Some factors affecting the arterial blood pressure 1
Some factors affecting the arterial blood pressure 1. GRAVITY: 100 – [0. 77× 50] = 62 mm. Hg ــــ 50 cm MABP =100 mm. Hg ــــ The magnitude of the gravitational effect is 0. 77 mm Hg/cm of vertical distance above or below the heart 105 cm 100 + [0. 77 × 105] = 180 mm Hg ــــ
2. specific factors arterial B. P = C. O. × TPR Factors affecting C. O affect systolic B. P Factors affecting TPR affect diastolic B. P During exercise ↑C. O ↑ systolic B. P ↓TPR ↓ diastolic B. P
3. Age old people have higher blood pressure than children 4. sex female has lower B. P. than male vlower S. V. v lower HR vlower TPR.
Methods of measuring blood pressure Methods Invasive method Palpatory method Non invasive method Auscultatory method
Auscultatory method
Cuff pressure Blood pressure
Palpatory method
Regulation of the arterial BP short term regulation q. Works within seconds or minutes qbaroreceptor mechanism long-term regulation q. Works within hours, days , weeks or years qthe rennin –angiotensin. Aldosteron system
Baroreceptors high pressure receptors Low pressure receptors • carotid sinus • aortic arch • Right atria • Left atria • pulmonary veins
carotid body Int carotid A Ext carotid A carotid sinus Common carotid A Aortic body Aortic arch
Mechanism of transduction AP Stretch receptor stretch activated Na channels
Reflexes initiated by stretchingh. N p o s s of the baroreceptors lo G s u g a e v r ne V NTS Medulla oblongata VMC CIC CEC parasym Symp to Sym p to p heart bl V
↑rate p o ss N. h o Gl Medulla oblongata Cardiorequlatory center & VMC ↓rate ve r e n s Vagu s n ↑rate parasy erve mp Symp n Symp chain Blood vessels
Function of the baroreceptors during changes in body posture. Standing pooling of blood in the lower extremities ↓C. O. ↓ BP ↑ C. O. ↑symp outflow. ↓ baroreceptors discharging rate
carotid sinus massage press on the carotid sinus ↑ baroreceptors discharging rate inhibition of CEC stimulation of CI. C ↓HR & ↓BP
Low-pressure receptors reflexes
Control of arterial pressure by the carotid & aortic chemoreceptors carotid body aortic bod. Y
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