CalRegional Medical Assistant Practice Exam

Blood pressure is regulated mainly by nervous and endocrine control, which adjust how hard the heart pumps, how fast it beats, and how wide or narrow the blood vessels are, as well as how much fluid is in the bloodstream. The autonomic nervous system quickly tunes BP by changing heart rate, contractility, and vascular tone in response to activity, stress, or posture. Hormonal systems provide longer-term regulation: the renin-angiotensin-aldosterone system constricts vessels and increases blood volume; vasopressin (antidiuretic hormone) promotes water retention to raise blood volume; atrial natriuretic peptide lowers BP by promoting salt and water loss and dilating vessels. Together, these nervous and hormonal mechanisms keep blood pressure within normal limits. The other options don’t fit as well because they don’t primarily regulate blood pressure through hormonal and nervous signals—the digestive system, muscular/skeletal systems, or integumentary/lymphatic systems aren’t the main controllers of BP via hormones and nerves.