Ch. 18

Front 1

Right side of heart

Back 1

Receives oxygen-poor blood from tissues via pulmonary circuit.

Pumps blood into pulmonary circuit.

Front 2

Left side of heart

Back 2

Receives oxygenated blood from lungs via systemic circuit.

Pumps blood into systemic circuit.

Front 3

Receiving chambers of heart

Back 3

Right atrium receives blood from systemic circuit. 3 veins enter. Superior & Inferior vena cava (return blood from body) and the coronary sinus.(returns blood from myocardium)

Left atrium receives blood from pulmonary circuit. 4 pulmonary veins enter from lungs.

Minimally contract to propel blood

Front 4

Pumping chambers of heart(Discharging chambers of heart)

Back 4

Right ventricle pumps bl via pulmonary circuit into pulmonary trunk. Thinner walled and is a slow, low-pressure circulation.

Left ventricle pumps bl via systemic circuit to aorta. Most of coronary bl supply. 3x thicker than right & can generate higher pressure so force can overcome resistance from systemic circulation.

Front 5

Heart size, location, and orientation

Back 5

Found in mediastinum, 2/3 to the left of the midsternal line.

Base towards right shoulder.

Apex points toward the left hip.

Front 6

Pericardium

Back 6

Double-walled sac that encloses the heart.

Front 7

Firbrous pericardium

Back 7

Superficial pericardium that protects the heart, anchors it to surrounding structures, and protects the heart from overfilling.

Front 8

Serous pericardium

Back 8

Deep to the fibrous pericardium, consisting of a parietal layer and a visceral layer

Front 9

Parietal layer

Back 9

Lines the inside of the pericardium

Front 10

Visceral Layer

Back 10

Aka Epicardium.

Covers the surface of the heart.

Front 11

Pericardial Cavity

Back 11

B/w the visceral and parietal layers.

Serous fluid that lubricates movement.

Front 12

Myocardium

Back 12

Cardiac muscle, bulk of heart.

Front 13

Cardiac skeleton

Back 13

Within the myocardium.

Network of CT tissue fibers that

reinforces the myocardium,

supports the heart valves,

and limits spread of action potentials to specific paths.

Front 14

Endocardium

Back 14

Lines the chambers of the heart and is continuos w/ the endothelial linings of the vascular system.

Front 15

Interatrial septum

Back 15

Separates atria

Front 16

Interventricular septum

Back 16

Separates ventricles

Front 17

Heart valves

Back 17

Make blood flow in one direction.

Open/close in respond to pressure.

2 types: AV & SL

Front 18

Atrioventricular Valves(AV)

Back 18

Prevent backflow into atria when ventricles contract.

B/w atria and ventricles.

2 AV Valves b/w atrial-ventricular junctions

Tricuspid valve in the right

Bicuspid valve(Mitral) in the left

Front 19

Semilunar Valves(SL)

Back 19

Prevent back-flow from major arteries into ventricles.

Located b/w ventricles and at the base of the arteries exiting the heart

3 cusps that resemble half-moon.

Pulmonary SL valve located b/w right ventricle and pulmonary trunk

Aortic SL valve b/w left ventricle and aorta.

Front 20

Why are there no valves at the entrances of the vena cava or pulmonary veins?

Back 20

B/c the inertia of blood and the collapse of the atria during contraction minimizes back-flow into these vessels.

Front 21

Coronary Circulation

Back 21

Supply blood to the heart itself when relaxed. Shortest circulation.

Aorta ---> R & L coronaries

3 Veins ---> Coronary sinus ----> Right Atrium

Front 22

Coronary arteries

Back 22

Arise from base of aorta. Encircle heart in coronary sulcus.

Receives 1/20 of body's Bl supply.

2 types: Right and Left coronary arteries.

Front 23

Right Coronary Arterty

Back 23

Supplies Right atrium and most of right ventricle.

Has 2 branches: Right marginal artery & posterior IV artery.

Front 24

Left Coronary Artery

Back 24

Supplies IV septum, anterior ventricular walls, left atrium, posterior wall of left ventricle.

Has 2 branches: Anterior IV artery & circumflex artery.

Front 25

Coronary veins

Back 25

Cardiac veins collect Bl from capillary beds

Coronary sinus empties to R atrium; formed by merging cardiac veins

Great cardiac vein of anterior interventricular sulcus

Middle cardiac vein in posterior interventricular sulcus

Small cardiac vein from inferior margin

Front 26

Cardiac muscle

Back 26

Striated and contraction occurs via the sliding filament mechanism.

Cardiac muscle cells have large mitochondria that occupy 25-35% of total cell volume.

Front 27

Intercalated discs

Back 27

are connecting junctions b/w cardiac cells that contain desmosomes for structural strength and gap junctions that allow electrical current to travel from cell to cell.

Front 28

Differences b/w skeletal muscle

Back 28

-Cardiac muscle cells are self-excitable & initiate their own depolarization and from the heart.

