Size of the heart is a function of the size of what?
The size of the person
Approximate dimensions of the heart?
5" long and 3.5" wide
The heart mass is a function of what?
The person's size, gender, age and contitioning
Approximate heart mass?
9 to 12 oz
Would the heart of an athlete weight more or less than an elderly individual and why?
MORE, because it is more muscular
Where is the heart positioned?
Thoracic cavity, AKA the mediastinum
- The _________ are located to the immediate right and left of the heart.
- the __________ is anterior to the heart.
- The __________ is posterior to the heart.
- The ____________ is inferior to the heart.
Which direction(s) does the apex point?
Inferiorly, anteriorly and to the left
Define the "Long axis of the heart"
The distance from the LV to the root of the aorta
How many heart borders are there and what are their names?
- Superior Border
- Left Border
- Inferior Border
- Right Border
What makes up the Superior Borde r?
Right and Left Atrium
What makes up the Left Border?
Primarily the Left Ventricle, some Left Atrium
What makes up the Inferior Border?
Primarily the Right Ventricle, some Left Ventricle near the Apex
**This side is almost horizontal
What makes up the Right Border?
Right Atrium in a straight line with the superior and inferior Venae Cava
The Heart and roots of the great vessels are enveloped by the....
Describe the pericardium
A fibrous sac that folds on itself and contains a thin film of fluid called the serous fluid or pericardial fluid
Functional roles of the pericardium (4):
- Extra layers of protection
- Structural anchoring to neighboring structures
- Viscous fluid reduces frictional forces
- Constrains the amount of blood filling
Components of the heart Wall Structure
- Simple Squamous epithelium
- Lines the inner chambers of the heart as well as the valve
- Indistinguishable from the lining of the blood vessels
- Smooth, sponge-like appearance, interlaced with trabecular carnae
- Cardiac myocytes from the contractile layer for the ejection of blood
- Divided into the subendocardial and subepicardial areas
Contractile units of muscle with specific arrangements of the proteins Myosin, actin and troponin
- Serous membrane on the outside of the middle layer of the heart
- Synonymous with the visceral pericardium
- Squamous epithelial cells that overlay connective tissues
What makes up the 4 Chambers of the heart?
- Right Atrium
- Left Atrium
- Right Ventricle
- Left Ventricle
Partitioning of the heart chambers involves what two septum?
- Interatrial septum
- Interventricular septum
The septum separating the RA from the LA has a shallow depression called the......
In the fetal heart this is where there was an opening called the foramen ovale
What direction is the Interventricular septum pushed to and why?
Due to pressure differences between the LV and RV, the inter ventricular septum is pushed to the RIGHT
Heart Features: Right Atrium
- Thin wall (2-3mm)
- Pressure ranges from 2-8 mm Hg during filled and contraction
- ~10% of the blood in the normal heart @ rest is delivered via Atrial contraction (AKA Atrial Kick), 40% during exertion
Heart Features: Right Ventricle
- Thicker than Atrium (3-4mm)
- Pressure ranges from 2-8 mmHg during PASSIVE FILLING
- Pressure increases to 15-30mmHg during CONTRACTION/Ventricular systole
- Inner wall of the outflow track is smooth, other parts are sponge-like with irregular projections (trabeculae carnae)
Heart Features: Left Atrium
- Thin wall ~2-3mm
- Pressure ranges from 2-10 mmHg
Heart Features: Left Ventricle
- Three times thicker than the RV(9-11mm)
- Cone-shaped during diastole and Spheroid during systole
- 3-12mmHg during Filling phase and 100-140mmHg during contraction/ventricular systole
- Inner wall of the outflow track is smooth, other parts are sponge-like with irregular projections that are finer but more in number than the RV
Name 4 Septal Defects
- Atrial Septal Defect (ASD)
- Patent Foramen Ovale (PFO)
- Ventricular Septal Defect (VSD)
- Hypertrophic Cardiomyopathy (HCM)
Describe Patent Foramen Ovale (PFO)
When the flap-like opening in the septum between the RA and LA in a fetus does not close after birth; 25% of the population
Describe Atrial Fibrilation
- Disorganized electrical conduction pathways in the atria
- Leads to less efficient pumping
- Causes the blood to stagnate >> leading to clotting >>> majority of these clots are formed in the left atrial appendage
- Stroke is a major risk factor
AFib treatment options
- Surgery/Implantable devices
Dilated LV with minimal hypertrophy
Marked LV Hypertrophy
Infiltrated or fibrotic LV
No longer flexible; restrictive & cannot expand as it should
Describe the heart valves
- 4 total = 2 inlet and 2 outlet
- Open and close to give UNIDIRECTIONAL flow of the blood WITHOUT BACKFLOW
- Attached to fibrous cardiac skeleton.
Inlet Valves are the .....
Atrioventricular Valves; separate the atria and ventricles
What makes up the Atrioventricular Valves?
- Tricuspid Valve
- Mitral (Bicuspid) Valve
Connected by the "heart strings" to the papillary muscles
Outlet Valves are the....
Semilunar Valves; separate the ventricles from the great arteries
What makes up the Semilunar Valves?
- Pulmonic Valve
- Aortic Valve
What is stenosis?
Obstruction of valve leading to decrease in forward blood flow
What is insufficiency?
Leaky Valve leading to backflow of blood
valve does not completely close; regurgitation
Describe blood flow velocity within a closed flow stream
The volume flow rate at Point 1 is equal to the volume flow rate at point 2
Describe blood flow velocity within an area that is narrowed
The velocity must increase in order to have the same volume flow
Consequences of Aortic stenosis (3)
- Elevated LV pressures
- Secondary Ventricular Hypertrophy
What are the two NORMAL Heart sounds heard in the normal adult heart?
- Lub = S1
- Dub = S2
Describe the First Heart Sound (S1)
Result of Mitral and Tricuspid valves closing at the beginning of systole
Describe the Second Heart Sound (S2)
Result of Aortic and Pulmonic Valves closing at the beginning of diastole
What are the 2 components of the Second Heart Sound?
A2 and P2
Major Coronary Arteries of the Heart? (5)