THE HEART http://www.youtube.com/watch?v=0Vn5AJ_Mjfs&NR=1 http://www.youtube.com/watch?v=m50596VvDPg&feature=related

UNIT K: HEART STRUCTURE & FUNCTION (Ch. 13, pp. 228-233) 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

VOCABULARY _____ Aorta _____ Inferior Vena Cava _____ Aortic valve _____ Atrioventricular (AV) valves _____ Atrium _____ Autonomic nervous system _____ AV node _____ Blood pressure _____ Brachial artery _____ Bundle of His _____ Chordae tendineae _____ Constrict _____ Coronary arteries _____ Coronary veins _____ Dilate _____ Hypertension _____ Hypotension _____ Hypothalamus _____ Inferior Vena Cava _____ Medulla oblongata _____ Pacemaker _____ Pulmonary artery _____ Pulmonary circuit _____ Pulmonary trunk _____ Pulmonary valve _____ Pulmonary vein _____ Purkinje fibres _____ SA node _____ Semi-lunar valve _____ Septum _____ Superior Vena Cava _____ Systemic circuit _____ Vagus nerve _____ Ventricle

Amazing 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

approximately 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 35-40 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

Basic Functions of the Circulatory System Transports oxygen from the lungs to body to be used 1 Transports carbon dioxide and hydrogen ions to the lungs to be removed 2 Transports nutrients from the small intestine to tissues 3 Fights infections 4

Transports water from the digestive system to the body and lungs 5 Carries waste products (ie: urea) to kidneys for removal in urine 6 Distributes body heat from internal source to skin (to get rid of it) 7 Seals wounds by forming blood clots 8

Transports hormones around the body 9 Maintains pH in tissues (acts as a buffer with HHb) 10 Regulates fluid levels in tissues (with Lymphatic system) 11

ANATOMY OF THE HEART

Where is it?

The Parts You Need To Know!

The human heart has 4 well developed chambers Right Atrium Left Atrium Right Ventricle The right side of the heart feeds the pulmonary circuit, and the left side feeds the systemic circuit. Left Ventricle

The right side of the heart pumps deO2 blood to the lungs. PULMONARY The left side of the heart pumps O2 blood to the body SYSTEMIC

the receiving chambers ATRIA the receiving chambers Left Atrium Right Atrium Receives oxygenated blood from the lungs via the pulmonary veins Receives deoxygenated blood from the body via the anterior & posterior vena cava.

ATRIOVENTRICULAR VALVES Tricuspid Valve 1. Separate the atria from the ventricles. Bicuspid Valve 2. 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.

bicuspid valve tricuspid valve

the real thing

Bicuspid Valve

CHORDAE TENDINAE Tendon-like pieces of tissue They keep the AV valves from inverting when the ventricles contract Point out that this is a TRI-CUSPID valve because it has 3 cusps.

They hold & support the chordae tendinae PAPILLARY MUSCLE

Can’t open properly Closed Open Can’t close properly                               Normal Heart Valves Heart Murmur

VENTRICLES 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

AT 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 LUNGS The PULMONARY VEINS take the O2 blood to the heart.

What carries the Oxygen? The protein HEMOGLOBIN binds the O2 tightly and carries it to the body cells as OXYHEMOGLOBIN!

pulmonary systemic

SEPTUM separates the 2 sides A muscular wall that separates the right side of the heart from the left side. Keeps the deO2 blood from mixing with the O2 blood

hole in the septum Some people are born with a hole in their septum

When 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 Ventricle The left ventricle has a THICKER muscle layer. WHY?

AORTA the biggest artery Aortic Arch Dorsal Aorta To the head To the arms & lungs Aortic Arch Coronary Artery: to the heart Dorsal Aorta To the lower body the biggest artery The aorta takes O2 blood to the body.

CORONARY 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.

VENA 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

exterior view of the heart Aortic Arch Superior vena cava Pulmonary Trunk Coronary artery Right Atrium Coronary Vein Right Ventricle Left Ventricle Inferior Vena Cava

draw the arrows Aortic Arch Superior Vena Cava Left Pulmonary Artery                                                                                                                                                                                                           Aortic Arch Superior Vena Cava Left Pulmonary Artery Right Pulmonary Artery Pulmonary Trunk Left Pulmonary Veins Right Pulmonary Veins Left Atrium Bicuspid (AV) Valve Right Atrium Pulmonary (semi-lunar) Valve Aortic (semi-lunar) Valve Left Ventricle Tricuspid (AV) Valve Right Ventricle Inferior Vena Cava Dorsal Aorta

this all happens at once! Keep in mind that this all happens at once!

CONTROL OF HEART FUNCTION

Why can a heart keep beating outside of the body? ?

