Transcript 35. Arterial system. Systemic circulation

The Circulatory System
The Heart, Blood Vessels, Blood Types
SYSTEMIC CIRCULATION
With blood RETURNING from the Lungs TO the Heart…(via the
Pulmonary Veins)
Left Atrium  Bicuspid Valve  Left Ventricle  Aortic Semilunar
Valve  Aorta  Arteries  Arterioles  Capillaries in Tissues, Muscles,
and Organs
ONCE BLOOD REACHES THE CAPILLARIES – GAS &
NUTRIENT EXCHANGE OCCURS!
In Systemic Circulation, this means that Oxygen and other Nutrients (like
Glucose)
are delivered to the tissues, muscles, & organs, and Carbon Dioxide and other
wastes are transferred into the bloodstream for removal.
 Venules  Veins  Superior OR Inferior Vena Cava  Right Atrium
The Closed Circulatory System
•Humans have a closed circulatory system,
typical of all vertebrates, in which blood is
confined to vessels and is distinct from the
interstitial fluid.
–The heart pumps blood into large vessels
that branch into smaller ones leading into the
organs.
–Materials are exchanged by diffusion between
the blood and the interstitial fluid bathing the
cells.
The Cardiovascular System
•Three Major Elements –
Heart, Blood Vessels, &
Blood
–1. The Heart- cardiac
muscle tissue
–highly interconnected
cells
–four chambers
•Right atrium
•Right ventricle
•Left atrium
•Left ventricle
Pathway of the blood
•Superior Vena Cava
•Right Atrium
•Tricuspid Valve
•Right Ventricle
•Pulmonary Semilunar Valve
•Lungs
•Pulmonary Vein
•Bicuspid Valve
•Left Ventricle
•Aortic Semilunar Valve
•Aorta
•To the bodies organs & cells
Circuits
•Pulmonary circuit
–The blood pathway
between the right side
of the heart, to the
lungs, and back to the
left side of the heart.
•Systemic circuit
–The pathway between
the left and right sides
of the heart.
The Cardiovascular System
2. Blood Vessels -A network of tubes
–Arteriesarterioles move away from the heart
•Elastic Fibers
•Circular Smooth Muscle
–Capillaries – where gas exchange takes place.
•One cell thick
•Serves the Respiratory System
–VeinsVenules moves towards the heart
•Skeletal Muscles contract to force blood back
from legs
•One way values
•When they break - varicose veins form
The Cardiovascular System
3. The Blood
A. Plasma
Liquid portion of the blood.
Contains clotting factors,
hormones, antibodies,
dissolved gases, nutrients
and waste
The Cardiovascular System
•The Blood
B. Erythrocytes - Red
Blood Cells
–Carry hemoglobin and
oxygen. Do not have a
nucleus and live only
about 120 days.
–Can not repair
themselves.
The Cardiovascular System
•The Blood
C. Leukocytes – White
Blood cells
–Fight infection and are
formed in the bone marrow
–Five types – neutrophils,
lymphocytes, eosinophils,
basophils, and monocytes.
The Cardiovascular System
The Blood
•D. Thrombocytes –
Platelets.
–These are cell fragment
that are formed in the
bone marrow from
magakaryocytes.
–Clot Blood by sticking
together – via protein
fibers called fibrin.
