The Cardiovascular System

November/December 2016

Danvers, MA

Sumita Handa

Interesting Facts

The heart beat is strong enough to squirt blood 30 feet

The longer a boy’s ring finger is, the less likely they are to have a heart attack

(according to one study)

The human heart beats ~35 million times per year

The heart pumps ~1,000,000 barrels of blood in a lifetime

Most heart attacks occur between 8-9 a.m.

Interesting Facts

The blue whale has the largest heart – it weighs ~ one ton

The hummingbird has a heart that beats 1000 times per minute

Your entire volume of blood goes through your entire body once every minute

Humans have ~60,000 miles of blood vessels in their bodies (more than twice the

circumference of the earth!)

Your heart beats 100,000 times and pumps ~2000 gallons of blood every day

Pig and baboon hearts have been transplanted into humans

Cardiovascular System

Heart

Vessels

Blood

Function: Transport gases, nutrients, wastes, hormones

A. HEART

The Heart

Size of a fist; less than a pound

In thorax; flanked by lungs; rests on diaphram

Top: base

Bottom: apex

Pericardium

Double-layered sac covering the heart

Outer layer anchors heart in chest

Inner layer (epicardium) attached to heart wall

Lubricating fluid in pericardial space (between layers) reduces friction

Heart Chambers

Four Chambers

2 atria: top of heart – receive blood from veins

2 ventricles: bottom of heart –pump blood through arteries

Valves

Septum: divides left from right heart

Valves: keep blood flowing in one direction

Four valves: 2 AV valves,

2 semilunar valves

Nodes (you need to know these)

Heart Polarization

3 Stages:

SA node fires, atria contract (depolarize)

Impulse travels to AV node, then travels thru bundle of His, bundle branches, & Purkinje fibers –ventricles contract (depolarize)

Contraction of ventricles has ‘wringing’ action, pushing blood upward and out through large arteries

Heart muscle repolarizes

B. Blood Vessels

Blood Vessels

Arteries: carry oxygenated blood away from the heart

Veins: carry deoxygenated blood towards the heart

Capillaries: connect arteries to veins & exchange gases with tissues

STRUCTURE OF VESSELS

How Blood Travels thru Vessels

Heart artery arteriole capillary venule vein heart

C. Blood

Blood Composition

55% Plasma (fluid matrix of water, salts, proteins, etc.)

45% Cellular elements: Red Blood Cells (RBCs): 5-6 million RBCs/ml of blood. Contain

hemoglobin which transport oxygen and CO2.

White Blood Cells (WBCs): 5,000-10,000 WBCs/ml of blood. Play an essential role in immunity and defense. Include:Lymphocytes: T cells and B cells

Macrophages: (phagocytes)

Granulocytes: Neutrophils, basophils, and eosinophils.

Platelets: Cellular fragments, 250,000- 400,000/ml of blood. Important in blood clotting.

Components of Blood

Centrifuged blood

45% Red blood cells (erythrocytes)

Hematocrit: RBC volume = ~45%

<1% Buffy Coat: White blood cells

(leukocytes)

55% Plasma: Serum and fibrinogen

Blood Circulation : A. Pulmonary Circulation

Right ventricle pumps deoxygenated blood through pulmonary artery to the lungs

The blood picks up O2 from the lungs and dumps CO2 into the lungs

Oxygenated blood is returned to the left atrium thru the pulmonary vein

Blood Circulation : B. Systemic Circulation

Oxygenated blood is pumped from left ventricle thru aorta to the body

Blood dumps oxygen into tissues and picks up CO2

Deoxygenated blood travels from body to vena cava to the right atrium

The Circulation

Bi

Erythropoiesis2.5 million RBCs are produced/sec

Lifespan of 120 days

Old RBCs removed from blood byphagocytic cells in liver, spleen, & bonemarrow

Iron recycled back into hemoglobinproduction

D. Disorders of the Cardiovascular System

Atherosclerosis

Narrowing of vessel lumen due to plaque/fat formation on inside of walls

Causes: diet high in fat, cholesterol, salt; inactive lifestyle; smoking

Risks: high BP, enlarged heart, embolus blocking circulation; stroke

Coronary Artery Disease

When Atherosclerosis affects the arteries that supply the heart muscle

Symptoms: short of breath after simple exertion, angina (chest pain)

Risk: MI, cardiac arrest, death

Vessel Disorders

Varicose Veins: twisted, dilated

veins resulting from pooling of blood

due to long periods of standing,

obesity, or inactivity

Aneurysm

Weakening in the wall of a vessel, causing it to balloon outwards.

Rupture of the site causes◦ Stroke (if in the brain)

◦ Death (in a large artery –aorta).

E. Video & References

VideoHuman Circulatory System

Reference

Pearson Education Inc 2005

HowStuffWorks.com

Center for Phlebotomy Education

The McGraw Hill Company

THANK YOU