6a Heart and blood vessels

• What is the heart made of?

  Cardiac muscle
• Who has double circulation?

  Mammals
• What are the two types of circulation?

  Pulmonary and systemic
• What is pulmonary circulation?

  The right side of the heart sends deoxygenated blood from the body, along the pulmonary artery, to the lungs
• What is systematic circulation?

  Pump on left side sends oxygenated blood, from the lungs, along the aorta to the rest of the body
• What does oxygenated mean?

  High concentration of oxygen, low concentration of carbon dioxide
• What does deoxygenated mean?

  Low concentration of oxygen, high concentration of carbon dioxide
• What is the advantage of a heart having two separate pumps?

  The right side generates pressure to get blood through lungs when pressure drops. The left side generates more pressure so the blood travels around the body at a fast enough rate
• What do the coronary arteries do?

  Deliver oxygenated blood to walls of heart, cardiac muscle
• Why does the cardiac muscle need a rich supply of blood?

  Needs good supply of oxygen and glucose for aerobic respiration- lots of ATP for heart muscle contraction
• How many chambers does the heart have + names?

  4- left/right atrium, left/right ventricle
• What separates the left and right chambers of the heart?

  Septum- wall of muscle
• Where does the left atrium receive blood from?

  Pulmonary vein
• Where does the right atrium receive blood from?

  Vena cava
• What happens when the atria contract?

  Blood passes through atrioventricular valves into thicker-walled lower chambers, ventricles
• Why are the muscles thicker on the left?

  Need to contract with more force to produce a higher pressure so the blood travels around the body
• What happens when the ventricles contract?

  Blood passes through the open semi-lunar valves into major arteries. Right- pulmonary artery , left- aorta
• When do the ventricles contract?

  Together after atrium contract
• What are the functions of atrioventricular and semi-lunar valves?

  Prevents backflow of blood when closed. AVV- from ventricle to atrium , SLV- arteries to ventricles
• The heart pumps blood by rhythmic contraction of the cardiac muscle in its walls. At rest, a human heart contracts and relaxes about 70 times a minute. One complete sequence of contraction and relaxation is called a cardiac cycle.
• Contraction of the atrial muscle is known as atrial systole, and contraction of the ventricular muscle is known as ventricular systole. Relaxation of the heart muscle is known as diastole.
• Where does blood flow?

  From a region of high pressure to a region of low pressure
• What happens during diastole?

  The heart relaxes so the atria can fill with blood from the vena cava and pulmonary veins
• Why are the semi-lunar valves closed during diastole?

  Pressure in arteries is higher than ventricles
• What happens in atrial systole?

  Blood fills the atria from the vena cava and pulmonary vein. The atrial muscle contracts, increasing the pressure above that of the ventricles. This forces the atrioventricular valves open and blood flows into the ventricles
• What happens during ventricular systole?

  The ventricle muscles contract. The volume of the ventricle decreases, increasing the pressure, causing the atrioventricular valves to close. Blood is pushed up towards arteries and the semi-lunar valves open so blood can flow in aorta and pulmonary artery.
• What does neurogenic mean?

  Muscles contract as a result of impulse reaching them from the nerves
• Why is the heart myogenic?

  Will still beat after nerve supply cut and contractions arise from within the cardiac muscles.
• What does the sinoatrial node (SAN) do?

  In wall of right atrium- initial stimulus for contraction of heart muscle