Download Cardiac Muscle

Cardiac Muscle
In The“Heart” of Muscles
Introduction
• Take a look the instruments that
are laid out before you
• These instruments are called
stethoscopes
• They are used to allow a person
to listen inside of the human
body
• Since they are going to highly
amplify sounds, please be
careful when they are in your
ears
Introduction
• Lets try to listen to the five
major places a doctor will listen
to a heart beat
Introduction
• What was the sound that you
heard?
• Can anyone describe it?
• Was there one sound or two
different sounds?
• Why was there multiple sounds?
• What is the purpose of these
sounds?
Cardiac Muscle
• Cardiac muscle is located in the
heart and is structurally different
from skeletal muscle
• However it works on the same
basic principals
• Contraction at pull on the Z line
of each sarcomere making each
sarcomere shorter
• This overall reduces the size of
each muscle fiber cell
Cardiac Muscle
• Each cardiac muscle cell is small
compared to a skeletal muscle
cell
• Most also only contain one
nucleus that powers each cell
• A few will have two or more nuclei
• Cardiac muscle cells are almost
completely dependent on
aerobic metabolism
Intercalated Discs
• Each cardiac muscle cell
connects to several others at
sites called intercalated discs
• These play a vital role in
contraction between cardiac
muscle cells
• They can be seen as dark lines
between each muscle fiber
Intercalated Discs
• Intercalated discs are elaborate
connections at the boundaries of
each cell
• These allow the cell to move
small molecules between the
cells so they can share materials
and information
• This also allows an action
potential to travel from one cell
to the next very rapidly
Intercalated Discs
• Since they are chemically,
mechanically and electrically
connected the heart muscle cells
work like one large organ
• This allows the entire system of
cells to beat at once, maximizing
their potential
• This process is called functional
syncytium (fused mass of cells)
The Heart
• The main organ that circulates
blood around the body is the
heart
• The heart is a four chambered
organ that uses two chambers to
force blood to the lungs and two
chambers to force blood to the
rest of the body
The Heart
• When looking at a heart you can
tell that not all four chambers
are the same
• Each side of the heart is divided
to an upper and lower part
• The atriums are the blood
collecting chambers in the heart
• The ventricles are the blood
pumping chambers in the heart
The Heart
• The heart is divided by the
septum
• This is a wall of muscle that
separates the atriums and
ventricles
• Valves are flaps of tissue that
separate the sections of the
heart
• These flaps prevent the different
sections of blood from mixing
How the Heart Pumps
• The heart has to have a
very systematic pattern
for how it beats
• This keeps the blood
flow to the body regular
and constant
• There are a few steps to
the heart pumping
How the Heart Pumps
• It is important to remember that
when the heart pumps it has
two different stages
• First the atriums contract
together
• After they contract the ventricles
contract together
• This gives a heart beat a distinct
“lub – dup” sound
Path of Blood
• 1. Deoxygenated (DOX)
blood enters the heart
through the right atrium
• This is the main
collecting chamber from
the body
• 2. The DOX blood is
forced into the right
ventricle when the
atriums contract
Path of Blood
• 3. The ventricles contract and
send the blood to the lungs
• After the blood returns from the
lungs it is oxygenated (OX)
• 4. The OX blood from the lungs
then collects in the left atrium
Path of Blood
• 5. The atriums pump and send
blood down to the left ventricle
• The left ventricle is the strongest
part of the heart
• 6. The ventricles then pump.
This sends blood to the various
parts of the body
Electrical Systems
• The heartbeat is
controlled by electrical
systems
• The heart only beats
when there is an
electrical current that
tells it how and why to
beat
• When this electrical
impulse is moving and
regular, people have a
normal heartbeat
Electrical Systems
• The SA node is a group of cells
on the right atrium that initiate
their own electrical signal
• This signal regulates the
heartbeat
• It also tells the atriums to
contract
• When this group of cells does
not work correctly, a pacemaker
is installed
Electrical Systems
• The AV node is located in the
septum and collects signals from
the SA node
• This tells the ventricles when to
contract
• This grouping of cells is reactive
and relies on the information
that is passes on to it from the
SA node
• http://www.youtube.com/watch
?v=H04d3rJCLCE
Reading a Heartbeat
• If the heart is not functioning
properly, there can be changes
to the oxygen levels of cells
• Because this can lead to several
serious complications, machines
called electrocardiograms (EKG
or ECG) read the electrical
signals that control the heart
• Reading these can help a
medical professional understand
what is wrong with a heart
Reading a Heartbeat
• The first reading on the EKG is
the P Wave
• The P Wave indicates the atria
are contracting and pumping
blood to the ventricles
• The second reading, the QRS
Waves, indicate the
depolarization and contraction
of the ventricles
• The T Wave represents
ventricular repolarization
Reading a Heartbeat
• Any deviations in the EKG can
show a medical professional if
there are some abnormalities in
the heart
• These simple charts can show a
medical professional what
condition the patient is in, how
to treat the patient or how long
the patient can go without care