Blood flows through the heart, arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries: Histology, capillaries Capillaries Capillaries are the primary structures in the circulatory system that allow the exchange of gas, nutrients, and other materials between the blood and the extracellular fluid (ECF). Capillaries are the smallest of the blood vessels. Because a capillary diameter is so small, only 1 RBC may pass through at a time. Capillaries: Histology, and veins Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. Veins: Histology in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance Resistance Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow. Ventilation: Mechanics of Breathing fluid encounters between 2 points. Vascular resistance Resistance Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow. Ventilation: Mechanics of Breathing is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular resistance Resistance Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow. Ventilation: Mechanics of Breathing is directly related to the diameter of the vessel (smaller vessels have higher resistance Resistance Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow. Ventilation: Mechanics of Breathing). Mean Mean Mean is the sum of all measurements in a data set divided by the number of measurements in that data set. Measures of Central Tendency and Dispersion arterial pressure (MAP) is the average systemic arterial pressure and is directly related to cardiac output Cardiac output The volume of blood passing through the heart per unit of time. It is usually expressed as liters (volume) per minute so as not to be confused with stroke volume (volume per beat). Cardiac Mechanics (CO) and systemic vascular resistance Resistance Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow. Ventilation: Mechanics of Breathing (SVR). The SVR and MAP are affected by the vascular anatomy as well as a number of local and neurohumoral factors.
Last updated: 2 May, 2022
Ohm’s law is an important basic formula in physics. A derivation of Ohm’s law can be used to calculate blood flow.
Flow: the volume of fluid passing a point per unit of time:
Laminar versus turbulent flow:
In smooth-walled vessels, blood moves by laminar flow. The blood moves the fastest in the center of the vessel where there is the least
resistance
Resistance
Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow.
Ventilation: Mechanics of Breathing. In atherosclerotic vessels with uneven walls, blood flow is turbulent.
Flow versus pressure gradient:
Vascular
resistance
Resistance
Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow.
Ventilation: Mechanics of Breathing is disproportionately higher in vessels with turbulent flow compared to vessels with laminar flow.
Resistance Resistance Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow. Ventilation: Mechanics of Breathing: forces opposing flow:
ΔP: the difference in pressure between 1 point and another
Pressure as a function of flow and
resistance
Resistance
Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow.
Ventilation: Mechanics of Breathing:
Pressure is directly related to both flow and
resistance
Resistance
Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow.
Ventilation: Mechanics of Breathing. As either flow or
resistance
Resistance
Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow.
Ventilation: Mechanics of Breathing increases, pressure increases proportionally.
ΔP (pressure gradient) = R (
resistance
Resistance
Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow.
Ventilation: Mechanics of Breathing) x F (flow)
Capacitance Capacitance The measure of a blood vessel’s ability to increase the volume of blood it holds without a large increase in blood pressure. The vascular capacitance is equal to the change in volume divided by the change in pressure. Venous Function: the amount a vessel can stretch without significantly increasing pressure:
The
relationship
Relationship
A connection, association, or involvement between 2 or more parties.
Clinician–Patient Relationship between flow and velocity:
Velocity is inversely related to area. If the
radius
Radius
The outer shorter of the two bones of the forearm, lying parallel to the ulna and partially revolving around it.
Forearm: Anatomy of the cylinder (r) is halved, the velocity increases 4-fold.
F: flow
V: velocity
A: area
r:
radius
Radius
The outer shorter of the two bones of the forearm, lying parallel to the ulna and partially revolving around it.
Forearm: Anatomy
Mean Mean Mean is the sum of all measurements in a data set divided by the number of measurements in that data set. Measures of Central Tendency and Dispersion arterial pressure is the average systemic arterial pressure.
Mean
Mean
Mean is the sum of all measurements in a data set divided by the number of measurements in that data set.
Measures of Central Tendency and Dispersion arterial intravascular pressure throughout the
cardiac cycle
Cardiac cycle
The cardiac cycle describes a complete contraction and relaxation of all 4 chambers of the heart during a standard heartbeat. The cardiac cycle includes 7 phases, which together describe the cycle of ventricular filling, isovolumetric contraction, ventricular ejection, and isovolumetric relaxation.
Cardiac Cycle
MAP:
mean
Mean
Mean is the sum of all measurements in a data set divided by the number of measurements in that data set.
Measures of Central Tendency and Dispersion arterial pressure
P: pressure
Sys: systolic
Dias: diastolic
Mean Mean Mean is the sum of all measurements in a data set divided by the number of measurements in that data set. Measures of Central Tendency and Dispersion arterial pressure is primarily affected by the CO and SVR:
CO = heart rate Heart rate The number of times the heart ventricles contract per unit of time, usually per minute. Cardiac Physiology x stroke volume Stroke volume The amount of blood pumped out of the heart per beat, not to be confused with cardiac output (volume/time). It is calculated as the difference between the end-diastolic volume and the end-systolic volume. Cardiac Cycle:
Systemic vascular resistance Resistance Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow. Ventilation: Mechanics of Breathing is primarily affected by:
Factors affecting
mean
Mean
Mean is the sum of all measurements in a data set divided by the number of measurements in that data set.