Disorders of the Circulatory System
• Anemia - lack of iron in the blood, low RBC count
• Leukemia - white blood cells proliferate wildly,
causing anemia
• Hemophilia - bleeder’s disease, due to lack of
fibrinogen in thrombocytes
• Heart Murmur - abnormal heart beat, caused by valve
problems
• Heart attack - blood vessels around the heart become
blocked with plaque, also called myocardial infarction
Unit 9 – The Heart
Cardiovascular System
The Heart
Functions of the Heart
• Generating blood pressure
• Routing blood
– Heart separates pulmonary and systemic
circulations
• Ensuring one-way blood flow
– Heart valves ensure one-way flow
• Regulating blood supply
– Changes in contraction rate and force match
blood delivery to changing metabolic needs
Size, Shape, Location
of the Heart
•Size of a closed fist
•Shape
–Apex: Blunt rounded
point of cone
–Base: Flat part at
opposite of end of
cone
•Located in thoracic
cavity in
mediastinum
Heart Cross Section
Pericardium
Heart Wall
• Three layers of tissue
– Epicardium: This serous membrane of
smooth outer surface of heart
– Myocardium: Middle layer composed
of cardiac muscle cell and
responsibility for heart contracting
– Endocardium: Smooth inner surface
of heart chambers
Heart Wall
External Anatomy
•Four chambers
–2 atria
–2 ventricles
•Auricles
•Major veins
–Superior vena
cava
–Pulmonary veins
•Major arteries
–Aorta
–Pulmonary trunk
External Anatomy
Coronary Circulation
Heart Valves
•Atrioventricular
–Tricuspid
–Bicuspid or mitral
•Semilunar
–Aortic
–Pulmonary
•Prevent blood from
flowing back
Heart Valves
Function of the Heart Valves
Blood Flow Through Heart
Systemic and Pulmonary
Circulation
Heart Skeleton
•Consists of plate of
fibrous connective
tissue between atria
and ventricles
•Fibrous rings around
valves to support
•Serves as electrical
insulation between
atria and ventricles
•Provides site for
muscle attachment
Cardiac Muscle
•
•
•
•
•
Elongated, branching cells containing 1-2 centrally located nuclei
Contains actin and myosin myofilaments
Intercalated disks: Specialized cell-cell contacts
Desmosomes hold cells together and gap junctions allow action
potentials
Electrically, cardiac muscle behaves as single unit
Conducting System of Heart
Electrical Properties
• Resting membrane potential (RMP)
present
• Action potentials
– Rapid depolarization followed by rapid,
partial early repolarization. Prolonged
period of slow repolarization which is
plateau phase and a rapid final
repolarization phase
– Voltage-gated channels
Action Potentials in
Skeletal and Cardiac Muscle
SA Node Action Potential
Refractory Period
• Absolute: Cardiac muscle cell completely
insensitive to further stimulation
• Relative: Cell exhibits reduced
sensitivity to additional stimulation
• Long refractory period prevents tetanic
contractions
Electrocardiogram
• Action potentials
through myocardium
during cardiac cycle
produces electric
currents than can be
measured
• Pattern
– P wave
• Atria depolarization
– QRS complex
• Ventricle
depolarization
• Atria repolarization
– T wave:
• Ventricle repolarization
Cardiac Arrhythmias
• Tachycardia: Heart rate in excess of
100bpm
• Bradycardia: Heart rate less than 60 bpm
• Sinus arrhythmia: Heart rate varies 5%
during respiratory cycle and up to 30%
during deep respiration
• Premature atrial contractions:
Occasional shortened intervals between
one contraction and succeeding,
frequently occurs in healthy people
Alterations in Electrocardiogram
Cardiac Cycle
• Heart is two pumps that work together,
right and left half
• Repetitive contraction (systole) and
relaxation (diastole) of heart chambers
• Blood moves through circulatory system
from areas of higher to lower pressure.
