Bio20B_Lecture6

Bio20B_Lecture6 - Bio 20B April 19, 2007 Respiratory...

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Bio 20B – April 19, 2007 Respiratory Continued Circulatory System Endocrine System (Freeman Fig. 44-12a graph) relationship between: how much oxygen is stored (saturated) on hemoglobin and partial pressure of oxygen in blood within tissue. If hemoglobin only has 20% of oxygen, the other 80% is in the tissues. At a low partial pressure of oxygen in blood within tissues, there is a low amount of oxygen stored in hemoglobin. At a high partial pressure of oxygen in blood within tissues, there is a higher amount of oxygen stored in hemoglobin. The S curve means that it is cooperative binding. The Bohr Effect: As the pH levels drop, it is easier for hemoglobin to dump oxygen into the tissues (Freeman Fig. 44-12a graph) The Heart o Muscle Fibers of the Heart: Myocardium (highly specialized) Atrial muscle Ventricular muscle Contract like skeletal muscle but: the duration of relaxation between contractions is longer (prevents lethal constant contraction state) Special excitatory, conductive muscle – serves as pacemaker Ventricles are more muscular than atria Left ventricle is more muscular than the right Left ventricle has to deliver blood at high pressure Because of this muscle arrangement, the Heart rotates slightly when it pumps o Specialized electrical conducting areas of the Heart & Self Regulation of Heart Rate (Campbell Fig. 42.7) Sino-Atrial (SA) node (pacemaker) Sets the rate and timing at which cardiac muscle cells contract Atrium contracts Atrio-Ventricular (AV) node Impulses from the SA node travel to the AV node At the AV node, the impulses are delayed and then travel to the Purkinje fibers that make the ventricles contract Ventricles contract A-V bundle Purkinje fibers o ECG Wave Form (Electrocardiogram) P-wave: atrial depolarization QRS Waves: ventricular depolarization T-wave: repolarization of ventricles Depolarization leads to contraction Campbell Fig. 42.6
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Circulation o Invertebrates have an open circulatory system – blood pumped by arteries but “oozes” back to heart o Vertebrates have a closed circulatory system (more efficient) Heart, arteries, and veins Represents a major evolutionary advancement
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Bio20B_Lecture6 - Bio 20B April 19, 2007 Respiratory...

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