Biology 12 - Circulation - Chapter Notes

Transcription

1 Biology 12 - Circulation - Chapter Notes Multicellular organisms (above the level of roundworms) rely on a circulatory system to bring nutrients to, and take wastes away from, cells. In higher organisms such as ourselves, circulation is so important that if the heart stops beating for a few minutes, death results. In this chapter, we will learn about the heart and how it works, plus the major vessels of the circulatory system. The Circulatory System consists of: Capillary Valve Vein Arteriole Artery BLOOD VESSELS (5 TYPES) carry blood from heart to tissues (i. arteries & ii. arterioles do this) and then back to heart (iii. veins & iv. venules do this). v. Capillaries connect the arterioles to venules, and exchange material with the tissues. i) - Arteries carry. They have composed 3 layers - elastic and muscular fibers (plus supporting tissue). The outer and innermost layer are very rigid. The structure of the walls are important to. ii) - Arteries branch into Arterioles, which are of arteries that are about 0.2 mm in diameter or smaller. Arterioles constricting and dilating cannot be controlled by the nervous system. : refers to the for increased blood supply to a specific area (tissues). E.g. blushing, muscles during exercise : refers to the which decreases blood supply to a specific area. E.g. returning to normacy after exercise. Arterioles branch into small vessels called capillaries. Note: a pulse is the expansion/contraction of the artery caused by the pumping heart. It can be used to measure your heart rate. The pulse can no longer be detected once it leaves the arteries/arterioles.

2 iii) ( hair-like in latin) are very narrow, microscopic tubes. The walls of these tubes are. Gases, nutrients, wastes, and small molecules of the capillaries. Sphincter muscles encircle the entrance to each capillary. Due to the narrow diameter, RBC move through in a SINGLE FILE In a capillary bed (networks of many capillaries), some, many, or most of these sphincter muscles may be closed off so that less or more blood flows to that area, as needed (e.g. more blood to muscles when they are working). iv & v) - take blood from the capillaries to the heart. Venules. Walls are also three layers thick but walls thus increased diameter. Veins also have. Blood leaving the capillary beds are rich in waste and low in oxygen. Blood pressure against the walls of venules/veins is To prevent backflow of flood there are 2 features in the venules/veins: a) allow blood to flow only toward the heart when the are open and prevent the backward flow of blood when they are closed. Damage to valves can lead to pooling of blood and bulding of veins (e.g. hemorroids) b) around the veins, helping blood move towards the next valve

3 THE HEART : 3,000,000,000 beats in an 80 year lifetime! Epithelial and fibrous tissue called pericardium 1 covers the heart. This tissue forms PERICARDIAL SAC, in which the heart is located. The sac contains LUBRICATING 2 LIQUID. Parts of the Heart: (visible heart) : The septum the left side of the heart from the right side. : On each side are two chambers. The smaller one, located on the, is called the atrium (plural = atria ). : The larger chamber, on the bottom. The left ventricle is considerably than the right ventricle because while the right ventricle only pumps blood to the lungs, the left ventricle must pump to the rest of the body. : valves located between the atria and ventricles. These valves control the flow of blood between the chambers, and TRICUSPID VALVE: The atrioventricular valve separating the Right Atrium from the Right Ventricle. BICUSPID/MITRAL VALVE: The atrioventricular valve between the left atrium and left ventricle I strongly suggest you label this diagram! : very strong, fibrous strings. The chordae tendinae are firmly attached to muscular projections of the ventricular wall. : located in each ventricle (called that because they look like half-moons) between it and its attached blood vessels. The blood flows through the semilunar valves on its way out of the heart. The right ventricle then, has a pulmonary semilunar valve (since it pumps blood out through the pulmonary artery), while the left side has an aortic semilunar valve (since it pumps out through the aorta).

