Cardiovascular System Lecture Notes

Vocabulary flashcards based on lecture notes about the cardiovascular system.

Somatic nervous system

Efferent neurons innervating skeletal muscle.

Pressure gradient

Drives Blood Flow Blood moves from areas of high pressure to low pressure.

Diastole

The heart relaxes and fills with blood (relaxation phase).

Systole

The heart contracts and pumps blood out (contraction phase).

Right Atrium (RA)

Gets deoxygenated blood from the body (via superior and inferior vena cava).

Right Ventricle (RV)

Pumps this blood to the lungs via the pulmonary artery.

Left Atrium (LA)

Gets oxygenated blood from the lungs (via pulmonary veins).

Left Ventricle (LV)

Pumps oxygenated blood to the body via the aorta.

Tricuspid valve

Between RA and RV. Opens to let blood flow from RA to RV Closes when RV contracts to prevent blood from going backward into the atrium

Mitral (bicuspid) valve

Between LA and LV. Opens to let venous blood (O2) flow into LV Closes during contraction to prevent backflow into atrium

Pulmonary Valve

Between RV and pulmonary artery Opens to let blood go into the lungs

Aortic Valve

Between LV and aorta Opens when left ventricle contracts to send blood out to the body Closes to keep blood from leaking back into the heart

Atrial Diastole (Relaxation)

All chambers are relaxed. Blood flows into the atria from the Body → RA and Lungs → LA. Both tricuspid and mitral valves are closed

Atrial Systole (Contraction)

Pressure from blood against walls raises blood pressure and AV valves (tricuspid and mitral) open Atria contract. Pushes blood into the ventricles through open AV valves (tricuspid and mitral).

Ventricular Systole (Contraction)

AV valves close to prevent backflow (you hear this as lub). Ventricles contract: RV → pulmonary valve opens → pulmonary artery → lungs and LV → aortic valve opens → aorta → body

Ventricular Diastole (Relaxation)

Ventricles relax. Semilunar valves close to prevent backflow (you hear this as dub). The AV valves reopen, and the cycle starts again.

Pacemaker cells

Specialized for automatic electrical activity. They initiate the heart's rhythm and spread the signal.

SA node

Located in the right atrium, near the opening of the superior vena cava. It spontaneously generates electrical impulses (action potentials) due to its automaticity, which then spread through the atria to initiate contraction.

AV node

The main role is to delay the impulse before it travels to the ventricles via the His-Purkinje system. This delay allows time for the atria to contract fully and push blood into the ventricles before the ventricles contract.

P wave

The SA node fires and sends an action potential through the right and left atria.

PR segment

The action potential reaches the AV node, which holds the signal briefly. (needs to go through AV node, otherwise atria and ventricles separated by fibrous tissue)

QRS Complex

The signal passes from the AV node → Bundle of His → Bundle branches → Purkinje fibers → ventricles depolarize.

ST Segment

The ventricles are fully depolarized, and calcium is flowing in to sustain contraction (plateau phase of the action potential).

T wave

The ventricles repolarize (return to resting state).

Cardiac output

Volume of blood pumped into the systemic circulation per minute, depends on both the heart rate and stroke volume (determines how well the heart is working as a pump)

Heart rate

Number of beats per minute

Stroke volume

Amount of blood pumped in a single contraction

Aorta & Arteries

Carry oxygenated blood away from the heart under high pressure, especially from the left ventricle. Act as pressure reservoirs using elastic recoil.

Arterioles

Regulate blood flow to specific tissues/organs. Create resistance to control blood pressure.

Capillaries

Exchange vessels – site of diffusion of: Oxygen, Nutrients, Hormones, CO₂ and metabolic waste

Venules

Collect blood from capillaries and begin return to the heart. Low pressure

Veins

Carry deoxygenated blood back to the heart (except pulmonary veins). Store blood – act as blood reservoirs