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UNIT K: HEART STRUCTURE & FUNCTION (Ch. 13, pp ) K1. Identify & give functions for the following: Left and right atria Left and right ventricles Coronary arteries and veins Anterior and posterior vena cava Aorta Pulmonary arteries and veins Pulmonary trunk Atrioventricular valves Chordae tendinaea Semi-lunar valves Septum
K2. 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 system K4.Relate factors that affect and regulate blood pressure to hypertension and hypotension K5.Demonstrate the measurement of blood pressure K6.Distinguish between systolic and diastolic pressure
Amazing Heart Facts Put your hand on your heart. Where is it? Your heart beats about 100,000 times in one day and about 35 million times in a year. Hold out your hand and make a fist. During an average lifetime, the human heart will beat more than 2.5 billion times. size of heart: child = 1 fist; adult = 2 fists! Even at rest, the muscles of the heart work twice as hard as the leg muscles of a person sprinting
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 seconds How 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
Transports oxygen from the lungs to body to be used 1 hydrogen ionsTransports carbon dioxide and hydrogen ions to the lungs to be removed 2 nutrientsTransports nutrients from the small intestine to tissues 3 infectionsFights infections 4
waterTransports water from the digestive system to the body and lungs 5 wasteCarries waste products (ie: urea) to kidneys for removal in urine 6 body heatDistributes body heat from internal source to skin (to get rid of it) 7 woundsSeals wounds by forming blood clots 8
pHMaintains pH in tissues (acts as a buffer with HHb) 10 fluid levels Regulates fluid levels in tissues (with Lymphatic system) 11 hormonesTransports hormones around the body 9
The human heart has 4 well developed chambers Right Atrium Left Atrium Right Ventricle Left Ventricle
The right side of the heart pumps deO 2 blood to the lungs.PULMONARY The left side of the heart pumps O 2 blood to the bodySYSTEMIC
Right Atrium Left Atrium deoxygenated vena cava. Receives deoxygenated blood from the body via the anterior & posterior vena cava. oxygenated pulmonary veins Receives oxygenated blood from the lungs via the pulmonary veins
backwards 3. They prevent the blood from going backwards when the ventricles contract. atria ventricles 1. Separate the atria from the ventricles. atria contract 2. They open when the atria contract. Bicuspid Valve Tricuspid Valve
Tendon-like pieces of tissue They keep the AV valves from inverting when the ventricles contract
They hold & support the chordae tendinae
Closed Normal Heart Valves Heart Murmur Can’t close properly Open Can’t open properly
When the right atrium contracts, it pushes the blood through the tricuspid valve and into the 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. 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. The BP forces PULMONARY VALVE open & the blood moves into the PULMONARY TRUNK. Right Ventricle
CO 2 O 2 The CO 2 is removed from the blood and is replaced with O 2. The PULMONARY ARTERIES take the deO 2 blood to the lungs. The PULMONARY VEINS take the O 2 blood to the heart.
HEMOGLOBIN OXYHEMOGLOBIN The protein HEMOGLOBIN binds the O 2 tightly and carries it to the body cells as OXYHEMOGLOBIN!
muscular wall separates A muscular wall that separates the right side of the heart from the left side. deO 2 mixingO 2 Keeps the deO 2 blood from mixing with the O 2 blood
Some people are born with a hole in their septum
AORTIC VALVE AORTA Blood is forced through the AORTIC VALVE and enters the AORTA. The left ventricle has a THICKER muscle layer. WHY? LEFT VENTRICLE BICUSPID VALVE When the LEFT VENTRICLE contracts, the BICUSPID VALVE is forced closed. Left Ventricle When the left atrium contracts, it pushes the blood through the bicuspid valve and into the left ventricle. When the left atrium contracts, it pushes the blood through the bicuspid valve and into the left ventricle.
O 2 The aorta takes O 2 blood to the body. Aortic Arch Dorsal Aorta To the head To the arms & lungs To the lower body Coronary Artery: to the heart
first branches coronary arteries The first branches of the aorta take the blood to the coronary arteries. heart muscle vena cava Takes blood into the heart muscle itself. The coronary veins return the deO 2 blood to the vena cava right atrium.
These are the BIGGEST VEINS! deO 2 They bring the deO 2 blood back to the heart so that it can be pumped to the lungs. Superior Vena Cava Inferior Vena Cava
Superior vena cava Coronary artery Right Atrium Right Ventricle Left Ventricle Pulmonary Trunk Aortic Arch Coronary Vein Inferior Vena Cava
Inferior Vena Cava Superior Vena Cava Right Atrium Tricuspid (AV) Valve Right Ventricle Pulmonary (semi-lunar) Valve Pulmonary Trunk Left Pulmonary Artery Right Pulmonary Artery Left Pulmonary Veins Right Pulmonary Veins Left Atrium Bicuspid (AV) Valve Aortic (semi- lunar) Valve Left Ventricle Aortic Arch Dorsal Aorta
ATP Heart cells naturally beat slowly if ATP is present no coordination randomly If there was no coordination, the heart cells would all beat randomly Beating Human Heart:
specialized tissueThere are two spots of specialized tissue in the heart. right atrium Both are located in the right atrium. muscle cells nerve cells Nodal tissue is unique: made of specialized muscle cells combined with nerve cells. contract It has the ability to contract independent of other stimuli.
