transports food, hormones, metabolic wastes, and gases (oxygen, carbon dioxide) to and from cells

CARDIOVASCULAR SYSTEM/ CIRCULATORY SYSTEM

Components of the circulatory system include:

A.blood: consisting of liquid plasma and cells

B.blood vessels (vascular system)

the "channels" (arteries, veins, capillaries) which carry blood to/from all tissues

Arteries carry blood away from the heart

Veins return blood to the heartCapillaries are thin-walled

blood vessels in which gas/ nutrient/ waste exchange occurs

C. heart: a muscular pump to move the blood

There are two circulatory "circuits":

A.Pulmonary circulation

involving the "right heart," delivers blood to and from the lungs

The pulmonary artery carries oxygen-poor blood from the "right heart" to the lungs, where oxygenation and carbon-dioxide removal occur

Pulmonary veins carry oxygen-rich blood from the lungs back to the "left heart" 

B. Systemic circulationdriven by the "left heart," carries blood to the rest of the body Food products enter the system from the digestive organs into the portal vein Waste products are removed by the liver and kidneys

All systems ultimately return to the "right heart" via the inferior and superior vena cavae

specialized component of the circulatory system is the lymphatic system, consisting of a moving fluid (lymph/interstitial fluid); vessels (lymphatics); lymph nodes, and organs (bone marrow, liver, spleen, thymus)

Through the flow of blood in and out of arteries, and into the veins, and through the lymph nodes and into the lymph, the body is able to eliminate the products of cellular breakdown and bacterial invasion

Blood Vessels

Arteries and veins run parallel throughout the body with a web-like network of capillaries connecting them

Arteries use vessel size, controlled by the sympathetic nervous system, to move blood by pressure

veins use one-way valves controlled by muscle contractions

Arteries

strong, elastic vessels adapted for carrying blood away from the heart at relatively high pumping pressure

Arteries divide into progressively thinner tubes and eventually become fine branches called arterioles

Blood in arteries is oxygen-rich, with the exception of the pulmonary artery, which carries blood to the lungs to be oxygenated

Arteries transport blood away from the heart

With thick walls composed of an inner endothelium layer, an outer connective tissue layer, and also a thick middle layer of elastic fibers and smooth muscle

The aorta is the largest artery in the body, the main artery for systemic circulation

The major branches of the aorta (aortic arch, ascending aorta, descending aorta) supply blood to the head, abdomen, and extremities

the right and left coronary arteries supply blood to the heart

Veins

Blood leaving the capillary beds flows into a series of progressively larger vessels, called venules, which in turn unite to form veins

Veins are responsible for returning blood to the heart after the blood and the body cells exchange gases, nutrients, and wastesPressure in veins is low, so veins depend on nearby muscular contractions to move blood along

Veins have valves that prevent back-flow of blood

Blood in veins is oxygen-poor, with the exception of the pulmonary veins, which carry oxygenated blood from the lungs back to the heart

The major veins, like their companion arteries, often take the name of the organ served except superior vena cava and the inferior vena cava, which collect blood from all parts of the body (except from the lungs) and channel it back to the heart

At any given time, more than half of the total blood volume is found in veins and venules

If blood is lost due to, for example, hemorrhaging, sympathetic nervous stimulation causes the veins to constrict, providing more blood to the rest of the body. In this way, the veins act as a blood reservoir.

Capillaries

arterioles branch into the microscopic capillaries, or capillary beds, which lie bathed in interstitial fluid, or lymph, produced by the lymphatic system

Capillaries are the points of exchange between the blood and surrounding tissues

Materials cross in and out of the capillaries by passing through or between the cells that line the capillary

HEART

a cone-shaped, muscular organ about the size of a clenched fist

It is located in the thorax between the lungs, anterior to the backbone and posterior to the sternum

Its apex is tilted to the left, and about two-thirds of the heart is located to the left of the body's midline

FUNCTIONS OF THE HEART:

1.Generating blood pressure

Contractions of the heart generate blood pressure, which is responsible for blood movement through the blood vessels

2. Routing blood

the heart separates the pulmonary and systematic circulations, which ensures the flow of oxygenated blood to the tissues

3. Ensuring one-way blood flow

The valves of the heart ensure a one-way flow of blood through the heart and blood vessels

4. Regulating blood supply

Changes in the rate and force of heart contraction match blood delivery to the changing metabolic needs of the tissues, such as during rest, exercise and changes in body position

The heart lies within a sac formed by the pericardial membranes:a. fibrous pericardium, a layer of fibrous connective tissue that adheres to the blood vessels at the heart's base and the sternal wall of the thorax and the diaphragm below

b. parietal pericardium, a serous membrane that is separated by a small space, called the pericardial cavityEpicardium is part of the heart wall which also has two other layers

