1 Circulatory System Biology 12 – Chapter 12

2 Overview/Objectives:Introduction Overview of the circulatory system 12.1 The Blood Vessels Three types of blood vessels; functions & differences 12.2 The Heart Path of blood through the heart What happens during a heartbeat/how it is controlled 12.3 The Vascular Pathways Path of blood to lungs and return Path of blood to major parts of the body and return Cause of blood to flow in arteries and veins 12.4 Blood Components of blood and their functions Steps of a blood clot Exchange of materials between blood and tissues 12.5 Cardiovascular Disorders

3 Introduction: What is the circulatory system?The circulatory system carries blood and dissolved substances to and from different places in the body. The Heart has the job of pumping these things around the body. The Heart pumps blood and substances around the body in tubes called blood vessels. The Heart and blood vessels together make up the Circulatory System.

4 blood from the heart gets around the body through blood vessels12.1 The Blood Vessels blood from the heart gets around the body through blood vessels There are 3 types of blood vessels a. ARTERY b CAPILLARY c VEIN

5 Arteries carry blood away from the heart.a.The ARTERY Arteries carry blood away from the heart. the elastic fibres allow the artery to stretch under pressure thick muscle and elastic fibres the thick muscle can contract to push the blood along. Arterioles- small arteries mostly composed of smooth muscle

6 b. The CAPILLARY Capillaries link Arteries with Veinsthey exchange materials between the blood and other body cells. the wall of a capillary is only one cell thick The exchange of materials between the blood and the body can only occur through capillaries.

7 The CAPILLARY A collection of capillaries is known as a capillary bed.artery vein capillaries body cell

8 Veins carry blood towards from the heart.c. The VEIN Veins carry blood towards from the heart. veins have valves which act to stop the blood from going in the wrong direction. thin muscle and elastic fibres body muscles surround the veins so that when they contract to move the body, they also squeeze the veins and push the blood along the vessel. venules- (small veins) drain blood from capillaries and join to form a vein

9 Summary of Blood VesselsBasis of Contrast Artery Capillary Vein Structure Thick, elastic walls Very thin walls Thin walls with valves Diagram Function Blood away from heart Connect artery and vein; exchange Blood to heart; one way flow by valves Location Deep along bones everywhere Surface surrounded by muscle Movement Spurts by heart Smooth and slow Smooth by muscle contraction Type of Blood oxygenated deoxygenated

10 now lets look inside the heartThis is a vein. It brings deoxygenated blood from the body, except the lungs. These are arteries. They carry oxygenated blood away from the heart. 2 atria Coronary arteries, the hearts own blood supply 2 ventricles The heart has four chambers now lets look inside the heart

11 Pulmonary Artery to Lungs Pulmonary Vein from LungsInside The Heart Pulmonary Artery to Lungs Aorta to Head and Body Superior Vena Cava from Head and Body Pulmonary Vein from Lungs Right Atrium Left Atrium Semilunar valve Atrioventricular valve Left Ventricle Right Ventricle

12 Heart Anatomy The heart is a cone-shaped, muscular organ about the size of a fist Myocardium= major portion of the heart consisting of cardiac muscle tissue Pericardium= thick, membranous sac where the heart lies Septum= separates the inside of the heart into right side and left side Chordae tendineae = strong, fibrous strings that support the valves; prevents valves from inverting

13 How does this system work?pulmonary vein lungs pulmonary artery head & arms aorta Superior vena cava Right Left liver digestive system kidneys legs Circulatory System

14 Our circulatory system is a double circulatory system. This means it has two parts parts. Lungs Body cells the right side of the system deals with deoxygenated blood. the left side of the system deals with oxygenated blood.

