Ch 20 Heart

Systemic Circuit

Carries blood to and from gas exchange surfaces of the body.

Systemic Circuit Function

Carries oxygenated blood from heart to all tissues except lungs and returns deoxygenated blood carrying waste products, such as carbon dioxide, back to heart.

Oxygen-Rich Blood Ejection

Ejected under high pressure out of left ventricle (hearts main pumping chamber) through aorta (largest artery)

Smaller Arteries Origin

Branch off from the aorta to various parts of the body.

Arterioles Formation

Smaller arteries branch out into even smaller arteries known as arterioles.

Capillaries Formation and Pressure

Arterioles become progressively smaller, eventually forming capillaries where blood pressure is greatly reduced.

Pulmonary Circuit Definition

Carries blood to and from the gas exchange surfaces of the lungs.

Return of Deoxygenated Blood

Travels from organs and tissues from right atrium to right ventricle.

Pathway to Lungs

Deoxygenated blood is pushed through the pulmonary artery to the lung.

Pulmonary Artery Division

Divides forming the pulmonary capillary region.

Alveoli Gas Exchange

Microscopic vessels pass adjacent to alveoli (air sacs) where gases are exchanged across thin membrane.

Gas Exchange Mechanics

Oxygen crosses membrane into blood while carbon dioxide leaves blood through same membrane.

Newly Oxygenated Blood Flow

Flows into pulmonary veins and is collected by left atrium of the heart (collecting pool for Left ventricle)

Completion of Circulatory Loop

Contraction of left ventricle sends blood into the aorta.

Three Types of Blood Vessels

Arteries, veins, and capillaries.

Arteries Function

Carry blood away from the heart.

Veins Function

Carry blood to the heart.

Capillaries Location

Form networks between arteries and veins.

Exchange Vessels

Alternative name for capillaries; exchange materials between blood and tissues.

Capillary Exchanged Materials

Dissolved gases, nutrients, and wastes.

Heart Chambers Count

4 chambers total: 2 for each circuit (left and right - ventricles and atria).

Left Atrium Function

Collects blood from the pulmonary circuit.

Left Ventricle Function

Pumps blood to the systemic circuit.

Right Atrium Function

Collects blood from the systemic circuit.

Right Ventricle Function

Pumps blood to the pulmonary circuit.

Heart Location

Located directly behind the sternum.

Base of the Heart

Location of great veins and arteries.

Apex of the Heart

The pointed tip of the heart.

Thoracic Cavity Relation

Surrounded by pericardial sac and located between 2 pleural cavities.

Mediastinum Definition

Central tissue mass that divides the thoracic cavity into 2 pleural cavities.

Pericardium Definition

Double lining of the pericardial cavity.

Parietal Pericardium

Outer layer that forms the inner layer of the pericardial sac.

Visceral Pericardium

Inner layer of the pericardium, also known as the epicardium.

Structures of Pericardium

Pericardial cavity and pericardial sac.

Pericardial Cavity Location

Located between parietal and visceral layers; contains pericardial fluid.

Pericardial Fluid Function

Acts as a lubricant to reduce friction between heartbeats.

Pericardial Sac Composition

Made of fibrous tissue containing collagen; surrounds and stabilizes the heart.

Pericarditis Definition

An infection of the pericardium.

Pericarditis Signs

Scratching sound heard due to rubbing of surfaces and fluid collecting around heart.

Atria Structure

2 thin-walled chambers with expandable outer auricles.

Sulci Coronary Sulcus

Divides the atria and ventricles.

Interventricular Sulci

Anterior and posterior sulci separate left and right ventricles and contain blood vessels of cardiac muscle.

Layers of the Heart Wall

Epicardium, myocardium, and endocardium.

Epicardium

The outer layer of the heart wall.

Myocardium

The middle layer of the heart wall.

Endocardium

The inner layer of the heart wall.

Epicardium Characteristics

Visceral pericardium, covers the heart, serous membrane, exposed mesothelium, areolar connective tissue.

Myocardium Characteristics

Muscular wall of the heart forming atria and ventricles; contains concentric cardiac muscle tissue, blood vessels, and nerves.

Atrial Myocardium

Wraps around great vessels like the pulmonary artery and aorta.

how many ventricular myocardium divisions are there?

2

Superficial Ventricular Muscles

Muscles that surround the ventricles.

Deep Ventricular Muscles

Muscles that spiral around and between the ventricles.

Intercalated Discs

Structures that interconnect cardiac muscle cells.

