vs. 30%) Bohr Shift Hemoglobin- like other proteins- is sensitive to temperature and pH You might recall that during exercise, CO re2cts with water to form carbonic acid, which lowers blood pH This decrease in pH alters hemoglobin's conformation to where it is more likely to unload O 2 This is important for tissues that are under oxygen stress to be returned to their normal state Fetal Hemoglobin Hemoglobin molecules can vary at different life stages oYou produce hemoglobin as a fetus Fetal hemoglobin has a higher affinity for oxygen than adult hemoglobin, which allows for efficient gas exchange at the placenta oRemember, curve shifted to the right has a lower affinity for oxygen CLICKER #1 Which direction does the curve shift when there is less affinity for oxygen? A Left B Right C It doesn’t ANSWER: B- right CO Transport 2 CO produced in the tissues as a result of a cellular respiration is carried to 2 the lungs via processes that occur in red blood cells When CO di2fuses into red blood cells, carbonic anhydrase quickly converts it to carbonic acid oThe carbonic acid quickly dissociates into bicarbonate ions and protons oThis helps to maintain a lower partial pressure of CO , f2voring its entry into the blood cells The protons produced induce the Bohr shift, which makes the hemoglobin more likely to release oxygen These protons can then bind to the deoxygenated hemoglobin The bicarbonate then gets transported into the blood plasma So most of the CO t2ansported in the blood is actually in the form of bicarbonate in the plasma Because hemoglobin takes up much of the H that is produced by the dissociation of carbonic acid, it acts as a buffer CLICKER #1 How is CO c2rried in the blood? A As carbonic acid in the red blood cell. B As bicarbonate in the red blood cell. C As CO in2the red blood cell. D As bicarbonate in the plasma. E As CO i2 the plasma. ANSWER: D In the lungs, the partial pressure gradient favors the diffusion of CO f2om the blood and into the atmosphere within the alveoli As CO 2iffuses from the blood into the alveoli, the partial pressure of CO 2 drops, which reverses the chemical reactions that occurred in tissues Circulation Different types of circulation utilized by organisms oNone oOpen oClosed Some animals have no circulatory system because their size and surface area allow for the diffusion of gases and key solutes However, this would not work in larger animals As a result, they have circulatory systems that contain a transport tissue that comes in close contact with every cell of the body Open circulatory systems, found in invertebrates, have a fluid connective tissue that is pumped throughout the body but does not stay confined to vessels o This connective tissue is known as hemolymph and comes in direct contact with the tissues A heart pumps the hemolymph into vessels that empty into an open, fluid- filled space Hemolymph is normally under low pressure, which is fine for sedimentary organisms with low oxygen demands o Insects, which have more rapid movements and more active lifestyles, overcome this issue with their tracheal respiratory organs In open circulatory systems, hemolymph can't be directed to tissues with a high oxygen demand o Crustaceans get around this issue by having networks of small vessels that go to these tissues CLICKER #2 What is the connective tissue found in open circulatory systems? A Blood B Hemocyanin C Hemolymph D Hemoglobin Answer: C Because blood is confined to vessels, a closed system generates enough pressure to maintain a high flow rate In closed circulatory systems, blood can be directed to tissues that have a high need for it o For example, after you eat a large meal, blood is shunted to the intestines to help with absorption Closed circulatory systems are found in o Vertebrates o Annelid worms o Cephalopods CLICKER #3 Which one of these organisms does not have a closed circulatory system? A Earthworm B Fly C Octopus D Cat ANSWER: Closed circulatory systems contain various types of blood vessels, each having a unique structure and function oArteries are thick-walled vessels that take blood away from the heart Small arteries are called arterioles All arteries have muscle fibers and elastic fibers in their walls The elastic allows the arteries to expand when blood enters it under high pressure from the heart The most well-known vessel that does this is the aorta The muscle fibers can relax or contract, changing the flow of the blood, which can regulate the amount of blood flowing to a tissue CLICKER #3 What happens to blood flow in a constricted vessel? A It increases B It decreases C It stays the same ANSWER: B o Blood from the arteries then get sent to the capillaries, the smallest blood vessels Their walls are one cell thick and are just wide enough to let red blood cells pass through one at a time Because of their structure, these vessels are ideal for the exchange of gases, nutrients, and wastes between the blood and tissues o While arteries experience high pressure, the pressure drops significantly by the time blood reaches the capillaries o Once blood passes through the capillaries, it returns to the heart via the veins Because blood is under much lower pressure in the veins, they have thinner walls and larger interior diameters CLICKER #4 Which type of blood vessel has thick walls with muscle fibers due to blood being under high pressure? A Artery B Capillary C Vein ANSWER: A o Some larger veins contain one-way valves to prevent the backflow of blood Because the pressure of the closed system and the thinness of capillaries, fluid leaks from the vessels into the surrounding spaces As the pressure drops along the length of the capillaries, fluid is able to enter again near the venules Not all liquid is reabsorbed by the capillaries and will enter the lymphatic system The lymphatic system consists of thin-walled branching tubules called lymphatic vessels The fluid that enters is called lymph Eventually, the fluid is returned to the circulatory system at the veins entering the heart
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