15 Passage of Blood Through the Heart (1)1) The Superior Vena Cava and the Inferior vena cava (which carry deoxygenated blood) enter the right atrium

16 Passage of Blood Through the Heart (2)2) The right atrium sends blood through the atrioventricular valve (tricuspid valve) to the right ventricle

17 Passage of Blood Through the Heart (3)3) The right ventricle sends blood through the pulmonary semilunar valve into the pulmonary trunk  divides into two pulmonary arteries  go to the lungs

18 Passage of Blood Through the Heart (4)4) Four pulmonary veins which carry oxygenated blood from the lungs, enter the left atrium

19 Passage of Blood Through the Heart (5)5) The left atrium sends blood through an atrioventricular valve (bicuspid valve) to the left ventricle

20 Passage of Blood Through the Heart (6)6) The left ventricle sends blood through the aortic semilunar valve into the aorta to go to the body

21 Regulation of HeartbeatCardiac Cycle= each heartbeat Systole= contraction of heart muscle Diastole= relaxation of heart muscle 1)Two atria contract (systole) while ventricles relax (diastole) ~ 0.15 sec 2) Two ventricles contract (systole) while atria relax (diastole) ~ 0.30 sec 3) All of the chambers relax (diastole) ~ 0.40 sec Normal adult heart rate = 60 – 80 bpm

22 Heartbeat

23 Intrinsic Control of HeartbeatSA (sinoatrial) node= located in upper dorsal wall of right atrium SA node initiates heartbeat and automatically sends out impulse every 0.85 sec, which causes atria to contract called pacemaker because keeps heartbeat regular AV (atrioventricular) node= located in the base of the right atrium when pulse from SA node arrives at AV node it signals (via AV bundle) ventricles to contract by way of Purkinje fibers

24 Intrinsic Control of Heartbeat

25 Extrinsic Control of HeartbeatCardiac control center in the medulla oblongata (heartbeat can be altered by the nervous system) 1)Parasympathetic= resting state  decreases SA and AV nodal activity 2)Sympathetic= active state  increases SA and AV nodal activity Hormones epinephrine and norepinephrine (released by adrenal medulla) also stimulate the heart ex. During exercise

26 Extrinsic Control of Heartbeat

27 The ElectrocardiogramElectrocardiogram (ECG)= recording of the electrical changes that occur in the myocardium during a cardiac cycle

28 12.3 The Vascular Pathways Two Paths of Blood:Pulmonary Circuit  heart and lungs Pulmonary arteries- take deoxygenated blood to the lungs Pulmonary veins- return oxygenated blood to the heart Systemic Circuit heart and all other parts of the body Superior Vena Cava- deoxygenated blood from head, chest and arms to heart Inferior Vena Cava- deoxygenated blood from lower body to heart b) Aorta – oxygenated blood from heart to the body

29 Vascular Terms to Know Coronary arteries= serves the heart muscle itself (the heart is not nourished by the blood in its own chambers) Hepatic portal system= connection between the circulatory system and the liver

30

31 Blood Flow Blood pressure= pressure of blood against the wall of a blood vessel Systolic pressure= reached during ejection of blood from the heart Diastolic pressure= occurs while heart ventricles are relaxing Blood pressure is normally 120/80 Hypertension= high blood pressure (result of diet [fat and salt], stress and lack of exercise etc.) Hypotension= low blood pressure (result of fitness, drugs etc.) systolic diastolic

32 Comparing Blood Flow Blood Flow in Arteries Blood Flow in CapillariesBlood pressure is highest in the aorta Blood pressure is lowest in the venae cavae Varies throughout body; decreases with distance from left ventricle Blood Flow in Capillaries Very slow blood flow; allows substances to be exchanged to tissues Blood Flow in Veins Minimal blood pressure Venous return depends on: Skeletal muscle contraction Presence of valves in veins Respiratory movements

33

34 Capillary Exchange Two forces primarily control exchange of fluid through the capillary wall: Osmotic pressure  causes water to move from tissue to blood (venous end of capillary) Blood pressure  causes water to move from blood to tissue (happens at the arterial end of a capillary) Tissue fluid= substances that leave a capillary/ fluid between the body’s cells Lymph= tissue fluid within lymphatic vessels

35 Creating and Maintaining Blood Pressure5 factors, listed in descending order of importance: Heart contractions- influenced by bpm and amount of blood per beat Peripheral resistance- influenced by diameter of blood vessel (smaller vessel = greater pressure required to force blood through) Elasticity of arteries- expansion and recoil action helps maintain blood pressure Viscosity of the blood- thicker requires more pressure to circulate it Volume of blood in the system- loss of blood decreases blood pressure

36

37 12.4 Blood BLOOD digested food red blood cells white blood cellsoxygen waste (urea) platelets carbon dioxide hormones plasma

