Unit 4 - Circulatory System Part 1

Review of the first half of unit 4 - General structures and functions of the heart, cardiac cycle, systemic and pulmonary circulation, cardiac output, regulation, conduction system, electrocardiography, and abnormalities

Heart, Blood, Blood Vessels

3 parts of the circulatory system

Functions of the circulatory system

Transportation of oxygen and nutrients, removal of carbon dioxide and waste, regulation of body temperature, transport of hormones, assistance with immune response

Atria

Upper Chambers of the heart, thin walled, deliver blood to ventricles

Ventricles

Lower Chambers, thick walled; left side thicker because it pumps blood further and experiences greater resistance. Pump to lungs and body

Left ventricle

Which ventricle has thicker walls (more muscular) and pumps blood to the body (systemic circulation)

Right Ventricle

Which ventricle has thinner walls (less muscular) and pumps blood to the lungs (pulmonary circulation)

Pulmonary and Aortic Valves

Two semilunar valves, allow ejection of blood into arteries

Tricuspid and Bicuspid Valves

Atrioventricular valves, valves found between atria and ventricles

Aortic Valve

Which valve is found between the left ventricle and the aorta

Pulmonary Valve

Which valve is found between the right ventricle and the pulmonary artery

Tricuspid Valve

Which valve is found between the right atria and right ventricle

Bicuspid Valve

Which valve is found between the left atria and left ventricle

Pericardium

Outer membrane that surrounds and protects the heart

Myocardium

Thick layer of cardiac muscle making up the walls of the heart

Chordae Tendineae

Tendon-like cords found within the ventricles that help prevent the backflow of blood through the valve

Trabeculae Carneae

Series of ridges caused by raised bundles of cardiac muscles

Papillary Muscles

Cone-shaped trabeculae carneae to which the chordae tendineae are attached

Auricles

Wrinkled, pouch-like structure found on anterior surface of the atria; increases capacity of atria slightly

Apex

Inferior portion of the heart that comes to a point

Base

Broad, superior portion of the heart

Septum

Muscular partition that prevents blood on two sides from mixing

Pericardial Fluid

Slipper secretion produced by pericardial cells which reduces friction as heart moves when it contracts

Pulmonary Trunk

Large vessel from the right ventricle, which splits into the pulmonary arteries

Coronary Arteries

Branches from ascending aorta that bring oxygenated blood to the heart

Relaxation, Atrial systole, ventricular systole

3 Phases of the cardiac cycle

Relaxation (diastole)

Begins at the end of a cardiac cycle, all 4 Chambers in diastole, initiated by repolarization of ventricles, ventricular pressure decreases, AV valves open, ventricles fill

Atrial systole

Action potential from SA node causes atrial depolarization, atria contract and complete filling of ventricles (LUB), AV valves still open, SL valves still closed

Ventricular systole

Contraction of ventricles; pushes blood against AV valves forcing them shut (DUB), ventricular pressure increases, both SL valves open; ejection of blood

Systemic Circulation

Left side of the heart pumps blood through vessels to the tissues of the body and back to the right side of the heart

Pulmonary Circulation

Right side of the heart pumps blood back through vessels to lungs and back to the left side of the heart

Cardiac Output

The volume of blood pumped from the heart per minute (mL/min)

Stroke volume (mL/beat) X heart rate (beats/min)

Stroke Volume

Amount of blood pumped per ventricle per contraction

Heart Rate

Number of beats/contractions of the ventricles per minute

Sympathetic Nerves

Nerves that speed up heart rate, excites/speeds up functions, stimulate the release of norepinephrine

Parasympathetic Nerves

Nerves that slow down the heart rate, inhibits/slows down functions, causes the release of acetylcholine

Autonomic Nervous System

Part of the nervous system that controls involuntary functions, includes the parasympathetic and sympathetic nervous systems

Nervous and Endocrine

Two body systems that stimulate the heart rate

Endocrine Stimulation

Stimulation of the heart with epinephrine/norepinephrine, hormones secreted by adrenal glands during stress and excitement, “fight or flight”, hormones in bloodstream bind to specific receptors

Nervous Stimulation

Stimulation of the heart with autonomic nervous system (parasympathetic and sympathetic), receipts in walls of arteries send signals to the medulla, medulla sends signal to pacemaker

Sinoatrial (SA) Node (pacemaker)

Right atrial wall. Initiates each heartbeat and sets basic pace for heart rate. Send action potential to both atria causing them to contract.

Atrioventricular (AV) Node

Interatrial septum. Picks up action potential from SA Node and passes it to the atrioventricular bundle

Atrioventricular Bundle (AV Bundle) (Bundle of His)

Interventricular septum. Picks up action potential from AV node and passes it to the right and left bundle branches.

Right and Left Bundle Branches

Interventricular septum. Picks up action potential and passes it to conduction myofibers

Conduction Myofibers (Purkinje Fibers)

Ventricular myocardium. Picks up action potential from bundle branches and passes it to ventricular myocardial cells, causing ventricles to contract

Electrocardiogram (ECG or EKG)

A recording/diagram of the electrical changes that accompany the heartbeat. Can be analyzed to determine abnormalities in heartbeat.

0.04

What interval of time does each box represent on an ECG

P Wave

Part of ECG that shows atrial depolarization. Electric current spreads from pacemaker over atria, atria contract.

QRS Complex

Part of ECG that shows onset of ventricular depolarization, hides atrial repolarization wave. Electrical impulse spreads to the ventricles, ventricles contract

T Wave

Part of ECG that shows ventricular repolarization. Ventricles relax (repolarize), atria and ventricles fill

Tachycardia

Rapid resting heart rate/pulse, over 100 bpm

Bradycardia

Slow resting heart rate/pulse, under 60 bpm

Arrhythmia

An irregularity in heart rhythm caused by problems in the conduction system of the heart

Atrial Fibrillation

Uncoordinated contraction of atrial muscles; muscle fibers quiver individually rather than contracting together

Ventricular Fibrillation

Asynchronous, haphazard ventricular muscle contractions. Ventricular ejection ceases → Death

Heart Murmur

Faulty heart valves, gurgling, blood backs up in chambers. Not detectable with an ECG