M1 Cadiovascular Flashcards
What are the 4 chambers of the heart?
Right atrium, right ventricle
Left atrium, left ventricle
What are the 4 valves inside the heart?
Bicuspid valve
Tricuspid valve
Aortic valve
Pulmonary valve
What are the 3 main functions of the cardiovascular system?
- Homeostasis: maintaining body temp through blood flow, blood column and pressure, pH lvl and interstitial fluid
- Transport system: oxygen + nutrients to cells, waste (CO2), hormones
- Protection: white blood cells -> immune response
What are the 3 major components of the cardiovascular system?
Blood
Blood vessels
Heart
What is the definition of diastole?
The heart is relaxing, filling with blood
What is the definition of systole?
The heart is contracting, pushing blood out
How does the blood travel inside the systemic circulation?
Down the pressure gradient
What is EDV?
End Diastolic Volume
The amount of blood in the ventricle immediately before ventricular contraction
What is ESV?
End Systolic volume
The amount of blood in the ventricle immediately after ventricular contraction
What is Stroke volume?
EDV - ESV = Stroke volume
The amount of blood the heart ejects PER BEAT
What is and how to calculate the Cardiac output?
Volume of blood pumped by each ventricle PER MINUTE
CO=Cardiac output
CO = Heartrate (beats/min) x stroke volume (ml/beat)
What is preload?
Degree of stretch of heart muscle during diastole
Determinant by left ventricular EDV
What is afterload?
Pressure or resistance the heart has to overcome to eject blood
What is venous return?
Volume of blood returning back to the heart each minute
- increased VR increases EDV
What is the Frank-starling law of the heart?
As cardiac muscle stretches, the next contraction will be stronger
The greater the EDV, the greater the force of contraction during systole (within limits)
What is the effect of increased sympathetic activities?
Increases stroke volume, EDV and venous return.
What are the two types of cells in the heart that contribute to heart contractions?
Autorhythmic (pacemaker) cells and contractile cells
What are desmosomes?
Mechanical anchors between the intercalated disks of cardiac cells.
What is the gap junction responsible for?
- They electronically join together muscle cells
- Allowing the passage of ions and transmission of action potentials.
What is the intercalated disk?
The junction between cardiac muscle cells
What is the sarcoplasmic reticulum responsible for?
The release of calcium ions in response to action potentials.
The presence of calcium ions allows the actin and myosin to bind, contracting the heart muscle.
What are the major arteries that supply blood and nutrients to the heart itself?
The Coronary arteries
The heart needs to act as 1 single unit. T or F
True
What is the name of the dividing wall between the left and right chambers of the heart?
Atrial or Ventricular septum
What are the layers of the pericardium?
Outer - Fibrous pericardium
Inner - Serous pericardium
(The inner is also composed of the parietal layer, The pericardial cavity [filled with serous fluid] and [Epicardium] -> Visceral layer)
What is the purpose of the pericardium?
- Maintain the heart’s position
- Stops the heart from overfilling
Compare and contrast the left and right ventricles
- The left ventricular wall is thicker: -> higher pressure -> systemic circulation.
- Right wall thinner -> lower pressure -> pulmonary circulation
What prevents inversion or prolapse of the bi/tricuspid valves during ventricular contraction?
Papillary muscles attach to the atrioventricular valves via chordae tendonae.
What is the purpose of semilunar valves?
It permits blood to be forced into the arteries but prevents blood from backflowing into the ventricles.
(No chordae tendonae)
Name 2 anatomical differences between the atrioventricular valves and semilunar valves
- AV valves are located in ventricles, and SL valves are in the major arteries.
- SL valves have no chordae tendonae.
Describe the blood circulation from entering the right atrium to leaving the left ventricle
- deoxygenated blood enters right atrium from superior + inferior vena cava
- enters right ventricle through tricuspid valve
- The right ventricle contracts, forcing blood into the pulmonary circulation through pulmonary valve + trunk
- gas exchange occurs, oxygenated blood re-enters through pulmonary veins -> left atrium
- enters left ventricle through bicuspid valve
- left ventricle contracts, pushing blood into the aorta through aortic valve.
- oxygenated blood is delivered into the systemic circulation.
Describe how blood travels through the components of the cardiovascular system
- heart (atria)
- heart (ventricles)
- arteries
- arterioles
- capillaries
6 capillary bed - venules
- veins (back to the heart)
How do the first and second heart sounds occur?
Lub - AV valves close
Dub - SL valves close
What are the 3 major changes in the ECG signify?
- P wave: Atrial depolarisation, occurs before atrial contraction.
* atrial fibrillation will show multiple or irregular P waves - QRS complex: ventricular depolarisation, occurs before ventricular contraction
- T wave: ventricular repolarisation, before ventricles relax, signifies start of diastole
When is the ventricular volume greatest and when is the smallest?
Highest: EDV, end of diastole
Lowest: ESV, end of systole
What are the 4 phases of blood flow?
- Ventricular filling
- Isovolumetric contraction
- Ventricular ejection
- Isovolumetric relaxation
When does the 3rd and 4th heart sound occur and what may have caused it?
3rd: early diastole, due to recoil of blood from ventricular wall and may be associated with heart failure and overload of the left ventricle (overly compliant LV)
4th: late diastole, due to blood being forced into a stiff or hypertrophic ventricle. (Under compliant LV)
What are the 3 features of non-contractile (pace-maker) cells?
- Can spontaneously initiate depolarisation of themselves and the rest of the heart
- Does not need neural input
- Drive contractile cells
What are cardiac muscles composed of?
- Tubular myofibrils
- Mitochondria
- Nucleus
- Sectioned cardiac muscle cells
- Intercalated disc between muscle cells
- Desmosomes
- Gap junctions
What are Myofibrils?
Repeating sections of sarcomeres which are contractile units with overlapping actin (thin filaments) and myosin (thick filaments)
What is the excitation-contraction coupling?
The process in which electrical stimulation produces a mechanical response.
e.g. action potential initiated by pace-maker cells (electrical stimulus) initiates cardiac contraction (mechanical response).
