2UNIT K: HEART STRUCTURE & FUNCTION (Ch. 13, pp. 228-233) K1. Identify & give functions for the following:Left and right atriaLeft and right ventriclesCoronary arteries and veinsAnterior and posterior vena cavaAortaPulmonary arteries and veinsPulmonary trunkAtrioventricular valvesChordae tendinaeaSemi-lunar valvesSeptum
3K2. Describe the location and functions of the SA node, AV node, and Purkinje fibers K3. Describe the autonomic regulation of the heartbeat by the nervous systemK4. Relate factors that affect and regulate blood pressure to hypertension and hypotensionK5. Demonstrate the measurement of blood pressureK6. Distinguish between systolic and diastolic pressure
5Amazing Heart Facts Put your hand on your heart. Where is it? Hold out your hand and make a fist.size of heart: child = 1 fist; adult = 2 fists!Your heart beats about 100,000 times in one day and about 35 million times in a year.During an average lifetime, the human heart will beat more than 2.5 billion times.Sure, you know how to steal hearts, win hearts, and break hearts. But how much do you really know about your heart and how it works?Even at rest, the muscles of the heart work twice as hard as the leg muscles of a person sprinting
6approximately 10 seconds In one day, the blood travels a total of 19,000 km. That's 4 times the distance across CANADA from coast to coast.When you are resting, it takes seconds for the blood to move through your body. What about when you are exercising?approximately 10 secondsHow much does your heart weigh?only 2/3 of a pound!Give a tennis ball a good, hard squeeze. You're using about the same amount of force your heart uses to pump blood out to the body
7Basic Functions of the Circulatory System Transports oxygen from the lungs to body to be used1Transports carbon dioxide and hydrogen ions to the lungs to be removed2Transports nutrients from the small intestine to tissues3Fights infections4
8Transports water from the digestive system to the body and lungs 5Carries waste products (ie: urea) to kidneys for removal in urine6Distributes body heat from internal source to skin (to get rid of it)7Seals wounds by forming blood clots8
9Transports hormones around the body 9Maintains pH in tissues (acts as a buffer with HHb)10Regulates fluid levels in tissues (with Lymphatic system)11
16The human heart has 4 well developed chambers Right AtriumLeft AtriumRight VentricleThe right side of the heart feeds the pulmonary circuit, and the left side feeds the systemic circuit.Left Ventricle
17The right side of the heart pumps deO2 blood to the lungs. PULMONARYThe left side of the heart pumps O2 blood to the bodySYSTEMIC
18the receiving chambers ATRIAthe receiving chambersLeft AtriumRight AtriumReceives oxygenated blood from the lungs via the pulmonary veinsReceives deoxygenated blood from the body via the anterior & posterior vena cava.
19ATRIOVENTRICULAR VALVES Tricuspid Valve1. Separate the atria from the ventricles.Bicuspid Valve2. They open when the atria contract.these flaps of tissue separate the atria from the ventricles. When blood pressure is greater in the atria (and the atria contract), the valves open and blood enters the ventricles on each side.3. They prevent the blood from going backwards when the ventricles contract.
23CHORDAE TENDINAE Tendon-like pieces of tissue They keep the AV valves from inverting when the ventricles contractPoint out that this is a TRI-CUSPID valve because it has 3 cusps.
24They hold & support the chordae tendinae PAPILLARY MUSCLE
25Can’t open properlyClosedOpenCan’t close properlyNormal Heart ValvesHeart Murmur
26VENTRICLES the sending chambers Right Ventricle When the right atrium contracts, it pushes the blood through the tricuspid valve and into the right ventricle.When the RIGHT VENTRICLE contracts, BP forces the TRICUSPID valve to close.The BP forces PULMONARY VALVE open & the blood moves into the PULMONARY TRUNK.Right Ventricle
27AT THE LUNGS The PULMONARY ARTERIES take the deO2 blood to the lungs. The CO2 is removed from the blood and is replaced with O2.AT THE LUNGSThe PULMONARY VEINS take the O2 blood to the heart.
34When the left atrium contracts, it pushes the blood through the bicuspid valve and into the left ventricle.When the LEFT VENTRICLE contracts, the BICUSPID VALVE is forced closed.Blood is forced through the AORTIC VALVE and enters the AORTA.Left VentricleThe left ventricle has a THICKER muscle layer. WHY?
35AORTA the biggest artery Aortic Arch Dorsal Aorta To the head To the arms & lungsAortic ArchCoronary Artery: to the heartDorsal AortaTo the lower bodythe biggest arteryThe aorta takes O2 blood to the body.
36CORONARY ARTERIES & VEINS The first branches of the aorta take the blood to the coronary arteries.Takes blood into the heart muscle itself. The coronary veins return the deO2 blood to the vena cava right atrium.