Myocardium is the thickest part of the heart wall and is made up of cardiac muscleInner endocardium includes an endothelium that not only lines the heart but also continues into and lines the blood vessels. The endotheliums' smooth nature helps prevent blood from clotting unnecessarily

Four chambers of the Heart: the right and left atria and superior to the right and left ventriclesThe atria are smaller and have thinner walls than the ventriclesInternally, the atria are separated by the interatrial septum, and the ventricles are separated by the interventricular septum. Thus, the heart has a right and left side

1.1.Right Coronary Right Coronary 2.2.Left Anterior Descending Left Anterior Descending 3.3.Left Circumflex Left Circumflex 4.4.Superior Vena Cava Superior Vena Cava 5.5.Inferior Vena Cava Inferior Vena Cava 6.6.Aorta Aorta 7.7.Pulmonary Artery Pulmonary Artery 8.8.Pulmonary Vein Pulmonary Vein

1.1.Right Atrium Right Atrium 2.2.Right Ventricle Right Ventricle 3.3.Left Atrium Left Atrium 4.4.Left Ventricle Left Ventricle 5.5.Papillary Muscles Papillary Muscles 6.6.Chordae Tendineae Chordae Tendineae 7.7.Tricuspid Valve Tricuspid Valve 8.8.Mitral Valve Mitral Valve 9.9.Pulmonary ValvePulmonary Valve

Passage of Blood Through the HeartPassage of Blood Through the Heart

Blood follows this sequence through Blood follows this sequence through the heart: superior and inferior vena the heart: superior and inferior vena cava cava →→ right atrium right atrium → tricuspid valve → tricuspid valve →→ right ventricle right ventricle → pulmonary → pulmonary semilunar valve →semilunar valve → pulmonary trunk pulmonary trunk and arteries to the lungs and arteries to the lungs →→ pulmonary pulmonary veins leaving the lungs veins leaving the lungs →→ left atrium left atrium → bicuspid valve →→ bicuspid valve → left ventricle left ventricle → → aortic semilunar valve →aortic semilunar valve → aorta aorta → to → to the bodythe body. .

Right Atriumreceives de-oxygenated blood from the body through the superior vena cava (head and upper body) and inferior vena cava (legs and lower torso)

The sinoatrial node sends an impulse that causes the cardiac muscle tissue of the atrium to contract in a coordinated, wave-like mannerThe tricuspid valve, which separates the right atrium from the right ventricle, opens to allow the de-oxygenated blood collected in the right atrium to flow into the right ventricle

Left Atriumreceives oxygenated blood from the lungs through the pulmonary veinAs the contraction triggered by the sinoatrial node progresses through the atria, the blood passes through the mitral valve into the left ventricle

Right Ventriclereceives de-oxygenated blood as the right atrium contractsThe pulmonary valve leading into the pulmonary artery is closed, allowing the ventricle to fill with bloodOnce the ventricles are full, they contract

As the right ventricle contracts, the tricuspid valve closes and the pulmonary valve opensThe closure of the tricuspid valve prevents blood from backing into the right atrium and the opening of the pulmonary valve allows the blood to flow into the pulmonary artery toward the lungs

Left Ventriclereceives oxygenated blood as the left atrium contractsThe blood passes through the mitral valve into the right ventricleThe aortic valve leading into the aorta is closed, allowing the ventricle to fill with blood

Once the ventricles are full, they contractAs the left ventricle contracts, the mitral valve closes and the aortic valve opensThe closure of the mitral valve prevents blood from backing into the left atrium and the opening of the aortic valve allows the blood to flow into the aorta and flow throughout the body

Superior Vena CavaThe superior vena cava is one of the two main veins bringing de-oxygenated blood from the body to the heart. Veins from the head and upper body feed into the superior vena cava, which empties into the right atrium of the heart

Inferior Vena CavaThe inferior vena cava is one of the two main veins bringing de-oxygenated blood from the body to the heart. Veins from the legs and lower torso feed into the inferior vena cava, which empties into the right atrium of the heart

AortaThe aorta is the largest single blood vessel in the body. It is approximately the diameter of your thumb. This vessel carries oxygen-rich blood from the left ventricle to the various parts of the body.

Pulmonary ArteryThe pulmonary artery is the vessel transporting de-oxygenated blood from the right ventricle to the lungs

Pulmonary VeinThe pulmonary vein is the vessel transporting oxygen-rich blood from the lungs to the left atrium.