Measures of Central Tendency and Dispersion arterial pressure
MAP:
mean
Mean
Mean is the sum of all measurements in a data set divided by the number of measurements in that data set.
Measures of Central Tendency and Dispersion arterial pressure
CO:
cardiac output
Cardiac output
The volume of blood passing through the heart per unit of time. It is usually expressed as liters (volume) per minute so as not to be confused with stroke volume (volume per beat).
Cardiac Mechanics
SVR: systemic vascular
resistance
Resistance
Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow.
Ventilation: Mechanics of Breathing
SV:
stroke volume
Stroke volume
The amount of blood pumped out of the heart per beat, not to be confused with cardiac output (volume/time). It is calculated as the difference between the end-diastolic volume and the end-systolic volume.
Cardiac Cycle
HR:
heart rate
Heart rate
The number of times the heart ventricles contract per unit of time, usually per minute.
Cardiac Physiology
Vascular anatomy has significant effects on SVR, which directly affects MAP.
Left: a vascular circuit in series with 3 different points of
resistance
Resistance
Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow.
Ventilation: Mechanics of Breathing
Right: a vascular circuit in parallel
Vessels have:
Distribution of pressure:
Endothelial cells lining blood vessels can secrete a number of factors causing vasodilation Vasodilation The physiological widening of blood vessels by relaxing the underlying vascular smooth muscle. Pulmonary Hypertension Drugs or vasoconstriction. Changing the radius Radius The outer shorter of the two bones of the forearm, lying parallel to the ulna and partially revolving around it. Forearm: Anatomy of the vessel changes the SVR, which changes MAP.
Chemical pathways lead to the production of
nitric oxide
Nitric Oxide
A free radical gas produced endogenously by a variety of mammalian cells, synthesized from arginine by nitric oxide synthase. Nitric oxide is one of the endothelium-dependent relaxing factors released by the vascular endothelium and mediates vasodilation. It also inhibits platelet aggregation, induces disaggregation of aggregated platelets, and inhibits platelet adhesion to the vascular endothelium. Nitric oxide activates cytosolic guanylate cyclase and thus elevates intracellular levels of cyclic gmp.
Pulmonary Hypertension Drugs, which ultimately causes smooth muscle relaxation and
vasodilation
Vasodilation
The physiological widening of blood vessels by relaxing the underlying vascular smooth muscle.
Pulmonary Hypertension Drugs.
GTP: guanosine triphosphate
Gq: gq protein
GC: guanylyl cyclase
cGMP
cGMP
Guanosine cyclic 3.
Phosphodiesterase Inhibitors: cyclic
guanosine monophosphate
Guanosine monophosphate
A guanine nucleotide containing one phosphate group esterified to the sugar moiety and found widely in nature.
Purine and Pyrimidine Metabolism
Ca
CA
Condylomata acuminata are a clinical manifestation of genital HPV infection. Condylomata acuminata are described as raised, pearly, flesh-colored, papular, cauliflower-like lesions seen in the anogenital region that may cause itching, pain, or bleeding.
Condylomata Acuminata (Genital Warts)2+:
calcium
Calcium
A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.
Electrolytes
Neurohumoral factors can affect Affect The feeling-tone accompaniment of an idea or mental representation. It is the most direct psychic derivative of instinct and the psychic representative of the various bodily changes by means of which instincts manifest themselves. Psychiatric Assessment both CO and SVR and include:
Neurohumoral factors (primarily via the ANS ANS The ans is a component of the peripheral nervous system that uses both afferent (sensory) and efferent (effector) neurons, which control the functioning of the internal organs and involuntary processes via connections with the CNS. The ans consists of the sympathetic and parasympathetic nervous systems. Autonomic Nervous System: Anatomy) can affect Affect The feeling-tone accompaniment of an idea or mental representation. It is the most direct psychic derivative of instinct and the psychic representative of the various bodily changes by means of which instincts manifest themselves. Psychiatric Assessment venous capacitance Capacitance The measure of a blood vessel’s ability to increase the volume of blood it holds without a large increase in blood pressure. The vascular capacitance is equal to the change in volume divided by the change in pressure. Venous Function, which can affect Affect The feeling-tone accompaniment of an idea or mental representation. It is the most direct psychic derivative of instinct and the psychic representative of the various bodily changes by means of which instincts manifest themselves. Psychiatric Assessment preload Preload Cardiac Mechanics and, as a result, CO and MAP:
Changes in venous tone and the effect on
capacitance
Capacitance
The measure of a blood vessel’s ability to increase the volume of blood it holds without a large increase in blood pressure. The vascular capacitance is equal to the change in volume divided by the change in pressure.
Venous Function
VSMC: vascular smooth muscle cell
The information presented below explains factors that determine blood pressure and how blood moves throughout the body. The foundational topics are critical to understanding Understanding Decision-making Capacity and Legal Competence how and why the body adjusts to different situations in order to maintain appropriate perfusion.