.

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

_____ Aorta_____ 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?

• 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 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

• Transports oxygen from the lungs to body to be used

1

• Transports carbon dioxide and hydrogen ionshydrogen ions to the lungs to be removed

2

• Transports nutrients nutrients from the small intestine to tissues

3

• Fights infectionsinfections4

• Transports waterwater from the digestive system to the body and lungs

5

• Carries waste waste products (ie: urea) to kidneys for removal in urine

6

• Distributes body heatbody heat from internal source to skin (to get rid of it)

7

• Seals wounds wounds by forming blood clots

8

• Maintains pHpH in tissues (acts as a buffer with HHb)

10

Regulates fluid levelsfluid levels in tissues (with Lymphatic system)

11

• Transports hormoneshormones around the body

9

The human heart has The human heart has 44 well developed chambers well developed chambers

Right Atrium

Left Atrium

Right Ventricle

Left Ventricle

The right side of the heart pumps deO2 blood to the lungs.

PULMONARYPULMONARY

The left side of the heart pumps O2 blood to the body

SYSTEMICSYSTEMIC

Right AtriumLeft Atrium

Receives deoxygenateddeoxygenated

blood from the body via the

anterior & posterior vena vena

cava.cava.

Receives oxygenated oxygenated blood from the lungs via the pulmonary veinspulmonary veins

3. They prevent the blood from going backwardsbackwards when the ventricles contract.

1. Separate the atriaatria from the ventriclesventricles.

2. They open when the atria atria contractcontract.

Bicuspid Valve

Tricuspid Valve

Bicuspid Bicuspid ValveValve

Tendon-like pieces of tissue

They keep They keep the AV the AV valves from valves from inverting inverting when the when the ventricles ventricles contractcontract

They hold & They hold & support the support the chordae chordae tendinaetendinae

Closed

Normal Heart Normal Heart ValvesValves

Heart MurmurHeart Murmur

Can’t close properly

Open

Can’t open properly

• When the right atrium contracts, it pushes the blood When the right atrium contracts, it pushes the blood through the through the tricuspid tricuspid valve and into the valve and into the right ventricleright ventricle. .

• When the When the RIGHT RIGHT VENTRICLEVENTRICLE contracts, BP contracts, BP forces the forces the TRICUSPID TRICUSPID valve to closevalve to close. .

• The BP forces The BP forces PULMONARY VALVEPULMONARY VALVE open & the blood moves open & the blood moves into the into the PULMONARY PULMONARY TRUNK.TRUNK.

Right Ventricle

The COCO22 is removed from the blood and is replaced with OO22.

The The PULMONARY PULMONARY ARTERIESARTERIES take the take the dedeOO22

blood to the lungs.blood to the lungs.

The The PULMONARY PULMONARY VEINSVEINS take the take the OO22

blood to the blood to the heart.heart.

The protein HEMOGLOBINHEMOGLOBIN binds the O2 tightly and

carries it to the body cells as OXYHEMOGLOBINOXYHEMOGLOBIN!

A muscular wallmuscular wall that separatesseparates the right side of the heart from the left side.

Keeps the deOdeO22 blood from mixingmixing with the OO22 blood

Some people are born with a hole in their septum

• Blood is forced through the AORTIC VALVEAORTIC VALVE and enters the AORTAAORTA.

• The left ventricle has a

THICKER muscle layer. WHY?

• When the LEFT LEFT VENTRICLEVENTRICLE contracts, the BICUSPID VALVEBICUSPID VALVE is forced closed.

Left Ventricle

• When the left atrium contracts, it pushes the blood When the left atrium contracts, it pushes the blood through the through the bicuspid valvebicuspid valve and into the and into the left ventricleleft ventricle. .

The aorta takes OO22 blood to the body.

Aortic Arch

Dorsal Aorta

•To the head

•To the arms & lungs

•To the lower body

•Coronary Artery: to the heart

The first branchesfirst branches of the aorta take the blood to the coronary arteriescoronary arteries.

Takes blood into the heart muscleheart muscle itself. The coronary veins return the deO2 blood to the vena cavavena cava right atrium.

These are the BIGGEST VEINS!

