More biology homework 3 questions! PLZ HELP?

[MrsSpalla]

The sinoatrial node is located in the?1-right ventricle2-left ventricle3-left atrium4-right atriumIn what part of the respiratory systemdoes the exchange od oxygen and carbon dioxide occur?1-Larynx2-Trachea3-Lungs4-PharynxIn rheumatic fever, damage to the heart valves is directly caused by1-an uncontrolled spread of streptococcus bacteria2-protein antibodies produced to defend the body againist streptococcus bacteria3-the contest between streptococcus and antibodies that takes place in the body4- a heart murmur due to weakness in the heart valvesIf you can help me out at all thanks a lot!!!

[Wyatt8281]

1) The sinoatrial node is located in the upper wall of the right atrium.2) Gas exchange occurs in the lungs.3) Heart valve damage is caused by protein antibodies produced to defend the body againist streptococcus bacteria.

[ElizabethH6058]

1 - between the right atrium and right ventricle2 - lungs3 - an interaction between antibodies