❤️ Flashcards by A M

adventitial layer

connective tissue

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medial layer

smooth muscle tissue

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intimal layer

endothelial cells

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elastic artery (% composition)

arteries: ELective Can Surely Educate

elastic tissue > connective tissue > smooth muscle > endothelium

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arteriole (% composition)

arterioles like to perform SCEEnes

smooth muscle > connective tissue > elastic tissue & endothelium [both 10%]

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capillary (% composition)

95% endothelium

5% basal lamina (connective tissue)

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venule (% composition)

Venules Can be like ENdangered blue Snakes🐍🐍🐍
connective tissue > endothelium & smooth muscle [both 20%]
NO elastic tissue [0%]

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vascular tone (def.)

a state of partial constriction (displayed by arteriolar smooth muscle)

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vascular tone is affected by:

myogenic activity

sympathetic activity

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vascular tone is important because… [tonic]

tonic activity makes it possible to decrease / increase contractile activity (vasodilation/vasoconstriction)

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flow rate depends on…

the pressure difference (ΔP)

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resistance to blood flow depends upon 3 factors:

blood viscosity Ƞ
vessel length L
VESSEL RADIUS r

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2-fold change in vessel radius will produce…

a 16-fold change in flow

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a slight change in radius…

brings about a notable change in flow

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🔼activity in the sympathetic nerves to the ❤️…

🔼 HR (tachycardia)

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🔼activity in the parasympathetic nerves to the ❤️…

🔽HR (bradycardia)

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🔼HR

tachycardia

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🔽HR

bradycardia

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PSNS (vagus nerve) releases…

acetylcholine (ACh; muscarinic receptors)

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SNS releases…

noradrenaline (NorAd, US: norepinephrine; β1-adrenergic receptors)

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ACh and NorAd alter the activity of the ________ in the innervated cardiac cells

cAMP 2nd messenger pathway

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ACh is coupled to ___(1)___ G-protein that ___(2)___ activity of the cAMP pathway

(1) an inhibitory

(2) reduces

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NorAd is coupled to ___(1)___ G-protein that ___(2)___ the cAMP pathway

(1) a stimulatory

(2) accelerates

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PSNS 🔽 HR through 2 effects on pacemaker tissue:

1) Hyperpolarisation of the SA node membrane (takes longer to reach threshold)
2) 🔽 the rate of spontaneous depolarisation

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ACh increases K+ permeability by...

slowing the closure of K+ channels

PS stimulation ________ (🔼/🔽) the AV node's excitability which _________ (prolongs/shortens) transmission of impulses to the ventricles

🔽 | prolongs

PS stimulation ________ (shortens/elongates) the plateau phase of the AP in atrial contractile cells, _________ (weakening/strengthening) atrial contraction

shortens | weakening

PS stimulation has _____ (no/little/big) effect on ventricular contraction

little

overall, PS stimulation causes: * _______ HR * _______ time between atrial and ventricular contraction * _______ (stronger/weaker) atrial contraction

🔽 🔼 weaker

SNS's main effect on the ❤️ is to ______ (speed up/slow down) depolarisation, so threshold is reached more _______ (rapidly/slowly)

speed up | rapidly

NorAd auguments ____ and ____ channel activity

If (lower case 'f'; funny current) | T-type

SNS stimulation of the AV node _____ (🔼/🔽) AV nodal delay by ______ (🔼/🔽) conduction velocity

🔽 | 🔼

SNS _____ (speeds up/slows down) the spread of the AP throughout the specialised conduction pathway

speeds up

SNS _____ (🔼/🔽) contractile strength of the atrial and ventricular contractile cells (heart beats _______ (more/less forcefully) and squeezes out _____ (less/more) blood)

🔼 more forcefully more

SNS _____ (🔼/🔽) Ca2+ permeability through prolonged opening of _________ channels

