LEARNING OBJECTIVES
Listed in the Class Notes below=
bold, and blue background
- Read the Class Notes, using the Textbook
illustrations to help understand the concepts. Read the chapter using the
Class Notes as your guide. There are many questions included
to help tie the systems and concepts together into an integrated,
holistic understanding of anatomy and physiology.
- Take the
Ch.
12 self test in the online textbook.
DO NOT EMAIL THIS TEST TO YOUR INSTRUCTOR. It is a learning tool
only.
These tests will also include
questions that are NOT covered in this course.
- Use any resources on the
Online Textbook,
to integrate your learning.
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Class
Notes
Chapter 12: The
Heart
Use the diagrams in the book to enhance
comprehension of these concepts.
What does CARDIO mean?
What is the function of the heart?
The Heart squeezes the blood, putting pressure on it and causing it
to move to an area with lower pressure - outside the heart. Blood
moves from one place to another due to differences in blood pressure.
I.e. Blood moves from an area of HIGH BP to an area of LOW BP.
What is the functional unit of the cardiovascular system
as a whole? Describe it.
Whole blood is THE functional unit. Whole blood
transports nutrients, wastes, and other substances around the body because
whole blood is a liquid.
The RBC is the
functional unit for transporting O2.
How does the function of the heart support the functional
units of the cardiovascular system?
The heart is really two (2) pumps, one is the right side
of the heart, the other is the left side of the heart.
The Function of the heart - MOVE the blood through the vessels.
There are two circuits of blood flow in the body:
2 pumps = 2
circuits
Pulmonary circuit – blood leaves right side of heart and goes to
the capillaries in the lungs, then
back to left side
of the heart.
Systemic circuit – blood leaves the left side of the heart and goes
to the capillaries
everywhere except the lungs. It goes to the
body (not to the lungs) and then returns to the right side of the heart.
Capillaries are the smallest blood vessels and are located
in all the peripheral tissues.
Capillaries are the site of EXCHANGE – of
O2, nutrients, cellular wastes, & CO2. Capillaries are specially designed for exchange
– the WALL of the capillary is a simple squamous epithelium.
There are capillaries in each circuit:
Pulmonary capillaries in the lungs
exchange O2 and CO2. This is exchange
between the
blood and air.
Systemic capillaries exchange nutrients,
wastes, hormones and other substances
as well as O2 &
CO2, with the body tissues. This is exchange between blood
and
interstitial fluid.
Describe the
structure of the capillary.
How does this structure facilitate the exchange of
nutrients and wastes? (hint – there are only two (2) CMs between blood and
interstitial fluid.)
Review the cellular transport mechanisms in chapter 3, Cell.
The heart is made up of cardiac muscle cells.
What is the structure of cardiac muscle?
How is it different from skeletal and smooth muscle cells?
What are the ‘intercalated discs’?
The heart wall is made up of three (3) layers of tissue:
Endocardium – a simple epithelium lines the chambers of the heart
Myocardium – heart muscle fibers
Epicardium – the visceral pericardium -another simple epithelium
Describe the structure of the heart wall.
Describe the location of the heart in terms of body
cavities and relationship to other structures
Review chapter 1 – body cavities and the membranes that
line them.
What is the membrane that lines the dorsal cavity?
What is the
name of the ‘heart’ cavity?
Name the two parts of the membrane that lines
this cavity.
What is the diaphragm?
The Heart is located in the
pericardial cavity in a region of the Thoracic cavity called the mediastinum, between the two
pleural cavities in the thoracic cavity. The mediastinum contains the esophagus, the
trachea, the aorta and the heart, all in a matrix of areolar loose
connective tissues.
The heart is:
- posterior to the sternum,
- superior to the diaphragm, and
- anterior to the thoracic vertebrae.
-
It is enclosed within the ribcage.
The pericardial cavity is lined with the visceral and parietal
pericardium.
Visceral pericardium - the membrane attached directly
to the surface of the heart.
Also called the epicardium.
Parietal pericardium - the membrane attached to the
wall of the pericardial cavity.
Pericardial fluid - the fluid between the 2 layers of
the pericardium.
Function is to reduce
friction between the 'beating/moving' heart muscle and
the wall of the cavity
(lungs, ribs, and diaphragm).
