What cavity is the heart located in?
mediastinum
The heart is located between which intercostal spaces?
- Left side: 2nd
- Right side: 5th
Where is the heart located in relation to the midsternal line?
2/3 to the left
Where is the apex located?
- left side
- between 5th and 6th rib
What is the heart enclosed in?
pericardium, double walled sac
Fibrous pericardium: which layer, function
- superficial layer
- protects, anchors, prevents overfilling
What is the fibrous pericardium attached to?
- diaphragm
- posterior side of sternum
Serous pericardium
- deep layer
- contains 2 layers that are continuous with one another
Parietal pericardium
lines the inside of the fibrous pericardium
Visceral pericardium
- called epicardium
- lines outer surface of the heart
What is the pericardial cavity?
- potential space between serous pericardium layers
- friction free environment: contains serous fluid
Pericarditis
- inflammation of the pericardium
- similar pain to heart attack: continuous central chest pain radiating to upper limb
- viral or bacterial in nature
Pericardial effusion
- Fluid accumulation between visceral and parietal layers of the serous pericardium
- Compresses ventricles (cardiac tamponade) leading to their failure
Epicardium
visceral layer of the serous pericardium
Myocardium
- spiral bundles of cardiac muscle cells
- contracts
- fibrous skeleton of the heart
Functions of the fibrous skeleton of myocardium (3)
- anchors cardiac muscle fibers
- Supports great vessels and valves
- Limits spread of action potentials to specific conduction paths
Endocardium
- continuous with endothelial lining of blood vessels
- contains capillaries
The atria are _____ _______ chambers
blood filling
Describe structure and location of pectinate muscle
muscle bundles on the anterior wall of R atria and auricle of L
Function of interatrial septum
-separates atria internally
Where is the fossa ovalis located?
interatrial septum
Location and function of auricles
- protrude off of atria
- increase atrial volume
Right atria receives _______ blood from…
deoxygenated
- superior vena cava
- inferior vena cava
- coronary sinus
Left atria receives _______ blood from….
oxygenated; R and L pulmonary veins (2 on each side, 4 total)
The ventricles are _____ pumps
- blood
- thick myocardium
Interventricular septum
separates ventricles internally
anterior and posterior interventricular sulci
mark the position of the interventricular septum externally
Trabeculae carnae
ridges of muscle on ventricle
Right ventricle receives _____ blood from the _____
deoxygenated; right atria
Right ventricle pumps ______ blood to the ______ ______ to the ______ via the ________arteries
deoxygenated; pulmonary trunk; lungs; pulmonary arteries
Left ventricle receives _____ blood from the ____ ______
oxygenated; left atria
Left ventricle pumps ______ blood out the ______ to the body
oxygenated; aorta
Why does the left ventricle have a larger myocardium
need larger force to pump blood to systemic circulation
Sinuatrial node: location, signal, innervation, resting bpm
- anterolateral R atrium
- signal to AV node
- sympathetic and parasympathetic innervation (vagus nerve)
- 70 bpm w/o other signal
Atrioventricular node: location, signal, resting bpm
- interatrial septum near coronary sinus opening
- signals to AV bundle
- 50 bpm w/o SA signal
Atrioventricular bundle: connections, route, resting bpm
- connects atria to ventricles electrically
- passes through fibrous skeleton of heart into interventricular septum to left and right bundle branches
- 30 bpm w/o AV signal
R and L bundle branches: signal, divide into…
- carry signal to apex
- divide into Purkinjie fibers
Purkinjie fibers bpm w/o AV
30 bpm
Characteristics of fibrous skeleton of heart (6)
- Dense, fibrous CT
- Forms connected rings between atria and ventricles
- Helps maintain valve openings
- Valve cusp attachment site
- Separates atrial and ventricular muscle
- Electrically isolates impulses between atria and ventricles
Heart valves ensure what type of flow through the heart?
unidirectional
What 2 valves are AV valves?
- Tricuspid (right)
2. Bicuspis (left)
What structure anchors AV valves to papillary muscle?
chordae tendinae
Where are semilunar valves located?
Between ventricles and large vesicles
What are the names of the 2 semilunar valves?
- aortic semilunar valve
2. pulmonary semilunar valve
When does heart begin to develop?
week 3 ( just made 3 germ layers, need nutrients)
Heart comes from what germ layer?
visceral/splanchnic lateral plate mesoderm
What forms around cranial end of the embryo?
Primary heart field
What are the derivatives of the primary heart field?
- atria
- L ventricle
- Most R ventricle
What is the embryologic origin of the pericardium?
visceral lateral plate mesoderm
What happens during week 3 of development?
-paired tubes develop and fuse with lateral folding
Rapid growth of brain pushes primary heart field in which directions?
ventrally and inferiorly
Secondary Heart Field: day, location, becomes…
- develops days 20-21
- located behind pharyngeal arches
- becomes some R ventricle and outflow vessels
Sinus venosus forms….
- veins that enter right atrium
- part of right atrium
Primitive atrium forms…
right and left atria
AV canal: location, forms….
- located between primitive atrium and ventricle
- forms AV valves
Primitive ventricle forms….
left ventricle
Bulbus cordis forms….
- right ventricle
- muscular outflow region
Truncus arteriosus forms…
- aorta and pulmonary arteries
- can be listed as part of bulbus cordosis
When does heart looping begin?
week 4
When is the beginning of sidedness?
days 16-18
When does the heart begin to beat?
- week 4
- connections to placental vessels are formed to allow circulation
What is looping?
primitive ventricle and bulbus cordis move ventrally, caudally, and to the right
When does septation occur?
week 5-6
Atrial septum contains… (3)
- septum primum
- septum secondum
- form foramen ovale
- fuse together in newborn
Ventricular septum contains… (2)
- membranous septum from endocardial cushions
- muscular septum from point between primitive ventricle and and bulbus cordis
- septums join to separate R and L ventricles
Endocardial cushions: location, future site of, function
- Located in AV canal
- Future site of valves
- Help close atria off from ventricles
Conotruncal septum: location, forms
- spiral septum in bulbus cordis and truncus arteriosus
- forms ascending aorta and pulmonary trunk
Neural crest cells migrate into….
pharyngeal arches
Aortic arches grow into…
pharyngeal arches
Neural crest cells are incorporated into…
aorta and pulmonary trunk
Neural crest cells may be a part of…
semilunar valves