Blood Flow Unit

Circulatory System

Consists of the heart, arteries, arterioles, capillaries, venules, and veins that transport blood throughout the body.

Venae Cavae

Two large veins that carry oxygen-poor blood from body tissues to the heart.

Oxygen-Poor Blood

Blood that has lost much of its oxygen after delivering it to body cells.

Right Side of the Heart

Receives oxygen-poor blood from the venae cavae.

Pulmonary Artery

Carries oxygen-poor blood from the right side of the heart to the lungs.

Unique Feature of the Pulmonary Artery

It is the only artery in the body that carries oxygen-poor blood.

Pulmonary Capillaries

Capillaries in the lungs where blood absorbs oxygen during inhalation.

Pulmonary Veins

Carry oxygen-rich blood from the lungs back to the heart.

Unique Feature of the Pulmonary Veins

They are the only veins in the body that carry oxygen-rich blood.

Pulmonary Circulation

The flow of blood from the heart to the lungs and back to the heart.

Left Side of the Heart

Receives oxygen-rich blood from the pulmonary veins.

Aorta

The largest artery in the body that carries oxygen-rich blood from the left side of the heart.

Ascending Aorta

The portion of the aorta that moves upward from the heart.

Descending Aorta

The portion of the aorta that arches and travels downward in front of the vertebral column.

Arteries

Branches of the aorta that carry oxygen-rich blood to all parts of the body.

Carotid Arteries

Supply blood to the head and neck.

Arterioles

Small branches of arteries that lead to tissue capillaries.

Tissue Capillaries

Small vessels near body cells where oxygen and nutrients are exchanged.

Function of Tissue Capillaries

Deliver oxygen to cells and remove carbon dioxide and other wastes.

Carbon Dioxide (CO₂)

Waste product released during cellular metabolism that enters the bloodstream.

Venules

Small vessels that collect blood from tissue capillaries.

Veins

Vessels that return oxygen-poor blood from tissues to the heart.

Systemic Circulation

The flow of blood from the heart to body tissues and back to the heart.

Pulse

The beat of the heart felt through the walls of arteries.

Tricuspid Valve

Located between the right atrium and right ventricle.

Pulmonary Valve

Located between the right ventricle and pulmonary artery.

Mitral Valve

Located between the left atrium and left ventricle.

Aortic Valve

Located between the left ventricle and aorta.

Conduction System of the Heart

Specialized pathway that initiates and conducts electrical impulses through the heart.

Sinoatrial (SA) Node

The pacemaker of the heart that initiates the heartbeat.

Location of the SA Node

Located in the posterior portion of the right atrium.

Pacemaker of the Heart

The sinoatrial (SA) node.

Function of the SA Node

Generates electrical impulses that cause the atria to contract.

Atrioventricular (AV) Node

Receives the electrical impulse from the SA node.

Location of the AV Node

Located within the interatrial septum.

Bundle of His

A bundle of specialized muscle fibers that carries impulses from the AV node.

Right Bundle Branch

Conducts electrical impulses through the right ventricle.

Left Bundle Branch

Conducts electrical impulses through the left ventricle.

Systole

Contraction phase of the heart when blood is pumped away from the heart.

Electrocardiogram (ECG or EKG)

A recording of the electrical activity of the heart.

Purpose of an ECG

Detects electrical changes in the heart muscle as the heart beats.

P Wave

Represents atrial depolarization on an ECG.

QRS Complex

Represents ventricular depolarization on an ECG.

T Wave

Represents ventricular repolarization on an ECG.

Normal Sinus Rhythm (NSR)

Normal heart rhythm originating in the SA node and traveling through the heart.

Sympathetic Nerves

Increase heart rate during stress or vigorous exercise.

Parasympathetic Nerves

Decrease heart rate when extra pumping is not needed.

Pathway of Blood Flow

Venae Cavae → Right Heart → Pulmonary Artery → Lungs → Pulmonary Veins → Left Heart → Aorta → Arteries → Arterioles → Capillaries → Venules → Veins → Venae Cavae.

Pathway of Electrical Conduction

SA Node → AV Node → Bundle of His → Right and Left Bundle Branches → Ventricles.