Chapter 9: Circulatory
|Why is the respiratory system and circulatory system called a coupled unit?||the respiratory system adds oxygen and removes carbon dioxide from the blood, while the circulatory sytem is responsible for the delivery of oxygenated blood and nutrients to tissues in accordance with their needs.|
|2 major adjustments of blood flow during exercise|| -increased cardiac output.|
-redistribution of blood flow.
|heart||creates pressure to pump blood.|
|arteries/arterioles||carry blood AWAY from the heart|
|capillaries||exchange of O2, CO2, and nutrients with tissues|
|veins/venules||carry blood TOWARD the heart|
|why is the circulatory system considered closed?||because arteries and veins are continuous with each other through smaller vessels.|
|the 4 chambers of the heart|| right atrium|
|the purpose of the 4 valves of the heart||to prevent backflow|
|right side of heart|| pumps deoxygenated blood to the lungs through the pulmonary arteries.|
returns oxygenated blood to the left side of the heart via pulmonary veins.
|left side of heart|| pumps oxygenated blood to the whole body via arteries.|
returns deoxygenated blood to the right side of the heart via veins.
|myocardium|| -the heart wall|
-receives blood supply via coronary arteries
-myocardial infarction (MI)
|the 3 layers of heart wall|| epicardium (outer layer)|
myocardium (middle layer)
endocardium (inner layer)
|myocardial infarction||-blockage in coronary blood flow results in cell damage.|
|myocardium||heart muscle that is responsible for contracting and forcing blood out of the heart|
|systole|| contraction phase.|
pressure in ventricles rises.
ejection of blood (2/3)
shorter at rest and during exercise.
|diastole|| relaxation phase.|
pressure in ventricles is low
filling with blood.
longer at rest, shorter during exercise.
|factors that influence arterial blood pressure|| determinants of mean arterial pressure (MAP)|
short term regulation (sympathetic nervous system)
long term regulation (kidneys)
|sinoatrial node (SA node)||pacemaker, initiates depolarization.|
|atrioventricular node (AV node)|| passes depolarization to ventricles.|
brief delay to allow for ventricular filling.
|steps of conduction system|| SA node|
|electrocardiogram (ECG)||a recording of the electrical changes that occur in the myocardium during the cardiac cycle.|
|p wave||atrial depolarization|
|QRS complex||ventricular depolarization and atrial repolarization|
|t wave||ventricular repolarization|
|which segment indicates myocardial ischemia?||ST segment.|
|atherosclerosis|| fatty plague that narrows coronary arteries.|
reduces blood flow to myocardium (myocardial ischemia)
|cardiac output|| -the amount of blood pumped by the heart each minute.|
-heart rate x stroke volume (amount of blood pumped per heartbeat)
|cardiac output increases due to:|| increases in heart rate|
increases in stroke volume
|end diastolic volume|| -Frank-Starling mechanism|
-dependent on venous return
|venous return increased by:|| venoconstriction (via SNS)|
skeletal muscle pump (push blood back toward the heart)
respiratory pump (changes in thoracic pressure pull blood toward heart)
|plasma||liquid portion of blood, contains ions, proteins, hormones|
|red blood cells||contain hemoglobin to carry oxygen|
|white blood cells||important in preventing infection|
|platelets||important in blood clotting|
|hematocrit||percentage of blood composed of cells. 42%|