Exam # 2 Flashcards
What are the nodes of the heart?
The SA node and AV node
What does AV node stand for?
Atrioventricular node
What does SA node stand for?
Sinoatrial node
What occurs when there is a P wave?
Atrial depolarization….two atria contract
What occurs during the Q wave?
Septal depolarization
What happenes during the QRS complex?
Ventricular depolarization…two ventricles contract
What happens during the t wave
Ventricular repolarization…ventricles relax
What happens during the ST segment?
Myocardium remains depolarized
What happens during the PR segment?
The av node temporarily holds the charge for 0.1 seconds
What happens when the AV node becomes depolarized
It’s gains the positive charge
Why is the PR segment a flat line?
Because the AV node is temporarily holding the charge
Where does the charge flow from after the atrioventricular node?
Down the bundle of hiss then to the bundle branches
what is occurring to the charge during depolarization?
it is going from -80 up into the positive
what does cardiac muscle require for contraction that skeletal muscle does not ?
Calcium
what does calcium do for cardiac muscle?
xxx
what type of muscle has interculated discs?
cardiac muscle
what is included in the interculated disc?
gap junction and desmose
what are the steps the steps to cardiac muscle contraction?
1) The nodal fires and a stream of positive ions comes in
2) The charge depolarizes from the Na entering the cell
3) Part way through depolarization the slow Ca gates open
4) Then K opens
5 The cardiac plateau occurs
6) The Ca gates close and K continue to flow in until the cell is repolarized
what is cardiac output?
the amount of blood ejected from the ventricle per minute
what is the equation for cardiac output?
Cardiac output = Heart Rate x Stroke Volume
what is the atrial reflex in terms of hear rate
since the SA node is on top of the right atrium it is stretched whe the right atrium is contracted causing the heart rate to increase
what does the ANS have to do with the heart?
there is a cardiac center in the medulla that monitors the body
in healthy people the parasympathetic is dominant allowing the SA node to control the heart beat creating sinus rhythm
what are positive chronotropic?
increases the heart rate
what are negative chronotropic?
decrease heart rate
where is the medulla located?
on the brain stem
what are thermoreceptors and where are they located?
sense temp chages…if your temp goes up so does your HR…if your temp goes down so does your HR
what are baroreceptors?
found in the carotid artery ….pressure goes up HR goes down
what are chemoreceptors?
sense for changes in pH….too much H+ your body will increase HR
what does HR do if you get too much CO2?
increase HR
What nerve is related to the Sympathetic NS to the heart?
cardiac nerve
what nerve is related to the PNS to the heart?
Vagus Nerve
what Neurotransmitter is used in the Cardiac Nerve?
Norepinephrine
what neurotransmitter is used in the Vagus nerve?
Acetylcholine
What receptor is related to the Cardiac Nerve?
Beta 2
what receptor is related to the Vagus nerve?
Choligenic
What does Norepinephrine do to the body?
Raise HR
Raise Resp
Dilates trachea and pupils
Blood sent to muscles instead of organs
what does ACH do for the body?
the opposite of Norepinephrine
what is stroke volume?
amount of blood ejected from ventricle per contraction
what is the equation for stroke volume?
Stroke volume = End Diastolic Volume - End Systolic Volume
What is end diastolic volume?
the amount of blood that enters the ventrilce before it starts to contract
What is end diastolic volume?
the amount of blood that enters the ventricle before it starts to contract
what is degree in relation to EDV?
degree to which the ventrilces stretch when filling with blood
When End diastolic volume is high what happens to systolic pressure?
Systolic goes up
what is the end systolic volume?
the amount of blood left over in the verntrilces after contraction
