Cardiovascular System

The Cardiovascular System A closed system of the heart and blood vessels –The heart pumps blood –Blood vessels allow blood to circulate to all parts of the body The function of the cardiovascular system is to deliver oxygen and nutrients and to remove carbon dioxide and other waste products

The Heart Location –Thorax between the lungs –Pointed apex directed toward left hip About the size of your fist

The Heart Figure 11.1

The Heart: Coverings Pericardium – a double serous membrane –Visceral pericardium Next to heart –Parietal pericardium Outside layer Serous fluid fills the space between the layers of pericardium

The Heart: Heart Wall Three layers –Epicardium Outside layer This layer is the parietal pericardium Connective tissue layer –Myocardium Middle layer Mostly cardiac muscle –Endocardium Inner layer Endothelium

Homeostatic Imbalance When the heart beats fast, it might not get all the blood it needs This leads to the myocardium being deprived of oxygen resulting in crushing chest pain This pain should not be ignored, as it could mean hearts cells are dying This could lead to a myocardial infarction (aka: heart attack)

External Heart Anatomy Figure 11.2a

The Heart: Chambers Right and left side act as separate pumps Four chambers –Atria Receiving chambers –Right atrium –Left atrium –Ventricles Discharging chambers –Right ventricle –Left ventricle Figure 11.2c

Blood Circulation Figure Pulmonary Circulation -Carry blood to the lungs for gas exchange and then return it to the heart - Systemic Circulation -Blood leaving your heart on the left side, nourishing your body tissues, and returning on the right side

The Heart: Valves Allow blood to flow in only one direction Four valves –Atrioventricular (AV) valves – between atria and ventricles Bicuspid valve (left) Tricuspid valve (right) –Semilunar valves between ventricle and artery Pulmonary semilunar valve Aortic semilunar valve

The Heart: Valves Valves open as blood is pumped through Held in place by chordae tendineae (“heart strings”) Close to prevent backflow

Operation of Heart Valves Figure 11.4

The Heart: Associated Great Vessels Aorta –Leaves left ventricle Pulmonary arteries –Leave right ventricle Vena cava –Enters right atrium Pulmonary veins (four) –Enter left atrium

Coronary Circulation Blood in the heart chambers does not nourish the myocardium The heart has its own nourishing circulatory system –Coronary arteries –Cardiac veins –Blood empties into the right atrium via the coronary sinus

Blood Groups and Transfusions Large losses of blood have serious consequences –Loss of 15 to 30 percent causes weakness –Loss of over 30 percent causes shock, which can be fatal The average adult has about 5.5 L of blood It takes one minute for blood to flow in a complete cycle The heart pumps about 6000 quarts of blood in a single day!

Blood Groups and Transfusions Transfusions are the only way to replace blood quickly Transfused blood must be of the same blood group

Human Blood Groups Blood contains genetically determined proteins A foreign protein (antigen) may be attacked by the immune system Blood is “typed” by using antibodies that will cause blood with certain proteins to clump (agglutination)

ABO Blood Groups Based on the presence or absence of two antigens –Type A –Type B The lack of these antigens is called type O

ABO Blood Groups The presence of both A and B is called type AB The presence of either A or B is called types A and B, respectively

Rh Blood Groups Named because of the presence or absence of one of eight Rh antigens (agglutinogen D) Most Americans are Rh + Problems can occur in mixing Rh + blood into a body with Rh – blood

Blood Typing Blood samples are mixed with anti-A and anti-B serum Coagulation or no coagulation leads to determining blood type Typing for ABO and Rh factors is done in the same manner Cross matching – testing for agglutination of donor RBCs by the recipient’s serum, and vice versa

Blood Typing Figure 10.8

Blood Pressure Pressure the blood exerts against the inner walls of the blood vessels It is the force that keeps blood circulating continuously throughout the body Blood pressure consists of 2 numbers Systolic Pressure = peak pressure Diastolic Pressure Relaxed pressure “Normal” blood pressure is 110 – – 80

Measuring Blood Pressure Get a blood pressure meter Sit in your chair like normal Strap it around your bicep Pump the air in Record the numbers Let the air out NOW, try it while bending over (arm below heart) Do you notice a difference?

Heart Sounds When using a stethoscope, 2 distinct sounds can be heard  lub, dup These sounds happen when valves in your heart shut Murmurs are sounds that can be heard that should not be there –Faulty valves or blocked blood vessels

Heart Sounds Get a stethoscope Listen to your heart beat or a group members heart beat Do you hear the lub dup? Do you hear any murmurs?