2 The Circulatory System We need oxygen to live!Blood brings air to our cells so oxygen can be absorbed and used to produce energy for the cellThe circulatory system transports blood throughout the body and backThe CS consists of the heart, a series of blood vessels, and the blood that flows through them
3 The Heart The heart is approximately the size of a clenched fist. It is made almost entirely of muscle.Myocardium: thick layer of muscle which produces powerful contractions to pump blood through the circulatory system.
4 The Heart Useless facts… The heart is the strongest muscle in the human bodyThe heart pumps about 72 times a minute on averageEach pump pushes 70ml of bloodIn one year, a heart pumps enough blood to fill up an olympic-size swimming pool!
5 The Heart Figure 37-3 The Structures of the Heart Section 37-1 Aorta Inferior Vena CavaVein that brings oxygen-poor blood from the lower part of the body to the right atriumTricuspid ValvePrevents blood from flowing back into the right atrium after it has entered the right ventriclePulmonary ValvePrevents blood from flowing back into the right ventricle after it has entered the pulmonary arteryPulmonary VeinsBring oxygen-rich blood from each of the lungs to the left atriumSuperior Vena CavaLarge vein that brings oxygen-poor blood from the upper part of the body to the right atriumAortaBrings oxygen-rich blood from the left ventricle to the rest of the bodyPulmonary ArteriesBring oxygen-poor blood to the lungsAortic ValvePrevents blood from flowing back into the left ventricle after it has entered the aortaMitral ValvePrevents blood from flowing back into the left atrium after it has entered the left ventricleLeft AtriumRight AtriumLeft VentricleSeptumRight Ventricle
6 The Heart The heart can be divided into four chambers Atrium: upper chambers which receive blood (enters)Ventricle: The lower chambers which pump blood out of the heart (exits)
7 Circulation Think of the heart as two separate pumps. Pulmonary circulation: Right side of heart that pumps blood from the heart to the lungsSystemic circulation: Left side of heart that pumps blood oxygen-rich blood to the rest of the body
8 Capillaries of head and arms Superior vena cavaAortaPulmonary arteryPulmonary veinCapillaries of right lungCapillaries of left lungInferior vena cavaCapillaries of abdominal organs and legs
10 Circulation Oxygen-poor blood enters heart through right atrium. Valve (connective tissue that opens & closes) opens so blood froms from R atrium to R ventricle.R ventricle pumps blood to lungsLungs replenish blood with oxygenOxygen-rich blood then flows to L atrium
11 CirculationValve opens and oxygen-rich blood flows from L atrium to L ventricleL ventricle pumps blood to the bodyBody absorbs oxygenOxygen-poor blood goes back to the heartCycle starts over!
12 Circulation Atriums contract first (by sinoatrial node) Contraction of atrium by SA triggers the ventricles to contract (atrioventricular node or AV)Together, these two nerves serve as the pacemaker.Remember sympathetic and parasympathetic?During exercise, sympathetic increases heart rate (can go up to 200bpm) and parasympathetic decreases it
13 Blood VesselsAorta: Large blood vessel where blood first leaves the L ventricleArteries: carry oxygen rich bloodThey have thick walls to withstand the pressure of bloodflowThink of arteries as the superhighways of the CS
14 Blood VesselsCapillaries: Narrow tubes where body absorbs oxygen and nutrients are exchangedCan be as narrow as one cell wideThink of capillaries as side streets and alleys
15 Blood Vessels Veins: Blood vessels that return blood to the heart Thinner than arteriesLarger veins have valves to prevent backflowMuscular contractions help push blood through veinsOtherwise, blood pools and vericose veins result
17 Blood Pressure Heart produces pressure when it pumps. The pressure allows blood to flow throughout the bodyIf pressure is too low, oxygen can’t get to bodyIf pressure is too high, heart has to work harder, damaging the CS
18 Blood Pressure BP is measured by systolic & diastolic pressures Systolic is the blood pressure when a ventricle contractsDiastolic is the blood pressure when a ventricle relaxesNormal BP is 120/80Atherosclerosis, a hardening of the arteries due to fat is a major cause of HBP and heart diseaseResult is heart attack or stroke