Arteries
carry blood away from the heart
Veins
carry blood back to the heart
great vessels
arteries and veins entering and leaving the heart
What ensures blood flow is unidirectional?
Heart valves
blood pressure
force of blood pushing against the inside walls of blood vessels (contraction & relaxation)
Pulmonary circulation:
-right side of heart pumping deoxygenated blood through pulmonary arteries to lungs
-pulmonary veins carry blood to left side of heart
Systemic circulation:
•Left side pumps oxygenated blood through systemic arteries to body’s cells
•Exchange nutrients, respiratory gases and wastes
•systemic veins-back to the right side of the heart
Location of heart,
-left of midline, deep to the sternum, in mediastinum
•Right border more anteriorly
What is Base, superior border, Apex and inferior border of heart?
-Base of the heart: mainly the left atrium
-Superior border: great arterial vessels and superior vena cava
-Apex: inferior conical end
-Inferior border: right ventricle
What is Pericardium and the layer? and space?
-tough sac enclosing heart
-Restricts heart movements, within the thorax
•Fibrous pericardium: tough outer sac
•Serous pericardium: composed of parietal and visceral layers
•Pericardial cavity: space between serous pericardium containing serous fluid
Three layers (from superficial to deep):
Epicardium: visceral layer of serous pericardium and areolar connective tissue
Myocardium: cardiac muscle; thickest
Endocardium: internal surface chambers; simple squamous epithelium and areolar connective tissue
Heart composed of four hollow chambers:
-two superior, smaller atria. (atrium singular)
-two inferior, larger ventricles
auricle
form from Anterior part of each atrium
Blood flow
•Blood passes from right atrium to right ventricle, pulmonary trunk, pulmonary circulation
•Blood passes from left atrium to left ventricle, aorta, systemic circulation
Coronary sulcus
groove separating atria and ventricles
Anterior and posterior interventricular sulcus are located
between the right and left ventricles
closure causes the first heart sound “lubb”
Two atrioventricular (AV) valves
closure causes the second heart sound “dupp”
Two semilunar valves at base of great arteries
Fibrous Skeleton
Dense regular connective tissue between the atria and ventricles
- structural support
- electrical insulator
Right atrium receives blood from? Which veins?
systemic circulation through three large veins:
•Superior vena cava
•Inferior vena cava
•Coronary sinus
1. Interatrial septum, 2. Pectinate muscles, 3. Right atrioventricular valve function?
1. divides left & right atrium
2. ridges on internal atrial wall
3. (tricuspid valve): one-way flow from right atrium to right ventricle
'right atrium
Right ventricle receives blood from?
receives deoxygenated blood from right atrium
1. Interventricular septum
2. trabeculae carneae
1. thick wall between right and left ventricles
2. Inner wall of each ventricle, irregular muscular ridges
'right ventricle
Papillary muscles
cone-shaped, attach to chordae tendineae (attach to atrioventricular valve, prevent cusps flipping when ventricle contracts)
'right ventricle
Septomarginal trabecula
connects anterior papillary muscle of right ventricle to atrioventricular septum
'right ventricle
Conus arteriosus
smooth funnel near top of right ventricle going to pulmonary semilunar valve (ensure 1 way flow from ventricle to pulmonary trunk)
'right ventricle
Left Atrium receives blood from?
Oxygenated blood from lungs travels through pulmonary veins
Left atrioventricular valve, aka
opening between left atrium and ventricle
- bicuspid (two flap) or mitral valve
•shut when the left ventricle contracts
Left ventricle pumps blood to? Who controls flow?
through entire systemic circulation
•Very high pressure
Aortic semilunar valve: controls flow from left ventricle to aorta
Who is thicker, left or right?
