Save
Busy. Please wait.
Log in with Clever
or
show password
Forgot Password?
Don't have an account?  Sign up 
Sign up using Clever
or
Username is available taken
show password


Make sure to remember your password. If you forget it there is no way for StudyStack to send you a reset link. You would need to create a new account. Your email address is only used to allow you to reset your password. See our Privacy Policy and Terms of Service.

Already a StudyStack user? Log In

Reset Password
Enter the associated with your account, and we'll email you a link to reset your password.
focusNode
Didn't know it?
click below
 
Knew it?
click below
Don't Know
Remaining cards (0)
Know
0:00
edit
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.

  Normal Size     Small Size show me how

Control of the Heart

Physiology and Pharmacology

QuestionAnswer
Intrinsic control of the heart Preload - increases stroke volume as myocardium stretched - Frank Starling law of the heart Afterload - decreases stroke volume as increased vascular resistance
Extrinsic control of the heart Contractility - autonomic nerves and circulating agents
Innervation of the heart SNS - ventricle and supraventricular space PSNS - mostly supraventricular space and limited in ventricles Vagus nerve - inhibits action of SNS
Neural remodelling during disease Pre disease phenotype - alterations in neural signalling Primary cardiovascular diseases are neurological
Hearts little brain Intrinsic nervous system of the heart Neuromodulation and afferent feedback
Why do we treat cardiovascular autonomic pathophysiology Hypertension, heart failure etc associated with impaired cardiac vagal function and sympathetic hyperactivity This is a negative prognostic indicator for both morbidity and mortality
Cardiac APs Different shaped Aps in different areas of the heart Changes in Na current gives rapid depolarisation ECG based on shape of AP - shows electrical activity
Brain heart connection in Arrhythmias Triggered arrhythmias due to activation of NS during stress Underlying channelopathy activated by stress e.g. exercise and REM sleep Often die in sleep between 3-6 am due to increases SNS action in REM sleep
Long QT syndrome Mutations in delayed rectifier K channels Leads to delayed repolarisation LQT1 = Iks LQT2 - Ikr
Catecholamine polymorphic ventricular tachycardias Gain of function of RYr Open for too long on depolarisation - too much Ca in cytoplasm Heart activates NCX to remove Ca - after depolarisation Premature contraction
Surgical Stellate denervation Used on patients at risk of sudden death Surgical cutting of stellate ganglia Overcomes side effects of beta blockers Has good prognosis - reduction in unexplained defibrillation
Starlings law of the heart The intrinsic relationship between EDV and SV Increased EDV - increased force of contraction - increased stroke volume - increased cardiac output When venous return is larger the myocardium stretched more and contracts with more force
Gravity influences venous return Standing causes blood to pool in the legs - causes hypotension and hypoxia in the brain Contracting muscles helps facilitate venous return Fainting helps movement of blood to the brain Orthostasis - ability to stand without fainting
Variations in starlings curves Normal exercise increases force for a given stroke volume due to SNS activation Heart failure decreases force for a given EDV due to worse circulation Build up of fluid on right side increases pulmonary pressure
Role of intracellular calcium Raising intracellular calcium increases contraction for a given sarcomere length Has a positive ionotropic effect Sympathetic stimulation drives up intracellular calcium by phosphorylating VGCCs giving greater influx
End organ responses to neural activation Sympathetic - increase in force and contraction Vagal - inhibition of action of SNS
Sympathetic signalling pathway Noradrenaline binds to beta receptors Activated adenylyl cyclase Activates cAMP Activates PKA Phosphorylates Ryr to increase Ca influx
Parasympathetic signalling pathway Ach binds to M2 receptor Decreases adenylyl cyclase Also activates Ach dependent K channel - hyperpolarises the membrane to decrease excitability
Increase in stroke volume in exercise when healthy Stroke volume increases a modest amount in dynamic exercise Starlings law of the heart is not the most important factor Increase in heart rate by SNS has the greatest effect
Stroke volume increase in exercise following transplantation HR still increases due to circulating catecholamines Due to denervation of the heart starlings law plays a larger role than increase in heart rate
Negative inotropism of ischaemia Cells respond by releasing cations leading to intracellular acidosis and a loss of force generation Also disturbs K regulation which affects ECC Hyperkalaemia changes Nernst potential - more depolarised so less Ca influx
Popular Medical sets

 

 



Voices

Use these flashcards to help memorize information. Look at the large card and try to recall what is on the other side. Then click the card to flip it. If you knew the answer, click the green Know box. Otherwise, click the red Don't know box.

When you've placed seven or more cards in the Don't know box, click "retry" to try those cards again.

If you've accidentally put the card in the wrong box, just click on the card to take it out of the box.

You can also use your keyboard to move the cards as follows:

If you are logged in to your account, this website will remember which cards you know and don't know so that they are in the same box the next time you log in.

When you need a break, try one of the other activities listed below the flashcards like Matching, Snowman, or Hungry Bug. Although it may feel like you're playing a game, your brain is still making more connections with the information to help you out.

To see how well you know the information, try the Quiz or Test activity.

Pass complete!
"Know" box contains:
Time elapsed:
Retries:
restart all cards