Click on a lesson name to select. The Circulatory System

Functions of the Circulatory System  Transports oxygen, waste and nutrients  Carries disease-fighting materials produced by the immune system  Contains cell fragments and proteins for blood clotting  Distributes heat throughout the body to help regulate body temperature

Blood Vessels  Arteries  Capillaries  Veins Arteries, Capillaries, and Veins

A. Arteries  Blood is carried away from the heart.  Under high pressure.  Thicker walls  Virtually all arteries carry oxygenated blood.  Arteries (like veins) are surrounded by a layer of involuntary, smooth muscle.

B. Capillaries  Microscopic blood vessels where the exchange of important substances and wastes occur  The walls are only one cell thick. C. Veins  Carry blood back to the heart  Usually carries deoxygenated blood.  Under low pressure.  Possess one-way valves to prevent back-flowvalves  Contraction of skeletal muscles helps keep the blood moving.  Veins are surrounded by smooth muscle.

Types of Muscle Cells

The Heart  A hollow organ with 4 chambers  Made up of cardiac muscle tissue. Role  Pumps oxygenated blood/nutrients to body cells.  Pumps deoxygenated blood to the lungs to pick up oxygen and drop off carbon dioxide. Coronary arteries provide the heart with oxygen and nutrients. Blockage of those arteries can result in a heart attack.

Structure of the Heart  Divided into four compartments called chambers  The right atrium and the left atrium receive blood returning to the heart.  The right and left ventricles pump blood away from the heart.  A strong muscular wall (septum) separates the left side of the heart from the right side of the heart.  Valves separate the atria from the ventricles and keep blood flowing in one direction.

GREAT HEART ANIMATION 1 GREAT HEART ANIMATION 2

Circulatory System

 Deoxygenated returns to the heart via the superior/inferior vena cava and enters the right atrium. The right atrium contracts and blood flows past the tricuspid valve into the right ventricle.  The right ventricle contracts and forces deoxygenated blood through the pulmonary semilunar valve into the pulmonary arteries. Deoxygenated blood makes its way to the lungs. O2 is picked up and carbon dioxide is dropped off.  Oxygenated blood from the lungs returns to the left atrium of the heart via the pulmonary veins.  The left atrium contracts and forces blood through the mitral valve into the muscular left ventricle.  The left ventricle contracts and forces oxygenated blood through the aortic semilunar valve into the ascending & descending aorta and on to the rest of the body PATHWAY OF BLOOD THROUGH THE HEART

How the Heart Beats (BEATING HEART)BEATING HEART HEART ANIMATION 1 HEART ANIMATION 2 HEART ANIMATION 3 HEART ANIMATION 4

HEART/PULSE RATE:  Rhythmic pulsing of blood through the arteries.  Can be felt along the wrist, neck, elbow and foot.  Resting Pulse Rate: beats per minute.  Fetal heart rate can be detected at roughly 6 weeks. BLOOD PRESSURE:  A measure of how much pressure is exerted against the vessel walls by the blood (120/80 mm Hg).  120 is the systolic # (measure of the pressure against the artery walls when the ventricles contract. 80 is the diastolic # (measure of the pressure against the artery walls when the ventricles relax).

Some Myocardial (Cardiac) Cells are Autorhythmic (Animation)

The Heart’s Electrical Conduction System The heart has its own ‘natural pacemaker;’ a collection of cells called the SA (sinoatrial node). These cells can generate their own action potential/electrical impulse and so the heart can beat without direction from the nervous system. The impulses will travel throughout the heart to cause contractions of the atria and ventricles. The brain stem (medulla) via the ANS can alter heart rate by influencing the SA Node. Hormones like epinephrine (adrenaline) also influence the heart.

ANIMATION

A. Plasma  Straw-colored. Carries glucose, fats, vitamins, minerals, hormones, and waste products from the cells THE COMPONENTS OF BLOOD

B. Red Blood Cells - Erythrocytes  Carry oxygen to all of the body’s cells  Consist of an iron-containing protein called hemoglobin  Hemoglobin chemically binds with oxygen molecules and carries oxygen to the body’s cells.

C. Platelets - Thrombocytes  Collect and stick to the vessel at the site of the wound and releases chemicals that produce a protein called fibrin.  Fibrin is a protein that weaves a network of fibers across the cut that traps blood platelets and red blood cells.

D. White Blood Cells - Leukocytes  Recognize disease-causing organisms  Produce chemicals to fight the invaders  Surround and ingest/kill the invaders A macrophage engulfing bacteria via phagocytosis

Common Circulatory System Disorders DISORDERCONSEQUENCES Coronary Artery Disease/Atherosclerosis Blockage of Blood Vessels Supplying the Heart. Heart muscle deprived of O 2 Heart Attack (Myocardial Infarct) Heart Muscle doesn’t receive nutrients/O 2. Death of cardiac muscle. Cardiac Arrhythmia Improper beating of the heart. High Blood Pressure (Hypertension) The pressure against the arterial walls is too high. Can lead to stroke. Stroke Interruption of Blood Flow due to rupture of blood vessel or blockage. These disorders can be caused by any number of factors: Genetics, Stress, Poor Diet, Smoking, Lack of Exercise, etc.

Heart Attack/Stroke Animations

Heart Disease Facts

Additional Videos Bozeman Biology: The Circulatory SystemThe Circulatory System CCB: Circulatory and Respiratory SystemsCirculatory and Respiratory Systems Bill Nye: Parts One and TwoOneTwo How the Heart Pumps Blood V1, V2, V3V1V2V3 What is a Heart Attack?