Cardio-Respiratory Week One Flashcards
What does the myocardium consist of?
Cardiac muscle. This is involuntary and striated.
What does the endocardium consist of?
Loose connective tissue, endothelium (simple squamous)
What is the passage of blood flow through the heart?
Superior or inferior vena cava - right atrium - tricuspid valve - right ventricle - pulmonary valve - pulmonary artery - lungs - pulmonary vein - left atrium - bicuspid (mitral) valve - left ventricle - aortic valve - aorta
Where is the coronary sinus?
Right atrium
Where is the chordinea tendinae located and what is their function?
These are connected to the atrioventricular valves and papillary muslces. When ventricles are relaxed, chordinea tendinae are loose and when contracted, the papillary muscles contract the chordinea tendinae, preventing the cusps from swinging into the atria.
What is the function of the crista terminals?
Divides the muscular pectani from smooth muslce of atrium.
What is the function of the pectinate muslces, located in the atria?
They improve voluminous nature as their folds act as volume reserves.
Where is the trabeculae carnae located?
In the ventricles and their function is the contract and pull on the chordinea tendinae
The crista terminalis splits the atrium into two parts, which two parts?
Sinus venarum: posterior side (pectinate muscles)
Atrium proper: anterior
Where are the auricles and what is their function?
Located in the atria and serve to increase capacity of the atria.
What is the function of the following:
- interatrial septum
- interventricular septum
- coronary sulcus
- anterior interventricular sulcus
- posterior interventricular sulcus
- interatrial septum: divides atria
- interventricular septum: divides ventricles
- coronary sulcus: divides atria and ventricles
- anterior interventricular sulcus: located on sternocostal surface and divides ventricles. Contains a branch of left coronary artery
- posterior interventricular sulcus: located on diaphragmatic surface and divides ventricles. It contains the posterior interventricular artery and middle cardiac vein.
What is the function of the cardiac skeleton?
Anchor valves to myocardium.
Where is the main nerve supply to the heart from?
Medullar Oblongata: cardiaccelatory centre and cardioinhibitory centre
Which Vagus nerve supplies the SA and AV node?
The right supplies the SA node and the left supplies the AV node.
What are the two types of intercalated discs in cardiomyocytes?
GAP junctions: molecules passage
Desmosomes: hold adjacent cell together
How many nuclei do cardiomyocytes have?
One
What is the pathway of cardiac impulses?
SA node (anatomical pacemaker which starts automaticity) - intermodal pathways - AV node - Bundle of HIS - Purkinje fibres
Where is the SA node located?
Superiorly to superior vena cava. This node spontaneously depolarises creating an AP around 100 beats a minute.
What is the function of the Bachmann’s bundle?
Transmit impulses from SA node to left atrium
What is the function of the AV node?
This slows down the impulse to around 40-60 beats and this allows a delay between atrial and ventricular contraction
Where is the bundle of HIS located?
Interventricular septum
What is resting membrane potential, threshold and depolarisation peak of SA action potential?
Resting: -60mV
Threshold: -40mV
Peak: +10mV
What causes a SA depolarization?
Calcium influx. Reversal is done by potassium.
What is resting membrane potential, threshold and depolarisation peak of cardiomyocytes?
Resting: -90mV
Threshold: -40mV
Peak: +25mV
What does depolarization of adjacent autorhythmic cells stimulate in cardiomyocytes?
Sodium channels opening
What is the plateau phase during cardiomyocytes depolarization?
This is maintained depolarization. There are slow voltage gated calcium channels open which causes calcium influx (this also causes calcium release from sarcoplasmic reticulum) and a potassium efflux.
What is a refractory period?
Period of not responding to stimuli
What is the difference between absolute and relative refractory periods?
Absolute: membrane cant respond to stimuli due to sodium channels already being open or closed and inactivated. This include plateau and initial rapid repolarization.
Relative: voltage-gated sodium channels are closed, but can open. Membrane can respond to strong stimuli
Describe the cardiac cycle
- Atrial systole begins: atrial contraction forces small amount of blood into relaxed ventricles
- Isovolumetric contraction (ventricular systole part one): atrial systole ends and diastole begins. Ventricular contraction push AV valves closed but does not create enough pressure to open semi-lunar valves.
- Ventricular systole (phase two): as ventricular pressure rises and exceeds pressure in arteries, semilunar valves open and blood is ejected
- Ventricular diastole early (isovolumetric relaxation): as ventricles relax, pressure in ventricles drop. Blood flows back against cusps of semi-lunar valves and forces them closed. Blood flows into relaxed atria.
- Ventricular diastole late: all chambers are relaxed and ventricles fill passively.
What is the difference between EDV and ESV?
EDV: blood in ventricle after diastole (filling)
ESV: volume of blood remaining in each ventricle at end of systole
What is stroke volume and how is it expressed?
This is amount of blood pumped out of ventricle during each beat.
SV = EDV - ESV
Why is the second heart beat split?
The split S2 can be commonly heard during deep inspiration. When there is a deep breath taken in, the decrease in the intrathoracic pressure will cause an increase in the venous return. This will mean that, because of the more blood in the right ventricle, it will take longer to pump the blood out during systole. This causes the pulmonary valve to close after the aortic valve. This is best heart in the pulmonic area.
What is S3?
Can be heard during early diastole and is caused by rapid ventricular filling.
What is S4?
This is caused by forceful atrial contraction against as stiff ventricle
When are systolic and diastolic murmurs heard?
Systolic: between S1 and S2. Occurs when heart contracts
Diastolic: occur between S2 and next S1. Occurs when heart relaxes and fills
Explain the grading system of murmurs
I - barely audible on listening carefully
II - faint but easily audible
III - loud and easily audible, no thrill
IV - loud murmur with no thrill
V - heard with scope barely touching chest
VI - audible with scope not touching chest
What are some common examples if people with innocent murmurs?
Young children, young and think patients.