Cardiovascular
The heart as a pump, the ECG, hemodynamics and how blood pressure is controlled.
55 pages
Exam priority: high
- Cardiac output and what sets itRegulation · Cardiac output is how much blood the heart pumps each minute: beats per minute times the volume…
- ECG basics: waves, intervals and leadsMeasurement · The ECG records the heart's electrical activity from the skin; each wave shows a part of the…
- Heart sounds and where they come fromMechanism · The 'lub-dub' you hear is the sound of heart valves snapping shut; extra sounds can mean the…
- How edema formsMechanism · Swelling appears when more fluid leaves the blood vessels than the lymph can carry back
- Shock physiologyMechanism · Shock is when the circulation cannot deliver enough oxygen to the organs; cells switch to…
- Starling forces at the capillaryMechanism · Blood pressure pushes fluid out of capillaries and blood proteins pull it back in; the lymph…
- Systolic, diastolic, mean and pulse pressureMeasurement · Blood pressure has a top number when the heart pushes, a bottom number when it rests, and an…
- The baroreceptor reflexRegulation · Pressure sensors in the neck and aorta tell the brain about blood pressure each second, and the…
- The cardiac conduction systemConcept · A wiring path carries each beat from the top of the heart to the bottom, with a short pause so…
- The cardiac cycleMechanism · One heartbeat is a fixed sequence: the heart fills, squeezes with closed valves, ejects…
- The Frank–Starling mechanismMechanism · The more the heart is filled, the harder it squeezes, so it pumps out whatever blood comes back…
- The renin–angiotensin–aldosterone systemRegulation · When blood pressure or salt falls, the kidney releases renin, starting a chain of hormones that…
- The SA node pacemaker potentialMechanism · Cells in the sinus node slowly charge themselves up until they fire, which sets the heart rate…
- The ventricular action potentialMechanism · Each ventricular muscle cell fires a long electrical signal with a plateau, so the heart…
- The ventricular pressure–volume loopMeasurement · Plotting the ventricle's pressure against its volume in one beat draws a loop whose shape shows…
Exam priority: medium
- Blood pressure control on three time scales: seconds, minutes and daysTable to know · Nerves fix blood pressure in seconds, hormones and fluid shifts in minutes to hours, and the…
- Bundle branch and fascicular blocksMeasurement · When one branch of the heart's wiring is cut, that side is reached slowly through muscle, so the…
- Cardiac excitation–contraction couplingMechanism · How each beat's electrical signal becomes force: a small calcium influx triggers a much larger…
- Central venous pressure and the jugular pulseMeasurement · Central venous pressure is the pressure of blood entering the right heart; the internal jugular…
- Coronary circulation and myocardial ischemiaConcept · The heart feeds mostly in diastole and already extracts almost all its oxygen at rest: if it…
- ECG leads: Einthoven's triangle, augmented and chest leadsConcept · Each ECG lead looks at the heart's electricity from one angle
- Flow, pressure and resistance: Poiseuille and turbulent flowConcept · Blood flows from high to low pressure; narrow vessels resist flow enormously, and fast…
- Heart failure over time: acute, compensated, decompensated and high-output failure on the curvesMechanism · After the heart is damaged, nerves act at once and the kidneys add fluid over days
- Heart failure physiologyMechanism · In heart failure the heart cannot pump enough at normal filling pressures; the body's rescue…
- Hemorrhagic shock: compensation, vicious cycles and irreversibilityMechanism · After bleeding, the body squeezes vessels and holds fluid
- How arrhythmias ariseMechanism · Abnormal heart rhythms come from cells that fire on their own, beats that trigger extra beats…
- How ECG waves are built: the vectors of the QRS, T and PMechanism · At each instant the heart's current has one main direction and size, an arrow
- How the circulation adapts to valve disease: aortic and mitral lesions at rest and in exerciseMechanism · A narrow or leaky valve makes the heart work harder
- Local and humoral control of blood flowRegulation · Each tissue adjusts its own arterioles to get the blood it needs, even when arterial pressure…
- Long-term blood pressure control by the kidneyRegulation · In the long run, blood pressure is set by the kidneys: if pressure rises, they excrete more salt…
- Measuring cardiac output: Fick, indicator and thermodilution, DopplerMeasurement · Cardiac output is measured from how much oxygen the body takes up, how fast an injected marker…
- Murmurs and the hemodynamics of valve diseaseMechanism · A murmur is the sound of blood flowing turbulently through a narrow valve, a valve that does not…
- Muscle blood flow and the cardiovascular response to exerciseRegulation · During exercise the heart pumps up to four or five times more blood and the working muscles take…
- Nervous control of the circulation and the CNS ischemic responseRegulation · The brain raises or lowers blood pressure within seconds through the sympathetic nerves and the…
- Other cardiovascular reflexes: chemoreceptor, atrial (Bainbridge), muscle and pressure wavesRegulation · Besides the baroreflex, sensors of blood gases, atrial stretch and brain signals also steer…
- Physiology of congenital shuntsMechanism · A hole between the two halves of the heart or the great vessels lets blood flow from the…
- Physiology of hypertensionMechanism · Hypertension is sustained high blood pressure; almost always, a kidney needs more pressure to…
- Preload, afterload and contractilityConcept · How much each beat pumps depends on how full the heart is, how hard it must push, and how strong…
- Sinus, junctional and escape rhythmsRegulation · The sinus node sets the pace and speeds up or slows down with need
- The cardiac electrical axisMeasurement · The axis is the average direction in which ventricular depolarization travels; you work it out…
- The ECG in chamber hypertrophy and low-voltage statesMeasurement · More heart muscle makes bigger ECG waves; fluid, air, fat or scar between heart and skin makes…
- The ECG in ischemia and infarctionMeasurement · When heart muscle runs short of blood, the ST segment, T wave and Q wave change, and point to…
- The ECG in potassium and calcium disordersMeasurement · Potassium and calcium reshape the cardiac action potential, and it shows in the T wave, the QRS…
- The layout of the circulation: vessel segments, pressures and how flow is measuredConcept · Blood runs through two circuits in series
- The microcirculation: capillary types, vasomotion, diffusion and the interstitiumConcept · Capillaries are thin tubes where blood swaps gases, nutrients and water with the tissue
- The response to standing upRegulation · When you stand, blood drops into the legs; fast reflexes speed the heart and tighten the vessels…
- Vascular compliance and capacitanceConcept · Arteries are elastic and cushion each beat; veins are so stretchy that they hold most of the…
- Venous return and the Guyton curvesMechanism · The heart can only pump the blood that reaches it
For completeness
- Cardiac work, oxygen use and efficiencyConcept · The heart spends energy to push blood against pressure
- How specific hypertensions arise: volume loading, Goldblatt kidney, obesity, neurogenic and monogenicMechanism · Each kind of high blood pressure ends the same way: the kidney needs a higher pressure to…
- How the lymphatic system worksConcept · Lymphatics collect the fluid and proteins that leak out of capillaries and return them to the…
- Long-term flow control: angiogenesis, collaterals and vascular remodellingRegulation · Over days to months, tissues grow new vessels when short of oxygen, open side channels around…
- Myocardial metabolism and the neural control of coronary vesselsConcept · The heart runs mostly on fat and needs oxygen every beat
- Peripheral venous pressure, gravity and the blood reservoirsConcept · Standing makes the weight of blood push hard on leg veins
- Skin blood flowRegulation · Skin gets far more blood than it needs for its own nutrition, because its flow is mostly used to…
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Educational physiology content; not a diagnostic or treatment guide and no substitute for a health professional's advice. Values are approximate references. No doses are given.
Representative model, for educational purposes only.