Contractile cells: responsible for contraction

Pacemaker cells: non-contractile cells that spontaneously depolarize

-Heart contracts as a unit b/c gap junctions electrically tie all cardiac muscle cells together.

-Influx of Ca2+ from extracellular fluid triggers Ca2+ release from SR

Front 29

Intrinsic Conduction system

Back 29

Consists of cardiac pacemaker cells have that have an unstable resting potential and produces pacemaker potentials that continuously depolarize, initiating the action potentials that are conducted throughout the heart.

Front 30

Sinoatrial node (SA)

Back 30

Primary pacemaker for the heart and is in the right atrium.

Front 31

Atrioventricular (AV)

node

Back 31

is the interatrial sepum, delays firing slightly, in order to allow the atria to finish contracting b/f the ventricles contract.

Front 32

Atrioventricular (AV) bundle

Back 32

Only electrical connection b/w atria and the ventricles and conducts impulses into the ventricles from the AV node.

Front 33

Bundle Branches (Right & Left)

Back 33

Conduct impulses down the interventricular septum to the apex.

Front 34

Subendocardial Conducting Network (Purkinjie Fibers)

Back 34

Penetrates throughout the ventricular walls, distributing impulses throughout the ventricles.

Front 35

Autonomic Nervous System (ANS)

Back 35

Modifies the heartbeat through cardiac centers in the medulla oblongata.

Front 36

Cardioacceleratory center

Back 36

Projects to sympathetic neurons throughout the heart, increasing both heart rate and contractile force.

Stimulates SA and AV nodes, heart muscle, and coronary arteries.

Front 37

Cardionhibitory center

Back 37

Sends impulses to the parasympathetic dorsal vagus nucleus in the medulla oblongata, which stimulated the vagus nerve to the heart, slowing the heart beat.

Inhibits SA and AV nodes via vagus nerves.

Front 38

Electrocardio graph

Back 38

can detect electrical currents generated by heart.

Front 39

Electrocardiogram (ECG or EKG)

Back 39

has 3 deflections:

a P wave; indicating depolarization of the atria

QRS complex; indicating ventricular depolarization

T wave; cause by ventricular re-polarization.

Front 40

Cardiac cycle

Back 40

describes the mechanical events associated w/ Bl flow through the heart in the series of pressure and volume changes during one complete heart beat.

Front 41

Systole

Back 41

Contractile phase of the cardiac cycle

Front 42

Diastole

Back 42

Relaxation phase of the cardiac cycle

Front 43

S1

Back 43

lub

closing of AV valves at beginning of ventricular systole

Front 44

S2

Back 44

dup

closing of SL valves at beginning of ventricular diastole

Front 45

Heart murmurs

Back 45

abnormal heart sounds heard when blood hits obstructions

due to turbulent back-flow of blood through a valve that does not closet tightly.

Front 46

Incompetent (or insufficient) valve

Back 46

fails to close completely, allowing backflow of blood

Causes swishing sound as blood regurgitates backward from ventricle into atria

Front 47

Stenotic valve

Back 47

ails to open completely, restricting blood flow through valve

Causes high-pitched sound or clicking as blood is forced through narrow valve

Front 48

Cardiac Output (CO)

Back 48

amt. of Bl pumped out of a ventricle per min.

CO = heart rate (HR) × stroke volume (SV)

Changes w/ demand; cardiac reserve is the diff. b/w the resting and maximal cardiac output.

Front 49

Stroke Volume (SV)

Back 49

Volume of Bl pumped out of a ventricle per min.

70 ml.

SV = EDV − ESV

End diastolic volume (EDV), the amt. of Bl that collects in the ventricle during diastole

End systolic volume (ESV), the volume of Bl that remains in the ventricle after contraction is complete.

Front 50

Avg. Adult HR

Back 50

75 bpm

Front 51

Frank-Starling law of the heart

Back 51

states that the critical factor controlling SV is pre-load, the degree of stretch of cardiac muscle cells immediately b/f they contract.

Preload: degree to which cardiac muscle cells are stretched just before they contract

Front 52

Venous Return of the heart

Back 52

Most important factor determining the degree of stretch of cardiac muscle

Front 53

Contractility

Back 53

Contractile strength achieved at a given muscle length; contractile strength increases if there is an increase in cytoplasmic calcium ion concentration

Front 54

Afterload

Back 54

back pressure exerted by arterial blood

Ventricular pressure that must be overcome b/f Bl can be ejected from the heart and does not b/c a significant determinant of SV except in hypertensive individuals.

Front 55

Factors that influence heart rate

Back 55

Age

Gender

Exercise

Body temp.

Front 56

Congestive heart failure (CHF)

Back 56

Occurs when pumping efficiency of the heart is so low that Bl circulation cannot meet tissue needs.

Front 57

Pulmonary congestion

Back 57

Occurs when the left side of the heart fails, resulting in pulmonary edema