PHYL 142 EXAM 2

Where is the heart positioned in the thoracic cavity?

Heart is located slightly to the left

There’s a concavity in the left lung to accommodate the heart

What is the heart’s own blood supply?

Coronary arteries

The right coronary artery is also known as

posterior descending artery (PDA)

The left coronary artery is also known as

left anterior descending (LAD) circumflex artery

What are the coronary veins draining from the posterior surface of the heart?

* great cardiac vein
* small cardiac vein
* posterior cardiac vein
* middle cardiac vein

What are the coronary veins draining from the anterior surface of the heart?

* great cardiac vein
* small cardiac vein
* anterior cardiac vein

Where do coronary veins go?

All drain into the coronary sinus

What is the function and location of epicardial fat?

Location:

* between the heart wall and pericardial sac

Function:

* insulate and cushion heart and coronary vessels
* provide energy to myocardium

What is excess epicardial fat associated with?

* heart disease
* obesity

How is fat distributed?

Visceral - apple shaped = more epicardial fat

Subcutaneous - pear shape = less epicardial fat

What is ischemia?

* INADEQUATE BLOOD SUPPLY TO AN ORGAN
* decreased blood flow to tissue
* decreased oxygen and nutrient to tissue
* builds up metabolic waste
* leads to cell death

What is myocardial infarction?

* a heart attack = cardiac ischemia
* cardiac muscle and cells die from lack of oxygen and nutrients

What is known as the widow-maker?

* left anterior descending artery blockage
* deadliest coronary occlusion
* caused by left anterior descending artery blockage

What does the left anterior descending artery of the heart supply?

Most of the left ventricle and interventricular septum

What is the blood flow of deoxygenated blood?

right ventricle → pulmonary arteries → lungs

What is the blood flow of oxygenated blood?

left ventricle → aorta → rest of the body

How does a myocardial infarction affect heart function?

Scar tissue develops

What is the most leading cause of death in the US?

heart disease

What is ventricular remodeling?

* loss of cardiomyocytes (heart muscle cells)
* remaining cardiomyocytes thicken
* fibroblast secrete collagen (fibrosis) that can’t contract

myocardial infarction symptoms

* chest pain
* dizziness, nausea, vomiting
* jaw/neck/back pain
* arm/shoulders pain
* shortness of breath

What is referred pain?

pain at a site different from where it is actually happening

common in myocardial infarctions

Which sex has a higher risk of getting a MI?

Males have higher lifetime risks and develop earlier

What are the myocardial infarction disparities?

* females die more often from MIs
* males are more likely to develop MIs at 65/yo
* females develop at 75 y/o

\

Different MI symptoms between male and female

females are more likely to experience shortness of breath, nausea, vomiting, and jaw/back pain

How can a MI be diagnosed?

MIs can be diagnosed using tests like electrocardiograms or echocardiograms

What are treatments for MI?

* drugs and medications
* anticoagulants (beta blockers)
* agioplasty and stent
* coronary bypass

What is percutaneous coronary intervention (PCI)?

used to unfold wire/metal meshes (stent) to hold vessels open

What is angioplasty?

Inflatable balloons that are used to widen blocked areas for blood to flow

What are risk factors for MI?

* age
* genetic and family history
* male (2x the risk)
* lifestyle factors: tobacco, hypertension, inactivity, obesity

\

What are symptoms of a stroke?

* drooping face
* asymmetry or weakness in arm
* slurred speech
* trouble seeing/walking/understanding

What is a coronary artery bypass graft? (CABG)

* uses blood vessels from elsewhere to deliver around blockages
* routes oxygenated blood from aorta or major arteries
* delivers blood downstream of blockage

What are types of strokes?

* brain attack
* cerebrovascular accident (CVA)
* ischemia
* blockage of arteries causing ischemia

What is systole?

* squeeze
* contract
* ejecting blood

What is diastole?

* dilate
* relaxation
* fills with blood

What happens during systole?

contraction → relaxation → fills with blood

What happens during diastole?

relaxation → pressure decreasing → filling

What are the phases of the cardiac cycle?

