The Circulatory SystemThe Circulatory System

Blood, Blood Vessels and the Blood, Blood Vessels and the HeartHeart

C5: 5 types of Blood VesselsC5: 5 types of Blood Vessels

a. arteriesa. arteries

b. b. arteriolesarterioles

c. veinsc. veins

d. venulesd. venules

e. e. capillariescapillaries

ArteriesArteries Have thick,

muscular walls so they are able to withstand the blood pressure coming from the heart

Carry blood AWAY from the heart

Elastic: handle change in blood volume after each ventricular contraction

ArteriolesArterioles Small arteries are called ARTERIOLES

Not as elasticNot as elastic as arteries

They relax causing the arteriole to dilate, resulting in the opposite effect: increase blood volume, decrease pressure

VeinsVeins Carry blood

TOWARDS heart Have a thin

muscle layer Contain VALVES

to help the blood return to the heart

Small veins are called venules

Valves in VeinsValves in Veins

there is there is not enough not enough blood pressure blood pressure to to make the blood make the blood return all the way to return all the way to the heartthe heart

One-way valves and One-way valves and the the skeletal skeletal muscles muscles work together to work together to squish the blood squish the blood back heartback heart

Varicose Varicose VeinsVeins If the If the valves

malfunction in the legs, a in the legs, a painful painful condition can condition can resultresult

Called Called Varicose veinsVaricose veins

Allows blood Allows blood to pool in the to pool in the elastic veins, elastic veins, causing them causing them to bulgeto bulge

Varicose veins in Varicose veins in rectum are called rectum are called hemorrhoidshemorrhoids..

CapillariesCapillaries Connect the veins Connect the veins

and arteriesand arteries Site of gas exchange Site of gas exchange

between blood and between blood and cellscells

Oxygen, nutrients Oxygen, nutrients and water and water diffuse out of the blood and out of the blood and into the cellsinto the cells

Carbon dioxide, Carbon dioxide, wastes and water wastes and water diffuse out of the diffuse out of the cells and into the cells and into the bloodblood

Capillaries Capillaries have extremely have extremely thin walls for for diffusion. diffusion.

Comparison of Comparison of Blood vesselsBlood vessels

Most of the bp Most of the bp that came that came from the heart from the heart is lost when is lost when the blood the blood travels travels through the through the capillariescapillaries

That is why That is why you need you need VALVES in VALVES in your veins. your veins.

C3: Your Heart – structure C3: Your Heart – structure and functionand function

Mostly Mostly Muscle Beats about 65-75 times Beats about 65-75 times

per minuteper minute Is comparable to Is comparable to two

pumps joined together joined together Has 4 chambers: Has 4 chambers:

Right Atrium, right Right Atrium, right ventricleventricle

Left Atrium, Left Left Atrium, Left VentricleVentricle

Anatomy diagrams Anatomy diagrams are labelled as if you are labelled as if you are looking down on a are looking down on a patient (unless patient (unless otherwise indicated) otherwise indicated)

Therefore, the R.A. is Therefore, the R.A. is the patient’s right – the patient’s right – not yours!not yours!

PIG HEARTPIG HEART

Structure of the HeartStructure of the Heart 4 4 One-Way-ValvesOne-Way-Valves between the atria and the between the atria and the

ventricles on both sides = ventricles on both sides = Atrioventricular valves

at the exit of both at the exit of both ventricles = ventricles = semi-lunar valves

prevent blood from prevent blood from flowing backwards flowing backwards

If one of your valves is If one of your valves is defective, you might have defective, you might have a “heart murmur”. a “heart murmur”.

Top View (looking down)

Chordae TendineaeChordae Tendineae Anchor AV Anchor AV

valves on valves on ventricles to ventricles to prevent valves prevent valves from invertingfrom inverting

Chordae TendineaeChordae Tendineae

Demonstrate the flow of Demonstrate the flow of blood from the aorta blood from the aorta through the body and through the body and

back to the left ventricle.back to the left ventricle.

good overview of circulation through heart, nodal control

Flow of Flow of Blood Blood througthrough the h the heartheart

Blood enters Blood enters the R.atrium the R.atrium via the superior via the superior and inferior and inferior vena cavavena cava

When the Atria When the Atria contract, blood contract, blood moves from the moves from the R.A. to the R.A. to the R.Ventricle, R.Ventricle, passing the AV passing the AV valve as it goesvalve as it goes

The The ventricles ventricles contract, and contract, and force the force the blood through blood through the semi-the semi-lunar valve lunar valve and out to and out to the body via the body via the AORTAthe AORTA

Blood Flow Video

Both atria fill and Both atria fill and contract at the contract at the same time. same time.

