cardiovascular system arteries blood vessels--arteries transport blood away from the heart. large...

Cardiovascular Cardiovascular SystemSystem

Blood Vessels--ARTERIESARTERIES

• Transport blood AWAY from the heart.

• Large Arteries are Thick like a garden hose

• Elastic (distensible) but strong to withstand great pressure

• Elastic recoil is the force that keeps blood pressure between beats

Structure of an ARTERYARTERY

• Hollow interior of vessel: LUMEN

• Thin inner layer of cells: ENDOTHELIUM. Flattened, squamous epithelial cells. Continuation of lining of the heart.

• Smooth Muscle layer with elastic tissue

• Outermost layer: tough supportive Connective Tissue (collagen)

AneurysmsAneurysms

• A balloning of the artery wall• Some cause smooth muscle & endothelial

layers to bulge inwards, narrowing the lumen—reduce blood flow to an organ

• Others bulge outwards.• Some can cause pain. Many are

asymptomatic until they rupture.• Aortic aneurysms kill 25,000 Americans

annually.

Arterioles and Precapillary Arterioles and Precapillary SphinctersSphincters

• In Arterioles Blood pressure falls considerably

• Arterioles help regulate the amount of blood flowing to each capillary.

• Precaplillary Sphincters: contract or relax to regulate blood flow

• Vasoconstriction & Vasodillation.

Capillaries: Blood ExchangeCapillaries: Blood Exchange

• Smallest Blood Vessels

• Thin-walled. 1/100th of a millimeter in diameter.

• Capillary beds found in all areas of body.

• Slits between epithelial cells allows Blood Exchange of oxygen, carbon dioxide, nutrients and waste with the Interstitial fluid.

Veins Return Blood to HeartVeins Return Blood to Heart

• Larger Lumen

• Thinner Walls

• Little to no blood pressure

• Highly distensible; can carry large volumes of blood at low pressures

• Blood Reservoir for whole system. Nearly 2/3 of blood is in veins.

• Distensibilty of veins can lead to problems trying to return blood to heart against force of gravity.

• Pooled blood in veins leads to permanently swollen veins.

• 1. Contraction of Skeletal Muscles

– (tire more easily standing still than walking)

• 2. One-way values in veins

– (open passively and close when blood back flows)

• 3. Movements associated with Breathing

– (respiratory pump—changes in air prssure in thoracic cavity)

Varicose Veins & GravityVaricose Veins & Gravity

HeartHeart

• Cardiac Muscle (does not connect to bone)

• Pumps about 75 beats per minute

• Never rests for more than 2/3 of second

• Covered by a tough fibrous sac: Pericardium protects and anchors it

• Pericardium Cavity contains lubricating fluid

Layers of the HeartLayers of the Heart

• EpicardiumEpicardium: outermost layer, thin layer of epithelial and connective tissue.

• MyocardiumMyocardium: Thick Middle layer of cardiac muscle that contracts. Electrical signals flow from cell to cell.

• EndocardiumEndocardium: Innermost layer, thin endothelium layer resting on a layer of connective tissue. Continuous with endothelium that lines blood vessles.

Human HeartHuman Heart

Pulmonary & Systemic CircuitsPulmonary & Systemic Circuits

Cardiac CycleCardiac Cycle

• Systole: Contraction• Diastole: Relaxation• Three Steps

– 1. Atrial & Ventricular Diastole: Both are relaxed. Blood fills right and left Artia and flows passively through AV Valves into Ventricles. Semi-lunar Values Closed

– 2. Atrial Systole: Both Artia contract, filling Ventricles to Capacity

– 3. Ventricular Systole: Both Ventricles contract. AV Values close. Semi-lunar Values Open. 60% of blood in Ventricles forced out

Lub DUB

Murmur

Artificial Heart Valve

http://www.post-gazette.com/stories/news/health/old-metal-heart-valve-did-its-job-for-42-years-383511/

Electrocardiogram Records Electrocardiogram Records Heart’s Electrical ActivityHeart’s Electrical Activity

• ElectrocardiogramElectrocardiogram records the electrical impulses in the cardiac conduction system

• ArrhythmiaArrhythmia: an abnormality in rate or rhythm of heartbeats.

