Date post: | 18-Jan-2016 |
Category: |
Documents |
Upload: | stephanie-jacobs |
View: | 221 times |
Download: | 0 times |
Human Anatomy and Physiology
Blood pressure and regulation of cardiac output
Blood vessels
Arteries, arterioles, capillary bed, venules, veins
Changes in blood pressure
Systemic blood pressure Systolic and diastolic pressure Pulse pressure (declines gradually)
Systemic blood pressure Mean arterial pressure
MAP = diastolic + pulse pressure pressure 3
MAP = 70 mm Hg + 50 mm Hg = 87 mm Hg 3
Cardiac output Increasing preload pressure increases
heart rate and stroke volume
Calculating Cardiac output Cardiac output (CO) = HR x SV HR = 80 beats/min SV = 0.07l/beat or 70 ml CO = 80 x 70 = 5.6 l/min
Starling’s law The greater the filling of the heart, the
greater the amount pumped by the heart
Blood pressure Determined by:
cardiac output vascular resistance (total peripheral
resistance) blood volume
Short Term Regulation Neural control Hormonal control
Venous return
Short Term Regulation Chemical control
Stimulus: decline in BP Adrenal medulla :norepinephrine (NE) Increases HR
Stimulus: increase in BP Atrial natriuretic peptide (ANP) Decreases blood volume and pressure
Short Term Regulation
Vascular resistance Altering blood flow by
changing vessel diameter Vasodilation/constriction
Short Term Regulation
Vasodilation Blood pumped faster Venous return
Muscle pump Respiratory pump
100%
Long Term Regulation Changes in blood
volume (kidneys) Renal autoregulation Angiotensin II (renin) Hormones ADH Aldosterone
Blood Pressure Regulation Baroreceptors
Nerve endings detect stretch Most important (aortic arch, carotid arteries) Information relayed to the brain