Cardio x2 Flashcards
- What is the heart surrounded by?
- What secretes serous fluid into the pericardium cavity?
- What movement does this allow?
- What are the layers of the serous pericardium?
- What do they line?
- The heart is surrounded by a loose sac called the pericardium
- The serous membrane secretes serous fluid into the pericardium cavity
- Allows for smooth movement of the heart
- The parietal layer of the serous pericardium lines the inside of the fibrous pericardium
- The visceral layer of the serous pericardium covers the heart and forms the part of the outermost layer of the heart wall (the epicardium)
What are the 3 layers of the heart wall?
- Epicardium
- Myocardium (thick muscular)
- Endocardium (inner)
The heart has 4 chambers
- What are the upper 2 called?
- What are the lower 2 called?
- Upper = atria
- Lower = ventricles
- Where does deoxygenated blood enter the heart?
- Where does it carry on and pass through?
- During ventricular contraction where does blood travel via to get to the lungs?
- What does oxygenated blood enter the heart via?
- Where does it enter the heart?
- During ventricular contraction, where is blood pushed?
- Deoxygenated blood enters the heart into the right atrium, and passes through the right ventricle
- During ventricular contraction, blood passes into the pulmonary trunk, and travels via pulmonary arteries to the lungs
- Oxygenated blood returns to the heart via pulmonary veins, emptying into the left atrium
- During ventricular contraction, blood is pushed into the aorta
- Where are the atrioventricular (AV) valves located?
- Where is the bicuspid (mitral) valve located?
- Where is the tricuspid valve located?
- What is each leaflet (cusps) anchored to?
- The atrioventricular valves are located between the atria and ventricles
- The bicuspid valve is located on the left side of the heart
- The tricuspid valve is located on the right side of the heart
- Each leaflet is anchored to papillary muscles via chords called the chord tendinae
- What are the 2 semilunar valves?
- Where are the located?
- Pulmonary valve
- Located at the entrance of the pulmonary trunk
- Aortic valve
- Located at the entrance of the aorta
- What is the first heart sound caused by?
- What is the second heart sound caused by?
- The first heart sound is caused by the AV valves closing at the start of ventricular systole
- The second heart sound is caused by the semilunar valves closing at the start of ventricular diastole
Cardiac muscle is striated, and consist of many short branched cells
- What makes up 25% of the cell?
- What are cells connected via?
- Mitochondria makes up 25% of the cell
- Cells are connected via intercalated disks (ICDs)
- What makes up the intercalated disks?
- What do these allow or link?
- Gap junctions
- Allow electrochemical communication
- Desmosomes
- link cytokeratin to cytokeratin
- Adhesion belts
- link actin to actin
- What carries blood away from the heart?
- What carries blood towards the heart?
- What are the layers of blood vessel walls?
- Arteries carry blood away from the heart
- Veins carry blood toward the heart
- Tunica adventitia (outermost)
- Tunica media
- Tunica intima (innermost)
- What is the tunica adventitia made up of?
- Which is this thickest in?
- What do larger vessels often have in this layer?
- What is the tunica media made up of?
- What is the tunica intima made up of?
- What is this layer more developed in?
- Tunica adventitia is made up of loose FCT
- Thicker in veins
- Vaso vasorum
- Tunica media is made up of smooth muscles as well as connective tissue containing collagen & elastin
- Tunica intima is made up simple squamous endothelium, some FCT and an internal elastic lamina IEL
- This layer is more developed in arteries
- Why do arteries need to be elastic?
- Do veins return blood at a high or low pressure to the heart?
- Because they can take up extra blood volume, what are they known as?
- To ensure blood flow is unidirectional, what do veins contain?
- What are they extensions of?
- To allow the vessels to stretch (eg the aorta)
- Veins return blood at low pressure to the heart
- They are known as capacitance vessels
- Veins contain valves
- Which are extensions of the endothelium
- What are the smallest blood vessels called?
- What do these allow?
- What are the 3 main types?
