Supplemental Circulatory Respiratory Notes

Respiratory features
   Tracheal systems: spiracles, book lungs.  Found in insects where access to cells for diffusion is short.
   See TB p. 886

   Lungs evolved to sustain larger body systems.  Most vertebrates have lungs and diaphragms to access O2.  Fe+ in the hemoglobin protein in RBC's attache to O- as the RBC's pass thru the capillaries in the
alveoli in the lungs.  CO2 is taken up by the RBC's but it also interacts with H2O to form H2CO3.
Read  Sec.42.7 on Resp pigments and review diag. 42.30  p. 893 in TB.

pH control of blood: Chemoreceptors in carotid arteries(neck) monitor blood pH.. When CO2 inc. pH inc.(blood becomes acidic).  Chemor. send impulse to diaphragm to inc. gas exchange, inc. pH and return to normal(7.3). Medulla(brain) us the control center for gas excheange.  See disg. 42.26 p. 890 in TB.
Another Neg. fdbk mech controls erythrocyte prod.  See p. 881 in TB.  Also read @ stem cells here.

Circulatory systems: Open and closed.
Open consists of a combination of blood and interstitial fluid.  This occurs in the hempcoel and sinuses(cavities); also known as hemolymph.
Closed systems are enclosed within vessels.  A lymphatic system is also enclosed by vessels. It processes fluid and is similar to interstitial fluid that leaks from the capillaries.  Both wastes and pathogens are filtered thru the lymph. sys.  Lymph nodes play the role in this.  See p. 878 in TB.

Heart valves and nodes: Valve bet. rt. atrium and rt. vent-tricuspid(round with 3 flaps).  Valve bet. Left Atrium and Left Ventricle is the bicuspid or mitral valve .Valve from Rt Vent. to aorta is semilunar(Rnd. w/ 2 flaps).  See p. 872-3 in TB.

Heart is a muscle which ha a self-contained nervous impulses known as the cardiac cycle.  See p. 873 in TB.  2 nodes SA and AV keep the heart pumping.  SA nodes begins cycle by stimulating both atria  and sends a delayed stimulus to the AV node.  Stimulus then goes to the Bundle of His (see bundle branches 42.8 p. 874) via Purkinje fibers.  Ventricles contract=systolic blood pressure; Ventricles relax=diastloic bl. press.