The Cardiovascular and
Respiratory System Review
Cardiovascular System
• Organ system which is responsible for the circulation of
blood throughout the body
– Consists of 2 main parts:
– the heart contracts to move the blood vessels which:
• Arteries transport oxygen rich blood away from the
heart to the tissues.
– allow for the exchange of substances between the blood
and the cells of the body
• Veins transport O2 poor CO2 rich blood back to the
heart which is sent to the lungs to be oxygenated.
Heart
• Considered to be a
duel pump because
the both sides work
independently of one
another.
– the right side pumps
blood to the lungs
(pulmonary circulation)
– the left side pumps
blood to all of the other
organs of the body
(systemic circulation)
Heart Wall
• Epicardium – Outermost
layer ,visceral layer of the
serous pericardium
• Myocardium – cardiac
muscle layer forming the
bulk of the heart.
• Endocardium – endothelial
layer of the inner
myocardial surface.
– Deepest layer that is
continuous with the lumen of
the heart and arteries.
Coronary Arteries
• Left coronary artery (LCA)
– anterior interventricular branch
• supplies blood to interventricular
septum and anterior walls of
ventricles
– circumflex branch
• passes around left side of heart in
coronary sulcus, supplies left atrium
and posterior wall of left ventricle
• Right coronary artery (RCA)
– right marginal branch
• supplies lateral R atrium and ventricle
– posterior interventricular branch
• supplies posterior walls of ventricles
Gross Anatomy of Heart: Frontal
Section
Blood Flow Through The Heart
Heart Valves
•
Heart valves ensure unidirectional blood flow through
the heart
Atrioventricular (AV) valves lie between the atria and
the ventricles
•
–
–
•
Tricuspid Right
Bicuspid (Mitral) Left
AV valves prevent backflow into the atria when
ventricles contract
Chordae tendineae anchor AV valves to papillary
muscles
•
–
First heart sound (LUB) when valves close
• During diastole there is less pressure in the in ventricle. AV Valves
open and filling the ventricle.
• During systole the AV valves prevent the back flow of blood into the
atrium.
– Failure to prevent the blood from going back into the atria (systolic heart
murmur)
Heart Valves
• Aortic semilunar valve lies between the left
ventricle and the aorta
• Pulmonary semilunar valve lies between
the right ventricle and pulmonary trunk
– Semilunar valves prevent backflow of blood
into the ventricles
• Second heart sound (DUB) when valves close
Figure 19.9b
• During systole the Semilunar valves allow blood to be
ejected from the ventricles into the aorta and pulmonary
artery.
• During diastole they prevent the back flow of blood back
into the ventricles.
Cardiac Muscle Cell Metabolism
• Aerobic respiration
– Large mitochondria
Rich in myoglobin and
glycogen
• Organic fuels:
– fatty acids, glucose,
ketones
• Fatigue resistant
Anatomy of Heart Muscle
• Cardiac muscle is striated, short, fat, branched,
and interconnected
• Intercalated discs anchor cardiac cells together
and allow free passage of ions
Sequence of Cardiac Excitation
• Note bundle branch and Purkinje fibers connection to
both the ventricular myocardium and papillary muscles
– This is important when considering how the ventricular
myocardium and AV valves can function in a coordinated
fashion.
Intrinsic Conduction System
•
Autorhythmic cells: cells that spontaneously generating
action potentials without any influence from the CNS.
–
Main pacemaker of the heart is the (SA node)
•
–
–
sets cardiac heart rate. 
Atrioventricular node (AV node) leads into Bundle of His 
which splits into branch bundles
Purkinjie fibers carry the impulse to the ventricular
myocardium
Electrocardiography
• Electrical activity is recorded by
electrocardiogram (ECG)
– P wave corresponds to depolarization of SA node
– QRS complex corresponds to ventricular
depolarization
– T wave corresponds to ventricular repolarization
– Atrial repolarization record is masked by the larger
QRS complex
EKG
Depolarization of Myocardium
Cardiac Cycle
• Cardiac cycle refers to all events
associated with blood flow through the
heart
– Systole – contraction of heart muscle
• Ejection on blood from the heart.
– Diastole – relaxation of heart muscle
• Myocytes repolarize allowing the heart to refill with
blood
• Coordination of the these phases is critical for
proper cardiac function.
Phases of the Cardiac Cycle
•
Ventricular filling – mid-to-late diastole
–
–
–
•
At the beginning of the cycle, the semilunar valves are
closed and the entire heart is in diastole.
Pressure in the heart blood is lower than in the vena
cavas and pulmonary veins resulting in the movement
of blood into the atria
As pressure in the atria now exceed ventricular
pressure the AV valves are open allow blood to flow
from the atria into the ventricles.