Papillary Musclesattach to the lower portion of the interior wall of the ventriclesThey connect to the chordae tendineae, which attach to the tricuspid valve in the right ventricle and the mitral valve in the left ventricleThe contraction of the papillary muscles opens these valvesWhen the papillary muscles relax, the valves close

Chordae Tendineaetendons linking the papillary muscles to the tricuspid valve in the right ventricle and the mitral valve in the left ventricleAs the papillary muscles contract and relax, the chordae tendineae transmit the resulting increase and decrease in tension to the respective valves, causing them to open and closestring-like in appearance and are sometimes referred to as "heart strings

Tricuspid Valveseparates the right atrium from the right ventricle It opens to allow the de-oxygenated blood collected in the right atrium to flow into the right ventricleIt closes as the right ventricle contracts, preventing blood from returning to the right atrium; thereby, forcing it to exit through the pulmonary valve into the pulmonary artery

Mitral Valueseparates the left atrium from the left ventricleIt opens to allow the oxygenated blood collected in the left atrium to flow into the left ventricleIt closes as the left ventricle contracts, preventing blood from returning to the left atrium; thereby, forcing it to exit through the aortic valve into the aorta

Pulmonary Valveseparates the right ventricle from the pulmonary arteryAs the ventricles contract, it opens to allow the de-oxygenated blood collected in the right ventricle to flow to the lungsIt closes as the ventricles relax, preventing blood from returning to the heart

Aortic Valveseparates the left ventricle from the aortaAs the ventricles contract, it opens to allow the oxygenated blood collected in the left ventricle to flow throughout the bodyIt closes as the ventricles relax, preventing blood from returning to the heart

Features of the Circulatory System

PulseThe surge of blood entering the arteries causes their elastic walls to swell, but then they almost immediately recoilThis alternate expanding and recoiling of an arterial wall can be felt as a pulse in any artery that runs close to the surfaceThe pulse rate indicates the heartbeat rate and also gives information about the strength and rhythm of the heartbeat

Blood Pressurethe force of blood against a blood vessel wallTwo aspects of blood pressure are considered: 1) how blood pressure is maintained in the arteries and arterioles, and 2) how blood pressure varies in other parts of the circulatory system

HeartbeatBlood is forced out of the ventricles with each heartbeatThe stroke volume is the volume of blood pumped by a ventricle with each beat

The cardiac output is the volume of blood pumped by one ventricle per minuteIn a resting adult, the cardiac output is usually about five liters--approximately the amount of blood in the body

Heart SoundsA heartbeat produces the familiar "lub-dub" soundsThese sounds are due to vibrations caused by pressure changes that occur when the chambers contract and the valves close

The "lub" sounds is heard when the ventricles contract and the atrioventricular valves closeThis sound lasts longer and has a lower pitch than the "dub" sound, which is heard when the semilunar valves close and the ventricles relax

Extrinsic Control of HeartbeatExtrinsic Control of Heartbeat

A A cardiac control centercardiac control center in the in the medulla oblongata speeds up or medulla oblongata speeds up or slows down the heart rate by way slows down the heart rate by way of the autonomic nervous system of the autonomic nervous system branches: branches: parasympathetic systemparasympathetic system (slows heart rate) and the (slows heart rate) and the sympathetic systemsympathetic system (increases (increases heart rate). heart rate).

Hormones Hormones epinephrineepinephrine and and norepinephrinenorepinephrine from the adrenal from the adrenal medulla also stimulate faster heart medulla also stimulate faster heart rate.rate.

Blood FlowBlood Flow

The beating of the heart is The beating of the heart is necessary to homeostasis necessary to homeostasis because it creates pressure that because it creates pressure that propels blood in arteries and the propels blood in arteries and the arterioles.arterioles.

Arterioles lead to the capillaries Arterioles lead to the capillaries where nutrient and gas where nutrient and gas exchange with tissue fluid takes exchange with tissue fluid takes place.place.

Blood Flow in ArteriesBlood Flow in ArteriesBlood pressureBlood pressure due to the pumping due to the pumping

of the heart accounts for the flow of the heart accounts for the flow of blood in the arteries. of blood in the arteries.

Systolic pressureSystolic pressure is high when the is high when the heart expels the blood. heart expels the blood.

Diastolic pressureDiastolic pressure occurs when the occurs when the heart ventricles are relaxing. heart ventricles are relaxing.

Both pressures decrease with Both pressures decrease with distance from the left ventricle distance from the left ventricle because blood enters more and because blood enters more and more arterioles and arteries.more arterioles and arteries.

Blood Flow in CapillariesBlood Flow in Capillaries

Blood moves slowly in capillaries Blood moves slowly in capillaries because there are more because there are more capillaries than arterioles. capillaries than arterioles.

This allows time for substances This allows time for substances to be exchanged between the to be exchanged between the blood and tissues.blood and tissues.