1. atrial systole
2. isovolumetric ventricle contraction
3. ventricle ejection
4. isovolumetric ventricle relaxation
5. ventricle filling

What happens during atrial systole?

* atria: systole (squeeze) blood is forced into the ventricles
* ventricle: diastole
* tricuspid and mitral valve: open
* pulmonary and aortic valve: close
* BLOOD FLOWS FROM HIGH TO LOW

What happens during isovolumetric ventricular contraction?

* first heart sound is beat
* ALL VALVES SHUT
* atria: diastole
* ventricle: systole
* tricuspid and mitral valve: close
* pulmonary and aortic valve: close

What happens during ventricular ejection?

* PRESSURE BUILDS UP IN VENTRICLES
* atria: diastole
* ventricle: systole
* tricuspid and mitral valve: close
* pulmonary and aortic valve: open

What happens during isovolumetric ventricular relaxation?

* VENTRICLES ARE RELAXING AND ALL VALVES ARE SHUT
* CAUSE SECOND HEART SOUND
* atria: diastole
* ventricle: diastole
* tricuspid and mitral valve: open
* pulmonary and aortic valve: close

What happens during ventricular filling?

* pressure in ventricles drop
* ATRIA HAS GREATER PRESSURE
* BLOOD FLOWS INTO ATRIA THEN VENTRICLES
* mitral & tricuspid valves: open
* atria & ventricles: diastole

What is the blood flow through the heart?

1. blood enters the body via the posterior and anterior vena cava into the right atrium
2. right atrium contracts, pushing the blood through the right atrial ventricular valve (tricuspid) into ventricle
3. ventricle contracts then pushes blood via the semilunar valve to the pulmonary arteries
4. goes to lungs and picks up oxygen
5. comes back oxygenated via the pulmonary veins to the left atrium
6. left atrium contracts then pushes blood into left ventricle
7. left ventricle contracts then pushes the blood via the aortic valve to the aorta
8. aorta to rest of the body

What does the cardiac conduction system do?

coordinates and drives cardiac muscle contraction

What are conducting cells?

* specialized cardiac muscle cells
* not nerves
* generate electrical action potentials and spread them throughout the heart
* control the cardiac conduction system

What is electrical potential?

* work needed to move a charge in an electric field
* potential energy per unit charge

What is membrane potential?

* electrical charge inside a cell based on \[+\] & \[-\] ion concentrations
* difference in electrical potential between cytosol inside a cell and extracellular fluid outside of the cell

What is autorhythmicity?

pacemaker cells triggering their own action potentials

What makes up the cardiac conduction system?

specialized cardiomyocytes

What are different anti-arrhythmic medications?

class 1: Na+ channel block

class 2: Beta blocker

class 3: K+ channel blocker

class 4: Beta blocker

What are different types of class 1 Na+ channel blocks?

weak: lidocaine & phenytoin

moderate: quinine & procainamide

strong: flecainide & propaferone

What are examples of class 2 Beta blockers?

* proparnolol


* metoprolol

What are different types of class 4 Ca+ channel blockers?

* verapamil
* diltiazem

What are different types of class 3 K+ channel blockers?

* amiodaron
* solatol

\

What makes up the conducting system of the heart and pacemaker potential?

* sinoatrial (SA) node
* atrioventricular (AV) node
* bundle branches
* purkinje fibers (subendocardial branches)

What happens when the action potential is at the SA node?

1. slow influx of Na+ pre potential
2. rapid influx of Ca 2+ depolarization
3. outflow of K+ repolarization
4. threshold

What is prepotential?

gradual slow increases in membrane potential toward threshold

What are contractile cell potentials?

* pacemaker cell action potentials (SA and AV node)
* purkinje action potential
* atrial action potentials
* ventricular action potentials

Intracellular fluid

has more K+ inside

Extracellular fluid

has more Na+, Cl-, and Ca2+

What is polarization?

unequal balance of ions and shared molecules on either side of a membrane

What happens when a resting cell’s membrane potential reaches a certain voltage?

