Cardiovascular System Overview

The ability of cardiac muscle to generate its own electrical signal to contract, independent of external stimuli.

The system of specialized cells in the heart that conducts electrical impulses, coordinating the heart's contractions.

The period of contraction in the heart cycle, where blood is pumped out.

The period of relaxation in the heart cycle, where the chambers fill with blood.

The branch of the autonomic nervous system that slows down heart rate by releasing acetylcholine (ACh).

The branch of the autonomic nervous system that speeds up heart rate by releasing norepinephrine.

The state where neurons become more polarized and less likely to fire an action potential.

The initial increase in heart rate during exercise, up to 100 beats per minute, is caused by the withdrawal of the vagal tone.

The system that transports blood throughout the body, consisting of the heart, blood vessels (arteries, veins, and capillaries), and blood itself.

Blood vessels that carry oxygenated blood away from the heart to the rest of the body.

Small blood vessels that connect arteries to capillaries, helping regulate blood flow.

Microscopic blood vessels that connect arterioles to venules, allowing for exchange of oxygen, nutrients, and waste products.

Blood vessels that carry deoxygenated blood back to the heart from the rest of the body.

Small blood vessels that collect blood from capillaries and carry it to veins.

A measure of the percentage of red blood cells in a sample of blood.

The oxygen-carrying protein found in red blood cells that binds to oxygen molecules.

Blood pressure (BP) is the force of blood pushing against the artery walls. It's measured in millimeters of mercury (mmHg) and has two components: systolic (highest pressure during contraction) and diastolic (lowest pressure during relaxation).

High blood pressure (hypertension) occurs when the force of blood pushing against artery walls is consistently too high. This increases the risk of heart disease, stroke, and other health problems.

Several factors can contribute to hypertension, including obesity, insulin resistance, high alcohol intake, high salt intake, aging, sedentary lifestyle, stress, low potassium intake, and low calcium intake.

Blood flow is driven by the difference in pressure between arteries and veins. It is also influenced by the resistance of blood vessels to flow.

Poiseuille's Equation describes the relationship between flow, pressure, and vessel radius. It shows that even a small change in vessel radius can have a large impact on blood flow.

Blood pressure is the force that blood exerts against the walls of blood vessels during each heartbeat.

Cardiac output is the amount of blood the heart pumps per minute. A stronger heart pumps more blood.

Blood volume is the total amount of blood in the body. More blood means higher pressure.

Blood viscosity is the thickness of blood. Thicker blood has higher pressure.

Peripheral vascular resistance is the resistance of blood vessels to blood flow. Narrower vessels have higher resistance.

The difference in oxygen content between arterial blood and venous blood.

The relationship between oxygen consumption (VO2), cardiac output (Q), and the difference in oxygen content between arterial and venous blood (a-vO2 diff).

The initial signal to the cardiovascular system at the start of exercise comes from higher brain centers.

Fine-tuning of the cardiovascular response to exercise is achieved through feedback loops from muscle chemoreceptors, mechanoreceptors, and arterial baroreceptors.

The increase in oxygen consumption during exercise, calculated by the product of cardiac output (Q) and the difference in oxygen content between arterial and venous blood (a-vO2 diff).

The maximum heart rate (MHR) achievable during an all-out effort. It remains relatively consistent over time, but can be influenced by factors like age and fitness level.

A method to calculate the target heart rate (THR) zone for exercise, based on a percentage of the difference between your maximum heart rate (MHR) and resting heart rate (RHR). This range is typically 75-85% of your heart rate reserve.

The volume of blood ejected from the left ventricle of the heart with each beat. It increases with exercise intensity up to a certain point.

The amount of blood pumped by the heart per minute. It increases with exercise intensity, influenced by both heart rate and stroke volume.

The ability of the heart's ventricle to contract more forcefully during exercise, leading to increased stroke volume and higher cardiac output.

The mechanism by which the heart adjusts its stroke volume based on the amount of blood returning to the ventricles. More blood in, stronger contraction, bigger stroke volume.

The pressure within the blood vessels during the resting phase between heartbeats. It decreases during exercise due to vasodilation in working muscles.

The process where the blood vessels in working muscles widen, allowing more blood flow to the muscles.