🔼 | L-type Ca2+

SNS ________ (speeds up/slows down) relaxation

speeds up

The overall effect of SNS stimulation on the ❤️ is to improve its effectiveness as a pump by: __ (🔼/🔽) HR __ (🔼/🔽) the delay between atrial and ventricular contraction __ (🔼/🔽) conduction time through the heart __ (🔼/🔽) the force of contraction __ (⏮/⏭) the relaxation process so that more time is available for filling

``` 🔼 HR 🔽 the delay 🔽 conduction time 🔼 the force ⏭ (speeding up) the relaxation process ```

under resting conditions _____ (PS/S) discharge dominates = vagal tone (___ - ___ bpm)

PS (parasympathetic) | ~70 - ~100 bpm

HR can be altered by shifting the balance of AN stimulation: * HR 🔼 by simultaneously 🔼 ___ and 🔽 ___ activity * HR 🔽 by simultaneously 🔼 ___ and 🔽 ___ activity

S; PS | PS; S

Activity of the autonomic nervous system is co-ordinated by the ________________, located in the brain stem

cardiovascular control centre

The hormone ___________ also exerts an important influence in HR regulation

adrenaline (epinephrine)

Adrenaline is released into blood in response to ____________

sympathetic stimulation

Hormone adrenaline and noradrenaline (______) 🔼 HR (_______) and force of myocardial contraction (_______)

catecholamines chronotropic action inotropic action

Adr acts on ❤️ in a ______ (different/similar) manner to NorAd to ____ (🔼/🔽) HR

similar | 🔼

Adrenaline ______ (lessens/reinforces) the direct effect of the sympathetic nervous system

reinforces

The pacemaker potential is regulated by a depolarizing current the ‘funny current’ (If) mediated by channels that are activated by: (i) ________ and (ii) ________

hyperpolarization | cyclic AMP

cyclic AMP are also known as HCN channels what does the HCN channel stand for?

Hyperpolarization-activated Cyclic Nucleotide gated channel

Hyperpolarization following the action potential activates ___ channels in the ___ node causing a ____ (fast/slow) depolarization aka the pacemaker potential

HCN SA slow for full text see p. 83

Block of HCN channels ______ (🔼/🔽) the slope of the pacemaker potential and ______ (🔼/🔽) heart rate

🔽 [decreases] | 🔽 [reduces]

________ is a selective blocker of HCN channels that is used to _____ (🔼/🔽) heart rate in angina _____ (🔼/🔽) rate ______ (🔼/🔽) O2 consumption

Ivabradine 🔽 🔽 🔽

angina

a condition in which coronary artery disease reduces the blood supply to cardiac muscle

β-adenoreceptor agonists (3)

Dobutamine, adrenaline and noradrenaline (catecholamines)

Pharmacodynamic effects of β-adenoreceptor agonists on ❤️: ___ (🔼/🔽) force, rate and cardiac output (i.e. HR x SV) and O2 consumption ___ (🔼/🔽) cardiac efficiency (O2 consumption___ (🔼/🔽) more than cardiac work) ____ (✅/❌) cause disturbances in cardiac rhythm (arrhythmias)

🔼 🔽 ✅

clinical uses of adrenaline (3)

* cardiac arrest * emergency treatment of asthma * anaphylactic shock

clinical uses of dobutamine (1)

(selective for 1-adrenoceptors) | acute, but potentially reversible, heart failure (e.g. following cardiac surgery, or cardiogenic shock)

cardiac arrest

sudden loss of pumping function

anaphylactic shock

life threatening respiratory distress and often vascular collapse

Pharmacodynamic effects of β-adenoreceptor antagonists on ❤️ depend upon the degree to which ___ is activated

the SNS

Antagonists may block β-adrenoceptors __________ [how?] in a competitive manner

non-selectively or selectively (e.g. β1)

Antagonists may possess...

partial AGONIST activity😱

Pharmacodynamic effects of propranolol: * At rest (normal subjects) - _____ (no/little/big) effect on rate, force, CO or MABP * During exercise, or stress, rate, force and CO are significantly _______ (going up/depressed) - _______ (increase/reduction) in maximal exercise tolerance * Coronary vessel diameter marginally _______ (increased/reduced) (β2-adrenoceptors mediate vasodilatation in small coronary vessels, but !myocardial O2 requirement falls even further!, thus _____(worse/better) oxygenation of the myocardium)