Cardiac Tamponade - excess fluid in the
pericardial sac that occupies space and
prevents the heart from
expanding to its full capacity.
Pericarditis - inflammation of the
pericardium. Caused by infection or too little
pericardial fluid.
What is the mediastinum?
Describe the membrane that surrounds the heart.
What are the two parts to the membrane around the heart.
What does 'visceral' indicate?
Name the chambers of the heart and the vessels that enter
or leave each
There are 4 chambers and 4 valves
Right Atrium
Left Atrium
Right Ventricle Left Ventricle
There are 3 vessels that empty into the right atrium
Superior Vena Cava
Inferior Vena Cava
Coronary sinus
The pulmonary trunk receives blood from the Right
Ventricle
and sends blood through the Pulmonary
Arteries to the lungs.
NOTE: the Pulmonary
ARTERIES are carrying DEOXYGENATED blood!
i.e. ARTERIES with blue blood in them.
This is blood from the right
side of the heart.
There are 4 vessels that empty into the left atrium
Right pulmonary veins (2 of em)
Left pulmonary veins ( 2 of em)
NOTE: the Pulmonary VEINS are
carrying OXYGENATED blood!
i.e. VEINS with red blood in them. This is
blood going to the left side
of the heart.
The Aorta receives blood from the Left Ventricle.
Where do you find arteries carrying
blue blood?
Where do you find veins carrying red blood?
The pulmonary circuit is 'backwards' from what we normally
think of as 'red' and 'blue' blood.
Why?
State the valves of the heart and their function
Where are these located?
Tricuspid - on the RIGHT side of the heart -
between the atrium and ventricle
aka - Right AV valve (atrioventricular)
Pulmonary semilunar valve - right
side of heart - passes blood into the pulmonary trunk.
Bicuspid - on the LEFT side of the heart -
between the atrium and ventricle
aka - Mitral valve, Left AV valve
Aortic semilunar valve - left side of the heart -
passes blood into the Aorta
What is the function of the valves?
Valves prevent backflow.
Valves FORCE blood to flow in one direction - and cannot go
backward.
List the 4 heart chambers - in
sequence.
List the 4 heart valves - put them
between the appropriate chambers.
List the vessels that exit the heart.
List the vessels that enter the heart.
Now - make a master list that
includes all the previous structures. Put each structure in the list
in the sequence that each occurs in the heart.
Start with the vessels that enter the RIGHT side of the heart.
State how heart sounds are created
S1 - Lubb - made when the AV valves close and the semilunar
valves open.
i.e. ventricular systole
S2 - Dupp - made when semilunar valves close - i.e. ventricular
diastole.
S3 - made by turbulent filling or Cardiac Heart Failure (CHF)
- i.e. NOT a healthy
sound. Sort of a gurgling sound.
S4 - atrial backfilling. Blood is forced backwards into
the heart due to hypertension or
stiff heart muscle. i.e. NOT a healthy sound.
S1 (Lubb) and S2 (Dupp) are the NORMAL heart sounds and
they have a particular rythym:
Lubb.. Dupp.... pause.... Lubb..Dupp.... pause.... Lubb, Dupp......
pause..... Lubb.. Dupp...... pause...and so on, and on.
S3, S4, heart murmurs, etc are burbling, gushing, gurgling
sounds that indicate that the valves are not able to completely control
backflow of blood.
Systole - contraction. Atrial systole is
contraction of the atria.
What is ventricular systole?
Diastole - relaxation. Ventricular diastole
is relaxation of the ventricles.
What is atrial diastole?
S1 and S2 are caused by valves closing at the end of
systole - i.e. after blood has flowed through the valves - or ---- when
the heart chambers are relaxing. S1 occurs as Atrial diastole
begins. S2 occurs as ventricular diastole begins. During the PAUSE -
the atria and ventricles (Left and Right side) are relaxed.
Ventricular systole is THE source of blood pressure in the
cardiovascular system.
The normal value for blood pressure is 120/80... i.e. a
systolic pressure of 120, and a
diastolic pressure of 80.
What is the normal value for blood pressure?
What is the range for blood pressure?
