Learning content
Module 1.1 The Cardiovascular System overview
1.1.a. Cardiovascular system overview and functional anatomy of the heart
In this topic we will learn about the anatomy of the heart and the major vessels entering and leaving the heart. This topic will also include important structures of the heart which includes the heart valves (and how they work) and the different layers that make up the wall of the heart chambers.
Learning Outcomes
- Describe the systemic and pulmonary circulation and name the major arteries and veins of each system.
- Identify all the heart structures (internal and external) and major vessels that enter and exit the heart.
- Describe the internal and external linings and layers of the heart, what they are composed of and their main functions.
Required Readings
- Refer to the course notes and Chapter 18 of Marieb.
Concept Check
Now is the time to ask yourself what can you recall about the following terms:
- Pulmonary and systemic circulation
- Left and right heart
- Atria and ventricles
- 3 layers of the heart. Pericardium, myocardium and endocardium.
- Four valves of the heart.
1.1.b. Electrical activity of the heart
In this topic we will look at the ECG, what it represents and how the action potential that spreads through the heart translates to mechanical events that allow the heart to work as a pump. We will also look at the phases of the cardiac cycle and the sequence of events in the heart during a typical cardiac cycle.
Learning Outcomes
- Draw and label a typical ECG and describe what each wave of the ECG represents in terms of electrical activity of the heart.
- List some of the cardiac abnormalities and changes that can be determined by clinicians when analysing an ECG.
- Describe the 5 phases and mechanical events during a cardiac cycle.
- Describe septal defects and how they may impact on heart function.
Concept Check
Now is the time to ask yourself what can you recall about the following terms:
- ECG
- The Cardiac Cycle
- Septal defects
Learning Experience
A great explanation on ECG trace!
Mechanical events of the cardiac cycle
Atria septal defect
Ventricular septal defect
Learning Activities
-Jeopardy quiz
-Practice questions
Mastering AnP
-Human heart develops from mesoderm
-The absolute refractory period refers to the time during which the muscle cell is not in a position to respond to a stimulus of any strength
-The absolute refractory period is the period during an action potential when another action potential cannot be triggered
-In skeletal muscle, the absolute refractory period is much shorter than the contraction, allowing multiple contractions to summate (tetanic contractions). If heart were to contract tetanically, it would be unable to relax and fill, and so would be useless as a pump. To prevent tetanic contractions, the absolute refractory period in the heart is nearly as long as the contraction itself.
-Myocardium is high resistance to fatigue due to large number of mitochondria in the cytoplasm
-SA node-> AV node-> AV bundle (bundle of His) -> Right and Left bundle branches -> Purkinje fibers
-The chordae tendinae, attached only to the AV valves, act as tethers that anchor the valve flaps in their closed position
-However, neither the chordae tendinae nor the papillary muscles attached to them, are responsible for opening and closing the AV valves. Heart valves open and close in response to differences in blood pressure on their two sides.
EPICARDIUM
= The visceral layer of serous pericardium
= Infiltrated with fat, especially in older people
PERICARDIUM
= double-walled sac, tough dense connective tissue layer
= protects the heart / anchors it to surrounding structures / prevents overfilling of the heart with blood
CORONARY ARTERIES
-The vessels that carry oxygen to the myocardium
-Although the heart is continuously filled with various amounts of blood, this blood provides little nourishment to heart tissue. (The myocardium is too thick to make diffusion a practical means of delivering nutrients) How, then does the heart get nourishment? It does so through the coronary circulation, the functional blood supply of the heart, and the shortest circulation in the body.
-The left and right coronary arteries both arise from the base of the aorta and encircle the heart in the coronary sulcus. They provide the arterial supply of the coronary circulation
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