• Ventricular FibrillationVentricular Fibrillation: irregular ventricular contractions.

• Artificial Pacemaker:Artificial Pacemaker: normalize heartbeat by sending out electrical signal to heart tissue

Blood Pressure

• Systolic Pressure: Pressure of Ventricular Systole

• Diastolic Pressure: During no contractions

• Sphygmomanometer: blood pressure cuff

• Normal: 120/80 mm Hg

HypertensionHypertension

• Significant Risk factor of heart disease

• Greater pressure, greater strain on vessels

• Become scarred and hardened

• Slient Killer

• 140/90

• Causes: Atherosclerosis

• Hypotension: Low Blood pressure—fainting

Inflammation

Matters of the Heart

http://news.bbc.co.uk/2/shared/spl/hi/pop_ups/03/health_bodyphotos/html/1.stm

Human Heart beats 100,000 time a day

Moving 6 quarts of bloodthrough 60, 000 milesOf vessels(that’s 20 times the Distance from coast toCoast)

The heart itself holds only 10 ounces of blood, but pumps at such a force that that a severed artery can propel blood several feet into the air.

National Geographic

• http://www7.nationalgeographic.com/ngm/0702/sights_n_sounds/index.html

• http://www.nationalgeographic.com/human-heart/your-heart.html?fs=www7.nationalgeographic.com&fs=magma.nationalge

• http://www7.nationalgeographic.com/ngm/0702/sights_n_sounds/index.html

• http://www.nationalgeographic.com/human-heart/your-heart.html?fs=www7.nationalgeographic.com&fs=magma.nationalge

Broken Hearts

• Coronary Heart Disease is the #1 killer in the USA

• 500, 000 people die from it each year in the USA

• 7.2 million die worldwide

• More than 400,000 heart bypasses are performed in the USA each year

http://www.daviddarling.info/images/heart.gif

Atherosclerosis animation

• http://www.nytimes.com/2007/04/08/health/08hside.html?ex=1177732800&en=e0f0fb9991a7734c&ei=5070

Misconceptions about Heart Disease

• Most think cholesterol silts into arteries, blocking them like a clogged pipe. Then the artery gets completely blocked causing a heart attack— no blood is getting through to the heart.

• When actually, Plaque is a pimple-like growth inside an artery wall with a “kind of chronic pus”

"Heart disease is not a one- or two-gene problem,"

• says cardiac researchers Steven Ellis. Like most researchers, he suspects that dozens of genes end up contributing to a predisposition: – Some affect arterial integrity, – others inflammation (which both causes and exacerbates arterial

cracks), – and still others the processing of lipids (the fats and cholesterol

that turn into plaques). • Of the several dozen genes, each may contribute just

one percent to a person's total risk—an amount that may be compounded, or offset, by outside factors like diet. As one doctor told me, any person's heart attack risk is "50 percent genetic and 50 percent cheeseburger."

• http://www7.nationalgeographic.com/ngm/0702/feature1/text2.html

Genes plus Other Risk Factors• By tracking these genetic mutations, researchers hope to create a

comprehensive blood test that could calculate a person's susceptibility to heart disease by adding up the number of risky variables:– High unhealthy cholesterol levels (quadruples risk)– Smoking (double or triple risk)– Abdominal obesity (more than doubles risk)– High blood pressure/Hypertension (nearly triples risk in men, doubled it for

women)– Stress & Depression (almost triples risk)– Lack of exercise (increases risk by 20%)– Diabetes (quadruples risk for women, doubles it for men)– Healthy Diet (decreases risk by 30%)

• Assessing risk is crucial, Ellis says, because heart disease is often invisible.

• In fact, 50 percent of men and 64 percent of women who die of heart disease die suddenly, without experiencing any previous symptoms.

Reducing Risk by Prevention

• Since detecting Heart Disease and predicting whether a heart attack is imminent is so difficult, prevention for everyone is advised.

