Cardiovascular System

The Cardiovascular System• A closed system of the heart and blood vessels– The heart pumps the blood.– Blood vessels allow blood to circulate to all parts of

the body.• The function of the cardiovascular system is to

deliver oxygen and nutrients and to remove carbon dioxide and other waste products.

• Your heart has special pacemaker cells that control the pumping action of the heart with an electrical signal.

Pace maker cells

The Heart• Location– In the chest between the lungs.

• Orientation– The pointed tip is directed toward left hip.

• About the size of your two fiststogether.

The Heart• The heart is surrounded by a layer of tissue that

protects it from damage and bacteria.

• The walls of the heart are 3 layers thick– Epicardium (Outer Layer)

– Myocardium: (Middle Layer) – cardiac muscular layer

– Endocardium (Inner Layer)

Myocardium

Four Chambers of the Heart• Left and right refers to persons right and left sides,

not yours.

• Right/Left Atrium (Atria plural)

– Receives blood into the heart

• Right/Left Ventricle

– Pumps blood out of heart

Internal Anatomy and Organization

• What separates the right side from the left side of the heart is the septum, in the heart oxygen rich and oxygen poor blood do not mix.

• To control the blood flow through the heart there are valves that control the movement of blood through the chambers and out of the heart.

• Atrioventricular (AV) valves: open and close to move blood from the atria to the ventricles.

• Semilunar valves: open and close to permit blood out of the heart.

Pathway of Blood• Blood arrives at the heart in the atriums• Blood leaves the heart from the ventricles– In from body to the Right Atrium (deoxygentated)– Right atrium to right ventricle (deoxygentated)– Right ventricle out to lungs (becomes oxygenated)– Back from lungs to left atrium (oxygenated)– Left atrium to left ventricle (oxygenated)– Left Ventricle to body (oxygenated)

Circulation

• Blood that has just picked up oxygen from the lungs comes into the heart and goes through the atrium and ventricles.

• Blood leaves the heart throughthe aorta: which takes bloodout to the body.– The aorta is the largest blood

vessel in the body.

Aorta

Circulation

• When blood leaves the heart and goes to the lungs to pick up oxygen then returns to the heart this is known as the pulmonary circulation.

• When blood leaves the heart through the aorta and goes out to the body to drop off the oxygen and pick up waste products then returns it is known as the systemic circulation.

Overview of the Cardiovascular System

Introduction to Cardiovascular System• Oxygen rich blood that is leaving the heart is

carried through the arteries.– Arteries carry blood away from the heart.

• Oxygen poor blood is carried in the veins from the body towards the heart.– Veins carry blood towards the heart

• Capillaries: network of blood vessels that connects the arteries and veins.

• Heart Artery Capillaries Veins Heart

Blood Vessels• The pressure in the blood vessels is highest in the

arteries and lowest in the veins.• To cause changes in the blood vessel’s pressure the

vessels expand and contract.– Using smooth muscle contractions.

• Muscles that can’t be voluntarily controlled (organs)

• Veins also use a skeletal pump:– When muscle contractions push blood through the veins.– Used to return blood from legs

Blood Pressure

• Measurements by health professionals are made on the pressure in large arteries– Systolic—pressure during a heart contraction.– Diastolic—pressure when heart is relaxed– Write systolic pressure first and diastolic last

(120/80 mm Hg)• Pressure in blood vessels decreases as

distance from the heart increases.

Blood Pressure

• Website

Variations in Blood Pressure• Normal human 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 blood pressure)• High systolic (above 140 mm HG)• Can be dangerous if it is chronic

High Blood Pressure

• When there is build up of fatty material in the blood vessels it causes the vessels and heart to have to work harder, and increased pressure in the vessels.– This is a disease known as Arthrosclerosis

• If this type of blockage occurs in the blood vessels that supply oxygen to the heart muscles it can cause a Heart Attack.

Stroke

• If a blockage occurs from a blood clot in the brain a stroke can occur.