Coordination of the Beating • Heart cells naturally beat slowly if ATP is present • If there was no coordination, the heart cells would all beat randomly Beating Human Heart: http://www.youtube.com/watch?v=iX6HnUyzgQ0&feature=related http://www.youtube.com/watch?v=GgPe3k-lK8c&feature=related

How 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.

The 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

S A NODE

The SA node initiates the heartbeat and has been given the nickname of the “PACEMAKER” a small electronic device that stimulates the SA node to fire You can ‘re-set’ your pacemaker by calling a number and holding the phone up to your heart. COOL! http://www.youtube.com/watch?v=CxJS0oEQeBQ People with irregular heartbeats may have to have an artificial pacemaker ‘inserted’.

PACEMAKER

The AV NODE (atrioventricular) 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 A.V. NODE PURKINJE FIBRES Because 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.

A V NODE & Purkinje fibres

the pacemaker cells WHY? • Atria beat from top down, then pause, and the ventricles beat from bottom up. WHY?

E K G http://www.youtube.com/watch?v=ew6Jp74vaN4 See page http://www.youtube.com/watch?v=nK0_28q6WoM

FROG DISECTION http://www.youtube.com/watch?v=fO7lBX5CSxw

There are two parts to the contraction of the heart EKG The 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.

P = 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 ventricles QRS: as ventricles contract, blood is forced into arteries T: restoration of normal electrical condition; preparation for subsequent contraction. T = the recovery of the ventricles (preparation for next contraction)

KNOW THIS DIAGRAM! R Q P S T KNOW THIS DIAGRAM!!

Some 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)

This 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

defibrillator We also try to do this artificially when people are in cardiac arrest!

HOW IS THE BRAIN INVOLVED

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).

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. Sympathetic (fight or flight): causes heart to speed up Parasympathetic: causes heart to slow down (via vagus nerve)

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.

Problems Of The Heart

Hardening of the arteries atherosclerosis

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

burst coronary artery

in men

in women

heart attack !

Before it gets to this point....

Heart Bypass Surgery

After surgery

If it gets too bad to repair... Heart Transplant

Perform your own heart transplant: http://www. pbs

If there isn't one available... Abiocor Heart Made from titanium metal and a special type of plastic. A rechargeable internal battery Normally an external power pack transmits power across the skin.

BLOOD PRESSURE

What 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?

BLOOD 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.

Blood 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)

DIASTOLIC PRESSURE (diastole): blood pressure as ventricles are refilling. This is between contractions, and the blood pressure is less (appox 80 mmHg).

A reading of 120/80 mmHg is normal. 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: 13-15 yrs. will be 136-144 over 86-92

HIGH BLOOD PRESSURE (ie: 150/100) HYPERTENSION HIGH BLOOD PRESSURE (ie: 150/100)

Limit Alcohol Be Active Eat less salt Don’t Smoke Lose Weight High blood pressure sometimes goes unnoticed until complications set in. Limit Alcohol Be Active Eat less salt Don’t Smoke Lose Weight Eat Healthy

High Blood Pressure puts constant strain on the tissues (especially the capillary beds). May cause capillaries to burst If 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.

LOW BLOOD PRESSURE (ie: 100/60) HYPOTENSION LOW BLOOD PRESSURE (ie: 100/60)

Low blood pressure is not particularly a good thing either. It can result from: Genetics Anemia *not enough iron* Dehydration *not enough water* Blood loss Shock Proper kidney function can only be maintained if there is sufficient pressure for filtration.

What Factors Affect Blood Pressure?

bigger (dilate) = lower BP smaller (constrict) = higher BP Vessel diameter: bigger (dilate) = lower BP smaller (constrict) = higher BP Vasodilation to lower BP Our 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

Blood viscosity: Thick blood (little water) = higher BP Thin (lots of water) = lower BP More water in our blood means decreased viscosity and lower resistance and blood pressure.

More fat = more vessels = more resistance = increased BP Total blood vessel length: More fat = higher BP Thinner = lower BP More fat = more vessels = more resistance = increased BP

ATHEROSCLEROSIS (hardening of arteries = decreased elasticity). Vessel elasticity: affected by plaques (fatty deposits). Elastic vessels = lower BP Hardened vessels = high BP Atherosclerosis - 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).

Blood volume: Eat lots of salt = more volume/water stays in body = higher BP Sweat a lot = less volume/water = lower BP Diet 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.

Cardiac output: Heart rate increases = higher BP Heart rate decreases = lower BP Stress 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).  

Young = very elastic = low BP Age: as you get older, there is a loss of elasticity in the blood vessels. Young = very elastic = low BP Old = not elastic = high BP

Stressed = constricted vessels = Higher BP 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  http://www.smm.org/heart/heart/top.html