WEEK 3: The Heart Flashcards
Deoxygenated blood is depicted in what colour?
Blue
Where is the heart? Name 4 different ways to describe its position
- In the thoracic cavity
- Inferior mediastinum
- posterior to the sternum
- Inferior to the sternal angle
what is a mediastinum
The area between the lungs
Where is the heart situated then, according to mediastinum
Middle mediastinum
Where is the sternal angle?
Manubrial sternal joint
Name 3 more ways to describe where the heart is
- Inside of the pericardial cavity
-Anterior to the esophagus
-superior to the diaphragm
how many layers of pericardium exist? name them
- parietal pericardium and visceral pericardium (epicardium)
why does the pericardium exist?
the pericardium consists of fluid that lubricates the heart - easier for heart to pump and reduce rubbing that could cause inflammation + seperates heart from lung & no opportunity for adhesion/scars
What other components make up the heart wall?
- mycocardium (heart muscle cells)
- endocardium (innermost)
what is cardiac tamponade?
if the heart wall ruptures, the pericardial sac can fill up with too much blood, and pressure becomes so high that the atria cannot be filled anymore - compression of the heart chambers can cause one to die
How many chambers in the heart?
4
How many atria and ventricles in the heart respectively?
2 & 2
What are the valves between the atria and ventricles called?
atrioventricular valves
What are the valves between ventricles and aorta & pulmonary trunk called?
semilunar valves
the right heart is equal to?
right atrium and right ventricle - receives deoxygenated blood from the body and pumps it towards the lungs
the left heart is equal to?
left atrium and left ventricle. receives oxygenated blood from the lungs and pumps it into the body
What are the 3 different surfaces of the heart called
- sternocostal (anterior)
- diaphgramatic (inferior)
- pulmonary (left/right)
Where is the apex?
towards the bottom of the heart
5th ICS, midclavicular, left ventricle
what is the rough part of the right atrium called?
pectinate muscles
what is the smooth part of the right atrium called?
sinus venarum
What are the other sections of the right atrium?
- auricle
-crista terminalis
-fossa ovalis
-opening coronary sinus
-superior vena cava
-inferior vena cava
What are the parts of the right ventricle
- tricuspid valve
-papillary muscles - tendinous cords
- conus arteriosus
- pulmonary valve
- interventricular septum
-trabeculae carnae
What important function does the tricuspid valve have?
The sails of the tricuspid valve flap and align into the papillary muscles and tendinous cords to avoid regurgitation of blood going back into right atrium
What two parts are the interventricular septum made out of?
- muscular part
-membranous part
what are the components of the left atrium
- 4 pulmonary veins
- left auricle
- floor oval fossa
what are the components of the left ventricle?
ventricular walls
bicuspid valve
aortic vestibule (smooth)
aortic valve
papillary muscles
trabeculae carnae (finer/delicate)
What is the most posterior part of the heart?
left atrium
What is the most anterior part of the heart
right ventricle (otherwise known as directly posterior to the sternum)
What is the function of the skeleton of the heart?
- electrical insulation
-support of leaflets and cusps - 4 fibrous rings
How many coronary arteries are there?
2, the left coronary artery (LCA) and right coronary artery (RCA)
What kind of fat are the coronary arteries surrounded by?
epicardial fat
Where do coronary arteries originate from
the aorta, superior to the aortic valves
What does functional endarteries mean and why are coronary arteries known as this?
When there is a limited blood supply, these dense connections between cappilarries, hence this part of the heart will become ischaemic- they cannot compensate
difference between left coronary and right coronary artery?
LCA- more the anterior part, septum and left side
RCA- more posterior and diaphragmatic and conduction system
coronary arteries are perfused with blood mainly during???
diastole
Define the heart
A muscular pump with 4 chambers, 2 receiving and 2 pumping, that distribute blood to 2 vascular circuits
Main vessels attached to the heart?
inferior cava/superior vena cava (return blood to heart)
aorta and pulmonary trunk (take blood to rest of body)
Main chambers of the heart
right atrium, left atrium, right ventricle, left ventricle
what are the three layers of the heart wall called?
- endocardium
- myocardium
- epicardium/ visceral pericardium
Wall thickness varies according to?
chamber type as thickness relates to workload done by walls
the entire heart is enclosed within the?
pericardial sac
what is the endocardium?
inner layer of wall that lines chambers
what is the myocardium
middle thickest layer
what is the epicardium
outer layer of wall in contact with pericardial cavity
the wall of the pericardial sac can be divided into what two sublayers?
- serious pericardium (parietal layer of the pericardium)
- fibrous outer pericardial layer
T or F: atrial walls are thinner than ventricular walls
T
right ventricle wall is thinner than?
left ventricle wall
parietal pericardium is seperated from the heart by the? why?
pericardial activity
- keeps heart in place and lubricates + protects the heart against infection and injury + prevents overexpansion
what is the histological composition of the pericardial sac?
- mesothelium (simple squamous epithelium) which covers the surface facing the pericardial cavity
-fibrous/dense connective tissue which anchors into surrounding CT structures
the makeup of the epicardium is?
- mesothelium which secretes lubricating pericardial fluid to prevent friction as heart beats
- underneath mesothelium: underlying connective tissue
- connective tissue contains adipocytes, nerves
-coronary vessels that send branches into myocardium
what is the makeup of the myocardium
-composed of cardiac muscle fibers in concentric layers
- superficial layers of ventricular muscle wrap around both ventricles
-muscle arrangement allows heart to pump blood more effectively
-vascular connective tissue between muscle fibres
what is the tissue composition of myocardial layer?
-> layer contains:
- loose connective tissue: endomysium surrounds fibres
-abundant blood capillaries in the endomysium tissues: reflects high oxygen demand of the muscle fibres
-small nerves
cardiac muscle is a type of muscle that is?
striated
cardiac muscle consists of
branched fibres, central nuclei, direct cell-cell communication via intercalated discs, abundant mitrochondria (25%), large energy stores in the form of glycogen
mitochondria and glycogen in the cardiac muscle reflect its high?
energy demand and constant supply of ATP needed due to the aerobic respiration of these fibres
why are largest diameter fibres in the left ventricle?
because the workload is greatest
endocardium layer varies in thicknes: T or F
T
thickest in atria, thinnest in ventricles
what are the 3 sublayers of endocardium?
endothelium- in contact with blood
subendothelial CT layer- dense and regularly arranged collagen & elastin fibres
deep connective tissue layer- more irregular & loose arrangement of collagen
what is the main subendocardial structure?
modified cardiac muscle conducting fibres - purkinje fibres, nerves and blood cells
characteristics of purkinje fibres?
- specialized fibres for rapid transmission of signals
-allow for coordinated/unified contraction of heart muscle
-larger cells, pale staining than contractile cardiac muscle cells (less myofibils)
-contain large stores of glycogen
what is the cardiac skeleton?
a region of fibro collagenous tissue located at the level of heart valves- and anchors valves and chambers together