Atria systole occurs (SA) node initiates
depolarization of both atria
–
–
Represented by the P-wave on an EKG
Both atrium contract forcing atrial blood into already
filled ventricles. (End Diastolic Volume)
Phases of the Cardiac Cycle
• Ventricular systole
• Atria relax( repolarization)
• There is a slight delay prior to the initiation of the AV node.
– This allows atrial blood time to enter the ventricles
• AV node sends action potential → along the bundle of His →
branch bundles → perkinje fibers depolarizing both ventricles
leading to the ventricle myocardium to contract.
– QRS complex on EKG
• This results in rising ventricular pressure causing the closing of
AV valves (LUB) 1st heart sound
• Isovolumetric contraction phase
• (The ventricles are contracting with all 4 valves closed )
• This allows ventricular pressure to increase rapidly.
Phases of the Cardiac Cycle
• Ventricular ejection phase: semilunar valves open once
pressure in the ventricles exceed the pressure in the aorta
and the pulmonary trunk.
– Blood will now flow out of the heart.( Stroke Volume)
– ST segment on EKG
• Isovolumetric relaxation – early diastole
– Ventricles relax represented by the T-wave on the EKG
– Backflow of blood in aorta and pulmonary trunk closes
semilunar valves making the second heart sound ( Dub)
– This marks the end systolic volume (ESV)
• Dicrotic notch – brief rise in aortic pressure caused by
backflow of blood rebounding off semilunar valves
– This rebounding of blood is when coronary artery perfusion takes
place. ( the heart receives blood during diastole)
Cardiac Output
• CO is how your body meets the demands that are placed on it.
The heart must:
– deliver vital nutrients such as O2, hormones and all the fuels
sources body as quickly as they are used
– remove CO2, urea, lactic acid… from the cells of the body as
quickly as they are produced
– Vigorous activities will increases systemic and cardiac O2
demands while producing more CO2 that will need to be
expired
• During strenuous activities the bodies CO will increase
dramatically to meet these demands.
Cardiac Output (CO)
• HR is the number of heart beats per minute
• SV is the amount of blood pumped out by a ventricle with
each beat
– SV = end diastolic volume (EDV) minus end systolic volume
(ESV)
• EDV = amount of blood collected in a ventricle during
diastole.
• ESV = amount of blood remaining in a ventricle after
contraction
• CO is the amount of blood pumped by each ventricle in
one minute
– CO is the product of heart rate (HR) and stroke volume (SV)
Cardiac Output
• Normal Cardiac Output
– CO (ml/min) = HR (75 beats/min) x SV (70
ml/beat)
– CO = 5250 ml/min (5.25 L/min)
• Exercise CO can increase 7 fold
– HR (160 beats/min) x SV (220 ml/beat)
– CO = 35200 ml/min (35.25 L/min)
Extrinsic Innervation of the Heart
• Heart is stimulated by
the sympathetic
cardioacceleratory
center.
– Sympathetic chain
gangland from levels
T1- T5.
• Heart is inhibited by
the parasympathetic
cardioinhibitory center
via the Vagas nerve.
Regulation of HR
• The sympathetic cardiac nerve originating from
the cardioacceleratory center in the medulla of
the brain releases the neurotransmitter
norepinepherine (adrenergic agent) onto the
cells of the SA node
– causes an increase in the frequency of action
potentials in the SA node leading to an increase in
HR.
• What gates would you open to increase the frequency of
action potentials?
– Force of contraction is also increased because of the
increased uptake of extra cellular calcium
Regulation of HR
• Parasympathetic: Stimulation via
(Vagus) nerve originating from the cardio
inhibitory center in the medulla.
• This center releases the neurotransmitter
acetylcholine (cholinergic agent) onto the
cells of the SA node
– which causes a decrease in the frequency of
action potentials in the SA node leading to a
decrease in HR
– Which gates will open?
Contractility and Norepinephrine
• Sympathetic
stimulation
releases
norepinephrine
and initiates a
cyclic AMP
secondmessenger
system
Frank-Starling Law of the Heart
• Preload : degree of myocardial
stretch is related to the volume of
blood in the ventricles .The
greater the stretch on the
ventricular walls, the greater the
force the myocardium will
contract thus increasing stroke
volume.
– Slower heart rate increase
ventricular filling time
(venous return) increasing SV
• How will blood loss effect heart
rate and stroke volume?
Factors Affecting Stroke Volume
• Afterload – back pressure exerted
by blood in the large arteries
leaving the heart
– The greater the afterload the
harder the heart has to work to
eject blood.
• During diastole the coronary
arteries fill with blood as blood
recoils off the aortic semilunar
valves.
• Patients with chest pain (angina)
are not getting enough blood to
meet myocardial demand.
Blood Vessels
• Blood is carried in a closed system of
vessels that begins and ends at the heart
• The three major, and types of vessels are
arteries, capillaries and veins
• Arteries carry blood away from the heart.