• The only thing proven to reduce the risk of a heart attack in someone with plaque is the same thing that works to prevent plaque from developing in the first place —– Lowering blood pressure and blood sugar – not smoking – and Controlling cholesterol levels with

Statins

Statins: Lipitor

• Is a Drug that reduces the amount of LDL (“bad” low-density lipoproteins) in the blood made by the Liver

• Made by Pfizer, it’s best selling drug ever made with $12 Billion in worldwide annual sales

• Statins in general are the most prescribed class of drugs in the world (11.6 million monthly prescriptions in US alone)

Statins: How do they work?• They work by blocking an enzyme in the liver that is involved in

producing cholesterol within liver cells.

"This tricks the liver cells into thinking the cholesterol levels are too low within the cell and the cell puts more receptors onto its surface, which drag the bad LDL cholesterol out of the blood," explains Dr. Rory Collins, professor of epidemiology at Oxford University. "The liver then breaks down that cholesterol and it's excreted into the bile and into the gut."

Collins has conducted the biggest study of statins to date, covering 20,000 people over five years. The study suggested that a person who has had high cholesterol for decades could reduce their risk of heart attack or stroke by 25 per cent within just a few years of statin treatment. The study also suggested that the risk would continue to decrease, the longer the treatment continued. http://www.cbc.ca/news/background/drugs/statins.html

Why do we make “bad” LDL in the 1st place?

• At one time, millennia ago, it may have been important for the human body to be able to produce cholesterol – because early humans may have gone long periods between meals, which meant they couldn't count on getting enough cholesterol. But Dr. David Jenkins – a Canada Research Chair in nutrition, and a professor of medicine at the University of Toronto – says that's not the case for the modern couch potato.

"We've got these ancient bodies with these ancient genes which are all destined to make sure that we've got enough cholesterol to fulfil essential functions," Jenkins told CBC Radio's Quirks and Quarks. "Today, unfortunately, we've taken out all those nice things in the diet that take cholesterol out of the body and have brought in a whole load of very nice refined foods that allow us to sit around, not do too much, and just synthesize cholesterol."

Those refined foods help your body produce the bad kind of cholesterol.

Controlling Risk Factors nearly eliminates heart attacks altogether

• A 50-year-old man with:– No diabetes – Doesn’t smoke – With normal cholesterol and blood pressure

• Has only a 5% chance of having a heart attack or symptoms of heart disease, like chest pain, over the next 45 years

• Same goes for a 50-year-old woman with those risk factors under control. Her chance of symptomatic heart disease is 8 percent, slightly higher than the man’s because women live longer

So Why does Heart Disease persist?

• Only 5 percent of 50-year-olds have those risk factors under control.

• Even with just one major risk factor, such as a high cholesterol level, and a man’s chance of having symptomatic heart disease rises to 50 percent.

• A woman’s chance rises to 39 percent.

Prevention gets little attention

• The fact is people like to eat cheeseburgers, watch TV and go around in cars

• It’s hard for a person to worry about a disease that hits 10 or 20 years down the road

• http://www7.nationalgeographic.com/ngm/0702/feature1/text4.html

What are Blocked Artery Treatments?

Heart Transplant

Heart Transplant at 6 days old

http://www.jordanzane.com/

Artificial Heart

Stents

• Figure 1(a) Angiogram shows critical stenosis in the intracranial right internal carotid artery, intrapetrous segment (arrow). (b) Post-angioplasty angiogram shows 40% residual carotid stenosis (arrow). (c) Follow-up angiogram shows recurrent carotid 70% stenosis (arrow). (d) Post-stent angiogram shows excellent results with no significant residual carotid stenosis (arrow).

Hypertrophic cardiomyopathy

Pulmonary Embolism

Atherosclorosis

• controlling cholesterol levels, blood pressure and blood sugar and not smoking

• Dr. Levy explains: Suppose a 50-year-old man does not have diabetes and does not smoke and keeps his cholesterol and blood pressure in the range recommended by national guidelines. Over the next 45 years, his chance of ever having a heart attack or symptoms of heart disease, like chest pain, is just 5 percent. The same goes for a 50-year-old woman with those risk factors under control. Her chance of symptomatic heart disease is 8 percent, slightly higher than the man’s because women live longer.

• But only 5 percent of 50-year-olds have those risk factors under control. And give that man just one major risk factor, for example a high cholesterol level, and his chance of having symptomatic heart disease rises to 50 percent. The woman’s chance rises to 39 percent.