– Contraction of heart produces the pressure
Cardiac Cycle
Events during Cardiac Cycle
Heart Sounds
• First heart sound or “lubb”
– Atrioventricular valves and surrounding fluid
vibrations as valves close at beginning of ventricular
systole
• Second heart sound or “dupp”
– Results from closure of aortic and pulmonary
semilunar valves at beginning of ventricular diastole,
lasts longer
• Third heart sound (occasional)
– Caused by turbulent blood flow into ventricles and
detected near end of first one-third of diastole
Location of Heart Valves
Mean Arterial Pressure (MAP)
• Average blood pressure in aorta
• MAP=CO x PR
– CO is amount of blood pumped by heart
per minute
• CO=SV x HR
– SV: Stroke volume of blood pumped during each
heart beat
– HR: Heart rate or number of times heart beats per
minute
• Cardiac reserve: Difference between CO at rest and
maximum CO
– PR is total resistance against which
blood must be pumped
Factors Affecting MAP
Regulation of the Heart
• Intrinsic regulation: Results from normal
functional characteristics, not on neural or
hormonal regulation
– Starling’s law of the heart
• Extrinsic regulation: Involves neural and
hormonal control
– Parasympathetic stimulation
• Supplied by vagus nerve, decreases heart rate, acetylcholine
secreted
– Sympathetic stimulation
• Supplied by cardiac nerves, increases heart rate and force of
contraction, epinephrine and norepinephrine released
Heart Homeostasis
• Effect of blood pressure
– Baroreceptors monitor blood pressure
• Effect of pH, carbon dioxide, oxygen
– Chemoreceptors monitor
• Effect of extracellular ion concentration
– Increase or decrease in extracellular K+ decreases
heart rate
• Effect of body temperature
– Heart rate increases when body temperature
increases, heart rate decreases when body
temperature decreases
Baroreceptor and Chemoreceptor
Reflexes
Baroreceptor Reflex
Chemoreceptor Reflex-pH
Effects of Aging on the Heart
• Gradual changes in heart function,
minor under resting condition, more
significant during exercise
• Hypertrophy of left ventricle
• Maximum heart rate decreases
• Increased tendency for valves to
function abnormally and arrhythmias to
occur
• Increased oxygen consumption required
to pump same amount of blood
The Heart
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The heart=a muscular double pump with 2 functions
Overview
• The right side receives
oxygen-poor blood from
the body and tissues
and then pumps it to
the lungs to pick up
oxygen and dispel
carbon dioxide
• Its left side receives
oxygenated blood
returning from the
lungs and pumps this
blood throughout the
body to supply oxygen
and nutrients to the
body tissues
simplified…
• Cone shaped muscle
• Four chambers
– Two atria, two ventricles
• Double pump – the ventricles
• Two circulations
– Systemic circuit: blood vessels that
transport blood to and from all the body
tissues
– Pulmonary circuit: blood vessels that
carry blood to and from the lungs
Heart’s position in thorax
PULMONARY CIRCULATION
With blood returning FROM the Body TO the Heart…(via the Vena
Cava):
Right Atrium  Tricuspid Valve  Right Ventricle  Pulmonary Semilunar
Valve Pulmonary Trunk  Pulmonary Arteries (2)  Alveoli in the Lungs 
 Capillaries in the Alveoli
ONCE BLOOD REACHES THE CAPILLARIES – GAS & NUTRIENT
EXCHANGE OCCURS!
In Pulmonary Circulation, this means that Carbon Dioxide is released to the
alveoli in the lungs and Oxygen is picked up by the bloodstream.
 Pulmonary Veins (4)  Left Atrium  Back to Systemic Circulation
REMEMBER…the Left & Right sides of the heart pump blood
SIMULTANEOSLY!