Blood Flow in VeinsBlood Flow in Veins

Venous blood flow is dependent Venous blood flow is dependent upon:upon:

1)1) skeletal muscle contraction, skeletal muscle contraction,

2)2) presence of valves in veins, and presence of valves in veins, and

3)3) respiratory movements. respiratory movements. Compression of veins causes Compression of veins causes

blood to move forward past a blood to move forward past a valve that then prevents it from valve that then prevents it from returning backward. returning backward.

Changes in thoracic and abdominal Changes in thoracic and abdominal pressure that occur with breathing pressure that occur with breathing also assist in the return of blood. also assist in the return of blood.

Varicose veinsVaricose veins develop when the develop when the valves of veins become weak. valves of veins become weak.

HemorrhoidsHemorrhoids (piles) are due to (piles) are due to varicose veins in the rectum. varicose veins in the rectum.

PhlebitisPhlebitis is inflammation of a vein is inflammation of a vein and can lead to a blood clot and and can lead to a blood clot and possible death if the clot is dislodged possible death if the clot is dislodged and is carried to a pulmonary vessel.and is carried to a pulmonary vessel.

Cardiovascular DisordersCardiovascular Disorders

Cardiovascular diseaseCardiovascular disease ( (CVDCVD) is the ) is the leading cause of death in Western leading cause of death in Western countries.countries.

Modern research efforts have Modern research efforts have improved diagnosis, treatment, and improved diagnosis, treatment, and prevention.prevention.

Major cardiovascular disorders Major cardiovascular disorders include atherosclerosis, stroke, include atherosclerosis, stroke, heart attack, aneurysm, and heart attack, aneurysm, and hypertension.hypertension.

AtherosclerosisAtherosclerosisAtherosclerosisAtherosclerosis is due to a build-up is due to a build-up

of fatty material (of fatty material (plaqueplaque), mainly ), mainly cholesterol, under the inner lining cholesterol, under the inner lining of arteries. of arteries.

The plaque can cause a The plaque can cause a thrombusthrombus (blood clot) to form.(blood clot) to form.

The thrombus can dislodge as an The thrombus can dislodge as an embolusembolus and lead to and lead to thromboembolismthromboembolism..

Stroke, Heart Attack, and AneurysmStroke, Heart Attack, and Aneurysm

A A cerebrovascular accidentcerebrovascular accident, or , or strokestroke, results when an embolus , results when an embolus lodges in a cerebral blood vessel or a lodges in a cerebral blood vessel or a cerebral blood vessel bursts; a cerebral blood vessel bursts; a portion of the brain dies due to lack portion of the brain dies due to lack of oxygen. of oxygen.

A A myocardial infarctionmyocardial infarction, or , or heart heart attackattack, occurs when a portion of , occurs when a portion of heart muscle dies due to lack of heart muscle dies due to lack of oxygen.oxygen.

Partial blockage of a coronary artery Partial blockage of a coronary artery causes causes angina pectorisangina pectoris, or chest , or chest pain. pain.

An An aneurysmaneurysm is a ballooning of a is a ballooning of a blood vessel, usually in the blood vessel, usually in the abdominal aorta or arteries leading abdominal aorta or arteries leading to the brain.to the brain.

Death results if the aneurysm is in a Death results if the aneurysm is in a large vessel and the vessel bursts.large vessel and the vessel bursts.

Atherosclerosis and hypertension Atherosclerosis and hypertension weaken blood vessels over time, weaken blood vessels over time, increasing the risk of aneurysm.increasing the risk of aneurysm.

Coronary Bypass OperationsCoronary Bypass Operations

A A coronary bypass operationcoronary bypass operation involves removing a segment of involves removing a segment of another blood vessel and replacing another blood vessel and replacing a clogged coronary artery. a clogged coronary artery.

It may be possible to replace this It may be possible to replace this surgery with surgery with gene therapygene therapy that that stimulates new blood vessels to stimulates new blood vessels to grow where the heart needs more grow where the heart needs more blood flow. blood flow.

Clearing Clogged ArteriesClearing Clogged Arteries

AngioplastyAngioplasty uses a long tube uses a long tube threaded through an arm or leg threaded through an arm or leg vessel to the point where the vessel to the point where the coronary artery is blocked; coronary artery is blocked; inflating the tube forces the vessel inflating the tube forces the vessel open. open.

Small metal Small metal stentsstents are expanded are expanded inside the artery to keep it open.inside the artery to keep it open.

Stents are coated with Stents are coated with heparinheparin to to prevent blood clotting and with prevent blood clotting and with chemicals to prevent arterial chemicals to prevent arterial closing.closing.