SA NODE The SA NODE (sino-atrial) right atrium This node is found along the wall of the right atrium chamber seconds It fires on average, every 0.85 seconds (or 72 times per minute). contraction of the atria It stimulates the simultaneous contraction of the atria. AV NODE It also sends a nerve impulse along a nerve trunk called the BUNDLE OF HIS to the AV NODE
S A NODE
The SA node initiates the heartbeat and has been given the nickname of the “PACEMAKER” PACEMAKER People with irregular heartbeats may have to have an artificial pacemaker ‘inserted’. a small electronic device that stimulates the SA node to fire
The AV NODE (atrioventricular) PURKINJE FIBRES A.V. NODE In the right atrium close to the AV (tricuspid) valve When the AV node receives the impulse from the SA node, it fires to initiate the contraction of the LARGE ventricles P.F. The AV node sends its message through the P.F., which cause ventricles to contract.
A V NODE & Purkinje fibres
bottom up. Atria beat from top down, then pause, and the ventricles beat from bottom up.
EKG There are two parts to the contraction of the heart An EKG (electrocardiogram) registers the voltage changes across the surface of the heart as it beats. The heart beat is a double sound ( ‘lub- dub’ ). The letters PQRST are the standard labels used to identify the parts of the EKG.
P = the simultaneous contraction of the atria (caused by SA node) QRS = the contraction of the ventricles (caused by AV node & purkinje fibres) T = the recovery of the ventricles (preparation for next contraction)
P R Q T S KNOW THIS DIAGRAM! KNOW THIS DIAGRAM!!
Some Abnormal EKG’s Tachycardia (a heart rate of over 100 beats/min) Ventricular Fibrillation (uncoordinated ventricles) Heart Block ( failure to stimulate ventricles after atrial contraction ) NORMAL
fibrillation If the system really breaks down, the heart could go into fibrillation. This is uncoordinated contractions of the cardiac muscle. strong shock When this happens, the pacemaker (SA NODE) will send a strong shock through the heart. This is known as defibrillation reset itself Hopefully the heart muscle will reset itself.
We also try to do this artificially when people are in cardiac arrest!
72 beats per minute The natural average resting heart rate is 72 beats per minute The SA node is connected to the brain by the VAGUS NERVE (cranial nerve #10).
AUTONOMIC NERVOUS SYSTEM The 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.
MEDULLA OBLONGATA The 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.
Hardening of the arteries
Cholesterol 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
Perform your own heart transplant:
Made from titanium metal and a special type of plastic. A rechargeable internal battery Normally an external power pack transmits power across the skin.
What is YOUR pulse rate at rest? After exercise? 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. 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.
70 mL BLOOD PRESSURE: the ventricles pump approx. 70 mL of blood each time they contract. stopping and starting arteries The pulse you feel is blood stopping and starting as it moves through your arteries.
SYSTOLIC PRESSURE (systole): blood pressure when the ventricles are contracting. Blood is being forced through the arteries (approx. 120 mmHg)
DIASTOLIC PRESSURE DIASTOLIC PRESSURE (diastole): blood pressure as ventricles are refilling. This is between contractions, and the blood pressure is less ( appox 80 mmHg ).
BRACHIAL ARTERY Blood pressure is normally measured along the BRACHIAL ARTERY of the arm. A reading of 120/80 mmHg is normal.
When you are younger, your BP will be higher. Example: yrs. will be over 86-92
HIGH BLOOD PRESSURE (ie: 150/100)
Limit Alcohol Be Active Lose Weight Eat Healthy Eat less salt Don’t Smoke High blood pressure sometimes goes unnoticed until complications set in.
High Blood Pressure puts constant strain on the tissues (especially the capillary beds). May cause capillaries to burst The longer you have high BP, the greater the potential for tissue damage. Sometimes high BP is normal (ie: when doing physical activity) If this happens in the brain = a stroke. If it happens in the heart = heart attack! However, the brain should return the BP to a normal, lower level.
LOW BLOOD PRESSURE (ie: 100/60)
Low blood pressure is not particularly a good thing either. kidney function Proper kidney function can only be maintained if there is sufficient pressure for filtration. Genetics Anemia *not enough iron* Dehydration *not enough water* Blood loss Shock It can result from:
1.Vessel diameter 1.Vessel diameter: bigger (dilate) = lower BP smaller (constrict) = higher BP Vasodilation to lower BP Vasoconstriction to increase BP
2.Blood viscosity 2.Blood viscosity: Thick blood (little water) = higher BP Thin (lots of water) = lower BP
3.Total blood vessel length 3.Total blood vessel length: More fat = higher BP Thinner = lower BP More fat = more vessels = more resistance = increased BP
4.Vessel elasticity 4.Vessel elasticity: affected by plaques (fatty deposits). Elastic vessels = lower BP Hardened vessels = high BP ATHEROSCLEROSIS (hardening of arteries = decreased elasticity).
Sweat a lot = less volume/water = lower BP Eat lots of salt = more volume/water stays in body = higher BP 5.Blood volume 5.Blood volume:
6.Cardiac output 6.Cardiac output: Heart rate increases = higher BP Heart rate decreases = lower BP
7.Age 7.Age: as you get older, there is a loss of elasticity in the blood vessels. Old = not elastic = high BP Young = very elastic = low BP
8.Stress 8.Stress: constricts blood vessels which means increased pressure to move the blood. Stressed = constricted vessels = Higher BP Calm = normal vessels = Lower BP
Heart Animations and Interactives Animation: Your heart valves at work Interactive: Label the heart Interactive: Listen to the heart with a virtual stethoscope Interactive: Explore the structures of the heart and trace the pathway of blood through the heart, lungs, and body Animation: See the flow of blood to and from the exterior heart