THE CARDIOVASCULAR SYSTEM

1. The heart pumps blood

2. Blood vessels allow blood to circulate to all parts of the body

3. Blood is the fluid that carries the substances throughout the body

A closed circulatory system made up of the heart, blood, and blood vessels

The function of the cardiovascular system is to deliver oxygen and nutrients and to remove carbon dioxide and other waste products

The Heart

• The heart is located in the thorax between the lungs

• The apex is pointed toward the left hip

• The heart is about the size of your fist

Chambers of the Heart

•Right and left side act as separate pumps

•Four chambers:Two atria act as receiving chambers

Right atriumLeft atrium

•Two ventricles act as discharging chambers

Right ventricleLeft ventricle

Valves

Allow blood to flow in only one direction

Pulmonary (semilunar) valve

Aortic (semilunar) valve

Semilunar valves are between ventricle and the arteries

Valves

The aortic valve shows three thin and delicate cusps. The coronary artery openings can be seen just above. The endocardium is smooth, beneath which can be seen a red-brown myocardium.

Bicuspid valve (left)

Tricuspid valve (right)

Atrioventricular valves are between atria and ventricles

Valves

This is the tricuspid valve. The leaflets and thin and delicate. Just like the bicuspid valve, the leaflets have thin chordae tendineae that attach the leaflet margins to the muscles of the ventricular wall below.

• Valves open as blood is pumped through

• Held in place by chordae tendineae (“heart strings”)

• Close to prevent backflow

The Heart’s Vessels

• Aorta– Leaves left ventricle

• Pulmonary arteries– Leave right ventricle

• Vena cava– Enters right atrium

• Pulmonary veins (four)– Enter left atrium

Stop ~

color the blood flow through the heart.

Practice blood flow through the heart

https://www.youtube.com/watch?v=T2iVqTckmPQ

Coronary Circulation• Blood in the heart chambers does not nourish the

myocardium• The heart has its own nourishing circulatory system• Coronary arteries• Blood empties into the right atrium via the coronary sinus

The Septum

• The wall that separates the right and left side of the heart

Stop

Structure of the mammalian heart

The Heart’s Conduction System

• Intrinsic conduction system (nodal system)– Heart muscle cells

contract, without nerve impulses, in a regular, continuous way

• Special tissue sets the pace

• Contraction is initiated by the sinoatrial node (Pacemaker)

The Heart Cycle

Cardiac cycle – events of one complete heart beat

Mid-to-late diastole – blood flows into ventriclesVentricular systole – blood pressure builds before ventricle contracts, pushing out blood

Early diastole – atria finish re-filling, ventricular pressure is low

The Heart Cycle

• Atria contract simultaneously

• Atria relax, then ventricles contract

• Systole = Contraction of the ventricles

• Diastole = Relaxation of the ventricles

The Cardiac Cycle

• Cardiac cycle – events of one complete heart beat

o Mid-to-late diastole – blood flows into ventricleso Ventricular systole – blood pressure builds

before ventricle contracts, pushing out bloodo Early diastole – atria finish re-filling, ventricle

pressure is low

BLOOD FLOW THROUGH THE HEART

http://www.youtube.com/watch?v=mH0QTWzU-xI

http://www.medmovie.com/mmdatabase/mediaplayer.aspx?Message=VG9waWNpZD03Njg7Q2xpZW50SUQ9NjU7VmVybmFjdWxhcklEPTE%3D-n3cYsAIEoB4%3D

http://www.youtube.com/watch?v=q0s-1MC1hcE&feature=related

http://www.youtube.com/watch?v=NF68qhyfcoM&feature=related

Vocabulary

• Cardiac output (CO)– Amount of blood pumped by each side of the

heart in one minute– CO = (heart rate [HR]) x (stroke volume

[SV])

• Stroke volume [SV]– Volume of blood pumped by each ventricle in

one contraction

• Heart Rate [HR]– The number of beats per minute

• Stroke volume usually remains relatively constant (in the short term)

• Starling’s law of the heart – the more that the cardiac muscle is stretched, the stronger the contraction (over the long term)

However:

• Changing heart rate is the most common way to change cardiac output during exercise.

What increases the heart rate?

• Sympathetic nervous system– Crisis– Low blood pressure

• Hormones– Epinephrine– Thyroxin

• Exercise

• Decreased blood volume

What decreases the heart rate?

