Heart & Blood Vessel Guided Notes Name:__________________________

Do NowWrite down 1-3 questions about how your heart works.

Cardiovascular SystemWhat is the major function of the cardiovascular system?

What is the heart’s role in this system, and what are the other major components?

Heart Size and Location

Heart Layers. Describe the location and function of the three layers.Pericardium –

Myocardium –

Endocardium –

Cardiac circulationCardiac vessels cover the outer surface of the heart and supply the heart muscle itself with blood.Heart disease (___________________________) occurs when the aorta or cardiac arteries

Describe the heart size, location, and tilt.

What is pericarditis?

Heart Anatomy (Frontal Section)

The heart is a double pump• The ____________________ of the heart receives

________________________________________

________________________________________ and

pumps it to the _____________________

________________________________________

• The ______________________ of the heart receives

_________________________________________

_________________________________________ and

pumps it to the _____________________

______________________________________

The heart has four chambers Each side has an ___________________________________________________ and a _____________

____________________________________________________________

Blood collects in atria while ventricles contract.

Then, as ventricles relax, atria contract slightly and ventricles refill.

Two sides of heart contract and relax simultaneously.

Flow of Blood

The walls of the ventricles are much thicker than that of the atria? Why?

Look at the diagram – how does the left ventricle differ from the right? What is the reason for the difference?

Use the diagram to determine the flow of blood

through the heart and body.

Vena cava

Vena cava

Heart valves ensure unidirectional flow of blood

_________________________________ (pulmonary and aortic)• forced open when ventricles contract• closed when ventricles relax

Prevent backflow from ______________________ to _____________________

In what stage of the cardiac cycle is the heart shown above? How do you know?

Heart SoundsNormal hearts make the sound:

LUB-dup LUB-dup LUB-dup

The “LUB” is caused by the closing of the _________________________________.

The “dup” is caused by the closing of the _________________________________.

Heart murmurs are __________________________heart sounds. • In children, these are often benign.• In adults, they usually indicate a problem – often, the _____________________________________

_______________________________________.

Why is it a problem if the valves don’t function properly?

valves (tricuspid and mitral)

• hang open when the ventricles are filling

• forced closed when the ventricles contract

• Anchored by ___________________________

Prevent backflow from ____________________

to ______________________________

ECG and the Heart’s Internal Conduction System Guided Notes

Do Now

What is an action potential and where do they occur?

Intrinsic conduction system

Interestingly, all the cells of the conduction system are

_______________________________.

That is, all will depolarize at a certain rate.

The __________________ has the fastest rate of

depolarization, though, so it sets the pace for the entire heart.

Quick Review – Intrinsic Conduction System

What is the function of

- AV node

- Gap junctions

_______________ is the heart’s natural pacemaker.

◦ It depolarizes ~75 times / min, to start each heartbeat.

Impulse travels throughout the ____________ and to the ________________

◦ Travels cell-to-cell through __________ _________________ in intercalated discs – another unique feature of cardiac muscle

_______________________________________ _______________________________to allow atria to finish contracting

The ______________ (aka bundle of His) transmits the impulse to the _______________________ and ______________________________________.

◦ These bundles and fibers speed the transmission of the impulse throughout the ventricles, to coordinate ventricular contraction

- SA node

- Purkinje fibers

Name 3 differences between cardiac and skeletal muscle contraction & explain why each is important to cardiac function.

ECG

ECG Questions

What is responsible for the delay between P wave and QRS complex?

What is responsible for the delay between T wave and next P wave?

An electrocardiogram (ECG or EKG) records the electrical current through the heart.

A normal ECG has three distinct waves:

◦ P wave – atrial depolarization

◦ QRS complex – ventricular depolarization AND atrial repolarization

◦ T wave – ventricular repolarization

Examine this normal ECG. When would the ventricles be in systole? When would they be in diastole? When would the heart sounds occur, and what do the heart sounds correspond to?

ECG abnormalities

Examine these ECG readouts, and identify how they differ from a normal ECG.

a)

b)

c)

d)

Descriptors –

Name Characteristic ECG Cause(s)AV block In severe cases, there is NO

relationship between P waves and QRS complex. QRS still occurs due autorhythmic cells in AV node, but at a slower rate.

Damage to AV node, such as from reduced blood flow (ischemia) or fibrosis.

Treatment: dual chamber artificial pacemaker- one that ‘listens’ to the SA node and sends a signal to the AV node

Atrial fibrillation Wavy baseline, no regular p wavesQRS normal shape but occurs randomlyLooks messy

Heart is doing uncoordinated, ineffective contraction due to lack of blood, excess alcohol, or infection

Tachycardia Heart beats faster than normal (more than 100 bpm)

Exercise, drugs

Bradycardia Heart beats slower than normal (less than 60 bpm)

Many conditions, including heart damage, medications, etc,

Regulation of Heart Rate

Earlier, we said that the SA node depolarizes at a rate of ~75 beats per minute, and that this acts as a pace maker for heart contraction.