Heart’s position in thorax
• In mediastinum – behind sternum and
pointing left, lying on the diaphragm
• It weighs 250-350 gm (about 1 pound)
Feel your heart beat at apex
(this is of a person lying down)
CXR
(chest x ray)
Normal male
Chest x rays
Normal female
Lateral (male)
Starting from the outside…
Pericardium
(see next slide)
Without most of pericardial layers
Coverings of the heart: pericardium
Three layered:
• (1) Fibrous pericardium
• Serous pericardium of layers (2) &
(3)
– (2) Parietal layer of serous pericardium
– (3) Visceral layer of serous pericardium
= epicardium: on heart and is part of its
wall
(Between the layers is pericardial
cavity)
How pericardium is formed around heart
Layers of the heart wall
• Muscle of the heart with inner and outer
membrane coverings
• Muscle of heart = “myocardium”
• The layers from out to in:
– Epicardium = visceral layer of serous
pericardium
– Myocardium = the muscle
– Endocardium lining the chambers
Layers of pericardium and heart wall
Chambers of the heart
sides are labeled in reference to the patient facing you
• Two atria
– Right atrium
– Left atrium
--------------------------------------------------------------------------------
• Two ventricles
– Right ventricle
– Left ventricle
Chambers of the heart
divided by septae:
• Two atriadivided by
interatrial septum
– Right atrium
– Left atrium
• Two
ventriclesdivided by
interventricular
septum
– Right ventricle
Valves
three tricuspid
(cusp means flap)
one bicuspid
• “Tricuspid” valve
– RA to RV
• Pulmonary or pulmonic valve
– RV to pulmonary trunk (branches R and
L)
• Mitral valve (the bicuspid one)
– LA to LV
• Aortic valve
– LV to aorta
Function of AV valves
Function of semilunar valves
(Aortic and pulmonic valves)
Pattern of flow
(simple to more detailed)
•
•
•
•
•
•
•
Body
RA
RV
Lungs
LA
LV
Boby
Body to right heart to lungs to
left heart to body
Body, then via vena cavas and
coronary sinus to RA, to RV, then to
lungs via pulmonary arteries, then to
LA via pulmonary veins, to LV, then to
body via aorta
From body via SVC, IVC & coronary
sinus to RA; then to RV through tricuspid
valve; to lungs through pulmonic valve
and via pulmonary arteries; to LA via
pulmonary veins; to LV through mitral
valve; to body via aortic valve then aorta
LEARN THIS
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Chambers with embryologic changes added
fetal in pink; postnatal in blue
(see next slide)
• Two atria------------divided by interatrial
septum
• Fossa ovalis left over from fetal hole in septum, the foramen
ovale
– Right atrium--------in fetus RA received
oxygenated blood from mom through umbilical
cord, so blood R to L through the foramen ovale
– Left atrium
• Two ventricles-----divided by interventricular
septum
– Right ventricle-----in fetus pulmonary trunk
high resistance & ductus arteriosus shunts blood
In the fetus, the RA
received oxygenated
blood from mom
through umbilical
cord, so blood R to L
through the foramen
ovale: fossa ovalis is
left after it closes
The pulmonary trunk
had high resistance
(because lungs not
functioning yet) &
ductus arteriosus
shunted blood to
aorta; becomes
ligamentum
arteriosum after
birth
• Note positions of valves
• Valves open and close in response to pressure
differences
• Trabeculae carnae
• Note papillary muscles, chordae tendinae (heart
strings): keep valves from prolapsing (purpose of
valve = 1 way flow)
Relative thickness of muscular walls
LV thicker than RV because it forces blood out against more resistance; the
systemic circulation is much longer than the pulmonary circulation
Atria are thin because ventricular filling is done by gravity, requiring little atrial
effort
more on valves
Simplified flow: print and fill in details
Heartbeat
Definition: a single sequence of atrial contraction followed by ventricular contraction
See http://www.geocities.com/Athens/Forum/6100/1heart.html
•
•
•
•
•
Systole: contraction
Diastole: filling
Normal rate: 60-100
Slow: bradycardia
Fast: tachycardia
***Note: blood goes to RA, then RV, then lungs, then LA, then LV,
then body; but the fact that a given drop of blood passes through the
heart chambers sequentially does not mean that the four chambers
contract in that order; the 2 atria always contract together, followed
