Transcript Circulatory System

The Circulatory
System
ROSELYN A. NARANJO
www.roselynnaranjo.vze.com
Functions of the
Circulatory System
 Brings blood containing
oxygen, nutrients, and
hormones to cells
 Transports CO2 and
other wastes away
from cells
Functions Continued
 Fights infection
 Regulates body
temperature
 Helps stabilize pH and ionic
concentration of body fluids.
Circulatory System
Components
 Heart
 Blood
 Vessels
 Arteries
 Veins
 Capillaries
The Heart
 A muscular pump
 Moves blood through the body
 Is suspended in the pericardial sac
 Composed of
four chambers
 Divided into right and left halves
 Made up of
cardiac
muscle cells
Pericardium
 Protective sac of connective
tissue
 Surrounds the heart
 Filled with fluid
Myocardium
 The muscle of the heart
 Strong and thick
 Composed of spontaneously contracting
Myocardium
(heart muscle)
shown in red
cardiac muscle fibers
Epicardium
(Outer surface
of myocardium)
Endocardium
(Inner surface of myocardium)
 Can conduct electricity
like nerves
 It’s blood supply comes from
the coronary arteries
Structures of the Heart
Chambers

Atria- (2) upper chambers
Pulmonary valve
Thin walled
 Receive blood from veins
 Send blood to ventricles


Ventricles- (2) lower chambers
Left atrium
Aortic valve
Right atrium
Thick walled
 Receive blood from atria
 Pump blood out through arteries

 Septum
 Wall that divides heart into right and left
halves
Mitral valve
Left ventricle
Tricuspid valve
Septum
Right ventricle
Structures of the Heart
Valves seen from above
 Valves
 Prevent backflow of blood
 Keep blood moving in one direction
Pulmonary
valve
Pulmonary veins
Tricuspid valve
Right atrium
Chordea tendinea


Mitral valve
Aortic valve
Between the chambers
At junctions of artery and chamber
Left atrium
Pulmonary valve
Structures of the Heart
 Chordae tendinease
 “Heart strings”
 Cord-like tendons
 Connect papillary
muscles to tricuspid
and mitral valves
 Prevent inversion
of valve
 Papillary muscles
 Small muscles that
anchor the cords
Papillary
muscle
Cardiac Cycle
 Refers to all of the events from the
beginning of one heart beat to the
beginning of the next heart beat
 When cardiac muscle contracts it does
so as a single unit, creating a heart
beat
 One heartbeat - a cardiac cycle -
consists of two parts called systole
and diastole
Cardiac Cycle
 Diastole is the
period of time
when the heart
relaxes after
contraction
 Oxygenated blood from the
lungs fills the left atrium
 Deoxygenated blood from
other parts of the body fills
the right atrium.

At the end of the
diastole, the atria
contract, starting
the Systole
Cardiac Cycle
The term systole is
synonymous with
contraction of a muscle.
 Atrial systole is the
contraction of the heart
muscle of the left and right
atria. Both atria contract at
the same time, sending
blood into the
corresponding ventricle

Ventricular systole is the
contraction of the muscles
of the left and right
ventricles, which contract at
the same time.
Cardiac Cycle
 During systole
the ventricles contract,
forcing the blood into
the pulmonary artery to
be re-oxygenated
in the lungs, and into
the aorta
for systemic
distribution of
oxygenated
blood
Cardiac Cycle
 Heart Sounds

 Two normal heart
sounds with each
heart beat

described as a…..

“Lub”- sound- due
to closure of the
atrioventricular
valves (mitral and
tricuspid)
“Dub”- sound- due
to closure of the
aortic valve and
pulmonary valve
Cardiac Cycle
 Heart Rate - count of each heart beat




On average, a heart beats 72 times a
minute when at rest
Usually it is calculated as number
of contractions of heart (heart beats)
in one minute and expressed as
"beats per minute" (bpm).
The pulse is the most
straightforward way of measuring the
heart rate
Heart rate is controlled by nervous system
Hearse on an
emergency
Cardiac Cycle



Sympathetic division
increases heart rate
Parasympathetic division
decreases heart rate
Heart rate increases when
more food and oxygen are
needed by the cells, or when
under stress
 Resting heart rate can be
significantly lower in athletes
Cardiac Cycle
An electrocardiogram abbreviated as EKG
or ECG is a test that measures the electrical
activity of the heartbeat or one cardiac cycle.
Cardiac Conduction System
 Why don’t the atria
and ventricles
contract at the
same time?
 Inefficient….
Blood would not be
moved
in one direction,
some would flow
backwards
Cardiac Conduction System
 Includes:




SA node
AV node
Bundle of His
Purkinje fibers
Purkinje fibers
Cardiac Conduction System
 Sinoatrial Node (SA node)
 Located high on the right atrium.
 Pacemaker of the heart.
 Causes the wave of
contractions in the atria.

Sending
blood
into the
ventricles
Cardiac Conduction System
 Atrioventricular Node (AV node)
 Located in the interatrial septum close to the
tricuspid valve
 Carries the electrical impulse
from the SA node to fiber
bundles in the ventricles.


This causes the ventricles to
contract
The location of nerve fiber
bundles cause the ventricles to
contract from the apex (bottom)
up squeezing blood up and out
Pathway of Circulation
 Oxygen-poor blood
draining from the body
through veins into the
superior and inferior vena
cava flows to the right
atrium, through the
tricuspid valve, and into
the right ventricle.
 As the right ventricle
contracts, oxygen-poor
blood passes through the
pulmonary valve into the
pulmonary arteries and
on to the lungs to receive
oxygen.
Pathway of Circulation
 Oxygen-rich blood from the
lungs enters the heart through
the pulmonary veins, passing
into the left atrium.
 Then through the mitral valve
to the left ventricle.
Contraction of the left
ventricle forces blood through
the aortic valve into the aorta.
 Various arteries branch off
from the aorta to supply
blood to all parts of the body.
Pathway of Circulation
Nutrients pass into tissues
Waste products filter back
Blood pumped out of
heart into arteries,
which branch into
smaller and smaller
vessels until blood
flows
into capillaries
Blood returns to the
heart through the veins
Heart
Capillary
Capillary
network
 Arteries branch into
smaller and smaller
vessels (arterioles)
 They eventually become
capillaries, which supply
blood to all body parts
 Capillaries merge into
(venuoles) which join into
veins and carry blood
back to the heart.
Pathway of Circulation
Pathway of Circulation
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It takes about 1 min. for
blood to make 1
complete cycle
And so on…
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 Get ¼ sheet of paper for a short quiz...
Questions
 Why don’t the atria and ventricles contract at the
same time?
 How does a blood is distributed throughout the
body?