Both ventricles Both ventricles will fill and will fill and contract at the contract at the same timesame time

The first heart sound, “lub” The first heart sound, “lub” occurs when the AV valves occurs when the AV valves

close. The second heart close. The second heart sound “dub” occurs when sound “dub” occurs when the other valves close. the other valves close.

distinguish between distinguish between systolic and diastolic systolic and diastolic

pressurespressures When the When the

cardiac muscle cardiac muscle contracts it is contracts it is calledcalled Systole Systole

When the When the chamber chamber relaxes it is relaxes it is called diastolecalled diastole

the SA node, AV node, and the SA node, AV node, and Purkinje fibres Purkinje fibres

    Our Our heartbeat is heartbeat is INTRINSICINTRINSIC. .

    SPECIAL TISSUESPECIAL TISSUE, , called called NODAL TISSUENODAL TISSUE, , has has characteristics of characteristics of both nerve and muscle both nerve and muscle tissuetissue, controls the , controls the heartbeat.heartbeat.

There are There are TWOTWO nodal nodal regions in the heart:regions in the heart:

1. SA (sinoatrial) NODE1. SA (sinoatrial) NODE

Located Located upper back upper back wallwall of of right atriumright atrium. .

INITIATES THE INITIATES THE HEARTBEATHEARTBEAT every every 0.85 seconds to make 0.85 seconds to make the the ATRIA CONTRACTATRIA CONTRACT. .

SA Node

The SA node is The SA node is called the called the ““PACEMAKER”” because it keeps the because it keeps the beat beat regular. .

ARTIFICIAL ARTIFICIAL PACEMAKERsPACEMAKERs, will , will send out an electric send out an electric signal every 0.85 signal every 0.85 seconds to stabilize seconds to stabilize the heart rate if the the heart rate if the SA node doesn’t SA node doesn’t work.work.

2.2. AV (atrioventricular) NODEAV (atrioventricular) NODE:: Located Located base of the R.A. base of the R.A.

near the septum.near the septum. When the pulse from SA When the pulse from SA

Node reaches AV node, the Node reaches AV node, the AV node will send out a AV node will send out a signal along conducting signal along conducting fibers called fibers called PURKINJE PURKINJE FIBERSFIBERS. They take the . They take the message to the message to the VENTRICLESVENTRICLES, and cause , and cause them to them to contractcontract. .

The contraction of the The contraction of the ventricles begins at the base ventricles begins at the base of the heart and moves up of the heart and moves up like a wave.like a wave.

SA Node

AV Node

Purkinje Fibers

Video Clip

autonomic autonomic regulation of regulation of

the heartbeat the heartbeat

Heart under Heart under involuntary control involuntary control by the brain by the brain MEDULLA OBLANGATA, ,

This center can This center can increase or decrease increase or decrease the heart rate the heart rate

Various factors, such as Various factors, such as stressstress, , oxygen levelsoxygen levels, , and and bpbp determine how determine how the ANS will affect heart the ANS will affect heart rate.rate.

distinguish between distinguish between pulmonary and systemic pulmonary and systemic

circulationcirculationHeart Beat

Heart in a Box

Flow of Blood: Blood travels in Flow of Blood: Blood travels in 2 loops2 loops

A. The Pulmonary A. The Pulmonary system system

- goes from the heart - goes from the heart to the lungs and to the lungs and back to the heart back to the heart againagain

Only place where deoxygenated Only place where deoxygenated blood is in ARTERIES, and blood is in ARTERIES, and oxygenated blood is in VEINSoxygenated blood is in VEINS

Pulmonary artery

Pulmonary Vein

Aorta

Superior Vena Cava

Inferior Vena Cava

ReviewReview

b. Systemic b. Systemic CircuitCircuit

When L. ventricle When L. ventricle pumps to push the pumps to push the blood to rest of bodyblood to rest of body

