Cardiovascular Disorders of the Human Body Flashcards
Endocardium
Inner most layer of the heart
Myocardium
Forms muscle layer between atria and ventricles, composed of myocytes
Pericardium
Outer layer: Tough, fibrous; resistant to distention by restricting left ventricle
Inner layer: serous; visceral (epicardium) & parietal layer
Pericardial cavity
contains 30-50 mL of serous fluid to lubricate/prevent friction
Autonomic Nervous System
SNS stimulation– Increases HR, controls smooth muscle tone of blood vessels
PNS stimulation– Decreases HR (vagus nerve), little/no control of blood vessels
SA Node
Pacemaker, 60-100 BPM, atrial systole
AV Node
40-60 BPM
Impulse travels down to eventually cause ventricular systole
Stroke Volume
The difference between end-diastolic & end-systolic volumes.
Ejection Fraction
Percentage of end-diastolic volume ejected w/ each heartbeat at systole. Normal = 60%. 30-40% is bad/HF
Cardiac Output
Is the amount of blood pumped by the ventricle per minute
CO=SV x HR
Ranges from 4 to 8 L/min
Frank Startling Law
Muscle stretching
Preload
The volume of blood in the ventricles at the end of diastole that the heart must pump w/ each beat
Determined by amt of venous return and degree of muscle stretch.
Afterload
The resistance or pressure the heart must overcome to eject blood from the left ventricle into the aorta. 184/100 BP.
Factors influencing CO
Cardiac Factors: HR, Contractility, Preload, Afterload
Renal, Fluid/Volume control
Renin-Angiotensin
Aldosterone
Atrial Natiuretic factor: released when there’s too much volume
Primary Hypertension
Essential or idiopathic hypertension/Silent Killer
Occurs without evidence of other disease
Affects 90% to 95% of individuals with hypertension
Blood pressure of 140/90 mmHg or higher
Some of the common causes:
Overactive SNS (sympathetic)
Secretion of norepi release of adrenaline (Epi) from adrenal medulla increase BP
Overactive Renin-angiotensin-aldosterone system
Salt and water retention & increased vascular tone
Insulin resistance/Metabolic Syndrome