Cardiac System Flashcards
(20 cards)
Where in the chest is the heart located?
-Between the second intercostal space and the fifth intercostal space
-The apex of the heart is found between the fifth intercostal space and the midclavicular line
Describe the structure of the heart?
-Ascending Aorta
-Right atrium forms the right border
-Right ventricle forms the inferior border and most of the anterior
surface
-Superior vena cava
-Left atrium
-Left ventricle form the left border an apex
- Inferior border
- Inferior vena cava
-Pulmonary artery
-Pulmonary vein
What are the four major blood vessels to and from the heart? And describe their function
-Superior and inferior Vena Cava: brings
deoxygenated blood from blood to right
atrium
-Pulmonary artery/trunk: takes deoxygenated
blood back to the lungs
-Pulmonary veins: bring oxygenated blood
back to left atrium
-Aorta: Take oxygenated blood to body
What are the 3 main layers of the heart ?
1) Tunica Adventitia
2) Tunica Media
3) Tunica Intima
Describe the layers surrounding the heart
-Fibrous Pericardium
-Parietal layer of serous pericardium, separated by fluid
-Pericardial space, fluid filled ballon
-Visceral layer of serous pericardium
Describe the layers of the heart?
-Endocardium, inner lining of blood vessels
-Myocardium, muscle of the heart, cardiac muscle
-Visceral pericardium
-Pericardial space with pericardial fluid
-Parietal pericardium
-Fibrous pericardium
-Intercalated disc
-Branching myocardial cell, it has a nucleus
What is the pericardium?
The outermost layer and made up of two sacs: fibrous pericardium and serous pericardium
Describe the fibrous pericardium?
-Outer sac, consisting of fibrous tissue
-Continuous with tunica adventitia of great blood vessels above and attached to diaphragm below
-Fibrous, inelastic and routed and prevents over-distension of heart
-allows movement of heart
Describe the serous pericardium?
-Continuous double layer of serous membrane
-Single layer of endothelium cells, folded over itself, forming a double membrane around heart with an enclosed space between layers
-Parietal pericardium is outer layer of serous pericardium, it lines fibrous pericardium
-Visceral pericardium (epicardium) is inner layer of pericardium and firmly attached to myocardium
Describe the myocardium?
-Specialised cardiac muscle
-Striated like skeletal muscle is under involuntary control
-Each fibre (cell) has a nucleus and one or more branches and rich in mitochondria to supply high demand energy needs
-Ends of cells and their branches are in very close contact with ends and branches of adjacent cells
-These joints or intercalated discs are thicker, darker lines than the striations
How does the arrangement of cells benefit myocardium?
-Gives cardiac muscle the functionality of heat of muscle rather than than a number of individual cells
-Due to end-to-end continuity of fibres each one does need a separate nerve supply
-When impulse initiated, it spreads from cell to cell via branches and intercalated discs over whole sheet of
muscles
-‘Sheet’ arrangement enables whole heart to contract in a coordinated and efficient manner
Describe the endocardium?
-Thin membrane lines chamber and valves of heart
-Single layer of flattered epithelial cells
-Continuous with endothelium lining the blood vessels
-It’s very smooth to minimise friction as blood flows over it
Describe the internal anatomy of the heart?
All structures is the same, but inside there’s valves:
-Mitral valve
-Tricuspid valves
-Semi lunar valves
Valves prevent the back flow of blood from the ventricles to the atria or from the body
Who holds the mitral valve in place?
Chordae tendineae
Papillary Muscles
What are cardiac myocytes?
-Striated muscle cells
-Don’t need nervous input to contract
-Spontaneously depolarise
-They are electrically coupled
-Depolarisation readily spreads via intercalated discs
-Depolarisation of myocytes allow Ca2+ intros to enter and cause contraction
-Rapid spread of depolarisation via the conduction system allows the heart depolarisation in a co-ordinated fashion
Explain the cardiac cycles?
-Heart goes through a rhythmic cycle of contraction and relaxation
-Ventricular contraction= systole
- Ventricular relaxation= diastole
How do valves work in the heart ?
Valves open fully and blood flows through-ventricular systole
Valves close tightly, blood cannot flow backward- ventricular
What type of cells depolarise the fastest ?
-Sinoatrial (SA) node cells and set the rate of contraction
-Depolarisation spreads through the atria to the atrioventricular node
-Bundle of His
-Left and right bundle branches
-Purkinje fibres carry the electrical activity throughout ventricular myocardium
Nomenclature of ECG deflection
P wave: Atrial depolarisation
P-R wave iterval: Time from start of atrial depolarisation
to start of ventricular depolarisation
S-T segment: Period between ventricular depolarisation and depolarisation
T way: Repolarisation
U way: Depolarisation of purkinje fibres
Autonomic innervation of the heart?
-Cells in the SA node and AV node have sympathetic and parasympathetic innervation
-Parasympathetic activity decreases heart rate through release of ACh
-Sympathetic Activity increases heart rate through release noradrenaline
-Cells in the ventricular myocardium only have sympathetic innervation
-Sympathetic activity increases the force of contraction through the release of noradrenaline
