title: A Discussion on the Regulation of Blood Flow and Pressure.
abstract: This paper discusses two kinds of regulation essential to the circulatory system: namely the regulation of blood flow and that of (systemic) arterial blood pressure. It is pointed out that blood flow requirements sub-serve the nutritional needs of the tissues, adequately catered for by keeping blood flow sufficient for the individual oxygen needs. Individual tissue oxygen requirements vary between tissue types, while highly specific for a given individual tissue. Hence, blood flows are distributed between multiple tissues, each with a specific optimum relationship between the rate of oxygen delivery (DO2) and oxygen consumption (VO2). Previous work has illustrated that the individual tissue blood flows are adjusted proportionately, where there are variations in metabolic rate and where arterial oxygen content (CaO2) varies. While arterial blood pressure is essential for the provision of a sufficient pressure gradient to drive blood flow, it is applicable throughout the arterial system at any one time. Furthermore, It is regulated independently of the input resistance to individual tissues (local arterioles), since they are regulated locally, that being the means by which the highly specific adequate local requirement for DO2 is ensured. Since total blood flow is the summation of all the individually regulated tissue blood flows cardiac inflow (venous return) amounts to total tissue blood flow and as the heart puts out what it receives cardiac output is therefore determined at the tissues. Hence, regulation of arterial blood pressure is independent of the distributed independent regulation of individual tissues. It is proposed here that mechanical features of arterial blood pressure regulation will depend rather on the balance between blood volume and venous wall tension, determinants of venous pressure. The potential for this explanation is treated in some detail.
authors.affiliation: Barts and the London School of Medicine and Dentistry, William Harvey Research Institute, Centre for Clinical Pharmacology, William Harvey Heart Centre, Queen Mary University of London, London, UK. chriswolff@doctors.org.uk.
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Wolff
authors.affiliation: Barts and the London School of Medicine and Dentistry, William Harvey Research Institute, Centre for Clinical Pharmacology, William Harvey Heart Centre, Queen Mary University of London, London, UK.
authors.forename: David J
authors.initials: DJ
authors.lastname: Collier
authors.affiliation: Barts and the London School of Medicine and Dentistry, William Harvey Research Institute, Centre for Clinical Pharmacology, William Harvey Heart Centre, Queen Mary University of London, London, UK.
authors.forename: Mussadiq
authors.initials: M
authors.lastname: Shah
authors.affiliation: Barts and the London School of Medicine and Dentistry, William Harvey Research Institute, Centre for Clinical Pharmacology, William Harvey Heart Centre, Queen Mary University of London, London, UK.
authors.forename: Manish
authors.initials: M
authors.lastname: Saxena
authors.affiliation: Barts and the London School of Medicine and Dentistry, William Harvey Research Institute, Centre for Clinical Pharmacology, William Harvey Heart Centre, Queen Mary University of London, London, UK.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Brier
authors.affiliation: Barts and the London School of Medicine and Dentistry, William Harvey Research Institute, Centre for Clinical Pharmacology, William Harvey Heart Centre, Queen Mary University of London, London, UK.|Barts BP Clinic, St Bartholomew's Hospital, Barts Health NHS Trust, London, UK.
authors.forename: Vikas
authors.initials: V
authors.lastname: Kapil
authors.affiliation: Anaesthetics Department, King's College School of Medicine and Dentistry, London, UK.
authors.forename: David
authors.initials: D
authors.lastname: Green
authors.affiliation: Barts and the London School of Medicine and Dentistry, William Harvey Research Institute, Centre for Clinical Pharmacology, William Harvey Heart Centre, Queen Mary University of London, London, UK.|Barts BP Clinic, St Bartholomew's Hospital, Barts Health NHS Trust, London, UK.
authors.forename: Melvin
authors.initials: M
authors.lastname: Lobo
mesh_terms: D062186:Arterial Pressure / Q000502:physiology*; D001160:Arterioles / Q000294:innervation; D001810:Blood Volume; D006801:Humans; D012039:Regional Blood Flow / Q000502:physiology*
keywords: Arterial blood pressure; Blood flow; Discussion; Regulation; Tissue response