4 THE PATH OF BLOOD THROUGH THE HEART 1. Blood LOW IN OXYGEN ( deoxygenated ) enters the RIGHT ATRIUM through the SUPERIOR (top) and INFERIOR (bottom) VENAE CAVAE, the body's largest veins. 2. The RIGHT ATRIUM contracts, forcing blood through the TRICUSPID VALVE and into the RIGHT VENTRICLE. 3. The right ventricle contracts, sending blood through the PULMONARY SEMILUNAR VALVE and into the PULMONARY TRUNK. 4. The pulmonary trunk divides into PULMONARY ARTERIES, which take the deoxygenated blood to the capillaries of the LUNGS. 5. At the lungs, carbon dioxide diffuses out of the blood, and, oxygen diffuses into it. The blood is now OXYGENATED. 6. The oxygenated blood feeds into the PULMONARY VEINS, which take it from the lungs to the LEFT ATRIUM. 7. The left atrium CONTRACTS, forcing blood through the bicuspid valve into the LEFT VENTRICLE. 8. The left ventricle CONTRACTS, forcing blood through the AORTIC SEMILUNAR VALVE into the AORTA, the body's largest artery. 9. The aorta divides into smaller arteries, which carry oxygenated blood to all BODY TISSUES. Note that deoxygenated blood with oxygenated blood. IN REALITY, the events described above don't happen in a linear sequence. Instead, the two atria contract SIMULTANEOUSLY, and the two ventricles also contract simultaneously.

5 THE PULMONARY CIRCUIT is the path of blood from the. blood from all tissues collects in the, is pumped to the ventricle, then is sent to the, which divides into, which divide up into the of the lungs. These arterioles take blood to the pulmonary capillaries, where CO 2 and O 2 are exchanged. The oxygenated blood then enters, then the pulmonary, and finally back to the. *** colour and label arrows of blood flow*** THE SYSTEMIC CIRCUIT The systemic circuit includes all blood vessels except those in the Pulmonary Circuit. It takes blood from the VENTRICLE, through the tissues & organs of the body, and back to the ATRIUM. in the circulatory system, veins carry blood, and arteries carry blood. E.g. heart (left ventricle) ascending aorta carotid arteries arterioles capillaries of the brain venuoles jugular vein superior vena cava heart (right atrium) ***refer to the diagram*** The systemic circuit contains some blood vessels you should know: : the largest artery. Branches of the aorta lead to all major body regions and organs. : large vein that collects blood from head, chest, and arms. : large vein that collects blood from the lower body regions and organs. : connects the blood vessels of villi to the liver, carries nutrient rich blood to liver for processing. A portal system begins and ends in capillaries (in small intestine, and other end in liver. carries blood from liver to inferior venae cava.

6 Summary of the Major Blood Vessels you Should know: (Refer to the Diagram) SUBCLAVIAN ARTERY AND VEIN -= around clavicle JUGULAR VEIN - blood from head CAROTID ARTERY - neck MESENTERIC ARTERIES - connect to intestines ANTERIOR AND POSTERIOR VENAE CAVA - superior PULMONARY VEIN - carry oxygenated blood to left atrium above, inferior below heart HEPATIC VEIN - connects to inf. venae cava HEPATIC PORTAL VEIN - connects intestine with liver RENAL ARTERY AND VEIN - connect kidneys and veins ILIAC ARTERY AND VEIN - leads from aorta into legs CORONARY ARTERY AND VEIN AORTA - largest artery, supplies all tissues You should also be able to describe the flow of blood around the body through any major organ. For example: e.g. path of blood to kidneys: Left ventricle aorta renal artery renal arterioles capillaries venules renal vein venae cava right atrium

7 THE HEARTBEAT The heartbeat that you can hear (the "lub-dupp" sound) can be divided into TWO PHASES: FIRST: The (the "lub" part) while the ventricles are relaxed. SECOND: Then the (the "-DUPP" part) while the atria relax. The actual sound you hear is caused b the vibrations of the heart when the. "lub" = closing of atrioventricular valves ( ), "DUPP" = closing of the semi-lunar valves ( ). If there is a problem with a, it creates a gurgling sound, and this can cause. If not treated, the heart beats faster to deliver proper amounts of blood. RHEUMATIC FEVER (caused by a bacterial infection) can cause a faulty valve (usually the bicuspid valve). Surgery or replacement with an artificial valve can often cure this. The CARDIAC CYCLE (= heartbeat ) occurs about 70 times per minute, and 100,000 times per day in the average adult. There are two terms that describe contraction and relaxation of heart muscle: SYSTOLE = of heart muscle. DIASTOLE = of heart muscle. Each heartbeat can be divided up as follows: TIME (DURATION) ATRIA are in... VENTRICLES are in SEC SEC SEC. WHAT CONTROLS THE HEARTBEAT? The heart can beat without the brain telling it what to do! This is because the (can contract on its own without external nerve stimulation) The answer is that the heart has its own SPECIAL TISSUE, called, which has characteristics of both nerve and muscle tissue, which controls the heartbeat. There are TWO nodal regions in the heart: 1. (also called the PACEMAKER): located in the upper back wall of the right atrium. The SA node INITIATES THE HEARTBEAT by sending out an electrical impulse automatically about every 0.85 seconds to make the ATRIA CONTRACT. The SA node is called the because it keeps the beat regular.