This ensures there is This ensures there is ample blood pressure ample blood pressure for the blood to for the blood to deliver it’s oxygen deliver it’s oxygen and nutrients to the and nutrients to the cellscells

The Coronary ArteriesThe Coronary Arteries The heart does not The heart does not

use the blood inside use the blood inside the atria or the atria or ventricles to get it’s ventricles to get it’s nutrients and nutrients and oxygenoxygen

Has own set of Has own set of arteries and veins to arteries and veins to supply oxygen and supply oxygen and nutrients = nutrients = coronary arteries

Circulatory ReviewCirculatory Review

Circulatory rap

AtherosclerosisAtherosclerosis

Excess fat and Excess fat and cholesterol stick to cholesterol stick to the arteries, forming the arteries, forming a PLAQUE a PLAQUE

Plugs up the arteries, Plugs up the arteries, restricting blood flowrestricting blood flow

If the blood flow that If the blood flow that is restricted is to the is restricted is to the heart, a heart attack heart, a heart attack may occurmay occur

Angioplasty – Angioplasty – possible possible procedure if the blockage isn’t too procedure if the blockage isn’t too

severesevere

Heart AttackHeart Attack When the cells of the heart do not get When the cells of the heart do not get

enough oxygenenough oxygen The severity of the attack depends on The severity of the attack depends on

how bad the coronary artery blockage is, how bad the coronary artery blockage is, and how many heart cells dieand how many heart cells die

At first, the victim may suffer angina pectoris (radiating pain in the left arm).

One cause of One cause of heart attack: heart attack:

SmokingSmoking Nicotine causes Nicotine causes

heart to pump heart to pump fasterfaster

Also causes some Also causes some arteries to contract arteries to contract (get smaller)(get smaller)

Puts unneeded Puts unneeded strain on the heart strain on the heart musclemuscle

            Coronary Bypass Coronary Bypass SurgerySurgery: segments of leg veins : segments of leg veins are grafted between the aorta are grafted between the aorta and coronary vessels, in order to and coronary vessels, in order to bypass a blockagebypass a blockage. Two to . Two to four such bypasses may be four such bypasses may be performed in a single operation. performed in a single operation. e.g. three such grafts would be e.g. three such grafts would be known as a “triple-bypass” known as a “triple-bypass” operation.operation.

            Coronary bypassCoronary bypass, , donor donor heart transplantsheart transplants, and , and artificial artificial heart implantationheart implantation (which don’t (which don’t work yet!) are surgical methods work yet!) are surgical methods that have been used for the that have been used for the treatment of heart attacks.treatment of heart attacks.

            More than More than 50% of all 50% of all deathsdeaths in Canada & U.S. are in Canada & U.S. are due to hypertension (high blood due to hypertension (high blood pressure), stroke, and heart pressure), stroke, and heart attack.attack.

Heart AttackHeart Attack: when : when portion of heart dies due portion of heart dies due to lack of oxygen. At to lack of oxygen. At first, the victim may first, the victim may suffer suffer angina pectorisangina pectoris (radiating pain in the left (radiating pain in the left arm). Death may result arm). Death may result if immediate treatment if immediate treatment not given.not given.

Some more nasty circulatory events:Some more nasty circulatory events:ThrombusThrombus: a stationary clot attached to an arterial : a stationary clot attached to an arterial wall. Slows the flow of blood.wall. Slows the flow of blood.EmbolusEmbolus: a thrombus that has become : a thrombus that has become dislodgeddislodged and and movesmoves along with the blood. When the vessel along with the blood. When the vessel narrows, the embolus gets stuck and narrows, the embolus gets stuck and entirely blocksentirely blocks the flow of blood in a small vessel. This is called an the flow of blood in a small vessel. This is called an embolismembolism..

StrokeStroke: when : when portion of brain dies portion of brain dies due to lack of due to lack of oxygen -- usually oxygen -- usually when arteriole when arteriole bursts or is blocked bursts or is blocked by an embolism. by an embolism. Strokes usually Strokes usually cause death or cause death or paralysis.paralysis.