• Many factors influence blood pressure by affecting the heart
(altering contractility or heart rate), and/or the blood vessels
(changing the resistance). These factors include alterations
in blood volume and cardiac output, changes in blood ves-
sel diameter, stimulation of sympathetic or parasympathetic
nerve activity, release of various hormones, and administra-
tion of drugs.
• Blood pressure is maintained by neural and hormonal mech-
anisms. The neural mechanisms involve sensing changes in
blood pressure (baroreceptors) and making adjustments.
The cardiac and vasomotor centers alter heart rate, con-
tractility, and blood vessel diameter through sympathetic
or parasympathetic outflow. Various hormones affect blood
pressure by causing increases in heart rate or contractility,
vasoconstriction, vasodilation, or alterations in blood vol-
ume. These neurological and endocrine mechanisms inter-
act to control blood pressure under changing physiological
circumstances, such as exercise, trauma, or disease.
Changes in pressure as blood flows through the
cardiovascular system • Figure 11.18
Key Terms
• anastomose 319
• anterior tibial veins 328
• aorta 312
• apex 311
• arrhythmia 316
• arteriole 321
• artery 312
• atherosclerosis 319
• atherosclerotic plaque 319
• atrial systole 316
• atrium 312
• autoregulation 324
• axillary veins 328
• baroreceptor 334
• baroreceptor reflex 334
• base 311
• basilic veins 328
• brachial veins 328
• brachiocephalic trunk 322
• brachiocephalic veins 328
• bronchial arteries 322
• capillary 324
• cardiac center 334
• cardiac conduction system
315
• cardiac cycle 316
• cardiac output (CO) 318
• cardiologist 316
• celiac trunk 322
• cephalic veins 328
• common iliac arteries 322
• coronary artery 312
• coronary sinus 312
• diastole 316
• dorsal venous arches 328
• edema 324
• electrocardiogram
(EKG
or ECG) 316
• esophageal arteries 322
• external jugular veins 328
• femoral vein 330
• glaucoma 337
• gonadal arteries 322
• great saphenous veins 328
• heart 310
• heart rate (HR) 318
• hepatic portal vein 330
• hypertension 337
• inferior mesenteric artery
322
• inferior phrenic arteries 322
• inverior vena cava (IVC) 328
• internal jugular veins 328
• left atrium 312
• left common carotid artery 322
• left subclavian artery 322
• left ventricle 312
• lumen 321
• mean arterial pressure (MAP) 332
• median antebrachial veins 328
• median cubital veins 328
• mediastinum 311
• myocardial infarction 319
• myocardial ischemia 319
• myocardium 312
• osmotic pressure 324
• pericardium 312
• popliteal vein 328
• portal vein 330
• posterior intercostal arteries 322
• posterior tibial veins 328
• precapillary sphincter 324
• radial veins 328
• renal arteries 322
• respiratory pump 327
• right atrium 312
• right subclavian artery 322
• right ventricle 312
• shock 335
• skeletal muscle pump 326
• small saphenous veins 328
• stroke volume (SV) 318
• subclavian veins 328
• superior mesenteric artery
322
• superior phrenic arteries
322
• superior vena cava (SVC)
328
• suprarenal arteries 322
• systole 316
• ulnar veins 328
• valve 312
• vasoconstriction 321
• vasodilation 321
• vasomotor center 334
• vein 312
• ventricle 312
• ventricular systole 316
• venule 326
• vertebral veins 328
Key Terms 339
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