The RANGE of systolic blood pressure is
100 to 135
the range of diastolic blood pressure is
60 to 90
Why does blood move from one place to the next?
It moves from High pressure to a place with lower
pressure.
What creates High pressure inside the heart?
Systole!
Describe the gradient of blood pressure in the
cardiovascular system.
Hint: which way does blood move?
List the structures in
order – that is the gradient of blood pressure.
Start with the heart. IN GENERAL - Blood moves from
the heart (Ventricles) into the the major arteries and then
to smaller arteries, to arterioles, to capillaries (exchange
of nutrients)
to venules, to small veins to larger veins
and to the largest veins and then back into the heart.
The HIGHEST pressure is in the ventricle when they contract
- blood moves OUT of the heart because the pressure in the large arteries is
lower than that in the ventricles.
The pressure in the large arteries is greater than in the
smaller arteries, therefore blood flows into the smaller arteries.
Pressure in the arterioles is less than that in the upstream
arteries, so blood flows into the arterioles.
Pressure in the capillaries is less than that in the
arterioles, and blood leaves the arterioles and flows into the capillaries.
The absolute LOWEST pressure is in the RELAXED heart (both
atria and ventricles).
So, blood flows from the capillaries, into the venules and into the small
veins and on into the large veins and into the atria. Blood flows from
one structure to the next because the next structure has a LOWER pressure.
Blood flows into the two atria, at the top of the heart,
when the heart is in diastole (RELAXED! - no pressure inside the heart!).
The atria are at the TOP of the heart, and there is a hole in the floor of
the atrium - the valve. Blood flows, by GRAVITY, into the atrium and
through the hole into the ventricle (RELAXED, too!). Blood flows
through the valve until the ventricle is full, and then fills the atrium.
This passive filling of the heart with blood due to gravity is called
Preload. Preload is PASSIVE - GRAVITY causes the blood to move
into the ventricles - the heart is RELAXED - no energy being used.
The blood fills the atria, and stretches them slightly.
The atria 'automatically' contract, pushing more blood into the already
full ventricles. This Atrial Kick completely fills the
ventricles, adding another 30% to the blood volume in the ventricles.
The ventricles contract, pushing all the blood out of the heart.
Both Atria contract at the same time - pushing
equal amounts of blood into the ventricles, slightly prior
to ventricular systole.
Both Ventricles contract at the same time - pushing equal amounts
of blood into their respective circuits.
Explain stroke volume, cardiac output and Starling’s law
of the heart
Cardiac Output (CO) = SV X HR
The CO is the amount (volume) of blood that leaves the heart per unit time.
SV = stroke volume.
About 80 ml per beat. I.e. each beat of the heart pushes
about 80 ml of blood out of the heart.
What
is the normal volume of blood pumped by each stroke, or heart beat?
HR = heart rate.
About 70 beats per minute.
What is
the normal heart rate?
What is the range of HR?
60 to 90 beats per minute.
Calculate the normal CO.
CO = 80 ml/beat X 70 beat/minute = 80 X 70
ml/minute = 5600 ml/min = 5.6 l/minute.
Remember there are about 6 liters of blood in the normal
body - i.e. all the blood in your body moves through your heart every
minute!
What is Preload?
The PASSIVE flow of blood into the heart.
How much blood flows into each ventricle during
Preload?
If the normal stroke volume is 80 ml, and Preload fills the
ventricle with 70% of that, then:
80 X 0.7 = 56 ml.
Atrial kick adds the other 24 ml to the ventricle.
Frank Starling's Law says that the amount of blood
going INTO the heart equals the amount that EXITS the heart. OR the
amount OUT = the amount IN.
The normal amount = the stroke volume = the maximum volume of the
ventricle.
Trace the pathway of a blood cell throughout the body
For the time being – concentrate on the pathway of a blood
cell through the heart and pulmonary circuit. Start with a blood cell in
the right atrium –
START with the RIGHT ATRIUM
From the right atrium the blood passes through the tricuspid (right AV
valve) into
the Right Ventricle.
From the Rt Ventricle, the blood is pumped through the Pulmonary Semilunar
Valve
into the pulmonary trunk. This goes
into the PULMONARY CIRCUIT.
