A&P Cardiovascular

Pulmonary circulation

Closed loop of vessels carrying blood between heart and lungs.

Systemic circulation

Circuit of vessels carrying blood between heart and other body systems

heart anatomy: location

Pericardium

A double-walled sac around the heart

Superficial Fibrous Pericardium

The outer protective layer.

Deep Two-Layer Serous Pericardium

Includes the parietal layer, which lines the internal surface of the fibrous pericardium.

Epicardium

Outermost layer of the heart, Visceral layer of the serous pericardium

Pericardial Cavity

A fluid-filled space between the parietal and visceral layers that reduces friction.

What are the three main roles of the pericardium?

cardiac skeleton

A layer of crisscrossing, interlacing connective tissue

What are three functions of cardiac skeleton?

Why is the heart described as a "Dual Pump"?

Because the right and left sides function as two separate pumps working in tandem.

Myocardium

Cardiac muscle layer forming the bulk of the heart

Endocardium

Endothelial layer of the inner myocardial surface

Atria

Receiving chambers. Small, thin-walled chambers; contribute little to propulsion of blood

Auricles

appendages that increase atrial volume

Right atrium

receives deoxygenated blood from body

Anterior portion(Right atrium)

smooth-walled

Posterior portion(Right atrium)

contains ridges formed by pectinate muscles

Superior vena cava

returns blood from body regions above the diaphragm

Inferior vena cava

returns blood from body regions below the diaphragm

Coronary sinus

returns blood from coronary veins

Left atrium

receives oxygenated blood from lungs, Four pulmonary veins return blood from lungs

Ventricles

Pumping chambers, Make up most of the volume of heart

Right ventricle

most of anterior surface; Pumps blood to the lungs.

Left ventricle

posteroinferior surface; Pumps blood to the rest of the body

Papillary muscles

project into ventricular cavity; Anchor chordae tendineae that are attached to heart valves

Name the two AV valves and their specific locations.

What is the primary job of the AV valves during the cardiac cycle?

They prevent the backflow of blood into the atria when the ventricles contract (systole).

Describe the relationship between chordae tendineae and papillary muscles during ventricular contraction.

Chordae tendineae (the "heartstrings") anchor the valve cusps to the papillary muscles on the ventricle walls.

Pulmonary Valve

Between the right ventricle and pulmonary trunk.

Aortic Valve

Between the left ventricle and aorta.

Systole

The phase of muscle contraction.

Diastole

The phase of muscle relaxation.

What physical events cause the "Lub" and "Dup" sounds?

What characterizes the "Isovolumetric" phases of the cardiac cycle?

All four valves are closed. The volume of blood in the ventricles remains constant while the pressure either builds (contraction) or drops (relaxation).

Sympathetic systems affect heart rate

Activated by emotional or physical stressors (e.g., "fight or flight"). Norepinephrine causes the pacemaker to fire more rapidly, increasing heart rate.

Parasympathetic system affect heart rate

Opposes sympathetic effects. Acetylcholine hyperpolarizes pacemaker cells, slowing the heart rate. The heart at rest exhibits vagal tone.

What triggers the Atrial (Bainbridge) reflex and what is the result?

It is a sympathetic reflex initiated by increased venous return (increased blood entering the atria). Stretching of the atrial walls stimulates the SA node and stretch receptors, which triggers increased sympathetic activity to raise the heart rate.

Epinephrine

From the adrenal medulla; increases heart rate and contractility.

Thyroxine

Increases heart rate and enhances the effects of epinephrine and norepinephrine

Ions

Normal heart function requires maintaining specific intracellular and extracellular concentrations of ions like Ca2+ and K+

Tachycardia

An abnormally fast heart rate (> 100 bpm). If persistent, it may lead to fibrillation.

Bradycardia

A heart rate slower than 60 bpm. While normal in athletes, it can lead to inadequate circulation in others.

What is the clinical definition of Congestive Heart Failure?

A progressive condition where the Cardiac Output ($CO$) is so low that blood circulation is inadequate to meet the metabolic needs of the body's tissues.

What are the four main causes of heart "weakening" that lead to CHF?

Pulmonary Circuit

Right side of the heart; carries deoxygenated blood to the lungs for gas exchange.

Systemic Circuit

Left side of the heart; pumps oxygenated blood to all body tissues.

How does the heart muscle itself receive blood?

Through Coronary Circulation. The left and right coronary arteries arise from the base of the aorta.

Left Coronary Artery

Branches into the anterior interventricular artery and circumflex artery.

Right Coronary Artery

Branches into the right marginal artery and posterior interventricular artery.

What are the unique microscopic features of cardiac muscle cells?

Cells are striated, short, fat, branched, and interconnected.

Intercalated Discs

Contain anchoring desmosomes (preventing cell separation) and gap junctions (allowing ions to pass between cells).

Functional Syncytium

Because of gap junctions, the entire myocardium behaves as a single coordinated unit.

Why is cardiac muscle highly resistant to fatigue?

What is the sequence of excitation through the heart's conduction system?

SA Node , AV Node , AV Bundle , Right and Left Bundle Branches , Purkinje Fibers

SA Node

The pacemaker; generates impulses

AV Node

Delays the impulse to allow atria to finish contracting

AV Bundle

Bundle of His; the only electrical connection between atria and ventricles

Purkinje Fibers

Complete the pathway through the ventricular walls

What electrical events do the P wave, QRS complex, and T wave represent?

Where are the cardiac centers located in the brain?

Located in the medulla oblongata

Cardioacceleratory Center

Sends sympathetic signals to increase heart rate and force.

Cardioinhibitory Center

Sends parasympathetic signals via the vagus nerve to decrease heart rate.

Cardiac Output (CO)

CO is the volume of blood pumped by each ventricle in one minute.

Cardiac Reserve

The difference between resting and maximal Cardiac Output. It represents the heart's capacity to ramp up performance during physical exertion.

What three factors regulate Stroke Volume (SV)?

Preload

The degree of stretch of cardiac muscle cells before they contract.

Frank-Starling Law

States that Stroke Volume is proportional to the End Diastolic Volume (EDV). The more the muscle is stretched (due to increased venous return), the more forcefully it contracts to eject blood.

Contractility

the contractile strength at a given muscle length (independent of stretch).

Positive Inotropic Agents (Increase SV)

Sympathetic stimulation (Ca2+ influx), thyroxine, glucagon, and epinephrine.

Negative Inotropic Agents (Decrease SV)

Acidosis, increased extracellular K+, and calcium channel blockers.

Afterload

Afterload is the pressure that the ventricles must overcome to eject blood (the back pressure from arterial blood).

How does hypertension affect afterload?

Hypertension (high BP) increases afterload, which results in a higher End Systolic Volume (ESV) and a decreased Stroke Volume.

Pulmonary Congestion

The left side fails to pump blood to the body, causing blood to back up in the lungs. This leads to pulmonary edema (fluid in the lungs).

Peripheral Congestion

The right side fails to pump blood to the lungs, causing blood to back up in the systemic circulation. This leads to systemic edema (swelling in the feet, ankles, and fingers).