• Parasympathetic nervous system

• High blood pressure or blood volume

• Decreased venous return

Blood Vessels

• Taking blood to the tissues and back– Arteries– Arterioles– Capillaries– Venules– Veins

• Walls of arteries are the thickest

• Lumens of veins are larger

Differences between blood vessel types

• Walls of capillaries are only one cell layer thick to allow for exchanges between blood and tissue

Movement of Blood Through Vessels

• Most arterial blood is pumped by the heart

• Veins use the milking action of muscles to help move blood

True capillaries – exchange vessels

– Oxygen and nutrients cross to cells– Carbon dioxide and metabolic waste products

cross into blood

Pulse• Pulse –

pressure wave of blood

• Monitored at “pressure points” where pulse is easily palpated

Blood Pressure

• Measurements by health professionals are made on the pressure in large arteries

• Systolic – pressure at the peak of ventricular contraction

• Diastolic – pressure when ventricles relax• Pressure in blood vessels decreases as the distance

away from the heart increases

Human normal range is variable

• Normal– 140–110 mm Hg systolic– 80–75 mm Hg diastolic

• Hypotension– Low systolic (below 110 mm HG)– Often associated with illness

• Hypertension– High systolic (above 140 mm HG)– Can be dangerous if it is chronic

Stop

Blood pressure/pulse lab

Blood

• The only fluid tissue in the human body

• Classified as a connective tissue

–Living cells = formed elements

–Non-living matrix = plasma

Characteristics of blood

• Color range– Oxygen-rich blood is scarlet red– Oxygen-poor blood is dull red

• pH must remain between 7.35–7.45

• Blood temperature is slightly higher than body temperature

Components of blood

• Plasma

• Erythrocytes (Red Blood cells)

• Leukocytes (White blood cells)

• Platelets

Plasma

• Composed of approximately 90 percent water

• Includes many dissolved substances– Nutrients– Salts (metal ions)– Respiratory gases– Hormones– Waste products– Proteins

• Albumin – regulates osmotic pressure

• Clotting proteins – help to stem blood loss when a blood vessel is injured

• Antibodies – help protect the body from antigens

Formed Elements

• Erythrocytes = red blood cells

• Leukocytes = white blood cells

• Platelets = cell fragments

Erythrocytes = red blood cells

• The main function is to carry oxygen

• Anatomy of circulating erythrocytes– Biconcave disks– Essentially bags of hemoglobin– Anucleate (no nucleus)– Contain very few organelles

• RBC’s outnumber white blood cells 1000:1

Hemoglobin

• Iron-containing protein

• Binds strongly, but reversibly, to oxygen

• Each hemoglobin molecule has four oxygen binding sites

• Each erythrocyte has 250 million hemoglobin molecules

Leukocytes (White blood cells)

• Crucial in the body’s defense against disease

• These are complete cells, with a nucleus and organelles

• Able to move into and out of blood vessels (diapedesis)

• Can move by ameboid motion• Can respond to chemicals released

by damaged tissues• Leukocyte levels in the blood• Normal levels are between 4,000

and 11,000 cells per mm3

• Leukocytosis– Above 11,000 leukocytes/mm3

– Generally indicates an infection

• Leukopenia– Abnormally low leukocyte level– Commonly caused by certain drugs

Platelets

• Derived from ruptured multinucleate cells (megakaryocytes)

• Needed for the clotting process

• Normal platelet count = 300,000/mm3

Blood clot formation

– Collagen fibers are exposed by a break in a blood vessel

– Platelets become “sticky” and cling to fibers– Anchored platelets release chemicals to attract more

platelets– Platelets pile up to form a platelet plug– Blood usually clots within 3 to 6 minutes– The clot remains as endothelium regenerates– The clot is broken down after tissue repair

Undesirable Blood Clots

– Thrombus• A clot in an unbroken blood vessel• Can be deadly in areas like the heart

– Embolus• A thrombus that breaks away and floats freely in the

bloodstream

This section of coronary artery demonstrates a thrombosis with recanalization leaving only two

small, narrow channels.

CARDIOVASCULAR DISORDERS

• greater than or equal to 140 mm Hg systolic pressure or

• greater than or equal to 90 mm Hg diastolic pressure.

• Some people experience high blood pressure only when they visit the doctor's office. This condition is called "white-coat hypertension."

High Blood Pressure

Angina

• Angina (angina pectoris) is a type of temporary chest pain, pressure or discomfort that occurs when the heart is not getting enough oxygen.

• The most common underlying cause of angina is coronary disease artery, which occurs when the coronary arteries that supply the heart with oxygen–rich blood become blocked with plaque deposits

Stable vs. Unstable Angina

• If the angina occurs in predictable situations, such as during exertion or exercise, it is known as stable angina

• If the painful episodes occur without warning, last longer than normal angina episodes and occurs more frequently, it is known as unstable angina. This is a dangerous medical situation that requires prompt medical attention. Unstable angina may signal that a heart attack is impending.

Heart Attack

A heart attack is an event that results in permanent heart damage or death. It is also known as a myocardial infarction, because part of the heart muscle (myocardium) may literally die (infarct). A heart attack occurs when one of the coronary arteries becomes severely or totally blocked, usually by a blood clot.

Heart Attack

Heart Attack

Ruptured septum

Coronary Artery Disease

Coronary artery disease (CAD) is a chronic disease in which the coronary arteries gradually harden and narrow (atherosclerosis).

This is a normal coronary artery. The lumen is large, without any narrowing by plaque deposits. The muscular arterial wall is of normal proportion.