- The smallest blood vessels are called capillaries
- These allow exchange of nutrients b/w the blood & surrounding tissues
- Continuous - Fenestrated - Sinusoidal
- What does continuous capillaries allow?
- Leaky?
- What are the endothelial cells joined by?
- What does the fenestrated capillaries contain?
- Leaky?
- Where would you find these capillaries?
- What does the sinusoidal capillaries have?
- What do they allow?
- leaky?
- Where would you find these capillaries?
- Only allow limited passage of fluids & small solutes
- These are the least leaky of the capillaries
- Endothelial cells joined by tight junctions
- Contain pores in the endothelium
- leaky
- you would find this type in the kidney
- These have pores and few tight junctions
- These allow large molecules or even blood cells to pass through
- Most leaky
- you would find this type in the liver
- What blood vessel controls blood flow through capillaries?
- What do they join?
- What do they contain that form the precapillary sphincter
- What does the precapillary regulate when it contracts?
- Metarterioles
- Join arterioles to capillary beds, and contain smooth muscle fibres that form precapillary sphincter that can contract to regulate blood flow
- What is the first blood vessel that branches off the aorta?
- What do they supply?
- What branches from these arteries?
- The first blood vessels which branch off the aorta are the left & right coronary arteries
- Which supply the heart tissue
- Branching from these arteries are the anterior & posterior inter ventricular arteries & the circumflex artery
- What drains the right side of the heart?
- What drains the left side of the heart?
- What do both these vessels empty into?
- where does this open?
- The small cardiac vein drains the right side of the heart
- The great cardiac vein drains the left side
- Both vessels drain into the coronary sinus
- Which opens into the right atrium of the heart
- What type of system is the lymphatic system?
- What is this involved in the balance with?
Within the lymphatic system it contains lymph nodes
- What is the function of lymph nodes?
- What does fluid enter the system via?
- Permeability?
- Why valves?
- Where does lymph fluid drain?
- This system is an open entry drainage system
- Involved in the balance of interstitial fluid
- Lymph nodes filter & screen lymph fluid
- Fluid enters the system via lymphatic vessels which are highly permeable and are blind ended, with valves to ensure a oneway flow of lymph from the tissues
- Lymph fluid drains from the right lymphatic duct into the right subclavian vein
- And from the thoracic duct into the left subclavian vein
- What is the electrical excitation of the heart driven by?
- Where is this located?
-electrical “wiring” of the heart:
6 parts of the conduction pathway
- Largely driven by the activity of the Sino-atrial (SA) node
- Located towards the top right of the right atrium
(1) Sinoatrial (SA) node (pacemaker) → interatrial bundle & fibres → (2) Left atrium & (3) Right atrium
Internodal bundle & fibres→ (4) Atrioventricular (AV) node
→ Subendocardial branches (purkinje fibres) → (5) Lateral wall & septum of right ventricle & (6) Lateral wall and septum of Left ventricle
- What is the normal range for resting heart rate?
- Which part of the autonomic nervous system is dominant during rest?
- Which part of the autonomic nervous system is dominant during exercise?
