Chapter 28 Flashcards
2/3 of heart lies to ____, 1/3 lies to ______
Left of body midline
Right
Apex of heart lies on ___
Diaphragm
Base of heart lies just below
2nd rib
Heart lies between
Body of sternum and the thoracic vertebrae, positioning makes cpr possible
Heart is _____ shape and shape can very wiht shape of ____
___- sized
Triangular
Shape of chest
Fist sized
Sac covering heart
Pericardium
2 parts of pericardium
Fibrous portion, serous portion
Fibrous portion is
Tough, loose-fitting inextensible sac
Attaches to the large blood vessels that leave the top of the heart
Serous portion has what two parts
Parietal (inside) and visceral (aka epicardium) (outside)
Pericardial fluid does what
Lubricates and decreases friction
Epicaridum
Visceral layer of the serous portion of the pericardium
Myocardium
Cardiac muscle tissue that makes ip the bulk of the heart wall/wall of each heart chamber
Recall intercalated discs -> functional units called syncitum
Endocaridum
Thin layer of very smooth tissue (endothelial tissue) that lines the inside of each heart chamber as well as the blood vessels
Atrium chambers divided by
Interatrial septum
Atrium can be considered
Right and left receiving chambers
Atrium have _____ and _____ walls compared to ventricles
Smaller and thinner
Ventricles seperates by
Interventricular septum
Ventricles are the _____ or ____ chambers
Discharging or pumping
Blood leaves the heart through the ventricles via the
Arteries
Left ventricle myocardium is ______ than the left
Thicker
Systole
Contraction of heart
Diastole
Relaxation of the herat
Direction of blood is controlled by
Valves
4 valves of the heart
2 atrioventricular (AV) 2 semilunar valves (SL)
The 2 type of AV valves
Tricuspid (right side)
Bicuspid or mital valve (left side)
Cordae teninae
Attach AV valves to wall of the heart
Two types of semilunar valves
Pulmonary SL valve
Aortic sl valve
Pulmonary SL valve
At enterance of the pulmonary artery/trunk
Between right ventricle and pulmonary artery
Aortic SL vlave
At entrance of the aorta
Between left ventricle and aorta
Two seperate pumps of the heart
With each heart beat, the LA and RA contract simultaneously to fill the LV and RV with blood = atrial systole
Next, the LV and RV contract simultaneously = ventricular systole
Blood flow through the heart
Venous blood RA (through sup. & inf. vena cavae) tricuspid AV valve into RV through pulmonary SL valve pulmonary artery (branches into right and left) lungs Pulmonary veins LA bicuspid/mitral AV valve LV aortic SL valve aorta arterial blood distributed throughout body
Oxygen and nutrients flow to the heart throug hthe
Coronary arteries
Most abundant blood supply goes to the
Myocardium of left ventricle
Coronary veins return blood to
The right atrium
Blockage of blood flow through the coronary arteries is called
Myocardial infarction (MI)
Or
Heart attack
Angina pectoris
Chest pain caused by inadequate oxygen to the heart
Coronary bypass surgery
Veins from other parts of the body are used to bypass blockages in coronary arteries
Myocardium is autoryhmic meaning
It can produce its own action potentials
Specialized network of fibres that can rapidly conduct impulses
Conduction system of heart
Changes in rhythm of myocardial contraction is controlled via
Motor neuron pathways of both efferent divisions of the ANS
4 specialized structures of the heart other intercalated disks
Sinoatrial node
Atrioventricular node
AV bundle (bundle of His)
Subendocardial branches (Purkinje fibers)
Sinoatrial node
the pacemaker
Initiates impulse/heartbeat and sets its pace
located in the wall of the RA near the opening of the superior vena cava
Atrioventricular AV node located in
Located in the RA along the lower part of the interatrial septum
AV bundle (bundle of his) located where
Located in the septum of the ventricle
Purkinje fibers located in
Located in the walls of the ventricles
Electrical impulses of the heart’s conduction system can be recorded as
Electrocardiogram
P wave represents
Depolarization of the atria (triggers contraction)
QRS complex represents
Depolarization of the ventricles
T wave represents
Repolarization of the ventricles (just before relaxation phase)
No visible recoring of
Repolarization of the atria (overshadowed by large QRS complex)
Damage to heart muscle/ cvd will change
Ecg
Each complete heartbeat is called
Cardiac cycle
Each cycle (beat is aprox _____ sec long
0.8
Average heart beat _____ beats/ minute
72
Lub=
Dub=
Systole
Diastole
Stroke volume
Amount of blood that one ventricle ejects with each beat
Cardiac output
Volume of blood that flows out of ventricle per unit of time
Phases of the cardiac cycle
Atrial Systole
Atria contract pressure gradient blood flows in to relaxed ventricles
Isovolumetric Ventricular Contraction
Intraventricular pressure begins to increase AV-valves close first heart sound
Ejection
SL-valves open blood leaves heart
Isovolumetric Ventricular Relaxation
Ventricles begin to relax SL-valves close, AV-valves open second heard sound
Passive Ventricular Filling
Intraventricular pressure drops; intraatrial pressure rises AV-valves open blood enters ventricles
Two distinct heart sounds in every heartbeat or cycle: “lub-dup” that provide clinical significance re: the heart valves
First (lub) and longer sound (systolic): caused primarily by the contraction of the ventricles and the vibrations of the closing AV valves
Second (dup) and shorter sound (diastolic): caused by the vibrations of the closing semilunar valves during relaxation of the ventricles