Anatomy of the Heart - Part 1

Question 1

Describe the Blood vascular and the Lymphatic (vascular) systems

Answer 1

Blood vascular system:
- A closed supply drainage system (a continuous loop)
- Starts at the heart and the goes to the exchange surfaces and then back to the heart

Lymphatic vascular system:
- A open-entry drainage system (a one-way system)
- Fluid that ends up in the interstitial spaces in the surrounding tissues is drained back into the blood vascular system using the lymphatic system

Question 2

What are the two types of circulation in the heart?

Answer 2

Pulmonary system:
- The deoxygenated blood on the right side of the heart is pumped into capillaries in the lungs where the blood is oxygenated and then goes back to the heart

Systemic circulation:
- Left side of the heart pumps oxygenated blood to the whole body

Question 3

What is the Supply side of the cardiovascular system?

Answer 3

• Arteries are the only supply path
• Major arteries are situated to avoid damage
  (eg. deep in the trunk; on flexor aspect of limbs)
• Important structures often receive supply from two sources (two seperate arteries)
• Arteries change their name at each major branch

Question 4

What is the Exchange network of the cardiovascular system?

Answer 4

Capillaries of varying degrees of permeability
- Continuous (controlled ~ tight)
- Fenestrated (leaky)
- Sinusoidal (very leaky)

Question 5

What is the Drainage side of the cardiovascular system?

Answer 5

3 pathways for drainage:
- Deep veins (deep in body)
- Superficial veins (where we can’t accomodate large arteries)
- Lymphatics

Low pressure, low velocity here - whereas the supply side is high velocity, high pressure. Therefore, to balance this the drainage system (veins) have a much larger cross sectional area (about 2x bigger) than arteries.

Question 6

Describe the shape of the heart and where it is located

Answer 6

Shape:
Blunt, cone shaped
Pointed end (bottom) - apex
Broad end (top) - base

Location:
- Base sits along the plane of the intercostal space between the second and third ribs
- Apex sits down the post of the left clavicular line between the fifth and sixth ribs. (which is where the PMI - point of maximal impulse is located [loudest heart beat here with stethoscope] and the apex beat can be seen)
- 2/3 of the heart sits to the left side of the chest. It is rotated so the right is more anterior and the left is more posterior

Question 7

Describe the atriums and ventricles of the heart (from the anterior view)

Answer 7

Right atrium is the receiving chamber for deoxygenated blood. It then goes into the right ventricle where it is pumped up into the pulmonary circuit to the lungs to be oxygenated.

Left atrium is the receiving chamber for oxygenated blood and the left ventricle is where the blood goes before it is pumped into the systemic system (all around the body).

Interventricular septum separates the two sides

Question 8

Describe the entry points for venous return to the atria of the heart and the valves that open to allow this

Answer 8

Right atrium receives deoxygenated blood from:
- Superior vena cava
- Inferior vena cava
- coronary sinus
Tricuspid valve opens to allow blood to enter right ventricle. Pulmonary (semilunar) valve opens to let blood leave the heart/right ventricle.

Left atrium receives oxygenated blood from:
- four pulmonary veins (two veins from left lung and two form the right lung)

Question 9

What are the layers of the heart wall (from innermost to outermost)?

Answer 9

Endocardium:
- Squamous epithelium (endothelium). Non-stick surface to avoid blood clotting.
- Supported by loose irregular fibrous connective tissue (FCT)

Myocardium:
- Left side is three times thicker than right side because it is pumping to the whole body rather than just the lungs

Epicardium:
- Contains visceral pericardium (thin outermost layer), blood vessels (veins and arteries), loose irregular FCT and varying amounts of adipose.

Pericardium

Question 10

Describe the layers of the pericardium of the heart in more detail (from inner to outer)

Answer 10

Visceral pericardium (visceral serosa)
Pericardial fluid (serous fluid)
Parietal pericardium (parietal serosa)

Pericardium is what we call a serous membrane.

Question 11

Describe the layers of the heart along with the detailed layers of the pericardium (from innermost to outermost)

Answer 11

Endocardium
Myocardium
Epicardium:
- visceral serous pericardium
- loose irregular FCT (adipose)
- blood vessels
Pericardial cavity
Parietal layer of serous pericardium
Fibrous pericardium