``` little depressed reduction reduced better ```

propranolol [features,e.g. agonist/antagonist, what channel affected?]

non-selective β-blocker, antagonist of β1 and β2

metoprolol [features,e.g. agonist/antagonist, what channel affected?]

selective β1-blocker

atenolol [features,e.g. agonist/antagonist, what channel affected?]

selective β1-blocker

metoprolol and atenolol | Have advantages because ______ is/are little affected

β2-adrenoceptors

Excessive sympathetic activity associated with stress or disease (e.g. heart failure, myocardial infarction) can lead to... (2) β-blockers ____ (🔼/🔽) excessive sympathetic drive and help restore normal sinus rhythm (i.e. rhythm driven by the ___ node)

* tachycardia * spontaneous activation of ‘latent cardiac pacemakers’ outside nodal tissue 🔽 SA

disturbances of cardiac rhythm are collectively all called...

dysrhythmias

β-adrenoceptor agonists can help in treatment of (3):

* hypertension (HT) * angina * ❤️ failure

Atropine [features,e.g. selective/non-selective, what channel affected?]

non-selective muscarinic receptor antagonist

Pharmacodynamic effects of atropine: * _____ (no/little/big) increase in HR (_______ bradycardia/normal/tachycardia) in normal subjects – more pronounced effect in highly trained athletes (who have increased vagal tone) * ______ (no/little/big) effect upon arterial BP (resistance vessels lack a parasympathetic innervation) * ______ (no/little/big) effect upon the response to exercise

little no no

Clinical uses of atropine (3):

* reverse bradycardia after MI (MI - vagal tone 🔼) * as an addition to anaesthesia * in anticholinesterase poisoning (to 🔽 excessive PSNS activity)

digoxin

a cardiac glycoside that 🔼 contractility of the ❤️

heart failure (def.)

a CO insufficient to provide adequate tissue perfusion

heart failure (causes, treatment)

* many causes, ultimately the ventricular function curve is depressed * inotropic drugs (e.g. digoxin, dobutamine) enhance contractility

``` presence of digoxin v. cell membrane: Na+/K+ATPase ______ (opened/blocked) ___ (🔼/🔽)[Na]i and ___ (🔼/🔽) Vm ___ (🔼/🔽)Na+/Ca2+ exchange and ___ (🔼/🔽) [Ca2+]i ___ (🔼/🔽)storage of Ca2+ in SR ___ (🔼/🔽) of CICR and contractility ```

``` blocked 🔼 and 🔽 🔽 and 🔼 🔼 🔼 ```

Digoxin binds to the ______ of Na+/K+ ATPase in competition with K+ - effects can be !dangerously! enhanced by low plasma [K+] (hypokalaemia). Particularly important because digoxin has a low T.R. [WHAT's TR?]

α-subunit

Digoxin has complex direct and indirect actions on electrical activity DIRECT * ___ (🔼/🔽) the length of AP and refractory period in atrial and ventricular myocytes * toxic concentration cause membrane (hyperpolarisation/depolarization/repolarisation) and !oscillatory afterpotentials!

🔽 | depolarization

Digoxin has complex direct and indirect actions on electrical activity INDIRECT: increased vagal activity (CNS?) ______ (🐢/🐇) SA node discharge ______ (🐢/🐇) AV node conduction ______ (🔼/🔽) refractory period

🐢 (slows) 🐢 (slows) 🔼

SUMMARY of PS stimulation (PSNS) * SA node ______ (🔼/🔽) * AV node (nodal delay) 🔼/🔽 nodal delay * ventricular conduction pathway (no effect/conduction speed up) * atrial muscle - contractility & strength 🔼/🔽? * ventricular muscle - contractility & strength 🔼/ no effect * veins & venous return * adrenal medulla (releasing adrenaline)

