blood, veins, arteries, and the heart

• The central organ responsible for pumping blood throughout the transport system is your heart

• Four chambers (two atria & two ventricles) and four valves (two semilunar & two atrioventricular)

• Five major blood vessels (aorta, superior & inferior vena cava, and pulmonary artery & vein)

• Make sure you know this basic anatomy of the heart

• The blood flows through the heart in the same path over and over again

Note the difference in thickness of the chamber walls…why such a difference?

• After leaving the left ventricle, blood enters the largest artery in the body, the aorta

• Many branches exist along the aorta, one of the first leads to the coronary arteries

• Coronary arteries supply oxygen and nutrients

• Blocked coronary arteries can lead to heart attacks

• The beating contractions of the heart are controlled by electrical impulses

• Contractions are not controlled by the nervous system (Myogenic muscle contraction)

• In the right atrium you’ll find the sinoatrial (SA) node• Natural pacemaker of the heart—sends out electrical signal

• The SA node impulse causes both atria to contract

• Simultaneously a signal is sent to the atrioventricular (AV) node• AV node delays ~.1 seconds then sends out its own signal

• This second impulse cause both ventricles to contract

• Exercise (increase need for O2) and adrenaline will cause the heart to beat faster• Exercise causes increase in CO2 , which signals the medulla in

the brain relays a signal to the SA node via the cranial nerve

• Heart splits the blood flow up into two distinct paths• Pulmonary circulation — capillary bed/terminal location LUNGS• Originates from right side of heart

• Systemic circulation — capillary bed/terminal location BODY• Originates from left side of heart

ARTERIES= awayNothing to do with O2

• Blood is the actual medium transport relies on

• Blood is made up of four components• Plasma, RBC (erythrocytes), WBC (leukocytes), platelets

• Main substrates transported by blood are • nutrients• oxygen, carbon dioxide• hormones• antibodies• urea• heat

• Arteries, capillaries and veins are the actual structures that allow blood to flow throughout the body

• Arteries have a smooth muscle layer which allows for contraction to regulate blood pressure

• Arteries aterioles capillary bed single capillary

• Capillaries have very thin walls to allow for chemical exchange

• Capillary beds all empty into venules veins heart• Veins have thin walls, larger diameter, and valves to help

move blood