8 2. : found in the base of the right atrium near the septum. The SA node sends its signal along fibers. When the pulse sent out by the SA node reaches the AV node, the AV node itself then sends out a signal along special conducting fibers called. These fibers take the message to the, and cause them to. The contraction of the ventricles begins at the base of the heart and moves up like a wave. This is because the Purkinje fibers first stimulate cardiac muscle at the base of the heart. The heart rate is controlled by the (the part of the nervous system that regulates vital functions) and by. Various factors, such as stress, oxygen levels, and blood pressure determine how the autonomic system will affect heart rate. The autonomic nervous system consists of the sympathetic and parasympathetic divisions. The sympathetic division increases the heart rate through a network of nerves, while the parasympathetic division decreases the heart rate through a single nerve. Heart rate is also influenced by hormones released into the bloodstream by the sympathetic division: - and : is released from the medulla oblongata at times of stress. This hormone stimulates an since it prepares the body for. - hormone: released into the bloodstream by the thyroid gland, also increases the heart rate. BLOOD PRESSURE & PULSE BLOOD PRESSURE: the pressure of the blood of a vessel, created by the of the heart. Measured at the artery (in your arm, close to surface) Measure blood pressure with an instrument called a. Unit measurement is: mm Hg (distance Hg is pushed in the tube) BLOOD PRESSURE: measures the, the highest arterial pressure reached during from the heart.

9 BLOOD PRESSURE: measures the, lowest arterial pressure. Normal resting blood pressure is 120 mm Hg over 80 mm Hg in brachial artery of arm (120 systolic/80 diastolic). Of course, blood pressure from left ventricle. It is higher in the arteries than in the arterioles, for example. Blood pressure accounts for the flow of blood in the arteries and arterioles, while accounts of the flow of blood in the venules and veins. PULSE: the alternate that can be felt in any artery that runs near the surface of the body. Radial artery in wrist, carotid artery in neck are common places to check. Pulse rate indicates the rate of heartbeat. BLOOD PRESSURE CONDITIONS AND REGULATION: a) : blood pressure than usual. b) : blood pressure than normal. Over 20% of Canadians/Americans suffer from it. Usually associated with cardiovascular disease. Many unaware they have it. CAUSES of Irregular blood pressure: a) : Can be caused by diet, (e.g. high salt diet causes water to be retained) stress (causes blood vessels to constrict). DIET is the most important factor. Animal products are the only source of dietary cholesterol. b) due to plaque buildup also causes hypertension --> due to saturated fats and cholesterol. REGULATING Blood Pressure: Rugulation is done by the Autonomic Nervous System by using 2 types of receptors that detect high blood pressure and blood volume. 1) : found in the arteries that detects an increase in blood pressure. Then a signal (nerve impulse) is sent to/from the Medulla Oblongata resulting in that reduce blood pressure. 2) : found in the detects the of blood entering. Then a signal (nerve impulse) is sent to/from the Medulla Oblongata to increase the heart rate.

10 CAPILLARY FLUID EXCHANGE Important substances are moved in/out of capillaries as blood travels through capillary beds. Fluids are of the capillary initially to the, the end of the capillary bed. Fluids are then into the capillary at the end of bed the capillary bed. The main answer lies in battle of blood pressure versus osmotic pressure. Two Forces (factors) that affect fluid exchange: (1) vs. (2) 1. Fluid Pressure (or blood pressure): the force/pressure placed on the capillary walls, created by the velocity and mass of the blood, is than osmotic pressure in the arteriole end. At the arteriole end: Fluids (O 2, nutrients (glucose & amino acid), and water). Larger Molecules (blood proteins and blood cells) are too large to diffuse across walls and in the capillaries. The pressure of blood in the blood vessels tend to of the blood. - this ENTIRE process is referred to as: - the blood pressure falls as blood moves towards the venule end. 2. Osmotic Pressure: the force of water At the venule end: The pressure of water (osmotic) in the cells in the capillary and therefore. Water along with CO 2 and other metabolic wastes (e.g. Ammonia) diffuse back into capillaries. - this ENTIRE process is referred to as: Note: This exchange results in a MINIMAL change in total blood volume.