Left ventricular wall is typically three times thicker than the right
Where do left and right coronary arteries travel in? function? where do they branch?
travel within coronary sulcus and supply heart wall with oxygen and nutrients
•Branch off ascending aorta just superior to aortic semilunar valve
right coronary artery branches into:
Right marginal artery: supplies right border
Posterior interventricular artery: supplies posterior surfaces of left & right ventricles
left coronary artery branches into:
Anterior interventricular artery: aka left anterior descending artery; supplies anterior surface of both ventricles and most of the interventricular septum
Circumflex artery: supplies the left atrium and ventricle
Where do major cardiac veins drains?
3 major cardiac veins drain into the coronary sinus, which drains into the right atrium
Great cardiac vein: anterior interventricular artery
Middle cardiac vein: posterior interventricular artery
Small cardiac vein: close to the right marginal artery
Similiarty and Differences between cardiac and skeletal muscle
Same: striated with extensive capillary networks
•Less SR quantity and organization
•No terminal cisternae
•Less contact between SR and T-tubules
Why cardiac muscle contract as single unit?
all connected with gap junctions
•Gap junctions are parts of intercalated discs between adjacent fibers
•Each electrical impulse is distributed immediately and spontaneously throughout the myocardium
autorhythmicity
initiates its own heartbeats
conducting system
consists of specialized cells that start and propagate electrical impulses to contractile cells
Electrical impulse of heart
-begins at the sinoatrial (SA) node (heart’s pacemaker)
-travels via gap junctions to left atrium and atrioventricular (AV) node on the floor of right atrium
•AV node delaying activation of ventricles as they fill with blood
-enters the atrioventricular (AV) bundle (bundle of His), interventricular septum
-AV bundle divides into left and right bundles (bundle branches)
- to Purkinje fibers that begin at the heart apex
sinoatrial (SA) node location
posterior wall of right atrium adjacent to the opening of the superior vena cava
Where does Purkinje fibers spread the impulse
superiorly from the apex to all of the ventricular myocardium
What is electrocardiogram (ECG)? What is P wave, QRS complex and T wave?
is a composite tracing electrical impulses
•P wave: atrial depolarization
•QRS complex: ventricular depolarization (and atrial repolarization)
•T wave: ventricular repolarization
cardiac plexus
Heart is innervated by sympathetic and parasympathetic divisions of the autonomic nervous system
•does not initiate a heartbeat, but it can increase or decrease the rate of the heartbeat
Sympathetic innervation
neurons in T1–T5 spinal cord
•Preganglionic axons enter sympathetic trunk and synapse on ganglionic neurons
•Postganglionic axons project from cervical and thoracic ganglia and travel to the heart via cardiac nerves
- increases rate and force of heart contractions
Parasympathetic innervation
-neurons in the medulla oblongata vagus nerves (CN X)
• decreases heart rate but no effect on force of contraction
What is cardiac cycle, systole, diastole?
cardiac cycle -time from start of one heartbeat to the start of the next. contraction and relaxation
•Contraction: systole
•Relaxation: diastole
5 Steps in the Cardiac Cycle
1.Atrial contraction and ventricular filling
2.Isovolumic contraction—occurs at beginning of ventricular contraction
3.Ventricular ejection
4.Isovolumic relaxation—occurs at beginning of ventricular relaxation
5.Atrial relaxation and ventricular filling
Aging and the Heart
-Decreased tissue elasticity with age often impairs heart valve function
-Decreased efficiency of heart’s conducting system can impair ability to pump extra blood needed during stress
-High blood pressure increases work required of heart and can lead to problematic hypertrophy of myocardium
How is the heart developed?
Begins during Week 3
•Heart tubes form and fuse
Primitive heart is beating by day 22
Sinus venosus- becomes Superior vena cava, coronary sinus, smooth posterior wall of right atrium
Primitive atrium-Anterior muscular portions of left and right atria
Primitive ventricle-Most of left ventricle
Bulbus cordis
Trabeculated part of right ventricle- Most of right ventricle
Conus cordis-Outflow tracts from ventricles to aorta and pulmonary trunk
Truncus arteriosus-Ascending aorta, pulmonary trunk