* 🔽 * 🔼 * no effect * contractility & strength 🔽 * no effect * no effect * no effect

SUMMARY of S stimulation (SNS) * SA node ______ (🔼/🔽) * AV node (nodal delay) 🔼/🔽 nodal delay * ventricular conduction pathway (no effect/conduction speed up) * atrial muscle - contractility & strength 🔼/🔽? * ventricular muscle - contractility & strength 🔼/ no effect * veins & venous return * adrenal medulla (releasing adrenaline)

* 🔼 * 🔽 * conduction speed up * contractility & strength 🔼 * contractility & strength 🔼 * reduces capacitance hence increasing venous return * 🔼adrenaline release & thus augment effect of symp NS action

cardiac cycle

the sequence of pressure and volume changes that takes place during cardiac activity

mechanical events of the cardiac cycle are caused by...

rhythmic changes in cardiac electrical activity

SYSTOLE

contraction and emptying

DIASTOLE

relaxation and filling

atria and ventricles go through ____ (separate/same) cycles of systole and diastole

separate

At rest, _____ (systole/diastole) is longer in duration, and accounts for ____ of cardiac cycle

diastole | ~65% or 2/3

at rest 70 ppm SYSTOLE ____ s DIASTOLE ___ s

0. 3 | 0. 55

at 200 bpm SYSTOLE ____ s DIASTOLE ___ s

0. 15 | 0. 15

formula for max HR

max. heart rate = 220 bpm – age in years

the valve opens when...

the pressure is greater behind it

the valve closes when...

the pressure is greater in front of the valve

a ____________ is the valve that won't open in the opposite direction even if the the pressure is greater in front of it

one-way valve

ECG

a record of the overall spread of the electrical activity through the ❤️

P wave

atrial depolarisation

PR segment

AV nodal delay

QRS segment

ventricular depolarisation (atria repolarising simultaneously)

ST segment

time during which ventricles are contracting and emptying

T wave

ventricular repolarisation

TP interval

time during which ventricles are relaxing and filling

the 5 phases of the cardiac cycle are:

1. passive filling [during ventricular and atrial diastole] 2. atrial contraction 3. isovolumetric ventricular contraction 4. ejection 5. isovolumetric ventricular relaxation

❤️ sounds are generated by...

❤️ action

❤️ sounds can be detected using a...

phonocardiogram

LUB sound is produced by... and coincides with the begging of...

* closure of the AV valves | * systole

DUB sound is produced by... and begins with the onset of...

* closure of the aortic and pulmonary valves aka semilunar valves * diastole

what happens during: MID-DIASTOLE Atrial and ventricular pressures (high/low) Ventricles contain ___% of final filled volume Aortic and pulmonary valves ____ (open/closed) Aortic pressure _____ (low/high)

low ~80% closed high

what happens during: LATE DIASTOLE ___a___ of ECG occurs Towards end of ___a.___ atria ______ (contract/relax), ______(🔼/🔽) atrial pressure - most of the blood in the atria is propelled into ventricles - adds ______% to ventricular filling - accompanied by ____ (no/small/big) increase in ventricular pressure Volume in each ventricle at end of diastole is: ____ ml - standing ____ ml - lying

``` a. P wave contract 🔼 ~20% small ~130 ml ~160 ml ```

what happens during: END OF DIASTOLE/EARLY SYSTOLE ____✩____ of ECG begins = start of ventricular ___________ (depolarisation/repolarisation/hyperpolarisation) ventricles contract at end of ____✩____ = early systole _____ (slow/rapid) ______ (increase/decrease) in ventricular pressure AV valves _____ (open up/snap shut), resulting in ________ Ventricles contract but both ____ and _____ are _____ - ____ (all/no) blood can enter or leave "Isovolumetric or Isometric Phase"

