2 IntroductionHumans and other vertebrates have a closed circulatory system:This means that circulating blood is pumped through a system of vesselsThis system consists of the heart (pump), series of blood vessels and the blood that flows through them.
4 The Heart Located near the center of your chest Hollow structure Composed almost entirely of muscleAbout the size of your clenched fist
5 The HeartEnclosed in a protective sac called the pericardium
6 The HeartIn the walls of the heart, two layers of tissue form a sandwich around a thick layer of muscle called the myocardium.Contractions of the myocardium pump blood through the circulatory system.
7 The Heart The heart contracts about 72 times per minute Pumps about 70mL of blood with each contraction.
8 The HeartThe right and left sides of the heart are separated by a septum, or wall.The septum prevents the mixing of oxygen rich and oxygen poor blood.
9 The Heart On each side of the septum are two chambers. The upper chamber (receives blood) is the atrium.The lower chamber (pumps blood out of heart) is the ventricle.
10 The HeartThe heart has a total of 4 chambers:2 atriums2 ventricles
11 Pathway of BloodDeoxygenated blood passes from the right atrium into the right ventricle and then goes to the lungs.From the lungs, blood moves back toward the heart into the left atrium to the left ventricle and then passes into the aorta to go to the rest of the body
12 ValvesAs the heart contracts, blood flows into the ventricles and then out through the ventricles.Flaps of connective tissue, called valves, are located between the atria and ventricles.Blood moving keeps the valves open.When the ventricles contract, the valves close which prevent blood from flowing back into the atria.
13 ValvesThere are also valves that stop blood from re-entering the ventricles after the blood has left.This system of valves keeps blood moving in one direction which increases the pumping efficiency of the heart.
14 Heart Beat Heart muscles are composed of individual fibers Each atrium and ventricle contracts as a unit.Each contraction begins with a group of cardiac muscle cells in the right atrium known as the sinoatrial node (SA node)
15 Heart BeatBecause the SA node paces the heart it is known as the pacemaker.The impulse spreads from the pacemaker to the rest of the atria.From the atria, a signal is sent to the atrioventricular node and then to a bundle of fibers in the ventricle.When the ventricle contracts, blood flows out.
16 Blood VesselsAs blood moves through the circulatory system it moves through 3 types of blood vessels:ArteriesCapillariesVeins
17 Arteries Large vessels Carry blood from heart to tissues of body Carry oxygen rich blood, with the exception of pulmonary arteries.Thick walls-need to withstand pressure produced when heart pushes blood into them.
18 Capillaries Smallest blood vessels Walls are only one cell thick and very narrow.Important for bringing nutrients and oxygen to tissues and absorbing CO2 and other waste products.
19 VeinsOnce blood has passed through the capillary systems it must be returned to the heart.Done by veinsWalls contains connective tissue and smooth muscle.Largest veins contain one way valves that keep blood flowing toward heart.Many found near skeletal muscles. When muscles contract, blood is forced through veins.
20 Blood Pressure The heart produces pressure The force of blood on the wall of the arteries is known as blood pressure.Blood pressure decreases as the heart relaxes, but the rest of the circulatory system is still under pressure.
21 Blood PressureWhen blood pressure is taken, the cuff is wrapped around the upper portion of the arm and pumped with air until blood flow in the artery is blocked.As the pressure in the cuff is relaxed, 2 numbers are recorded.Systolic pressure- the first number taken, is the force felt in the arteries when the ventricles contract.Diastolic pressure- the second number taken, is the force of the blood on the arteries when the ventricles relax.
22 Disorders of Circulatory System AtherosclerosisFatty deposits (plaque) in walls of arteriesDeposits can obstruct flow of blood which can raise blood pressureIncreases risk of blood clotsIf clot breaks free it can obstruct blood flow to tissues.
23 Disorders of Circulatory System Heart AttackDue to atherosclerosis, coronary arteries may become blocked (blood can’t get to heart muscle)Heart muscle begins to die due to lack of O2
24 Disorders of Circulatory System StrokeBlood clot may break free and block a vessel leading to the brain.Brain cells are starved of oxygen and nutrientsLoss of function may occurCan cause paralysis, loss of ability to speak or death.
25 Blood Composed of plasma and blood cells Types of Cells are: Red Blood CellsWhite Blood CellsPlatelets
26 Blood Plasma Straw colored 90% water 10% dissolved gases, salts, nutrients, enzymes, hormones, wastes, and proteins.
27 Blood Plasma proteins 3 Types: Albumins, globulins and fibrinogen. Albumins and Globulins- transport substances such as fatty acids, hormones and vitamins.Fibrinogen- Responsible for blood’s ability to clot
28 Blood Red Blood Cells Most numerous type Transport oxygen Get color from hemoglobinDisk shapedMade in red bone marrowCirculate for 120 days
29 Blood White Blood Cells Guard against infection, fight parasites, and attack bacteriaNumber of WBC’s increases when body is fightingLymphocytes produce antibodies which fight pathogens and remember them
30 Blood Platelets Aid the body in clotting Small fragments Stick to edges of broken blood cell and secrete clotting factor to help form clot.
31 Blood Clotting Problems HemopheliaGenetic disorder that disrupts clottingPeople must be very careful to avoid injuryCan be treated by injecting extracts that contain the missing clotting factor.