Module 8 Vocabulary

Anti-dysrhythmic drugs

Medications used to treat or prevent abnormal heart rhythms (dysrhythmias).

Atrial kick

The additional volume of blood pushed into the ventricles by atrial contraction before systole.

Automaticity

The ability of cardiac cells to generate their own electrical impulses without external stimulation.

AV node

A cluster of cells in the heart that delays the electrical impulse before passing it to the ventricles.

Bradycardia

A slower-than-normal heart rate, typically below 60 beats per minute.

Bundle branches

Pathways that conduct electrical impulses from the bundle of His to the left and right ventricles.

Bundle of His

A collection of heart muscle fibers that transmit electrical impulses from the AV node to the ventricles.

Conductivity

The ability of cardiac cells to transmit electrical impulses.

Defibrillation

The delivery of an electric shock to the heart to restore normal rhythm in cases of life-threatening arrhythmias.

Dysrhythmia/Arrhythmia

An abnormal heart rhythm.

Electrocardiogram (EKG/ECG)

A test that records the electrical activity of the heart.

Electronic pacemaker

A device that sends electrical impulses to the heart to regulate its rhythm.

Fibrillation

Rapid, irregular heart contractions that reduce the heart’s ability to pump blood effectively.

Normal sinus rhythm

The normal rhythm of the heart, originating from the sinoatrial (SA) node.

P wave

The part of an ECG representing atrial depolarization (atrial contraction).

Premature ectopic beat

An early heartbeat originating from outside the normal conduction pathway.

Purkinje fibers

Specialized fibers that distribute electrical impulses through the ventricles.

QRS complex

The part of an ECG representing ventricular depolarization (ventricular contraction).

R-R interval

The time between two consecutive R waves on an ECG, used to measure heart rate.

Reentry mechanisms

Abnormal electrical conduction patterns that can cause arrhythmias.

Refractory period

The period during which the heart muscle cannot respond to another electrical stimulus (absolute) or can only respond to a very strong stimulus (relative).

SA node

The heart's natural pacemaker, located in the right atrium.

Supernormal excitatory period

A brief period when a weaker-than-normal stimulus can trigger a heartbeat.

T wave

The part of an ECG representing ventricular repolarization (recovery phase).

Tachycardia

A faster-than-normal heart rate, typically above 100 beats per minute.

Affinity of hemoglobin for oxygen

The strength with which hemoglobin binds to oxygen, affecting oxygen transport.

Air-trapping

Retention of air in the lungs due to airway obstruction, commonly seen in conditions like COPD.

Airway resistance

The opposition to airflow in the respiratory tract, influenced by airway diameter.

Alveolar-capillary membrane

The thin barrier between alveoli and capillaries where gas exchange occurs.

Alveolar cells (type I and II)

Type I cells facilitate gas exchange; Type II cells produce surfactant to prevent alveolar collapse.

Alveoli

Tiny air sacs in the lungs where oxygen and carbon dioxide are exchanged.

Atelectasis

Partial or complete lung collapse due to alveolar deflation.

Carbonic acid-bicarbonate buffer equation

CO₂ + H₂O ⇌ H₂CO₃ ⇌ HCO₃⁻ + H⁺, which helps regulate blood pH.

CO₂ narcosis

A condition in which high CO₂ levels suppress respiratory drive, often seen in COPD.

Conducting airways

The airways (trachea, bronchi, bronchioles) that transport air but do not participate in gas exchange.

Cyanosis

A bluish discoloration of the skin and mucous membranes due to low oxygen levels.

Dead air space

Areas of the respiratory system where no gas exchange occurs.

Diffusion

The movement of gases (O₂ and CO₂) across the alveolar-capillary membrane.

Gas exchange

The process of O₂ entering the blood and CO₂ exiting the blood in the lungs.

Hypercapnia

Excess carbon dioxide in the blood, often due to hypoventilation.

Hypoxia

Insufficient oxygen supply to tissues.

Lung compliance

The lung’s ability to expand and recoil.

Mucociliary blanket

A layer of mucus and cilia that helps trap and remove debris from the airways.

Oxygen saturation (SaO₂)

The percentage of hemoglobin molecules bound to oxygen.

Partial pressure of a gas

The pressure exerted by a specific gas within a mixture of gases.

Perfusion

The process of delivering oxygenated blood to tissues.

Pleura

The double-layered membrane surrounding the lungs.

Pleural space

The small space between the pleural layers containing lubricating fluid.

Pleuritic chest pain

Sharp chest pain caused by inflammation of the pleura, worsened by breathing.

Pleuritis/Pleurisy

Inflammation of the pleura, causing chest pain.

Pneumothorax

Air in the pleural space, leading to lung collapse.

Pulmonary embolism (PE)

A blockage in a pulmonary artery due to a blood clot, fat embolism, or air embolism.

Respiratory center

The brainstem region that controls breathing.

Respiratory failure

Inadequate gas exchange leading to dangerously low oxygen or high carbon dioxide levels.

Shunt

A condition where blood bypasses ventilated alveoli, leading to impaired oxygenation.

Surface tension

The force that tends to collapse alveoli, counteracted by surfactant.

Surfactant

A substance secreted by Type II alveolar cells that reduces surface tension and prevents alveolar collapse.

Ventilation

The movement of air in and out of the lungs.

Ventilation/perfusion (V/Q) mismatch

A condition where airflow (ventilation) and blood flow (perfusion) are not properly matched, leading to inefficient gas exchange.