Desmosomes in Intercalated Discs

Secure cardiac muscle cells together.

Gap Junctions in Intercalated Discs

Link cardiac muscle cells to convey force of contraction and propagate action potentials.

Cardiac Muscle Cell Characteristics

Small size, single central nucleus, branching interconnections, and intercalated discs.

septa/ Interatrial Septum

Separates the left and right atria.

Interventricular Septum

Separates the left and right ventricles.

Vena Cava Function

Delivers systemic circulation to the right atrium.

Superior Vena Cava Receives blood From

Head, neck, upper limbs, and chest.

Inferior Vena Cava Receives blood From

Trunk, viscera, and lower limbs.

Coronary Sinus Function

Cardiac veins return blood to coronary sinus; coronary sinusopens into the right atrium.

Foramen Ovale Definition

An opening through the interatrial septum before birth that connects the two atria.

Fossa Ovalis

Formed when the foramen ovale seals off at birth.

Pectinate Muscles

Contain prominent muscular ridges on anterior atrial wall and inner surfaces of right auricle.

Valve Cusps

Fibrous flaps that form bicuspid (2) and tricuspid (3) valves.

Free Edges of Cusps

Attach to chordae tendineae from papillary muscles of the ventricle.

Valve Cusp Prevention

Cusps prevent valves from opening backward.

Right Atrioventricular (AV) Valve / Tricuspid Valve

Opening from right atrium to right ventricle with 3 cusps; prevents backflow.

Trabeculae Carneae

Muscular ridges on the internal surface of the right ventricle.

Moderator Band

Ridge in right ventricle containing part of conducting system that coordinates cardiac muscle cell contractions.

Right vs Left Ventricle Wall

Right ventricle wall is thinner and develops less pressure than the left ventricle.

Right vs Left Ventricle Shape

Right ventricle is pouch-shaped while the left ventricle is round.

Atrioventricular (AV) Valves Location

Located between atria and ventricles; one-way valves prevent backflow during contraction.

Blood Pressure on AV Valves

Closes valve cusps during ventricular contraction.

Papillary Muscles Function

Tense chordae tendineae to prevent valves from swinging into atria.

Semilunar Valves Function

Pulmonary and aortic tricuspid valves prevent backflow from pulmonary trunk and aorta into ventricles.

Semilunar Valves Structure

Have no muscular support; 3 cusps support like a tripod.

Aortic Sinuses Location

Located at the base of the ascending aorta.

Aortic Sinuses Functions

Prevent valve cusps from sticking to aorta and serve as origin of right and left coronary arteries.

Carditis Definition

An inflammation of the heart that can result in valvular heart disease (VHD). can cause rheumatic fever

Rheumatic Fever Cause

Develops after a streptococcal infection.

Rheumatic Fever Symptoms

High fever, joint pain, and rash.

Rheumatic Fever Cardiac Impact

50-60% develop carditis and scar tissue in myocardium and heart valves.

Rheumatic Fever Latency

May not appear for 10-20 years.

Rheumatic Fever Valve Changes

Valves become thick and calcified, though blood flow is not totally blocked.

Rheumatic Fever Infection Risk

Heart is more susceptible to bacterial infections causing endocarditis (hence antibiotics from dentist).

Coronary Circulation Components

Coronary arteries and cardiac veins supplying blood to heart muscle tissue.

Coronary Arteries Origin

Left and right arteries originate at aortic sinuses.

Coronary Arteries Blood Flow

Driven by high pressure and elastic rebound forcing blood between contractions.

Right Coronary Artery Supplies

Right atrium, portions of both ventricles, cells of sinoatrial SA and atrioventricular AV nodes, marginal arteries (surface of right ventricle) , and posterior interventricular artery.

Marginal Arteries Location

On the surface of the right ventricle.

Left Coronary Artery Supplies blood to

Left ventricle, left atrium, and interventricular septum.

Branches of Left Coronary Artery (2 main branches)

Circumflex artery and anterior interventricular artery.

Cardiac Veins List

Great cardiac vein, anterior cardiac vein, posterior, middle, and small cardiac veins.

Great Cardiac Vein Function

Drains blood from area of anterior interventricular artery into coronary sinus.

Anterior Cardiac Vein Function

Empties directly into the right atrium.

Posterior, Middle, and Small Cardiac Veins

Empty into the great cardiac vein or coronary sinus.

The Heartbeat Definition

A single contraction of the heart.

Heart Contraction Sequence

The entire heart contracts in series: first the atria, then the ventricles.