11 Summary: Blood Pressure Osmotic Pressure Net Movement ARTERIOLE END VENUOLE END Sustances CARDIOVASCULAR DISORDER: CORONARY ARTERIES and VEINS 1. ATHEROSCLEROSIS is a form of arteriosclerosis ( ). Atherosclerosis is the (due to the ) caused by. As plaque builds up, the inner layer of the artery walls become thick and irregular. Fat, cholesterol, and other materials accumulate in certain areas. This gradual build of plaque which then plugs an artery is named: (a stationary blood clot). Plaque that breaks off and begins travelling is named: (a travelling blood clot). People with atherosclerosis can suffer from : a) : condition where the portion of the heart does due to lack of oxygen. Death may result if immediate attention is not given. b) : when a portion of the brain dies due to lack of oxygen usually when arterioles burst or is blocked by embolism.

12 Differences between Fetal and Adult Systems Heart develops in 3rd and 4th weeks in uterus. At end of 8 weeks, the embryo s organ systems, including heart, are functioning. During fourth month, fetal heartbeat is loud enough to be heard with stethoscope. However, the fetal circulatory system can t be the same as the adult, if you Oval Opening stop to think about it. The fetus, first of all, can t breathe air inside the womb, so sending blood to the lungs won t do much good. Likewise, the fetus must get all its nutrients from Mom, as well as let her take care of its wastes. Obviously, some serious plumbing problems must be solved. To solve these problems, the fetus has not present in adults: a) (foramen ovale):, covered by a flap that acts like a valve. Some of the blood from the right atrium is therefore this flap and into the, bypassing the pulmonary circuit. b) : (ductus arteriosus). Much of the blood being pumped out of the heart from the right ventricle to the lungs will be directed away from the lungs and into the aorta. Like the oval opening, the arterial duct s function is to. c) : vessels that (a membrane shared by the mother and baby across which gases, nutrients, and wastes are exchanged). The two umbilical arteries are grafted to, and branch from the iliac arteries. d) (ductus venosus): to bring the blood back to the baby s heart. It attaches right at the babies liver, but. This is why chemicals ingested by the mother can seriously affect the baby! Arterial Duct PATH OF BLOOD THROUGH FETUS 1. blood from the Plancenta enters the fetus through the 2. The via the and combines with DEOXYGENATED BLOOD in the 3. Blood joins deoxygenated blood from the and empties into the right atrium.

13 4. From the R. Atrium, blood can go into through plus into R. Ventricle through atrioventricle valve. 5. From the R. Ventricle blood travels up the Pulmonary Trunk to the Pulmonary Artery. However, most of blood will. 6. Also, blood from the Left Atrium, travels to the Left Ventrical and up to aorta. 7. From the Aorta blood circulates through the body tissue and returns to the placenta via the UMBILICA VEIN..

14 The Lymphatic System The lymphatic system is vascular (circulatory) system in your body. It is system (i.e. it has its own veins and capillaries) but it is ultimately with the cardiovascular system (i.e. the fluid from the lymphatic system eventually gets sent back into the bloodstream). Basically, the lymphatic system (fluid that surrounds cells and tissues) from the tissues and it to the cardiovascular system. It is a system that starts in the tissues and empties into the cardiovascular system. Lymph vessels consist of: - LYMPH CAPILLARIES: - LYMPH VEINS (which have valves): Note: there are no lymph arteries since there is no pump in this system. Once fluid enters the lymph vessels it is called. Lymph is collected in vessels that join to form two main trunks: a) : drains the of the body and empties into the right subclavian vein b) : drains the and drains into the left subclavian vein. Lymph contains which are a type of white blood cell. Some lymphocytes produce antibodies. OTHER LYMPHATIC PARTS & ORGANS: : blind ends of lymph vessels in villi of the small intestine. : small oval or round structures that occur along strategic places on lymph vessels. They, and of damaged cells and debris. : located behind the stomach.. : located in the upper thoracic cavity, functions in. Decreases in size with age (may be a factor in aging). : is the site of stem cells produce blood cells.

15 : a condition of localized swelling caused by accumulation of tissue fluid that has not been collected by the lymphatic system. Can lead to tissue damage. Summary of Main Functions of Lymphatic System 1. transport of excess tissue fluid back to cardiovascular system 2. absorption of fat from the intestine and transport to blood 3. fighting infection by cleansing lymph and production of lymphocytes (a type of white blood cell). Some lymphocytes produce antibodies. The following are graphs from the Prov. Exam. Interpret the graph and write a summary for each.