2. Label the structures of the heart and describe the path of blood flow through the heart

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1 1. Describe the difference between an open and closed circulatory system? Open: the fluid (called Hemolymph) directly surrounds organs. Think of a circulatory system as a circuit. In an open circulatory system the circuit is open! The fluid is pumped by the heart through vessels and then into sinuses that surround organs. Closed: the fluid is called blood and travels through a CLOSED circuit. Blood remains in vessels throughout the whole process of circulation 2. Label the structures of the heart and describe the path of blood flow through the heart A mnemonic to help remember blood flow: Left receives blood from the Lungs. Oxygenated blood enters the left atrium through the pulmonary vein à left ventricle à aorta à arteries à arterioles à capillaries à (you are now carrying deoxygenated blood) venules à veins à inferior/superior vena cava à right atrium à right ventricle à pulmonary artery (still deoxygenated) à capillaries in alveoli (you are now oxygenated) à pulmonary vein à left artrium You can t say that arteries carry oxygenated blood and veins carry deoxygenated blood. Why? The pulmonary artery contains deoxygenated blood and the pulmonary vein carries oxygenated blood. However, you can say that veins carry blood towards the heart and arteries carry blood away from the heart

2 3. How does heartbeat originate? Describe the flow of electricity through the heart The sinoatrial node (SA) is the pacemaker of the heart. It is found in the right atrium and is what determines the rate of the heartbeat (why its called the pacemaker). The impulse generated from the SA node travels through the walls of the atria, which causes them BOTH to contract. The impulse then reaches the atrioventricular node (AV), which is located between the atria. The impulse next travels through the Purkinje fibers and the walls of the ventricles, causing them to contract. 4. Compare the structure of arteries and veins Arteries -Thicker and stronger than veins because they have to withstand the higher blood velocity and pressure - Thicker layer of connective tissue and muscle lined with endothelium Veins - Smaller diameter than arteries because the blood pressure in the vein is much lower - Contain valves to prevent blood from flowing backwards -Lined with a smaller layer of muscle and endothelium 5. Describe the structure of a capillary blood vessel and how fluid is exchanged at the capillary level structure: one cell thick of endothelial tissueà it is important for capillaries to be thin to maximize nutrient and fluid exchange when blood enters the capillary, the blood pressure is high, which forces out fluid into the interstitial space. Small things like oxygen and CO2 can diffuse into the interstitial space also. Other small nutrients like amino acids can be pushed out at the arterial end. Not everything can move out, however. Big molecules like proteins are too big to be pushed or diffused out so they remain in the capillary. This causes a concentration gradient! There is no protein in the outside space but the concentration is high in the capillary so fluid will move BACK INTO the capillary to overcome the gradient at the venous end. 6. Describe the counter current exchange mechanism This mechanism maximizes the amount of oxygen fish can get. The blood flowing in from the water will always be 100% deoxygenated and therefore higher in 02 content than the blood. The oxygen will diffuse down a concentration gradient from the water to the blood. IF the water and blood were flowing in the same direction, at one point there would be 50% oxygen in the blood and water and diffusion would stop because equilibrium would be reached. See image below for comparison

3 7. List the 4 things inward and outward respiratory systems have in common: they have to stay moist, they have to have a large SA, there must be a way to transport substances from the environment to the cells, a way to protect fragile structures 8. What happens when air enters the nose? Mucous moistens the air Air is warmed Nose hairs filter the air 9. Describe the path of air through the respiratory system nasal cavity à trachea à bronchi à bronchioles à alveoli 10. Describe the structure of alveoli and how gases are exchanged here? One cell thick with a lot lot lot of blood vessels, coated with a lipoprotein that prevents collapse Oxygen that is in the air in the lungs passively diffuses into the capillaries that surround the alveoli. Carbon dioxide diffuses in the opposite direction: out of the capillary and in to the alveoli which then leaves the body during exhalation 11. Describe the process of negative pressure breathing: 1. Brain sends message to nerves in the diaphragm and ribcage which causes them to contract (the diaphragm contracts and flattens out, the ribcage expands) 2. The ribcage expands and the lungs open up which both increase the size of the chest cavity

4 3. Air rushes in because of the pressure difference: The pressure in the lungs is below the atmospheric pressure. Air will move from high to low pressure like diffusion (Think about physics: Pressure = Volume/ Area. When the chest cavity expands the area increases, which in turn decreases the pressure. Because the pressure is now lower than the atmospheric pressure, the air outside moves into the body) 4. Intake of air causes the alveoli to stretch, which sends a signal to the brain 5. Ribcage relaxes, diaphragm relaxes and moves back up, and air is pushed out which decreases the volume of lungs and returns the size of the chest cavity to normal 12. Describe the mechanisms used to detect low oxygen levels a. There are breathing control centers in the pons and medulla which detect a change in CO2 or ph levels b. There are chemoreceptors found in the carotid arteries and aorta that detect oxygen levels (Why are the chemoreceptors found in these particular areas? Carotid artery leads to the brain and aorta leads to the rest of the body. If blood CO2 level is high in these areas it means bad news to the body and brain so the receptors are here in order to detect early alerts. ** You don t breathe because O2 levels are low, you breathe because CO2 levels are HIGH. CO2 causes an increase of H ions and in turn drops the ph (acidic, ph <7) 13. What is tidal air? Vital capacity? Residual volume? -Tidal air: the volume of air taken in and out in a normal breathe -Vital capacity: the maximum volume of air that can be inhaled or exhaled -Residual volume: the amount of air that remains in the lungs after you force air out 1. A human red blood cell in an artery of the left arm is on its way to deliver oxygen to a cell in the thumb. From this point in the artery, how many capillary beds must this red blood cell pass through before it returns to the left ventricle of the heart? a. One b. Two c. Three d. Four e. Five 2. Damage to the sinoatrial node in humans a. Is a major contributor to heart attacks b. Would block conductance between the bundle branches and the purkinje fibers c. Would have a negative effect on peripheral resistance d. Would disrupt the rate and timing of cardiac muscle contractions e. Would have a direct effect on blood pressure monitors in the aorta 3. If the AV node could be surgically removed from the heart without disrupting signal transmission to the Purkinje fibers, what would be the effect? a. No apparent effect would be observed b. The heart rate would be decreased c. Only the ventricles would contract d. Only the atria would contract e. Atria and ventricles would contract at the same time

5 4. Large proteins such as albumin remain in the capillaries rather than diffusing out. Which of the following does this cause? a. Loss of osmotic pressure in the capillaries b. Creation of an osmotic pressure difference across capillary walls c. Loss of fluid from capillaries d. Increased diffusion of CO2 e. Increased diffusion of Hb 5. Human plasma proteins include which of the following? I. Fibrinogen II. III. Hemoglobin Immunoglobulin a. I only b. II only c. I and III only d. II and III only e. I, II, and III