Week 10 - Study Guide Flashcards
P-wave
- atrial depolarization initiated by the SA node
(the spreading of the electrical signal (depolarization) through the atria)
Pause after P wave and before QRS complex
- Atrial depolarization complete, the impulse is delayed at the AV node
QRS complex
- Ventricular depolarization begins at the apex, causing the QRS complex.
Atrial Repolarization occurs.
When the QRS wave initiates - that is the signal (depolarization phase) spreading down the bundle of His, and up the Purkinje fibers.
It covers up the repolarization phase of the atria.
Ventricular depolarization is complete after_____
the QRS complex - before the T wave
- once the ventricle is get the electrical signal (depolarization) is able to go through contraction
T- wave
- Ventricular repolarization of the ventricle begins at the apex, causing the T wave.
Repolarization phase will occur in the ventricles
Line after T wave
- Ventricular repolarization is complete
Common symptoms of heart attack (myocardial infarction)
- Crushing pain in chest (50%) or squeezing sensation
- Nagging discomfort, achy pain under shoulder blade, along clavicle, or jaw
- Cold sweats
- Shortness of breath at rest
- Nausea
- Episodes of dizziness and lightheadedness
Heart block is a
disorder of the hearts electrical system
1st-degree heart block
- asymptomatic - found on EKG as delayed transmission
person not aware
2nd-degree heart block
- arrhythmias
- skipped beats
- periodic absence of QRS wave
- AV node does not always respond
P-wave –> no QRS complex –> no T-wave
T-wave only occurs at the repolarization of the ventricles
So - you get a P-wave and then a flat line until the next P-wave occurs
Not life-threatening but the person would be aware of it
3rd-degree heart block
- Life-threatening
- Requires a PACEMAKER
- can lead to heart failure
The signals being sent by the pacemaker are not being responded to appropriately. SO - replacement of the pacemaker is essential to keep the signaling in the heart going so the heart will continue to function as an appropriate pump
4 types of Circulatory shock
- Cardiogenic
- Hypovolemic
- Vasodilatory (Vasogenic)
- Neurogenic
Hypovolemic Shock
- Blood volume loss (hemorrhage or bleeding ulcer)
- Fluid loss - fluid out of circulation means you do not have enough blood volume
Low arterial pressure (circulatory shock
Low cardiac output
Low blood volume due to loss of blood and/or loss of body fluids
Cardiogenic shock
- Cardiac output is insufficient (myocardial infarction)
A heart problem that is now creating insufficient cardiac output
In the beginning where the formation occurred - at the level of the heart itself
Vasogenic Shock
- Vasodilation - cannot get blood back to the heart
- vascular tone is lost
- blood vessels relax
usually due to septic shock & spinal cord injury
Blood volume is normal but the blood is not being delivered appropriately.
Due to the loss of vascular tone we do not have enough blood to send equally to all places of the body at the same time.
So- we have to reduce the amount of blood flow to some regions to get blood to others
Can result in Anaphylactic shock and Septic shock
Anaphylactic shock
Histamines released in severe allergic reactions
Immune-related where the body overreacts to a stimulus
Septic Shock
Vasodilator substances released from bacteria
A bacterial overload in the bloodstream - and all the toxins cause a problem.
Infection causing vasodilation
Neurogenic shock
a SNS issue - loss of control over the cardiovascular system.
Without sympathetic innervation, the parasympathetic innervation of the heart (Vagus Nerve) is left without antagonism.
This results in bradycardia and diminished contractility.
you have trouble keeping your heart rate, blood pressure, and temperature stable because of damage to your nervous system after a spinal cord injury.
Fatal issue because blood flow is too low
In all circulatory shock cases - you suffer from —
a reduction in cardiac output
Compare and Contrast
Blood Flow vs Perfusion
-blood flow: RATE of blood flowing through a tissue in a given time (ml/min)
Blood flows through vessels to get to tissues. When blood is in a tissue it is perfused.
-perfusion: RATE of blood flow PER GIVEN MASS OF TISSUE (ml/min/g)
*more imp. than blood flow
- spreads out in tissue
When the blood gets to a tissue so it can do its job of oxygenating
How does Epinephrine affect the Circulatory system?
- In the heart it increases the rate and force of contraction
- thus increasing the output of blood
- and raising the blood pressure
dilates bronchioles
raises blood pressure
How does ADH affect the Circulatory system?
- Helps control blood pressure by acting on the kidneys and the blood vessels
- retains water - raises BP
How does Aldosterone affect the Circulatory system?
- Holds Na+
- Gets rid of K+
- increase BP
Retention of sodium causes water to be retained, aldosterone increases blood volume which causes blood pressure to rise
Circulatory Shock is ___.
- An inadequate blood flow throughout the body, to the extent that the body tissues are damaged.
- Shock results in inadequate output.
- Decline in tissue perfusion resulting in hypoxia - low oxygen at the tissues.
meaning - insufficient oxygen for supporting metabolism
Circulatory Shock:
Functionality causes ____
- Stressed cells & blood vessel endothelial cells release chemical mediators
saying - I do not have enough oxygen!
What are the chemical mediators that are released by cells and actions due to circulatory shock?
- Chemical mediators cause vasodilation in heart and lungs. Trying to keep the core organs alive.
- Epinephrine - will increase cardiac output by increasing heart rate and peripheral resistance
- Hormones for water retention - Aldosterone & ADH trying to hold on to body water -
Symptoms of circulatory shock
- Pale, clammy, or cyanotic skin
- drop in body temperature
- rapid and feeble pulse
- shallow rapid breathing
Congestive Heart Failure (CHF)
- Decline in the efficiency of the heart to pump
- Cardiac output is not sufficient to meet the needs of the body (tissues)
in terms of metabolism
Common causes of Congestive Heart failure
- Coronary Atherosclerosis
- Persistent high blood pressure
- Multiple myocardial infarcts
- Dilated cardiomyopathy (DCM)
Right-sided Congestive Heart Failure
- Fluid accumulates in systemic circuit (backs up)
- Ascites - protein-fluid in abdomen Cirrhosis is most common cause
- Fluid will build up from the right ventricle
- to the right atria (increase in size of right atria)
- build up in the body’s extremities
-typically the abdomen or extremities like ankles
Left-sided Congestive Heart Failure
- Fluid accumulates in the lungs (leading to PCWP = high Left atria pressure)
(PCWP = pulmonary capillary wedge pressure)
long way of saying - build-up of fluid in the lung and associated with high pressure in left atria - Does not lie down while sleeping - cannot breathe
- Left ventricle backs up to
- left atrium
- backs up to lungs
Congestive Heart Failure Symptoms
- Cough (edema in lungs)
- Swelling (location will vary)
- Shortness of breath (build-up of fluid in lungs)
- Weight gain
- Irregular, rapid pulse
- Fatigue, weakness, fainting (heart not able to meet needs of metabolism)
- Nausea, vomiting
- Decreased urine output (all fluid is building up in the body tissue)
- Difficulty sleeping (build up fluid in lungs)
Cor Pulmonale
Right-sided heart failure
due to high pulmonary pressure
Cor Pulmonale most commonly caused by
Pulmonary hypertension
which causes right ventricle to enlarge
which causes it to fail
Cor Pulmonale - other causes
- pulmonary hypertension
- High blood pressure in lungs due to chronic lung disease
(COPD, CF, obstructive sleep apnea)
Cor =
heart
Pulmonale =
lungs