The coronary artery shown here has narrowing of the lumen due to build up of atherosclerotic plaque. Severe narrowing can lead to angina,

ischemia, and infarction.

This distal portion of coronary artery shows significant narrowing. Such involvement is typical of severe coronary atherosclerosis, such as can appear with diabetes mellitus

or a history of high cholesterol. This would make a coronary bypass operation difficult.

Atherosclerosis

• Also known as “hardening of the arteries,” atherosclerosis is a disease in which the arteries are hardened and narrowed as a result of plaque that has built up along the inside of the artery walls.

Aortic Aneurysm

Here is an example of an atherosclerotic aneurysm of the aorta in which a large "bulge" appears just above the aortic bifurcation. Such aneurysms are prone to rupture when they reach about 6 to 7 cm in size. They may be felt on physical examination as a pulsatile mass in the abdomen. Most such aneurysms are conveniently located below the renal arteries so that surgical resection can be performed with placement of a graft.

Aortic Aneurysm

This speed CT scan with contrast demonstrates an abdominal abdominal high aortic aneurysm approximately 6 cm in diameter. At this size, there is increased risk for rupture.

Anemia

• Anemia occurs when the number of red blood cells (or the Hb in them) falls below normal and the body gets less oxygen and therefore has less energy than it needs to function properly

• When the number of red blood cells decreases, the heart works harder, pumping more blood to send more oxygen throughout the body. If the heart works too hard, it can develop a rapid heartbeat (tachycardia), and/or another serious condition known as left ventricular hypertrophy (LVH), an enlargement of the heart muscle that in turn can lead to heart failure.

Types of Anemia

• Hemorrhagic anemia: results from sudden hemorrhage

• Hemolytic anemia: results from bacterial infections

• Pernicious anemia: results from a lack of Vitamin B12

• Aplastic anemia: results from destruction of bone marrow by cancer

• Iron deficiency anemia: results from a diet low in iron or slow or prolonged bleeding

• Abnormal hemoglobin in RBCs: sickle cell anemia

Sickle Cell Anemia

• Sickle cell anemia is a serious condition in which the red blood cells can become sickle-shaped (that is, shaped like a “C”).

• Sickle-shaped cells don’t move easily through blood. They’re stiff and sticky and tend to form clumps and get stuck in blood vessels.

• The clumps of sickle cells block blood flow in the blood vessels that lead to the limbs and organs. Blocked blood vessels can cause pain, serious infections, and organ damage.

Sickle Cell Anemia

Leukemia

• Leukemia or leukaemia (Greek leukos λευκός, “white”; aima αίμα, “blood”)

• a cancer of the blood or bone marrow and is characterized by an abnormal production of blood cells, usually white blood cells (leukocytes). It is part of the broad group of diseases called hematological neoplasms.

Leukemia

• White blood cells, which are involved in fighting pathogens, may be suppressed or dysfunctional. This could cause the patient's immune system (white blood cells etc.) to start attacking other body cells.

LeukemiaSome other related symptoms:• Fever, chills, night sweats and other flu-like symptoms • Weakness and fatigue • frequent mood swings • Loss of appetite and/or weight • Swollen or bleeding gums • Excess bleeding (from a minor cut) • Neurological symptoms (headache) • Enlarged liver and spleen • Easy bruising • Frequent infection • Bone pain • Joint pain • Dizziness • Swollen tonsils

Normal blood smear

Leukemia blood smear

Bleeding disorders

• Thrombocytopenia– Platelet deficiency– Even normal movements can cause bleeding

from small blood vessels that require platelets for clotting

• Hemophilia– Hereditary bleeding disorder– Normal clotting factors are missing

Hemophilia

• Hemophilia is a rare genetic bleeding disorder caused by a shortage of certain clotting factors. Blood clotting factors are needed to help stop bleeding after a cut or injury to prevent spontaneous bleeding

• In a healthy individual, a minor bump can damage a blood vessel, causing blood to leak into the surrounding tissue, producing a bruise. A process called hemostasis (coagulation) plugs the hole in the damaged vessel and forms a clot that stops the blood loss and limits the size of the bruise.

Hemophilia

• In people with hemophilia and related problems, bleeding can take a very different course. The blood does not clot normally because of one or another of the blood proteins (clotting factors) that collaborate to repair damaged vessels and form clots is defective, deficient, or totally absent.

Hemophilia• The photo to the right shows

a person with mild hemophilia after an injection in the buttocks and the bruising that occurred afterward from uncontrolled bleeding. When the blood doesn't clot normally, even minor injuries can cause serious bleeding. This can lead to blood loss, injury to internal organs, or permanent damage to muscles or joints.

Hemophilia

• The idea that people with hemophilia can bleed to death from a minor cut or injury is a misconception. In fact, external bleeding is seldom a serious problem for hemophiliacs. They may bleed somewhat longer than other people, but minor bleeding episodes can generally be controlled by ordinary first aid measures.

• Though there is no cure for hemophilia, it can be controlled with regular infusions of the deficient clotting factor