Cardio Flashcards

Question

Ejection fraction

Answer 1

proportion of EDV pumped out with each heart beat (SV/EDV x 100)

Answer 2

pressure against which the heart must work to eject blood during systole. This increases in hypertension.

Answer 3

Faster HR reduces filling time however, passive filling occurs quite fast at the start of diastole then slows before being increased by active filling. With increase HR the rapid filling still occurs and the time lost in diastole only effects the period in which filling is slower (right before active filling) meaning SV is not effected.

Answer 4

Normal heart produces two sounds a lub (S1) and a dub (S2) S1 is caused by closing of AV (beginning of systole) and S2 is caused by closing of semilunar (right before diastole) However you dont actually hear the closing of the valves, you hear the turbulence of the remain blood bouncing against them.

Answer 5

S3 is the end of the rapid filling phase in early diastole, it is from the recoil of blood from ventricular walls S4 is with atria contraction (indicates pathology of strong atrial contraction

Answer 6

These are always pathological and are caused from the failure of the valves to open or close properly resulting in abnormal turbulence Regurgitation - valves cant close tightly enough, blood can flow in wrong direction Stenosis - Passages contain valves decrease in size (cant open properly), blood flow in the right direction is effected.

Answer 7

Contains parasympathetic (longer post ganglionic neuron) and sympathetic (longer pre ganglionic neuron). Both act on AcH with their pre ganglionic neurons. Sympathetic innervates SA node, AV node, myocardium and conduction system Parasympathetic: SA node, AV node and atrial muscle

Answer 8

Both para and symp have chronotropic effects (change heart rate) and inotropic effect (activate or deactivate voltage gated ion channels). Heart rate is balance between the two inputs, if this did not occur then HR would be at extrmeities. It is under constant inhibitory (parasympathetic) control referred to as vagal tone.

Answer 9

Parasympathetic control: - Via AcH - Causes a slower depolarisation (decerases slow inward Na and Ca) as well as increased hyperpolarisation (more K out) meaning it takes longer time to reach threshold agian. Sympathetic control: - Via noradrenaline - Causes faster depolarisation (increases slow inward Na and Ca) as well as decreasing hyperpolarisation (less K out) meaning it takes lees time to reach threshold agian.

Answer 10

Altered by sympathetic nervous system Extrinsic control - direct increases in muscle contraction result in large SV Intrinsic control - adrenal (produced in adrenal medulla) increases venous return, increased EDV and therefore increased SV through frank starling la

Answer 11

Heart will adjust its output (SV) to meet its input (EDV) Fibre length is below optimal length for cardiac muscle, increased in EDV will move fiber length closer to optimal length

Answer 12

Difficult for this to occur in systole because: - Coronary arteries branch off the aorta close to semilunar valve. During contraction, when valve is open, it partially blocks the coronary arteries. - Contracting myocardium is compressed meaning major branches of coronary arteries are as well

Answer 13

Heart is good at getting nutrients out of blood as it can remove 65% of O2 (skeletal does 25%). However, it has little capacity to increase this therefore blood flow must increase through vasodilation. This happens due to local release of adenosine) This can lead to complications when the coronary arteries have pathological changes that limit blood flow.

Answer 14

Arteries: Thick, highly elastic, muscular and large radius Pressure reservoir Arterioles: Highly muscular and well innervated Determine flow to tissues through resistance Capillaries: Very thin but large CSA Site of exchange Veins: High compliance and large radius Volume reservoir (largest volume)

Answer 15

There is a parallel arrangement of vessels, this ensure that adequate blood flow is able to reach all organs. More blood goes to organs responsible for reconditioning blood, meaning that they need blood not only for their own function but other bodily functions. Organs such as kidneys, skin, liver ect. This parallel arraignment also means that blood flow to each organ can change independently. With exercise the blood supply to the brain is constant at the expensive of the reconditioning organs.

Answer 16

Flow rate is directly proportional to pressure gradient and inversely proportional to resistance. However, the radius is the only factor that can alter resistance so it can be said that blood flow is pressure gradient x radius of vessel (^4)

Answer 17

- Difference between start and end of vessel. Blood flows down pressure gradient - Contraction of the heart establishes the pressure gradient, it then gets lower along the vessel due to frictional losses. - The larger the pressure gradient the greater the flow

Answer 18

- Larger the R the lower the flow - Three factors in resistance - Directly proportional to viscosity of blood (doesn't change) and the length of vessel (doesn't change) - Inversely proportional to the radius of the vessel

Answer 19

CO will increase, causing an increases in pressure therefore larger pressure gradient.