38 Composition of Blood Formed Elements – 45% by volume (solid)Erythrocytes (red blood cells)  transport O2 and CO2 Leukocytes (white blood cells)  fight infection  5 types (neutrophils, eosinophils, basophils, lymphocytes, monocytes) Thrombocytes (platelets)  blood clotting

39 Composition of Blood Cont’B) Plasma- 55% by volume (liquid) Water maintains blood volume (pressure) transports material Plasma protein (ex. Fibrinogen clots, albumin and prothrombin) Gases  oxygen, carbon dioxide in the form of bicarbonate ions (HCO3-)=base Nutrients glucose, amino acid, fatty acid etc. Electrolytes  (ions: Na+, K+, Cl-) Wastes  ex. Urea and creatine

40 Plasma It also contains useful things like; carbon dioxide glucoseamino acids proteins minerals vitamins hormones waste materials like urea. A straw-coloured liquid that carries the cells and the platelets which help blood clot.

41 The Blood white blood cell red blood cell plasma platelets

42 Red Blood Cells contain haemoglobin, a molecule specially designed to hold oxygen and carry it to cells that need it. a biconcave disc that is round and flat without a nucleus can change shape to an amazing extent, without breaking, as it squeezes single file through the capillaries.

43 White Blood Cells there are many different types and all contain a big nucleus. the two main ones are the lymphocytes and the macrophages. macrophages ‘eat’ and digest micro-organisms . some lymphocytes fight disease by making antibodies to destroy invaders by dissolving them. other lymphocytes make antitoxins to break down poisons.

44 Platelets Platelets are bits of cell broken off larger cells.Platelets produce tiny fibrinogen fibres to form a net. This net traps other blood cells to form a blood clot.

45 Summary: Difference Between Blood CellsFeature Red Blood Cell White Blood Cell Platelet Shape Biconcave (no nucleus) Variable Tiny cell fragments Function Transports O2 and CO2 Fight infection Blood clots Origin Bone marrow Bone marrow and lymph tissue Life span 120 days Varibable: days years day “Name” erythrocyte lukocyte thrombocyte

46 Blood Clotting Damaged tissue cells release tissue thromboplastin. Platelets form a platelet plug Prothrombin activator Prothrombin (protein in blood) Ca2+ Thrombin enzyme Ca2+ Hemophilia= inherited clotting disorder; deficiency in clotting factor Fibrinogen (protein in blood) Fibrin threads (red blood cells are trapped among fibrin threads Blood clot

47 Bone Marrow Stem Cells Stem cell=Cell that is ever capable of dividing and producing new cells that go on to differentiate into different cell types

48 Fetal Circulation The fetus has 4 features not present in adults: 1)Oval opening= an opening between the atria. This allows blood to by-pass the right ventricle  doesn’t go to pulmonary artery and lung 2)Arterial ducts= Duct between pulmonary trunk and aorta which allows blood that has gotten into the pulmonary trunk to by-pass the lung 3)Umbilical Arteries and Vein= travel to and from the placent 4) Venus Duct= connection between the umbilical vein and inferior vena cava to allow blood high in oxygen and nutrients from the mother to go directly to the heart of the baby

49 12.5 Cardiovascular DisordersAtherosclerosis- accumulation of fatty material (usually cholesterol) beneath the inner lining of the arteries = plaque Thrombus= stationary plaque Embolus= plaque that is dislodged and moves along with blood Thromboembolism= clot that has been carried in the blood stream but is now stationary (must be treated or serious occur)

50 Cardiovascular Disorders Cont’Stroke (cerebrovascular accident)= small cranial arteriole bursts or is blocked by an embolus  lack of oxygen to brain  death or paralysis Heart attack (myocardial infarction)= portion of the heart muscle dies due to lack of oxygen Aneurysm= ballooning of a blood vessel

51 Some Solutions to Cardiac DisordersCoronary Bypass Operations Angioplasty (clearing clogged arteries) Dissolving Blood Clots Heart Transplant Artificial Heart They key is prevention! Stay fit and eat well!

52 Video Time! If you have time (20 min) The Circulatory System: Short Video The Circulatory System 3D