Double Circulatory System - Humans
1 – pulmonary circuit – pumped to lungs through right artery (pulmonary artery) for gas exchanged then travels back to heart where 2 occur.
2 – systemic circuit – pumped to the rest of the body through left pulmonary vein.
1st pump gas exchange occurs.
2nd pump gets sent to the body.
The human heart
Blood without oxygen s right side of the heart.
Blood flow through the heart in one direction.
Valves control the blood flow (2 on each side) – open and close at different times.
Heart has two sides with two chambers (atrium - top and ventricle - bottom).
Arteries and veins are main tubes (plumbing).
Arteries away from heart
Veins to heart
Cardiac muscle is the only muscle in the heart – bottom. Never gets fatigue or tired, once stops heart stop pumping.
Septum – divider of the two chambers of the heart – to keep both types away from each other – types: oxygenated blood (left) and deoxygenated blood (right)
Double Circulatory System:
Deoxygenated blood
Enters the heart through the Vena Cava (superior and inferior)
Exits the heart though the Pulmonary Artery
Oxygenated blood
Enters the heart through the pulmonary vein
Exits the heart throughout aorta.
Coronary Circulation:
Cardiac muscle has its own blood supply. (Coronary arteries and veins.)
Small arteries are easily blocked by cholesterol buildup leading to a heart attack.
Affected by a number of factors.
Cardiac Cycle:
Blood moves through the heart in a series of contractions and relaxations of cardiac muscle
Contraction of cardiac muscle – Systole
Relaxing of cardiac muscle – Diastole
The Atrio-Ventricular (AV) valves control the passage of blood from an atrium to a ventricle.
In the first part of the cardiac cycle, the atria relax and blood from the lungs and the body flows into them.
Once the atria have filled with blood, the muscles of the atria walls contract (systole), forcing the blood down into the ventricles. This occurs as a wave of muscular contractions. The walls of the atria are not very thick. Since they only have to push the blood to the ventricle. The AV then closes to stop blood from flowing back into the atria.
The ventricle walls now relax, and the cycle starts once more, filling the atria with blood.
Exercise and Heart Rate
CO2 levels increase when exercising
Aorta and carotid artery sensors recognize low pH
Signal sent to medulla
Medulla sends signal to the accelerator nerve in the pacemaker.
Heart beats faster
Circulatory System: Blood Vessels
Blood is transported in a closed circuit.
Blood vessels are a network of tubes that carry blood throughout the entire body.
The three types of blood vessels are;
Artery: carrying blood away from the blood, with very thick muscular walls (they have thick walls as the blood from the heart comes from a very high pressure therefore they need to be thick to withstand that pressure), blood travels at high pressure, no valves (because the blood is traveling at such high pressure therefore it cant travel backwards), carries oxygenated blood. Diseases: plaque builds up in artery if one doesn’t exercise much; therefore there is a decrease in blood flow.
Arteriole: branches from the arteries, feed blood into the capillaries, can constrict or dilate under nerve control, carry oxygenated blood.
Capillaries: thin; thickness of 1 cell (they are thin due to diffusion), brings blood in contact with body tissues, blood travels at low pressure (to allow sufficient time for diffusion to occur), permits substances to pass through.
Venule: carries blood from capillaries to veins, blood travels at low pressure.
Veins: carry blood towards the heart, have thin walls, blood travel at low pressure, deoxygenated blood, have semilunar valves.