``` ✩ QRS complex depolarisation rapid increase snap shut first heart sound AV and aortic valves shut no ```

what happens during: EJECTION PERIOD Ventricular pressure exceeds arterial pressure aortic and ______ valves open Blood is ejected into the _____ and ___❅___ Aortic pressure ____(🔽/🔼) from diastolic minimum of ____ mmHg to systolic peak of ____ mmHg Corresponding pressures in ___❅____ are ___ mmHg diastolic and ___ mmHg systolic

``` pulmonary aorta and pulmonary artery 🔼 80 mmHg 120 mmHg 8 mmHg 25 mmHg ```

what happens during: END OF VENTRICULAR SYSTOLE _____ of ECG signals ventricular _____ (depolarisation/repolarisation/hyperpolarisation) ventricles start to ____ (contract/relax) - ventricular pressure ____ (rises above/falls below) aortic pressure - aortic valve ____ (opens/shuts) - second heart sound, and Dicrotic notch (incisura) on aortic pressure record _____ valves also shut - no blood can enter or leave "Isometric Ventricular Relaxation"

``` T wave repolarisation relax falls below shuts AV ```

what happens during: FILLING PERIOD Ventricular pressure ____ (rises above/falls below) atrial pressure AV valves ____ (open/shut) *Major part of ventricular filling* Blood which entered atria during ventricular systole is released into ventricles by opening of ______ Atrial and ventricular pressures ____ (rise/fall) sharply and ventricular volume (🔼/🔽) rapidly

``` falls below open AV valves Atrial and ventricular pressures fall sharply and ventricular volume increases rapidly fall 🔼 ```

baroreceptors are activated by...

stretch, not pressure

carotid sinus afferents travel via ____ and later _____ to the cardiovascular centre in the _______

sinus nerve glossopharyngeal (cranial IX) nerve medulla

aortic arch afferents travel in _____

vagus (cranial X) nerve

Baroreceptors are the terminals of _______ and ________ sensory fibres that express ______-selective ion channels activated by ______. When opened, these generate a graded receptor potential that causes AP generation which has both ______ and _____ components

``` myelinated unmyelinated cation stretch dynamic static ```

Blood pressure is measured using _____________

a sphygmomanometer

Korotkoff sounds begin when...

cuff pressure is just below systolic pressure

Korotkoff sounds fade when...

cuff pressure is close to diastolic pressure

systolic blood pressure at rest (20 y.o. person) [values]

100-140 mmHg

diastolic blood pressure [values]

50-90 mmHg

systolic pressure is mainly affected by...

STROKE VOLUME and in particular EJECTION VELOCITY

diastolic pressure is mainly affected by... (2)

TOTAL PERIPHERAL RESISTANCE and the time allowed for blood to flow out of the arteries-- depends on HR

typical venous pressure in a limb vein on a ❤️ level... (mmHg)

8-10 mmHg

central venous pressure (pressure in venae cavae) is... (mmHg)

0-7 mmHg

typical venous pressure in a foot vein while standing is... (mmHg)

90 mmHg

minimum value for CO in untrained adults...

~5.6 (l/min)

maximum value for CO in untrained adults...

21.5 (l/min)

minimum value for CO in trained adults...

~5.3 (l/min)

maximum value for CO in trained adults...

~30.0 (l/min)