From the pulmonary trunk the blood passes into the pulmonary arteries and
into
the Capillaries of the lungs.
EXCHANGE of O2 and CO2 in these capillaries.
From the capillaries, the blood passes into the pulmonary veins.
The pulmonary veins dump oxygenated blood into the Left
Atrium.
From the Left Atrium, the blood passes through the Biscuspid (mitral
valve, or left AV valve)
and into the Left Ventricle.
From the left ventricle, the blood passes through the Aortic Semilunar
valve into the
ascending Aorta. This goes into the SYSTEMIC
CIRCUIT.
From here- it becomes more a LAB question. ... depending
on where the RBC is going (right hand, left hand, head, right leg, left
leg, etc) the pathway will change a little...
but in general, the RBC will be fed back into either the
superior or inferior Vena Cava.
The superior and inferior vena cavas dump venous blood
into the right atrium.
END with the RIGHT ATRIUM
List the chambers, valves and vessels it has to pass
through to get to the left ventricle.
What is the pulmonary circuit?
Is the blood in the pulmonary arteries oxygenated (red) or
deoxygenated (blue)?
Is the blood in the pulmonary veins oxygenated (red) or
deoxygenated (blue)?
Did you list the pulmonary capillaries and what happens
there?
Describe coronary circulation
List the coronary arteries and veins.
What happens if a coronary artery gets plugged up with
‘plaque’?
First, blood flow to the heart muscle cells decreases
- which means the heart muscle cells get less O2,
resulting in less
energy for heart muscle contractions, and
weaker
contractions mean decreased blood flow around the body
therefore, all the cells in the body receive fewer nutrients, O2, and
waste products and
hormones are not well distributed or processed.
Anastomoses - alternate flow routes, allow blood to
reach tissues via 'detours' around
'blockages and damaged vessels'.
- two blood vessels merge, and then split again.
Where do the coronary arteries ‘start’?
The coronary arteries start at the base of the ascending AORTA just
after the aortic semilunar valves. These arteries follow the sulci
on the surface of the heart, and diverge into smaller arterioles that
carry blood to the cardiac capillaries. The capillaries carry blood
to the cardiac venules which merge to form the cardiac veins and cardiac
sinus.
Where does the coronary sinus ‘stop’?
The Cardiac sinus dumps 'used' blood into the right atrium.
Define myocardial infarction.
Heart attack
Define infarct:
An area of dead tissue.
Describe the cardiac conduction pathway and its
relationship to a normal electrocardiogram
First - let's look at an EKG - or electrokardiogram.
This is a measure of the electrical activity of the cells in the heart.
Muscle contraction results from an AP (action potential), which is a
CHANGE in the electrical activity of the muscle cell. ECG's measure
these 'changes' - or APs.
What is an EKG (ECG)?
What does it measure?
What are the parts of the EKG and what does each
measure?
P-wave -
measures atrial systole
QRS-wave complex - measures
Ventricular systole
T-wave - measures Ventricular
diastole
Remember - the Atria
contract together 'automatically' and push Atrial Kick blood into the
ventricles, Then the ventricles contract at the same time and push the
blood along the respective circuits.
Why do the Atria contract
'automatically'?
Remember, Preload
fills the Ventricles, then the Atria - and STRETCHES the wall of the
Atria.
The Sino Atrial Node (SA node) is a group of
hypopolarized cardiocytes in the wall of the
Right Atrium. Blood fills the atrium
and stretches the CM of these cardiocytes - which depolarize
and produce an AP.
What is the SA node and what else is it called?
What does SA stand for?
How are the cells of the SA node ‘stimulated’?
When blood enters the right atrium, the walls of the
atrium are stretched - stretch receptors in the cell membrane of
cardiocytes in the SA nodes open, producing an 'automatic' AP.
Because this is 'automatic', the SA node is also called
the 'pacemaker of the heart'.
How many times per minute does the SA node normally
depolarize?
Normally, about 60 - 70 times per minute.
What is the normal HR?
Remember -
blood is flowing around the circuit, and during diastole, Passively
fills the heart - about 70 times per minute. Frank Starlings law
says that each 'fill' is about 80 ml.
What is the AV node?