• Veins carry blood toward the heart
– 70% of blood is located in the veins
• Capillaries contact tissue cells and
directly serve as site for gas and nutrient
exchange
Generalized Structure of Blood Vessels
• Arteries and veins are
composed of three
tunics –
– tunica interna, tunica
media, and tunica externa
• Lumen – central bloodfill area
• Capillaries are
composed of
endothelium only:
– necessary for exchange
of gases and nutrients.
Tunics
• Tunica interna (tunica intima)
– Endothelial layer that lines the lumen of all vessels (inner
most layer)
• Tunica media (middle layer)
– Smooth muscle and elastic fiber layer, regulated by
sympathetic nervous system
– Smaller vessels have a more muscular layer than larger
vessels
• SNS causes vasoconstriction.
– (no stimulation ) results in vasodilatation of vessels
– This will affect blood pressure and distribution)
• Tunica externa (tunica adventitia)
– Collagen fibers that protect and reinforce vessels
– Larger vessels like the aorta have more to allow them to
deal with higher pressures
Capillary Beds
Blood Flow Through Capillary
• There are 5-6 liters of blood
• 60 thousand miles of vessels
in the circulatory system.
• SNS causes precapillary
sphincters to constrict
shunting blood to where it is
needed.
• If all the precapillary
sphincters open the blood
pressure will drop
dramatically.
– This is what we call SHOCK.
Blood Pressure (BP)
• Force per unit area exerted on the wall of a
blood vessel.
– Expressed in millimeters of mercury (mm Hg)
– Systolic pressure – pressure exerted on arterial walls
during ventricular contraction
– Diastolic pressure – lowest level of arterial pressure
during a ventricular cycle
• The differences in BP within the vascular system
provide the driving force that keeps blood
moving from higher to lower pressure areas
Systemic Blood Pressure
• The pumping action of the heart generates blood
flow through the vessels along a pressure
gradient, always moving from higher- to lowerpressure areas
• Pressure results when flow is opposed by
resistance
• Systemic pressure:
– Is highest in the aorta
– Declines throughout the length of the pathway
– Is 0 mm Hg in the right atrium
• The steepest change in blood pressure occurs in
the arterioles
Systemic Blood Pressure
Velocity of Blood Flow
Factors Aiding Venous Return
• Venous BP alone is too low to promote
adequate blood return and is aided by the:
– Respiratory “pump” – pressure changes
created during breathing suck blood toward
the heart by squeezing local veins
– Muscular “pump” – contraction of skeletal
muscles “milk” blood toward the heart
• Valves prevent backflow during venous
return
Factors Aiding Venous Return
Baroreceptor Reflexes
The Respiratory System
Functions:
– To provide the body with means of taking in(O2) for
the production of ATP and eliminating (CO2) a
byproduct of aerobic respiration.
– To help maintain the body’s pH, by regulating the
blood CO2 levels in the body.
– Work in conjunction with the cardiovascular system
to move these gases from the lungs to the cells
and from the cells to the lungs.
Organs of Respiratory System
Conducting Zone
• Conducting zone
– Provides rigid
conduits for air to
reach the sites of gas
exchange
– Respiratory
structures include
(nose, nasal cavity,
pharynx, trachea,
primary, secondary
and tertiary bronchi)
– No Gas exchange
Respiratory Zone
• Respiratory zone:
– begins as terminal
bronchioles →
respiratory
bronchioles →
alveolar ducts, →
alveolar sacs
composed of alveoli
– This is where gas
exchange occurs!
Respiratory Membrane
4 Processes of Respiration
1. Pulmonary ventilation – air moving into and out of the
lungs along their pressure gradients.
•
•
Inspiration – air(O2)flows into the lungs
Expiration – air (CO2) exit the lungs
2. External respiration – gas exchange between the lungs
(alveolus) and the blood (pulmonary capillaries)
3. Transport – transport of oxygen and carbon dioxide
between the lungs and tissues via the circulatory system.
4. Internal respiration – gas exchange between systemic
blood vessels (capillaries) and the tissues (cells)
•
Gases must diffuse into interstitial fluid prior to any exchange
between the tissue and the cell.
Pulmonary Ventilation
• Taking of air into and out of the lungs.
• A mechanical process that depends on
respiratory muscles changing the size of the
thoracic cavity
– Because this cavity is connected to the lungs
via the parietal membranes it may also
influence the lung (alveolar )volume.
• A increase in alveolar volume will move air into the
lungs down it concentration gradient.
• A decrease in alveolus volume will move air out of
the lungs.
Pleurae
Parietal
pleurae
Visceral
pleurae
Intrapleural
space
Inspiration
Expiration
Figure 22.13.2
Internal Respiration
External Respiration