major drug classes used in the treatment of heart failure (5):

``` venodilators vasodilators positive ionotropes ACE inhibitors diuretics ```

venodilators [mechanism of action in ❤️ failure + effects]

dilate veins reduce increased central venous pressure (pressure in venae cavae) reduce preload (extent of filling)

vasodilators [mechanism of action in ❤️ failure + effects]

dilates blood vessels decreases afterload (arterial BP) increases tissue perfusion

positive ionotropes [mechanism of action in ❤️ failure + effects]

🔼 [Ca2+ intra] or 🔼 the sensitivity of receptor proteins to Ca2+ => 🔼 myocardial contractility [bind to TRANSMITTER-GATED ION CHANNELS aka Ionotropic Receptors] increase CO

ACE inhibitors [mechanism of action in ❤️ failure + effects]

prevent conversion of Angiotensin I into Angiotensin II (RAAS) stop the chain reaction leading to oedema, 🔼 central venous pressure & 🔼 preload

diuretics [mechanism of action in ❤️ failure + effects]

makes you pee additional indirect venodilator action (before diuresis) that is beneficial in pulmonary oedema caused by heart failure prevents/reduces extent of oedema

afterload [def.]

arterial BP | workload imposed on the ❤️ after contraction has begun

DIURETICS Inhibit ____, _____, and _____ reabsorption in the thick _________________________ [location] by blocking the ________________ Cause up to_______ of filtered Na+ to be excreted along with H20 producing a ‘_______’ diuresis ______(🔼/🔽) the tonicity of the interstitium of the medulla ______(🔼/🔽) the load of Na+ delivered to distal regions of the nephron (causing K+ loss) ______(🔼/🔽) excretion of Ca2+ and Mg2+ Possess an additional, indirect, venodilator action (before diuresis) that is beneficial in pulmonary oedema caused by heart failure– possibly results from: 1) ______(🔼/🔽) formation of vasodilating prostaglandins 2) ______(🔼/🔽) responsiveness to angiotensin II and noradrenalin 3) ______(opening/closing) of K+ channels in resistance vessels

``` Na+, K+ and Cl- ascending limb of the loop of Henle Na/K/2Cl- co-transporter 15-25% 'high ceiling' ``` 🔽 🔼 🔼 🔼 🔽 opening

DIURETICS -- adverse effects K+ loss producing low serum K+ levels (__________) – corrected by the accompanying use of ____________ or ____________ (note 🔼 toxicity of digoxin and Class III antidysrhythmic drugs) Shift in acid-base towards ______ side (__________) – caused by increased _____ secretion from intercalated cells in collecting tubule ______(🔼/🔽) volume of circulating fluid (________) and _______ (particularly in the elderly) Depletion of ______ and _____ [ions] ______(🔼/🔽) plasma uric acid (_______) – partially explained by competition between uric acid and loop agents for the organic acid secretory mechanism in the proximal tubule

hypokalaemia potassium sparing diuretics or potassium supplements alkaline metabolic alkalosis H+ 🔽 hypovolaemia hypotension Ca2+ and Mg2+ 🔼 hyperuricaemia

Spironolactone - example of Aldosterone Receptor Antagonist (K+-sparing diuretic) Has ______(an unlimited/a limited) diuretic action (modulated by aldosterone levels) Competitively antagonises the action of aldosterone at cytoplasmic aldosterone receptors, gains access to cytoplasm via the _________ [structure] ______(🔼/🔽) excretion of Na+ ______(🔼/🔽) excretion of K+ ______(poorly/well) absorbed from the G.I. tract and rapidly metabolised to_______ (which accounts for most of the action of the drug)

a limited basolateral membrane 🔼 🔽 well canrenone

Clinical indications for the use of Spironolactone [Aldosterone Receptor Antagonist (K+-sparing diuretic)] The major use of potassium sparing diuretics is in... Given alone, they cause______

conjunction with other agents that cause potassium loss | hyperkalaemia

Aldosterone antagonists are used in the treatment of (4):

- Heart failure - Primary hyperaldosteronism (Conn’s syndrome) - Resistant essential hypertension - Secondary hyperaldosteronism (due to hepatic cirrhosis with ascites)

diuretic drugs in the treatment of hypertension and heart failure (3):

Ionotropic Drugs Other than Digoxin Calcium-sensitizers Levosimendan

Levosimendan - Binds to _______ [protein] in cardiac muscle sensitizing it to the action of Ca2+ - ______ (Opens/Closes) KATP channels in vascular smooth muscle causing _________ (vasoconstriction/vasodilation) - Relatively new agent, used in treatment of ______ ______ heart failure

troponin C Opens vasodilation acute decompensated

❤️ Flashcards

(143 cards)