Circulatory system Chapter 7 Circulatory system PREVENTS CELLS

Circulatory system Chapter 7

Circulatory system PREVENTS CELLS FROM SUFFOCATING l BRINGS CELLS OXYGEN AND NUTRIENTS l Also called the cardiovascular system l

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 l INNER- simple squamous epithelium + connective tissue= endothelium l Middle- smooth muscle l Outer- loose and fibrous connective tissue Arterioles- tiny arteries

Capillaries Nourish individual cells l can be closed when muscles in precapillary sphincter are contracted l 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 l

Veins Venules- tiny veins that drain capillary beds l 3 layers, but less muscle and connective tissue l Have one way valves to prevent blood from staying in the legs l Vein walls can expand- 70% of all the blood is in the veins l

Heart Cone shaped, fist sized l Myocardium- the cardiac muscle l Pericardium- the thick sac around the heart l Septum- the internal wall that separates the right and left halves l Upper 2 chambers- atria l Lower 2 - ventricles l

Valves Chordae tendineae- strings that prevent one way valves from opening backwards l Atrioventricular valves- separate upper and lower chambers Right- tricuspid Left- bicuspid or mitral l Semilumar valves- downstream of ventricles pulmonary- right aortic- left l

Major vessels Right half source of blood- from superior and inferior vena cavae l Right blood output- to Pulmonary arteries l Left blood input- from pulmonary veins l Left output- to Aorta l

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) l The Left side works harder

Cardiac cycle l l l l 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 Medulla oblongata- nerve impulses from brain stem l Endocrine hormones from adrenal glands- epinephrine and nor epinephrine l l 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 l PART TO HEART MUSCLE SUFFOCATES l IF ENOUGH MUSCLE TISSUE STOPS WORKING THEN THE HEART CAN’T PUMP BLOOD (massive heart attack) l

Other Problems/Treatments Aneurysm- ballooning of weakened artery, can burst and cause massive internal bleeding Treatments for clogged vessels l Nitroglycerine- dilates blood vessels l Clot dissolving drugs- to treat heart attack l Angioplasty- balloon inflated inside a partially clogged artery to expand it l

BLOOD PRESSURE THE FORCE THAT BLOOD EXERTS AGAINST THE WALLS OF OUR BLOOD VESSELS l CONTRACTION OF VENTRICLES= HIGH PRESSURE- SYSTOLE l PRESSURE DROPS MOMENTARILYwhen the heart relaxes- DIASTOLE l

BLOOD PRESSURE SYSTOLE/DIASTOLE l MEASURED WITH A STETHOSCOPE AND PRESSURIZED CUFF l CUFF CUTS OFF BLOOD AT A HIGH ENOUGH PRESSURE l SYSTOLIC- 110 -140 = NORMAL l BELOW 100 - LOW l HYPERTENSION- 140/90 or greater l

Other Problems Hypertension= High blood pressure l Atheriosclerosis- cholesterol under endothelium of arteries l Blood clots may form on the irregular artery walls l Thrombus- attached clot- embolus- free clot which is moving through the vessels l Stroke- burst or blockage of brain arteriole l

Veins Weak one way valves- causes swelled veins (spider veins and varicose veinsusually in the legs/feet) Hemorrhoids- swelled veins of rectum Phlebitis- inflammation of veins l