Answer 20

Blood pressure is the force exerted by blood against a vessel wall. It depends on volume of blood and compliance of vessel.

Answer 21

Mean arterial pressure - average pressure during each cardiac cycle diastolic + 1/3 (systolic-diastolic) This is because we spend more time in diastole (2/3)

Answer 22

Branches of an artery within an organ that controls the flow of blood to tissues. They are very high resistance vessels meaning there is a large drop in pressure, this pressure difference helps to maintain blood flow (pressure gradient) resistance in arterioles alters to: - Distribute blood depending on activity - Regulate MAP

Answer 23

Vascular tone is present in arterioles, this is baseline resistance due to myogenic activity and continuous sympathetic innervation, meaning there is some level of contraction (allows for dilation) **Vasocontraction/dilation** within arterioles is sensitive to various intrinsic and extrinsic factors and innervated by sympathetic nerves. It is also important to remember that vascular smooth muscle can undergo changes in force without APs meaning there is not an all or nothing response.

Answer 24

Regulate blood distribution These factors will override the extrinsic factors - Chemical - Metabolic changes - Oc, CO2, lactic acid → vasoactive paracrines from the endothelia cells act on smooth muscle - Histamine release - not from local changes, important in pathology (swelling from injury) - Physical - Vessel/stretch → opening of mechanically gated cation channels cause Ca influx and increased flow - Shear stress - friction of blood on inner surface of vessels creates shear forces, releasing nitric oxide - Hot/cold - heat causes localised vasodilation and cold dose constriction

Answer 25

Regulate blood pressure - Sympathetic nervous system - Innervates smooth muscle for vasoconstriction except the brain. Noradrenalin binds to receptors on smooth muscle - Contributes to ongoing vascular tone and generalised vasoconstriction increases TPR and therefore MAP (increased MAP will increase flow to the brain) - Hormonal - Noradrenalin and adrenalin normally reinforce the sympathetic nervous system (constrict), expect in skeletal and cardiac muscle where the beta receptors cause dilation - Anti diretic hormone and angiotensin 2 also important for blood volume and fluid balance

Answer 26

- Minimal distance - Single layer of endothelial cells - Small diameter meaning the RBCs have to flow single file and slightly deform, this pushes the plasma to the wall which is what carriers the nutrients. - Maximal surface area (large number of capillaires) - Maximal time - Velocity of blood is slow to due extensive branching (flow rate remains the same as CVS is closed loop), velocity is inversely proportional to total CSA

Answer 27

Capillaries have tightly joint endothelial cells with narrow water filled spaced between them meaning that small water soluble substance can pass through (varies in tissues). These are referred to as water pores/clefts. Lipid soluble substances pass through endothelia cell wall Substances such as proteins normally (hormones) still need to be exchanged via vesicle through the wall due to their large size.

Answer 28

This permeability (tightness of endothelial cells) varies between organs. - Cerebra has tight junctions so no clefts are present (blood brain barrier, more selective) - Skeletal muscle and lungs with 4nm water filled clefts, small water soluble substance can pass (ions, glucose, amino acids) but proteins cannot and need to be transported via vesicles - Kidneys and intestines have large clefts meaning the capillaries are leaky for rapid movement - The liver has clefts that very large meaning proteins can pass Histamine can increases this leakiness

Answer 29

- No smooth muscle present - Pre capillary sphincters are not innervated and sensitive to local factors - metabolic activity increase →sphincters relax increasing flow - If metabolic activity decreases → sphincters contract meaning flow is bypassed

Answer 30

Exchange between blood and organs through the interstitial fluid occurs in two ways: - Diffusion (passive) - Down a concentration gradient - Specific to ion or molecule - Bulk flow (only occurs in capillaries as they have pores) - Regulates the distribution of ECF between plasma and interstitial fluid, maintains plasma volume - Hydrostatic (fluid pressure) and oncotic pressure (protein pressure) influce bulk flow. Increased blood pressure in vessel = hydrostatic pressure out of the vessels, movement into ECF

Answer 31

Return excess fluid and protein that leaked out of capillaries (from bulk flow) back into the venous system, normally more proteins and fluid is filtrated than what is resorbed. Lymphatics vessels have overlapping endothelial cells, when there is increased pressure outside the vessel this pushes inwards creating an opening. Lymph is picked up around capillaries an deposited right before right atrium.