Does this mean our hearts always beat at ~75 bpm?

What are the two branches of the autonomic nervous system, and how do they affect heart rate?

Other factors that influence heart rate Age (fastest in fetus, young children) Gender (faster in females) Temperature (faster in heat) Exercise (faster with exercise) Ions imbalances & medicines (faster or slower) Weak / damaged heart (can be either faster / slower)

Blood Vessels

Types of Blood Vessels

Blood Vessel Tunics

Draw a cycle that shows how blood flows through the heart and blood vessels.

All vessels except capillaries have three layers, or tunics

Capillaries have a single layer of epithelial cells

Comparison of the blood vessels

Blood vessel micrograph

How does blood return to the heart?

Different vessels differ in the thickness and adaptations of each tunic.

Explain the function of each special feature

Which is which? How can you tell?

Muscular pump Respiratory Pump

How does the muscular pump work? How does the respiratory pump work?

Capillary Bed

Capillary Exchange

What is the difference between the vascular shunt and a true capillary?

What is the function of the precapillary sphincters?

Capillary exchange is the _________________________

______________________________________________

Clefts and fenestrations are most important for the diffusion of what kinds of substances?

What can get through without their help?

What type of capillaries don’t have fenestrations or intercellular clefts?

Differences in pressure in blood pressure and osmotic pressure help fluids move out of capillaries at the arterial end and into capillaries at venous end.

Capillary exchange is the _________________________

______________________________________________

Blood pressure and cardiac disorders guided notes

Pulse Points

Blood Pressure

Blood pressure is the pressure the _______________________________________________________ _______________________________________________________________________.

Usually, we refer to the pressure of the arteries.

Why does blood pressure drop so low in the capillaries?

Areas where can easily feel pulse

Also act as ____________________________.

Compressing these points will reduce downstream blood flow

useful when dealing with major wounds.

Why do we record blood pressure as two numbers?

Measuring Blood Pressure

Korotkoff sounds

• Cuff pressure > systolic pressurethere ______________________________ through artery NO SOUNDS

• Cuff pressure = systolic pressure blood begins to __________________________ through artery TAPPING SOUND BEGINS

• Cuff pressure = diastolic pressureblood begins to __________________________ SOUNDS DISAPPEAR

Factors which affect blood pressure

Increased ______________________________________________ increases blood pressure

Exercise

Stress / Sympathetic nervous system

Systolic pressure occurs due to ______________________________

Diastolic pressure occurs when _____________________________

1. A sphymomanometer is placed over the brachial artery.

2. The cuff is inflated to ~150 mmHg (above systolic pressure)

3. Air pressure is slowly released from cuff while a stethoscope is used to listen for _____________________________ in the artery.

Increased _______________________________________________ (friction of blood traveling through vessels) increases BP

Atherosclerosis

Constriction of blood vessels (due to sympathetic nervous system, cold, chemicals such as nicotine)

Number of vessels (body size / fat / pregnancy)

Increased _________________________________ increases blood pressure

Kidney problems

What factors might lead to decreased blood pressure?

Resting Blood Pressure

_________________________________ is high blood pressure.

____________________________________________, which may lead to clots and atherosclerosis

____________________________________________, leading to enlarged heart that will eventually weaken

____________________ is low blood pressure.

May cause dizzy spells, especially when rising

Not problematic among young, healthy people

Acute hypotension may indicate shock

Why can high blood pressure cause a positive feedback cycle?

Myocardial Infarction (aka heart attack)

A myocardial infarction (or heart attack) occurs when one of the blood vessels that supplies the heart with oxygen becomes blocked suddenly due to a __________________and/or ____________________________.

The heart tissue begins to die due to lack of oxygen (______________________),often over a period of several hours.

Risk Factors

Atherosclerosis High blood pressure High cholesterol Obesity Diabetes Smoking Genetics / family history Sedentary lifestyle

Treatment

The immediate goal of treatment is to restore blood flow and reduce the stress on the heart.

Drugs used:

_________________ and other blood thinners – reduces blood clotting

_________________ – reduce formation of platelet plug

_________________ – enzymes that dissolve blood clots

_________________ – dilates blood vessels

_________________ – relax heart muscle, reducing damage

_________________ – lower blood pressure and reduce stress on heart

Surgical Options:

______________________________________________________________________

A long thin tube (catheter) in inserted into an artery in the leg and thread through to the blockage in the heart. A balloon in the tube then inflates at the site of the blockage to open up the artery. A mesh stent (tube) may also be inserted to keep the artery open long term.

________________________________________________________________________

Doctors sew in new arteries or veins to bypass a blockage, restoring blood flow to the heart