* ion channels open and close
* ions move in and out of the cell
* big change in action potentials occur

What is an action potential?

* a set of sequence of ion movement and membrane potential change in excitable cells
* do not occur until a certain voltage is reached

What is a cardiac action potential?

* different with neuronal action potential
* pacemaker cell
* ventricular

What is a threshold?

* membrane potential voltage needed for a cell to start an action potential
* slightly positive

What is a prepotential?

* gradual slow increase in membrane potential toward threshold
* can be used by the pacemaker cells to reach their threshold

What are calcium channel blockers?

* block Ca2+ channels
* can be used to treat arrythmias (lower blood pressure)
* verapamil

What are different types of cardiomyocyte action potentials?

* pacemaker cell action potentials
* SA node potential
* AV node potential
* His-purkinjie action potentials
* contractile cell action potentials
* atrial action potential
* ventricular action potential

What is the normal adult heart rate?

60 - 100 bpm

Heart rate (HR)

* changes with age and health
* newborns and children have faster heart rate
* max HR decreases with age

What is chronotropy?

refers to heart rate (changes)

What is tachycardia?

heart rate that is greater than 100 bpm

What is bradycardia?

heart rate that is less than 60 bpm

Big box of ECG length

0\.2 sec

Little box of ECG length

0\.04 sec

Fast (L-type) Ca2+ channel

can cause a huge peak in the action potential

What is the sinus rhythm?

normal depolarization of the sinus node (SA) and atria

What is the normal sinus rhythm?

normal human heart rhythm with normal ECG tracings

What is an ECG?

* gives a lot of information on how conduction and heart system is working
* changes in wave shapes or timing could indicate abnormalities or disease

What is autorhymicity?

the ability of pacemaker cells to trigger their own action potentials

What is cardiac muscle excitation?

Na+ and Ca+ flow from conducting cell to contractile cell through gap junctions

What is the process of action potentials in cardiac contractile cells?

1. sodium channels open with more sodium outside
2. sodium flows in which makes cell more positive
3. depolarization occurs and sodium channels close
4. calcium channels plateau and repolarize
5. K+ channel closes

What happens during skeletal muscle contraction?

calcium binds to myosin and actin

What does ECG stand for?

electrocardiogram

What is superventricular tachycardia (SVT) also known as?

paroxysmal atrial tachycardia

What is superventricular tachycardia?

SVT occurs when the electrical system that controls the heart rhythm is not working properly

What is ventricular fibrillation? (V-Fib)

* ventricle depolarization becomes erratic which usually leads to cardiac arrest
* heart doesn’t pump blood to rest of the body

What is a cardiac arrest?

sudden stop in heart function that is deadly

What is an automated external defibrillator? (AED)

* delivers about 3000 volt charge
* depolarizes the entire heart
* stops arrhythmia
* allows SA node to restore rhythm
* ineffective on hearts that have stopped beating completely

What is the cardiac output equation?

CO = HR (heart rate) x SV (stroke volume)

What is cardiac output? (CO)

* amount of blood pumped by each ventricle in one minute
* unit of volume (L or mL/min)

What is stroke volume? (SV)

volume of blood pumped from the left ventricle in one beat

What is the sympathetic effect on heart rate?

increases the sympathetic cardiac nerve heart rate

What is the parasympathetic effect on heart rate?

decreases the vagus nerve heart rate

What is the stroke volume equation?

SV = EDV (end-diastolic volume) - ESV (end systolic volume)

What is end-diastolic volume (EDV)?

* amount of blood in ventricles at the end of atrial systole
* “preload”
* volume when fully relaxed

What is the ejection fraction equation?

SV (stroke volume) / EDV (end-diastolic volume) x 100

What is cardiac reserve?

difference between maximum and resting CO

measures the residual capacity of the heart to pump blood

What is a venous return?

amount of blood returning from the __**vena cava**__ to the __**right atrium**__

What is a preload?

amount of blood or stretch in the ventricles just before systole