Answer 32

Accumulation of interstitial fluid = increased space therefore decreased efficiency for diffusion between blood and cells.

Answer 33

They have a large diameter, low resistance, low elastic and little smooth muscles Making them highly compliant and large storage capacity. The blood is not stagnate, still flowing. When required vein capacity can decrease which will increase venous return to the heart

Answer 34

Veins have really low pressure (lost has been lost) but atrial pressure is near zero so there is still a gradient to induce flow

Answer 35

MAP = diastolic + 1/3 (sytolic-diastolic) Main purpose of MAP is to drive blood into the tissues (pressure gradient for flow)

Answer 36

Blood flow to tissues depends on: - MAP - Resistance of arterioles (opening arterioles decreases pressure in arteries, therefore less MAP as TPR has decreases) - Vascularisation/open capillaries

Answer 37

MAP must be closely monitored to ensure sufficient drive (despite local adjustments) and low enough to avoid damage to heart and vessels. MAP = COxTPR

Answer 38

Many mechanics can detect changes in MAP: - Baroreceptors in aortic arch and carotid sinus (short term) - Left atrial volume receptors and hypothalamic osmoreceptors (long term) - Chemoreceptors in carotid and aortic arteries sensitive to low O2 and high H (short term) - Cerebral cortex hypothalamic pathway sensitive to behaviour and emotion which influence MAP (fight/flight) - Hypothalamus sensitive to body temp, which affects cutaneous arterioles and overrides regulation of MAP

Answer 39

Baroreceptors are mechanoreceptors that constantly monitor MAP, regulate short term response to MAP. - Baroreceptors fire APs in response to pressure in these arteries (increased Bp then increases firing rate, decreased…) - Afferent neurons to CV control center in medulla of brain stem for integration. Correct output is decided here (symp/para) - Sympathetic and parasympathetic outflow via efferent nervous - Para - decrease HR → decrease CO → BP - Sympathetic → HR and Contractile strength (therefore SV) → CO → BP - Sympathetic → Vasoconstriction of arterioles → TPR increase → BP - Sympathetic → Vasoconstriction → venous return → SV → CO → BP - Heart and blood vessel change status to restore MAP

Answer 40

Left atrial volume receptors and hypothalamic osmoreceptors regulate long term responses. Related to regulating blood volume. Hypothalamic osmoreceptors: - Dominant factor (controls thirst and vasopressin secretion) - Both of these will increases ECF volume therefore decreasing ECF osmolarity Left atrial volume receptors: - Only important in large changes in ECF volume - ADH from vasopressin causes vasoconstriction therefore decreasing arterial BP

Answer 41

PR segment - AV node delay TP interval - ventricles are relaxed and filling ST interval - ventricles are contracting

Answer 42

HR would increase as constant inhibitory input (vagal tone) would be removed.

Answer 43

In the veins it increases the pressure gradient while also not really effecting the resistance as the radius is very large (r^4, so exponential effect)

Answer 44

- Sympathetic induced vasoconstriction - Increases venous pressure (therefore larger gradient) - This doesn't effect resistance due to large radius - Skeletal muscle pump - Large veins sit between muscles, contraction compresses veins → increasing venous pressure → venous return - Counter effects of gravity, blood pools in legs → increases hydrostatic pressure → decreases gradient - Venous valves - Help skeletal muscles pump, gravity and constriction by preventing backflow - Respiratory pump - Resp action creates external pressure gradient as pressure in chest veins decreases (sub atmopheric) causes blood in lower limbs to flow up to chest. This further increases with exercise - Cardiac suction - AV valves drawn down which increases volume in atria therefore decreasing pressure. Further increasing gradient → venous return - Increased blood volume - Short term = bulk flow → increased plasma volume - Long term = salt and water retention → increased plasma volume

Answer 45

Short - autonomic nervous system to heart, veins and arterioles → CO+TPR Long - kidney and thirst responses to regulate total blood volume → CO

Answer 46

Cuff inflated to pressure greater than systolic Slowly deflated until a sound is heard. This is systolic and is flowing turbulently Last sound heard is diastolic and flow becomes lamina

Answer 47

Pulmonary surfactant deficiency - seen in premature babies and is Infant Respiratory Distress Syndrome. Increases alveolar surface tension leading to increases in pressure gradient. Pneumothorax

Cardio Flashcards

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