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Explore the circulatory system's role in delivering oxygen and nutrients, pathway of blood flow, heart structure, blood pressure, and common disorders like heart attacks and hypertension.
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Circulatory system and the blood Chapters 5 and 6
Circulatory system • PREVENTS CELLS FROM SUFFOCATING • BRINGS CELLS OXYGEN AND NUTRIENTS • Also called the cardiovascular system
PATHWAYS HEART- PUMPS BLOOD ARTERIES- CARRY BLOOD AWAY FROM THE HEART VEINS- CARRY BLOOD TOWARD THE HEART CAPILLARIES- TINY VESSELS THAT REACH SINGLE CELLS- THE SITE WHERE EXCHANGE OCCURS
ARTERIES WALL- have 3 LAYERS • INNER- simple squamous epithelium + connective tissue= endothelium • Middle- smooth muscle • Outer- loose and fibrous connective tissue Arterioles- tiny arteries
Capillaries • Nourish individual cells • can be closed when muscles in precapillary sphincter are contracted • an arteriovenous shunt is a vessel allows the blood to bypass the capillaries and move on to a venule while the precapillary sphincter is closed
Veins • Venules- tiny veins that drain capillary beds • 3 layers, but less muscle and connective tissue • Have one way valves to prevent blood from staying in the legs • Vein walls can expand- 70% of all the blood is in the veins
Heart • Cone shaped, fist sized Myocardium- the cardiac muscle Pericardium- the thick sac around the heart Septum- the internal wall that separates the right and left halves • Upper 2 chambers- atria • Lower 2- ventricles
Valves • Chordae tendineae- strings that prevent one way valves from opening backwards • Atrioventricular valves- separate upper and lower chambers Right- tricuspid Left- bicuspid or mitral • Semilumar valves- downstream of ventricles pulmonary- right aortic- left
Major vessels • Right half source of blood- from superior and inferior vena cavae • Right blood output- to Pulmonary arteries • Left blood input- from pulmonary veins • Left output- to Aorta
HEART RIGHT SIDE- PUMPS OXYGEN POOR BLOOD FROM BODY (VENA CAVA) TO LUNGS (PULMONARY ARTERY) LEFT SIDE- PUMPS OXYGEN RICH BLOOD FROM LUNGS (PULMONARY VEIN) TO THE REST OF THE BODY (AORTA) • The Left side works harder
Cardiac cycle Systole- period of muscle contraction Diastole- resting period • Lub dub- sound of heart valves slamming shut • Murmur- caused by leaky valves SA node- the heart’s pacemaker- located on the right atrium, creates the electrical impulse AV node- below right atrium- electrical impulse passes through on its way to Perkinje fibers- conducts the impulses to the muscle cells that cause contraction of ventricles
Control of heart rate 1 Medulla oblongata- nerve impulses from brain stem 2. Endocrine hormones from adrenal glands- epinephrine and nor epinephrine Defibrillation- an electrical shock to reestablish ventricular rhythm given to persons with heart problems
HEART ATTACK • BLOCKAGE OF A CORONARY ARTERY which supplies the heart muscle with oxygen and nutrients • PART TO HEART MUSCLE SUFFOCATES • IF ENOUGH MUSCLE TISSUE STOPS WORKING THEN THE HEART CAN’T PUMP BLOOD (massive heart attack)
Other Problems/Treatments Aneurysm- ballooning of weakened artery, can burst and cause massive internal bleeding Treatments for clogged vessels • Nitroglycerine- dilates blood vessels • Clot dissolving drugs- to treat heart attack • Angioplasty- balloon inflated inside a partially clogged artery to expand it
BLOOD PRESSURE • THE FORCE THAT BLOOD EXERTS AGAINST THE WALLS OF OUR BLOOD VESSELS • CONTRACTION OF VENTRICLES= HIGH PRESSURE- SYSTOLE • PRESSURE DROPS MOMENTARILY- when the heart relaxes- DIASTOLE
BLOOD PRESSURE SYSTOLE/DIASTOLE • MEASURED WITH A STETHOSCOPE AND PRESSURIZED CUFF • CUFF CUTS OFF BLOOD AT A HIGH ENOUGH PRESSURE • SYSTOLIC- 110-140 = NORMAL • BELOW 100- LOW HYPERTENSION- 140/90 or greater
Other Problems Hypertension= High blood pressure Atheriosclerosis- cholesterol under endothelium of arteries • Blood clots may form on the irregular artery walls Thrombus- attached clot- embolus- free clot which is moving through the vessels Stroke- burst or blockage of brain arteriole
Veins • Weak one way valves- causes swelled veins (spider veins and varicose veins- usually in the legs/feet) Hemorrhoids- swelled veins of rectum Phlebitis- inflammation of veins