The Circulatory SystemThe Circulatory System

The Circulatory SystemThe Circulatory System

The human The human circulatory circulatory system consists system consists of the heart, a of the heart, a series of blood series of blood vessels, and the vessels, and the blood that flows blood that flows through themthrough them

The HeartThe HeartA hollow organ composed mostly of A hollow organ composed mostly of musclesmuscles

About the size of a clenched fistAbout the size of a clenched fist

The heart is enclosed in a protective sac The heart is enclosed in a protective sac called the pericardiumcalled the pericardium

The heart contracts roughly 72 times a The heart contracts roughly 72 times a minute, moving the blood (about 5 Liters) minute, moving the blood (about 5 Liters) once around the bodyonce around the body

The Heart (cont…)The Heart (cont…)

The heart is divided The heart is divided into two sides (left & into two sides (left & right) by the septum. right) by the septum. This prevents the This prevents the mixing of Omixing of O2 2 poor poor

blood with Oblood with O2 2 rich rich

blood.blood.

Four valves in the Four valves in the heart prevent backflowheart prevent backflow

The heart functions as two The heart functions as two separate pumpsseparate pumps

The left side The left side pumps blood pumps blood through the body through the body and back to the and back to the heart, this pathway heart, this pathway is known as is known as systemic systemic circulationcirculation

The right side The right side pumps blood to pumps blood to and from the lungs, and from the lungs, this is known as this is known as pulmonary pulmonary circulationcirculation

Blood moves Blood moves from the heart to from the heart to the lungs and the lungs and back to the heart. back to the heart. Then it travels to Then it travels to all the cells of the all the cells of the body and returns body and returns again to the heartagain to the heart

The heart has 4 chambersThe heart has 4 chambers

Right AtriumRight Atrium

Left AtriumLeft Atrium

Right Right VentricleVentricle

Left Left VentricleVentricle

Blood flow through the heartBlood flow through the heart

1. O1. O2 2 poor blood returns from the body to poor blood returns from the body to

the Right Atrium, the Right Atrium pumps the Right Atrium, the Right Atrium pumps the blood to the Right Ventriclethe blood to the Right Ventricle

2. The Right Ventricle pumps O2. The Right Ventricle pumps O2 2 poor blood poor blood

into the pulmonary arteries then to the into the pulmonary arteries then to the lungs, where, the blood exchanges COlungs, where, the blood exchanges CO2 2

for Ofor O22

Blood flow through the heartBlood flow through the heart

3. The pulmonary veins carry O3. The pulmonary veins carry O2 2 rich blood rich blood from the lungs back to the heart into the from the lungs back to the heart into the left atriumleft atrium

4. The left atrium pumps the O4. The left atrium pumps the O2 2 rich blood rich blood into the left ventricleinto the left ventricle

5. The left ventricle pumps O5. The left ventricle pumps O2 2 rich blood rich blood into the aorta where it is sent to the entire into the aorta where it is sent to the entire bodybody

Follow the pathway…….Follow the pathway…….Foot → de-Foot → de-oxygenated Ooxygenated O2 2 vein → vein →

right atrium → right right atrium → right ventricle → ventricle → pulmonary arteries → pulmonary arteries → lungs → gas lungs → gas exchange → exchange → oxygenated blood → oxygenated blood → pulmonary vein → left pulmonary vein → left atrium → left ventricle atrium → left ventricle → aorta → to body → → aorta → to body → to footto foot

Arteries: Blood vessels that direct blood Arteries: Blood vessels that direct blood away away from the heart. They have thick elastic walls.from the heart. They have thick elastic walls.

Capillaries: The smallest blood vessels in your Capillaries: The smallest blood vessels in your body. The allow nutrients, oxygen and other body. The allow nutrients, oxygen and other substances to diffuse through the capillary walls substances to diffuse through the capillary walls (which are one cell thick!)(which are one cell thick!)

Veins: Blood vessels that direct blood back Veins: Blood vessels that direct blood back toward toward the heart. The veins have valves that the heart. The veins have valves that keep the blood from backtracking.keep the blood from backtracking.

Disorders of the Disorders of the Circulatory SystemCirculatory System

ArtherosclerosisArtherosclerosis

Fatty deposits called plaque build up on Fatty deposits called plaque build up on the walls of the arteries. If the deposits the walls of the arteries. If the deposits get too large, they obstruct blood flowget too large, they obstruct blood flow Blood pressure increases (high blood Blood pressure increases (high blood

pressure)pressure) Blood clots could form. If a clot breaks free, it Blood clots could form. If a clot breaks free, it

can get stuck in an artery and obstruct blood can get stuck in an artery and obstruct blood flowflow

High Blood Pressure High Blood Pressure (Hypertension)(Hypertension)

Causes the heart to work harderCauses the heart to work harder

May weaken or damage heart muscles May weaken or damage heart muscles and blood vesselsand blood vessels

Increases the risk for heart attack and Increases the risk for heart attack and strokestroke

Heart AttackHeart Attack

Atherosclerosis in the coronary arteries Atherosclerosis in the coronary arteries may lead to a heart attackmay lead to a heart attack

If one of these arteries becomes blocked, If one of these arteries becomes blocked, part of the heart muscle may begin to die part of the heart muscle may begin to die due to lack of oxygendue to lack of oxygen

StrokeStroke

A stroke occurs when blood clots (formed A stroke occurs when blood clots (formed from atherosclerosis) break free and get from atherosclerosis) break free and get stuck in one of the blood vessels leading stuck in one of the blood vessels leading to a part of the brain.to a part of the brain.

Can also occur if a weakened artery in the Can also occur if a weakened artery in the brain bursts and fills the area with bloodbrain bursts and fills the area with blood

Strokes can cause paralysis, loss of Strokes can cause paralysis, loss of speech or deathspeech or death