The AV node is another group of hypopolarized cells, located on the AV disc. The
AV node receives
the AP from the SA node and transmits that AP to the AV
Bundle and on to the Ventricles.
The AV node can also depolarize due to stretching at a rate of about 40-60
beats/ minute - therefore,
the AV node is the BACKUP Pacemaker for the
heart.
Where is the AV node located?
What is the AV bundle and the Purkinje fibers?
The AV Bundle is also called the Bundle of His. These are
fibers that carry the AP from the AV node down through the
interventricular septum to the Apex of the heart.
What is their function?
The function of the Bundle of His is to carry the
AP from the AV node to the Purkinje fibers. The Purkinje fibers
spread the AP into the cardiocytes of the ventricles - to cause
ventricular systole.
Where is the AV bundle located?
Where are the Purkinje fibers located?
What is bradycardia?
Too SLOW heart rate.
What is tachycardia?
Too FAST heart rate.
What is the maximum heart rate?
About 200 beats per minute.
What conditions affect heart rate?
Physical condition
Weight
Stress
Emotions
More....
Explain how the nervous system regulates the function of the
heart
Where are the cardiac regulatory centers located?
In the Brainstem.
cardioacceleratory center
cardioinhibitory center
The Brainstem contains the ANS centers that control heart
rate.
The Sympathetic NS - increases HR.
The Parasympathetic NS - decreases HR.
Blood pH, CO2 concentration and tissue O2 content, all can
affect HR.
Emotional state: fear, excitement, relaxation, etc affect HR.
What is the primitive brain? Review the info in
the Nervous System chapter.
Why is it called that?
Why is damage or injury to the brain stem often fatal?
What is the most important of the Cranial Nerves? Why?
How does aging affect this system?
Valves begin to malfunction.
SA node and AV node begin to malfunction.
Chronic stress causes the heart to enlarge.
Chronic stress causes the heart to weaken- not enough pressure to
effectively move blood.
Atherosclerosis and Arteriosclerosis - the WALL of the
artery becomes 'hard' - not flexible.
Blocked coronary arteries - leads to a Myocardial Infarction
CHF - blood backs up in one or both of the circuits - due to too
high Blood Pressure, resistance
to blood flow such as emboli, or other factors.
CVD - cardiovascular disease
HDL - High density lipoprotein - the so-called 'good' cholesterol
LDL - Low density lipoprotein - the so-called 'bad'
cholesterol
Total Blood Cholesterol -
Triglycerides - the most common form of plasma fat.
CRP - C-reactive Protein. Produced by the liver in response to
inflammation. Indicates that the
vascular system is inflamed - high potential for plaque
formation.
How does this system interact with the other systems?
Remember – all the systems have to work together to
maintain homeostasis.
The suffix ‘-itis’ means ‘an inflammation of...’.
The suffix '-sclero' means 'hard' or 'hardening'
Carditis is an inflammation of the heart muscle.
Sinusitis – an inflammation of the sinuses.
Rhinitis – an inflammation of the nose.
What is Atherosclerosis and arterosclerosis?
What are some factors that affect these?
List the hormones that affect blood pressure (urine
concentration).
See the Endocrine system for these hormones.
How do these affect blood pressure?
What is the matrix of blood? - WATER!
How does urine concentration affect the amount of water in the blood?
LAB
Heart
NOTE: These structures are
listed in the correct sequence that blood flows through the heart -
KNOW them in this sequence!
- Superior and Inferior Vena Cava
- Right Atrium
- Tricuspid right (right atrioventricular valve; Right AV valve)
- Right ventricle
- Pulmonary semi lunar valve
- pulmonary trunk
- pulmonary arteries
- pulmonary capillary beds (exchange of O2 and CO2 takes place here)
- pulmonary veins
- Left atrium
- Bicuspid Left (Left atrioventricular valve; left AV valve)
- Left ventricle
- Aortic semi lunar valve
- Ascending aorta
- Aortic arch
- Descending aorta
Where does 'exchange' take place?
What occurs during 'exchange'?
What is 'exchanged'?
What moves from the blood?
What moves into the blood?
Where else does 'exchange' take place? (I.e. what is
the other circuit of the cardiovascular system?)
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