37VENA CAVA Superior Vena Cava Inferior Vena Cava These are the BIGGEST VEINS!They bring the deO2 blood back to the heart so that it can be pumped to the lungs.Inferior Vena Cava
38exterior view of the heart Aortic ArchSuperior vena cavaPulmonary TrunkCoronary arteryRight AtriumCoronary VeinRight VentricleLeft VentricleInferior Vena Cava
45Why cana heart keep beatingoutside of the body??
46Coordination of the Beating • Heart cells naturally beat slowly if ATP is present• If there was no coordination, the heart cells would all beat randomlyBeating Human Heart:
47How Does The Heart Work to Pump The Blood There are two spots of specialized tissue in the heart.Both are located in the right atrium.Nodal tissue is unique: made of specialized muscle cells combined with nerve cells.It has the ability to contract independent of other stimuli.
48The SA NODE (sino-atrial) This node is found along the wall of the right atrium chamber.It fires on average, every 0.85 seconds (or 72 times per minute).It stimulates the simultaneous contraction of the atria.It also sends a nerve impulse along a nerve trunk called the BUNDLE OF HIS to the AV NODE
50The SA node initiates the heartbeat and has been given the nickname of the “PACEMAKER” a small electronic device that stimulates the SA node to fireYou can ‘re-set’ your pacemaker by calling a number and holding the phone up to your heart. COOL!People with irregular heartbeats may have to have an artificial pacemaker ‘inserted’.
52The AV NODE (atrioventricular) In the right atrium close to the AV (tricuspid) valveWhen the AV node receives the impulse from the SA node, it fires to initiate the contraction of the LARGE ventriclesA.V. NODEPURKINJE FIBRESBecause the ventricles are so massive (as compared to the atria), the AV node works through the PURKINJE FIBRES, a set of nerves that conducts impulses throughout the ventricles. The P. F. contract in unison & cause the ventricles to contract at the same time from the bottom, upwards.The AV node sends its message through the P.F., which cause ventricles to contract.
57There are two parts to the contraction of the heart EKGThe heart beat is a double sound (‘lub-dub’).An EKG (electrocardiogram) registers the voltage changes across the surface of the heart as it beats.The letters PQRST are the standard labels used to identify the parts of the EKG.
58P = the simultaneous contraction of the atria (caused by SA node) QRS = the contraction of the ventricles (caused by AV node & purkinje fibres)P: as atria contract blood is forced into ventriclesQRS: as ventricles contract, blood is forced into arteriesT: restoration of normal electrical condition; preparation for subsequent contraction.T = the recovery of the ventricles (preparation for next contraction)
61Some Abnormal EKG’s NORMAL Tachycardia (a heart rate of over 100 beats/min)Ventricular Fibrillation (uncoordinated ventricles)Heart Block (failure to stimulate ventricles after atrial contraction)
62This is known as defibrillation If the system really breaks down, the heart could go into fibrillation. This is uncoordinated contractions of the cardiac muscle.When this happens, the pacemaker (SA NODE) will send a strong shock through the heart.Hopefully the heart muscle will reset itself.This is known as defibrillation
63defibrillatorWe also try to do this artificially when people are in cardiac arrest!
68The regulation of the heartbeat is under the influence of the AUTONOMIC NERVOUS SYSTEM (not under conscious control)Sympathetic Nervous System: When the brain is not receiving blood quickly enough, the brain will signal the SA node (via the vagus nerve) to speed up its contraction. This will usually occur in circumstances of FIGHT or FLIGHT. It will also occur when the blood pressure is too low.Parasympathetic Nervous System: this system will reestablish the resting heart rate (~60-70 beats/minute) by sending a message via the vagus nerve to slow the heart rate.Sympathetic (fight or flight): causes heart to speed upParasympathetic: causes heart to slow down (via vagus nerve)
69The part of the brain that governs the speed of the heart rate is called the MEDULLA OBLONGATA It will speed up or slow down the heart rate when needed. **Under normal circumstances, the heart controls itself.
73Cholesterol in the blood can become deposited on the inside walls of the arteries. This seems to happen faster in people who: •Smoke•Have high blood pressure•Eat high fat, high cholesterol foods, or, for other reasons, have high cholesterol•Are overweight•Have a lot of tension and stress•Do not exercise regularly•Have diabetes and/or family members with a history of atherosclerosis
89What is YOUR pulse rate at rest? After exercise? Feel your pulse by placing two fingers at pulse points on your neck or wrists. Now count the beats for 15 seconds & multiply by 4.As a kid, your resting pulse might range from 90 to 120 beats per minute.As an adult, your pulse rate slows to an average of 72 beats per minute.1. The pulse you feel is blood stopping and starting as it moves through your arteries. As a kid, your resting pulse might range from 90 to 120 beats per minute. As an adult, your pulse rate slows to an average of 72 beats per minute.What is YOUR pulse rate at rest? After exercise?
