Cardiovascular System

Blood vessels, heart and blood

Functions

• Transport oxygen, nutrients, waste, hormones

• White blood cells fighting disease

• Temperature regulation

Blood vessels

• Arteries carry blood away from the heart

• All (except the pulmonary artery) carry oxygen-rich blood which is bright red

• Artery walls are thick and muscular

• Arteries expand and relax as the heart beats

• This results in a pulse

• Arteries have high pressures

Pulse Points

Blood vessels

• Veins carry blood back to the heart

• Veins carry deoxygenated blood (except the pulmonary veins) which is dark reddish/blue

• Walls of veins are thin and pressures are low

• Veins have valves to prevent backflow of blood

Blood Vessels

• Capillaries are the tiniest of blood vessels

• Capillaries connect the arteries and the veins

• Walls are very thin – only one cell layer

• Diffusion of substances (e.g. oxygen) occurs through the walls of the capillaries

Lymph Vessels

• Lymph vessels travel near the veins and carry fluids similar to blood but without the red blood cells

• Eventually lymph vessels empty their contents into large veins

• Lymph vessels travel through lymph nodes that have the job of filtering the lymph

Heart

• “cardia-” means heart

• Located slightly left of center in your chest cavity and surrounded by lungs on each side

• Made of striated involuntary muscle

Heart chambers contain blood

• Left and right atrium (atria pl.)

• Left and right ventricle

Heart valves

• One way valves keep blood moving in one direction

• As valves close, one hears the characteristic “lub-dupp” sound of the heart beating

• Valves between the atrium and ventricle on each side

• Valves between the ventricles and the arteries on both sides

Blood flow through heart

• Superior & Inferior Vena Cava• Right atrium• Right ventricle• Pulmonary artery to lungs• Pulmonary veins• Left atrium• Left ventricle• Aorta

• Vena Cava has deoxygenated blood

• Pulmonary artery has deoxygenated blood

• Pulmonary vein has oxygenated blood

• Aorta has oxygenated blood

Coronary arteries

• The heart muscle itself gets its oxygen and nutrients from the coronary arteries

• What would happen if a coronary artery would get blocked?

Heart Physiology

• SA node is the pacemaker of the heart• Located in the wall of the right atrium• The SA node cardiac muscle cells contract

faster than all of the other heart muscle cells and all cardiac muscle cells are interconnected.

• The SA node sets the pace of the entire heart and beats about 60-80 beats per minute at rest.

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Heart Physiology

• Heart muscle contraction is electrical, so can be monitored with electrodes and recorded as an ECG or EKG - electrocardiogram

Cardiac Cycle

• The cardiac cycle is one complete heart beat.

• Systole is the contraction phase when blood is ejected from the heart ventricles

• Normal systolic pressure is 120 mm Hg

Cardiac Cycle

• Diastole is the relaxation phase of the cycle

• Heart chambers refill with blood during diastole

• While diastolic pressure is quite low in the heart, it can be represented by measuring an artery and normal is 80 mm Hg

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Cardiovascular Pathology

• Hypertension is continuous high blood pressure.

• > 160/95 mm Hg

• Affects 20 % of American Population

Hypertension

• Causes include heredity

• Obesity

• Stress

• Smoking

• Diet

• Arteriosclerosis is “hardening” of the arteries

• Often a complication of hypertension

• Arteries become more susceptible to getting an unwanted blood clot

Aneurysm

• Weakening and ballooning of an artery

• Can be a complication of hypertension

• Can lead to a burst artery which is very serious

Coronary Artery Disease

• Excessive cholesterol can build up in the wall of arteries – especially the coronary arteries

• Saturated fats from the diet can build up too

• Atherosclerosis is the condition of having fatty plaques in the wall of an artery

Atherosclerosis is a fatty plaque

Heart Attack

• As coronary arteries become blocked, the heart muscle dies from lack of oxygen and nutrients

• Treatments include “clot busting” drugs, angioplasty to open up clogged arteries and bypass surgery around the blockage

Angina

• Chest pains due to heart muscle cells being deprived of oxygen

• Often occurs after physical exertion

• Forewarning of worse things to come, like a heart attack

Varicose Veins

• Damaged veins leading to overly distended veins

• Damage to valves in the veins

• Varicose veins near the anus are called hemorrhoids

• Treatments include anti-inflammatory drugs, rest, vein injections and surgery