They bring the deOdeO22 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 ArteryRight Pulmonary

Artery

Left Pulmonary VeinsRight Pulmonary

Veins Left Atrium

Bicuspid (AV) Valve

Aortic (semi-lunar) ValveLeft

Ventricle

Aortic Arch

Dorsal Aorta

• Heart cells naturally beat slowly if ATP ATP is present

• If there was no no coordinationcoordination, the heart cells would all beat randomlyrandomly

Beating Human Heart: http://www.youtube.com/watch?v=iX6HnUyzgQ0&feature=related

http://www.youtube.com/watch?v=GgPe3k-lK8c&feature=related

•There are two spots of specialized tissuespecialized tissue in the heart.

• Both are located in the right atriumright atrium.

• Nodal tissue is unique: made of specialized muscle muscle cellscells combined with nerve cellsnerve cells.

• It has the ability to contractcontract independent of other stimuli.

SA NODE

The SA NODE (sino-atrial)The SA NODE (sino-atrial)

This node is found along the wall of the right atriumright atrium chamber.

It fires on average, every 0.85 seconds0.85 seconds (or 72 times per minute).

It stimulates the simultaneous contraction contraction of the atriaof the atria.

It also sends a nerve impulse along a nerve trunk called the BUNDLE OF HIS to the AV NODEAV 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

http://www.youtube.com/watch?v=CxJS0oEQeBQ

The AV NODE (atrioventricular)

PURKINJE PURKINJE FIBRESFIBRES

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

• The AV node sends its message through the P.F.P.F., which cause ventricles to contract.

A

VNODE

&

Purkinje fibres

• Atria beat from top down, then pause, and the ventricles beat from bottom bottom up. up.

http://www.youtube.com/watch?

v=ew6Jp74vaN4

http://www.youtube.com/watch?v=nK0_28q6WoM

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

EKGEKG

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

QTS

KNOW THIS DIAGRAM!

KNOW THISKNOW THIS

DIAGRAM!!DIAGRAM!!

Some Abnormal EKG’sSome 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

• If the system really breaks down, the heart could go into fibrillationfibrillation. This is uncoordinated contractions of the cardiac muscle.

• When this happens, the pacemaker (SA NODE) will send a strong shockstrong shock through the heart.

• This is known as defibrillation

• Hopefully the heart muscle will reset itselfreset itself.

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

The natural average resting heart rate is 72 beats per minute72 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 SYSTEMAUTONOMIC 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.

The part of the brain that governs the speed of the heart rate is called the MEDULLA OBLONGATAMEDULLA 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: http://www.pbs.org/wgbh/nova/eheart/transplantwave.html

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?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.

BLOOD PRESSURE: the ventricles pump approx. 70 mL70 mL of blood each time they contract.

The pulse you feel is blood stopping and startingstopping and starting as it moves through your arteriesarteries.

SYSTOLIC PRESSURE (systole): blood pressure when the ventricles are contracting.

Blood is being forced through the arteries (approx. 120 mmHg)

DIASTOLIC PRESSUREDIASTOLIC PRESSURE (diastole): blood pressure as ventricles are refilling.

This is between contractions, and the blood pressure is less (appox 80 mmHg).

Blood pressure is normally measured along the BRACHIAL ARTERYBRACHIAL 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)HIGH BLOOD PRESSURE (ie: 150/100)

Limit Alcohol Be Active

Lose Weigh

t

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 (ie: 100/60)

Low blood pressure is not particularly a good thing either.

Proper kidney functionkidney 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:

1.1. Vessel diameterVessel diameter:

bigger (dilate) = lower BP smaller (constrict) = higher BP

Vasodilation to Vasodilation to lower BPlower BP

Vasoconstriction Vasoconstriction to increase BPto increase BP

2.2. Blood viscosityBlood viscosity:

Thick blood (little water) = higher BP Thin (lots of water) = lower BP

3.3. Total blood vessel lengthTotal blood vessel length:

More fat = higher BP Thinner = lower BP

More fat = more vessels = more resistance = increased BPMore fat = more vessels = more resistance = increased BP

4.4. Vessel elasticityVessel 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

5.5. Blood volumeBlood volume:

6.6. Cardiac outputCardiac output:

Heart rate increases = higher BP Heart rate decreases = lower BP

7.7. AgeAge: as you get older, there is a loss of elasticity in the blood vessels.

Old = not elastic = high BP

Young = very elastic = low BP

8.8. StressStress: constricts blood vessels which means increased pressure to move the blood.

Stressed = constricted vessels = Higher BP

Calm = normal vessels = Lower BP

Heart Animations and InteractivesHeart 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