- 40-100 bpm
- Parasympathetic
- Sympathetic
ECG & cardiac cycle
P wave - Atrial depolarisation - Atrial contraction QRS complex - Ventricular depolarisation - Ventricular contraction - Rise in ventricular pressure - Ejection of blood - Fall in ventricular volume - Rise in aortic pressure T wave - Ventricular repolarisation - Ventricular relaxation .... fall in ventricular pressure .... atrioventricular valves open ... filling of the ventricles occur
Cellular mechanism of cardiac contraction
(1) Increase in cytosolic Ca2+ levels
- Ca2+ induced Ca2+ release from sarcoplasmic reticulum (SR)
(2) Actin binding site revealed
- Myosin binds forming the X-bridge
(3) A/M filaments slide relative to each other
- Sarcomere shortens
- Force generated
(4) Every myocyte activated each heart beat
Ways to increase cardiac contraction
(1) Every cardiomyocyte is activated during each heart beat
(2) Extent of x-bridges formed not maximized at rest…
- ↑ cytosolic Ca2+ level
- ↑ number of x-bridges formed
- ↑ force of contraction
Cellular mechanism of cardiac relaxaition
(1) ATP binds to myosin
(2) Decrease in cytosolic Ca2+ levels
- Ca2+ into SR
(3) X- bridges release
- A/M separate
(4) Reduction in force
(5) All cardiac myocytes relax each beat
Blood pressures throughout the systemic circulation
- Blood pressure high in major arteries - Oscillatory
- Blood pressure falls steeply across the “microcirculation”
- Oscillatory nature is reduced
- Blood pressure is very low in veins
- Large difference in pressure (ΔP) between the arterials and venous sides
- Creates a driving force for blood flow
Blood pressure throughout the systemic system
- Highest to lowest
Left ventricle → large arteries → resistance vessels → capillaries & pulmonary artery → venules → veins
Cardiac cycle and it’s main phases
Atrial systole → isovolumetric ventricular contraction → ejection → Isovolumetric ventricular relaxation → passive ventricular filling
Features (4) of Pulsatile blood flow in arteries
- Intermittent injection of blood into aorta from the left ventricle
- Elastic arteries - stretches then recoils - storing and releasing energy
- cycles of increase (systolic) and decrease (diastolic) pressure
- Pulse wave is a pressure wave - travels along the arteries - ahead of the blood
Features (2) of Electrical cells of the heart
- 1%
- ‘Pale’ striated appearance - low actin and myosin
Features (3) of contractile cells of the heart
- Striated appearance
- High actin and myosin
- ‘working myocardial cell’
- What is the MABP equation?
- What happens to MABP during exercise?
MABP = CO x TPR
During exercise, the net effect of the regional vasoconstriction & vasodilation is a decrease in TPR. This is usually enough of a decrease to offset the increase in CO and MABP only rises very slightly
Cardiac output is determined by?
Cardiac Output (L/min) = Stroke Volume (L/beat - pulse strength) x Heart Rate (beats/min - Pulse speed)
Compliance definition & equation
- The extent to which a vessel allows deformation in response to an applied force
- ΔV/ΔP
Compliance of Vein vs Artery
- Vein = thin wall → compliant
- Vein - Large volume = small pressure = high compliance
- Artery = think wall → rigid
- Artery - Small volume = large pressure = low compliance
Features of blood transfusion from venous to arterial system
- Arterial puncture
- Loss of arterial blood
- Life threatening fall in arterial pressure
- Leads to vasoconstriction (under neural control)
- Blood transfusion from venous to arterial system
Features (4) of High vascular compliance (pooling in veins)
- Venous volume (blue) is larger than arterial volume (red)
- While supine (laying down), venous volume is uniform from head to toe
- In the upright position, venous volume below the heart increases; whereas venous volume above the heart decreases
- Extreme venous pooling in the legs and feet
Features (2) of venous valve counteracting venous pooling
- No valves → continuous column: heavy at bottom
- Valves → discontinuous column: more even distribution of weight
Features (4) of ‘tone’ of surrounding tissue counteracting venous pooling
- Particularly the case for skeletal muscle, because it can alter it’s tensile state
- resting muscle tone varies between individuals
- Muscle tone acts to stiffen the veins - makes them less compliant and prone to pooling
- Some people prone to fainting have low muscle tone and excessive venous pooling
How does the skeletal muscle pump affect ‘venous return’ to the heart?
- Muscle relaxed = low pressure
- Muscle contracted = high pressure
- Muscle contraction increase venous blood flow
- Increased venous return means increase stroke volume
Features (3) of Starlings law of the heart
- The more stretched muscle fibres are before a contraction, the stronger the contraction will be
- ↑ in stroke volume (mL) = ↑ ventricular volume (mL) at end of diastole - increasing venous return
- ↑ venous return means ↑ stroke volume