90BLOOD PRESSURE: the ventricles pump approx BLOOD PRESSURE: the ventricles pump approx. 70 mL of blood each time they contract.The pulse you feel is blood stopping and starting as it moves through your arteries.
91Blood is being forced through the arteries (approx. 120 mmHg) Blood pressure is not constant, it fluctuates with each heartbeat. SYSTOLIC PRESSURE (systole): blood pressure when the ventricles are contracting.Blood is being forced through the arteries (approx. 120 mmHg)
92DIASTOLIC PRESSURE (diastole): blood pressure as ventricles are refilling. This is between contractions, and the blood pressure is less (appox 80 mmHg).
97Limit Alcohol Be Active Eat less salt Don’t Smoke Lose Weight High blood pressure sometimes goes unnoticed until complications set in.Limit AlcoholBe ActiveEat less saltDon’t SmokeLose WeightEat Healthy
98High Blood Pressure puts constant strain on the tissues (especially the capillary beds). May cause capillaries to burstIf this happens in the brain = a stroke If it happens in the heart = heart attack!The longer you have high BP, the greater the potential for tissue damage.Sometimes high BP is normal (ie: when doing physical activity)However, the brain should return the BP to a normal, lower level.
100Low blood pressure is not particularly a good thing either. It can result from:GeneticsAnemia *not enough iron*Dehydration *not enough water*Blood lossShockProper kidney function can only be maintained if there is sufficient pressure for filtration.
102bigger (dilate) = lower BP smaller (constrict) = higher BP Vessel diameter:bigger (dilate) = lower BP smaller (constrict) = higher BPVasodilation to lower BPOur bodies can adjust blood pressure. The Hypothalamus monitors our blood pressure and controls the size of our arterioles. The body can dilate (widen) arterioles to lower blood pressure [vasodilation] OR constrict (narrow) arterioles to raise the blood pressure [vasoconstriction].Vasoconstriction to increase BP
103Blood viscosity:Thick blood (little water) = higher BP Thin (lots of water) = lower BPMore water in our blood means decreased viscosity and lower resistance and blood pressure.
104More fat = more vessels = more resistance = increased BP Total blood vessel length:More fat = higher BP Thinner = lower BPMore fat = more vessels = more resistance = increased BP
105ATHEROSCLEROSIS (hardening of arteries = decreased elasticity). Vessel elasticity: affected by plaques (fatty deposits).Elastic vessels = lower BP Hardened vessels = high BPAtherosclerosis - accumulation of soft masses of fatty material, esp. cholesterol, beneath inner linings of arteries. These protrude and interfere with blood flow and increase blood pressure. The presence of hard plaque on artery walls can cause blood to form clots. If the clots stay in place they will block blood flow in the artery (thrombus). An embolus occurs if the clot moves. An embolus causes an embolism when it stops and blocks off a smaller blood vessel. This causes a heart attack if the artery is a coronary artery or a stroke if it is an artery in the brain.ATHEROSCLEROSIS (hardening of arteries = decreased elasticity).
106Blood volume:Eat lots of salt = more volume/water stays in body = higher BPSweat a lot = less volume/water = lower BPDiet and lifestyle are often to blame for elevated blood pressure. High salt intake from diet or kidneys will increase BP. Excessive salt will retain water in the body – greater fluid volume leads to greater blood pressure.
107Cardiac output:Heart rate increases = higher BP Heart rate decreases = lower BPStress can also cause high blood pressure. The brain controls all of these increases and decreases in blood pressure. One way that it can control BP (other than vaso-contriction/dilation of arterioles) if to increase and decrease the heart rate. This is controlled by the vagus/parasympathetic nerve (which decreases heart rate), and the sympathetic nerve (which during stress increases the heart rate).
108Young = very elastic = low BP Age: as you get older, there is a loss of elasticity in the blood vessels.Young = very elastic = low BPOld = not elastic = high BP
109Stressed = constricted vessels = Higher BP Stress: constricts blood vessels which means increased pressure to move the blood.Stressed = constricted vessels = Higher BPCalm = normal vessels = Lower BP
110Heart Animations and Interactives Animation: Your heart valves at workInteractive: Label the heartInteractive: Listen to the heart with a virtual stethoscopeInteractive: Explore the structures of the heart and trace the pathway of blood through the heart, lungs, and bodyAnimation: See the flow of blood to and from the exterior heart