Heart dissection Flashcards
How does the heart appear at a posterior view?
the left and right are swapped around
Where is the tricuspid valve located?
between the right atrium and right ventricle
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What is the role of the tricuspid valve and bicuspid valve?
make sure blood flows in a forward direction from the atrium to ventricle
prevent back-flow of blood
What is the structure of the tricuspid valve?
Has 3 flaps that open and close, allowing the blood to flow from right atrium to ventricle in heart.
What are the 2 AV valves?
Tricuspid
Mitral (Bicuspid)
Where is the mitral/bicuspid valve located?
between the left atrium and left ventricle
What is the structure of the mitral/bicuspid valve?
have 2 flaps in the heart which lies between the left atrium and ventricle
What are the layers of the heart?
epicardium
Myocardium
Endocardium
What is the endocardium?
Smooth frictionless lining- simple endothelium
- Inner layer of the heart which protects valves and heart chambers
What is the pericardium?
the membrane enclosing the heart, consisting of an outer fibrous layer and an inner double layer of serous membrane.
-produces pericardial fluid
What does the pericardial fluid do?
- Lubrication to minimise friction generated by the heart as it contracts
- If cavity dries up- causes Pericarditis- acquired defect
What is the myocardium?
Thick middle layer of the heart
Muscular tissue/cardiac- which serves the pump oxygenated blood around the body
What is the function of the right atrium?
recieves deoxygenated blood from body and pumped to right ventricle
What is the function of the right ventricle?
pumps deoxygenated blood back to lungs
What is the function of the left atrium?
recieves oxygenated blood from the lungs and pumps to ventricle
What is the function of the left ventricle?
pumps oxygenated blood around the body
What is the coronary blood vessels?
When the aorta branches off into 2 main coronary blood vessels known as arteries.- left and right
These then branch off into smaller arteries -
What is the role of the coronary blood vessels?
supplies oxygen rich blood to the entire heart and heart muscle
What are the 3 openings of the heart?
superior vena cava
Fossa ovalis
Inferior vena cava
What is the function of the superior vena cava?
large vein
which returns deoxygenated blood from the head and neck to the heart
What is the function of the inferior vena cava?
returns deoxygenated blood from lower body to the heart
What is the fossa ovalis/coronary sinus?
brings deoxygenated blood to right atrium from the heart
Why is the left side of the heart much stronger?
left ventricle is more developed
-a greater force is needed to push blood through the systemic circulation
What is the function of the left and right coronary blood vessels?
supply the heart muscle with oxygen rich blood.
Where do the right and left coronary artery branch from?
branch off the aorta
What is the function of the aorta?
Main artery which carries oxygenated blood from left ventricle to the body
takes 5% of hearts daily output
What are the 2 mains valves in the heart?
AV- mitral and tricuspid
Semi lunar- pulmonary and aortic
What is the function of the 4 valves of the heart?
passive
-ensure blood flows around the heart in the correct direction
What is the structure of the semi-lunar valve?
- 3.5 moon shaped cups
What is the action of the SL valves?
- when ventricle is full of blood , ventricle contracts
- pressure rises , blood is pushed up against semilunar valve forcing them open
- ventricles relax , blood flows back down due to gravity , filling cups of semilunar valve forcing them to close
- semilunar valve stops blood falling back to ventricle
What is the AV valves made of?
flaps of connective tissue
What is the action of the AV valve?
- atrium contracts
- pushes AV valve open and blood comes into ventricle
- ventricle contracts papillary muscle contracts and chordae tendinae tighten preventing valve from everting into atria
What is the main function of the chordae tendinae?
Holds AV valve in place
-Tension is put on the AV valves during ventricular contraction to stop eversion by the chordae tendinae
What is the difference between AV and SL valves?
AV valves have muscle in then which is the chordae tendinae attached to the papillary muscle
What is lub ?
AV valve shut
What is dub?
SL valve shut
What are the 2 phases of cardiac cycle?
Systole (contractions)
Diastole (relaxation)
What is the differences between cardiac and skeletal muscle?
Skeletal muscle fibres have several peripheral nuclei and cardiac have a single central nucleus
- Skeletal muscle fibres do not branch however cardiac do
- Cardiac muscle are joined via gap junction - intercalated discs- forming syniticum
What is a syncitium
Sheet of muscle where the individual cells are connected vis gap junctions
they form 2 - one around atria and other around ventricle- joined by the bundle of his
What is the pulmonary artery function?
Carries deoxygenated blood away from the (right ventricle) heart to the lungs
What is the pulmonary vein?
carries oxygenated blood back to the heart via into the left atrium
What are the units of blood pressure?
mmHg
How do you measure blood pressure/.
Using a sphygmomanometer
How is blood pressure test carried out?
- Wrap a cuff around the arm - locate the brachial artery.
- Apply a stethoscope so you are able to hear the sounds of korotkoff
- Inflate the cuff to around 150mmHg- putting pressure on the brachial artery
- Apply enough pressure until the artery has collapsed
- When you have collapsed that artery- you are above the systolic pressure
- The pressure is released from the cuff until the point at which there is some blood flow= systolic pressue
- The pressure is further reduced and more blood will flow through the artery which is being collapsed less and less
- Eventually a point is reached when blood flow is no longer restricted= Diastolic pressure
How else can the systolic and diastolic pressure be determined?
By listening to blood flow in the artery below the cuff- these are the sound of korotkoff
What are the sounds of korotkoff?
- When the artery is collapsed you can not hear anything as no blood flowing
- When the pressure starts to decrease at the systolic pressure- will hear a soft intermittent tapping sound- first hear the sound
- As you decrease the pressure more- louder and more continuous rushing sound
- Then there is no turbulent blood flow and no constricting blood vessel= the sound has now died away,- you are at diastolic pressure- dies away
What is the brachial artery?
superficial blood vessel in the upper arm
Why is there variation in the readings of blood pressure from different people?
- Age
- Different diet/lifestyle/activities
Why is there variation in the readings of blood pressure from different people?
- Age
- Different diet/lifestyle/activities
What is an ECG?
Electrocardiogram
What does the ECG measure?
recording on the body surface of the electrical events in the heart (atrial and ventricular depolarisation and repolarisation)
What is a normal blood pressure?
120/80
Explain the shape of a normal ECG in terms of the events of the cardiac cycle?
§
What does the gap between the P and Q wave mean?
How long it takes the action potential to get through the Bundle OF His
What does S-T mean?
How long is the ventricle contraction
What does T- mean?
Ventricle relacxing- repolarisation
How is heart block presented in the ECG?
Some P waves are not transmitted thus the QRS and T waves are not present
how is congenital long QT syndrome presented in ECG ?
- It is a genetic defect causing Na ion channels to stay open
. distance from Q - T is long meaning ventricles stay open
What is the irregularities of the ECG?
- Heart block
- Ventricular Fibrillation
- Congenital Long -QT syndrome
- Variable QT interval
What is ventricular fibrillation?
is a series of very high frequency uncoordinated contractions (>300 bpm)
What is Heart block?
A complete break in the system (Bundle of His)
What can defects in the system result in?
cardiac arrhythmias
- Bradycardia <60 bpm
- Tachycardia > 100 bpm
What is the variable QT interval?
represents the time of ventricular activity including both depolarisation and repolarisation. It is measured from the beginning of the QRS complex to the end of the T wave.
What are Purkinje fibres?
One of the specialized cardiac muscle fibers, part of the impulse-conducting network of the heart, that rapidly transmit impulses from the atrioventricular node to the ventricles
What is the diameter of the purkinje fibres?
70-80um
What is the diameter of cardiac muscle
10um in diamter
50-200um in length