by the simultaneous contraction of the 2 ventricles
Heart sounds
• Called S1 and S2
• S1 is the closing of AV (Mitral and Tricuspid)
valves at the start of ventricular systole
• S2 is the closing of the semilunar (Aortic and
Pulmonic) valves at the end of ventricular
systole
– Separation easy to hear on inspiration therefore
S2 referred to as A2 and P2
• Murmurs: the sound of flow
– Can be normal
– Can be abnormal
Places to auscultate
• Routine places are
at right and left
sternal border and
at apex
To hear the sounds:
http://www.med.ucla.edu/wilkes/intro.html
Note that right border of heart is
formed by the RA; most of the
anterior surface by the RV; the LA
makes up the posterior surface or
base; the LV forms the apex and
dominates the inferior surface
Cardiac muscle
(microscopic)
Automaticity:
inherent rhythmicity
of the muscle itself
“EKG”
(or ECG, electrocardiogram)
• Electrical
depolarization is
recorded on the
body surface by up
to 12 leads
• Pattern analyzed in
each lead
P wave=atrial depolarization
QRS=ventricular depolarization
T wave=ventricular repolarization
Electrical conduction system:
specialized cardiac muscle cells that carry
impulses throughout the heart
musculature, signaling the chambers to
contract in the proper sequence
(Explanation in next slides)
Conduction system
• SA node (sinoatrial)
– In wall of RA
– Sets basic rate: 70-80
– Is the normal pacemaker
• Impulse from SA to atria
• Impulse also to AV node via
internodal pathway
• AV node
– In interatrial septum
Conduction continued
• SA node through AV bundle (bundle
of His)
– Into interventricular septum
– Divides
R and L bundle branches
become subendocardial
branches (“Purkinje
fibers”)
• Contraction begins
at apex
12 lead EKG
Artificial
Pacemaker
Autonomic
innervation
• Sympathetic
– Increases rate and
force of contractions
• Parasympathetic
(branches of Vagus
n.)
– Slows the heart rate
For a show on depolarization:
http://education.med.nyu.edu/courses/old/physiology/courseware/ekg_pt1/EKGseq.html
Blood supply to the heart
(there’s a lot of variation)
A: Right Coronary Artery; B: Left Main Coronary Artery; C: Left Anterior Descending (LAD, or Left
Anterior Interventricular);
D: Left Circumflex Coronary Artery; G: Marginal Artery; H: Great Cardiac Vein; I: Coronary sinus,
Anterior Cardiac Veins.
Anterior view
L main coronary artery arises from the left side of the aorta
and has 2 branches: LAD and circumflex
R coronary artery emerges from right side of aorta
Note that the usual name for “anterior
interventricular artery” is the LAD (left
anterior descending)
A lot of stuff from anterior view
Each atrium has an “auricle,” an ear-like flap
A lot of stuff from posterior view
Again posterior view
Note: the coronary sinus (largest cardiac vein) –
delivers blood from heart wall to RA, along with SVC & IVC)
another flow chart
Embryological development during week 4 (helps to
understand heart defects)
(day 23)
(day 28)
(day 24)
Day 22, (b) in diagram, heart starts pumping
Normal and
abnormal
Congenital (means born with)
abnormalities account for nearly half
of all deaths from birth defects
One of every 150 newborns has some
congenital heart defect
more…
• See Paul Wissman’s website:
main link; then Anatomy and
Physiology then Human heart:
• http://homepage.smc.edu/wissmann_paul/
• http://homepage.smc.edu/wissmann_paul/anato
my1/
• http://homepage.smc.edu/wissmann_paul/anato
my1/1heart.html
click-on
the following list of Human
– Then
from from
this site:
Heart Anatomy Web Sites:
1) SMC pictures of the Human Heart:
http://homepage.smc.edu/wissmann_paul/heartpics/
3) Human Heart Anatomy
7) NOVA PBS animation of Heart Cycle:
http://www.geocities.com/Athens/Forum/6100/1heart.html
http://homepage.smc.edu/wissmann_paul/heartpics/
• There are
dissections
like this
with roll
over
answers
• LOOK AT
THESE!
OTHER
CARDIOVASCULAR LINKS
http://library.med.utah.edu/WebPath/CVHT
ML/CVIDX.html#2 (example upper right)
http://www.geocities.com/Athens/Forum/6
100/1heart.html (heart contraction
animation & others)
http://www.med.ucla.edu/wilkes/intro.htm
l (heart sounds)
http://education.med.nyu.edu/alexcoursew
are/physiology/ekg_pt1 (depolarization
animation)
Use to study