LPN-C
Unit Two
Anatomy and Physiology of the
Circulatory, Pulmonary, and
Renal System
Circulatory,
Pulmonary, and
Renal System
The Heart
The Heart

Apex
◦ Points forward, downward, and to the left at the
4th or 5th intercostal space

Base
◦ “Broad” side that faces upward
The heart is 12cm long and 8cm wide at its
base, and is 6cm thick
 The heart weighs an average of 280g, and
weighs more in men than in women
 The layers of the heart are the pericardium,
epicardium, myocardium, and
endocardium

The Heart (cont’d)
The pericardium is a fibroserous sac that
surrounds the heart and the roots of the
great vessels; it provides the heart with
physical protection and a barrier to
infection
 The epicardium is known as the visceral
layer, and covers the entire heart and great
vessels; the epicardium also forms the
parietal layer that lines the pericardium
 The myocardium is the muscular portion of
the heart, which forms the walls of the
atria and ventricles

The Heart (cont’d)

The endocardium is a thin, 3-layered
membrane that lines the heart.
◦ Inner layer = smooth endothelial cells
supported by connective tissue
◦ Middle layer = dense connective tissue
◦ Outer layer = irregularly arranged connective
cells

There are 4 chambers of the heart
◦ Right and left atrium
◦ Right and left ventricle
The Heart (cont’d)
The right atrium receives deoxygenated
blood from the superior vena cava, inferior
vena cava, and coronary sinus
 The left atrium receives oxygenated blood
from the pulmonary veins
 Blood is emptied into the ventricles from
the atria during diastole
 The ventricles are thick, muscular walls
that make up the bulk of the heart
 A septum separates the ventricles and
extends between the atria, dividing the
heart into the right and left sides

The Heart (cont’d)
The great vessels of the heart are the
superior vena cava, the inferior vena cava,
the coronary sinus, pulmonary arteries,
pulmonary veins, and the aorta
 Superior Vena Cava

◦ 2nd largest vein in the body
◦ Returns deoxygenated blood from the upper
half of the body to the right atrium
◦ 2cm in diameter and 7cm long

Inferior Vena Cava
◦ Returns deoxygenated blood to the heart from
parts of the body below the diaphragm
The Heart (cont’d)

Coronary Sinus
◦ Drains 5 coronary veins through a single
semilunar valve
◦ Coronary veins include the great cardiac vein,
the small cardiac vein, the middle cardiac vein,
the posterior vein of the left ventricle, and the
oblique vein of the left atrium

Pulmonary Arteries
◦ Deoxygenated blood leaves the right heart
through the pulmonary artery, which divides
into the left pulmonary artery (which enters the
left lung) and the right pulmonary artery (which
enters deoxygenated blood into the right lung)
The Heart (cont’d)

Pulmonary Veins
◦ One of two pairs of large vessels that return
oxygenated blood from each lung to the left
atrium of the heart

Aorta
◦ The main trunk of arterial circulation; consists
of 4 parts
◦ Ascending aorta
◦ Arch of the aorta
◦ Thoracic aorta
◦ Abdominal aorta
The Heart (cont’d)
Valves of the heart - Atrioventricular (AV) valves
◦ Control the flow of blood between the atria and
the ventricles
◦ Form cusps: 2 on the left side of the heart
(bicuspid, or mitral, valve) and 3 on the right
side of the heart (tricuspid valve)
◦ Supported by papillary muscles, which project
from the walls of the ventricles, and chordae
tendinae, which are chord-like structures that
prevent the AV valves from reverting into the
atria during systole
The Heart (cont’d)
Valves of the heart - Semilunar valves
◦ The aortic valve controls the flow of blood into
the aorta
◦ The pulmonic (or pulmonary) valve controls the
flow of blood into the pulmonary artery
The Heart (cont’d)
Blood supply of the heart –
 2 coronary arteries that arise from the
coronary sinus, just above the aortic valve
 The left coronary artery extends for 3½cm,
then divides into the anterior descending
artery and the circumflex branch
◦ Anterior descending artery
 Passes between the two ventricles
 Forms diagonal branches, which supply the left
ventricle
 Forms perforating branches, which supply the
anterior portion of the heart
The Heart (cont’d)
Blood supply of the heart –
◦ Circumflex branch
 Passes through the left and moves posteriorly in the
groove that separates the left atrium and ventricle
 Forms branches that supply the left lateral wall of the
left ventricle

The right coronary artery lies in the right
AV groove, and its branches supply the
right ventricle; the right coronary artery
moves to the back of the heart, where it
forms the posterior descending artery,
which supplies the interventricular septum,
AV node, and posterior papillary muscle
The Heart (cont’d)
The conduction system –
 Sinoatrial (SA) node
◦ Pacemaker of the heart
◦ Located in the right atrium, next to the superior
vena cava
◦ Impulses initiated at the SA node at an intrinsic
rate of 60-100 beats per minute

Atrioventricular (AV) node
◦ Connects the two conduction systems
 Atrial activity
 Ventricular activity
◦ Provides a “one-way” conduction between the
atria and ventricles
The Heart (cont’d)
The conduction system –
 Bundle of His (AV Bundle)
◦ Causes a delay in conduction that provides a
mechanical advantage by allowing the atria to
complete their ejection of blood before
ventricular contraction begins
◦ Penetrates into the ventricles and divides into
the right and left bundle branches
◦ The bundle branches subdivide into the
Purkinje fibers, which branch out and supply
the outer walls of the ventricles
◦ The Purkinje system supplies rapid conduction
and excitation of the right and left ventricles
The Heart (cont’d)
The physiology of the cardiac cycle –
 The cardiac cycle refers to the events
related to the flow of blood that occur from
the beginning of one heartbeat to the
beginning of the next; used to describe the
pumping action of the heart
◦ Isometric ventricular relaxation = both
ventricles are relaxed and both AV and
semilunar valves are closed
◦ Ventricular filling = AV valves open and blood
fills the ventricles
◦ Ventricular contraction = blood is forced out of
the ventricles
The Heart (cont’d)
The physiology of the cardiac cycle –
 Systole = contraction of the ventricles
◦ Atrial systole is the contraction of the atria of
the heart that precedes ventricular contraction
by a fraction of a second
◦ Ventricular systole is the contraction of the
ventricles, which begins with the closure of the
AV valves

Diastole = relaxation of the ventricles
during which they are filling with blood
◦ Ventricular diastole marks the closure of the
semilunar valves; this constitutes ventricular
filling
The Heart (cont’d)
The physiology of cardiac output –
 Cardiac output = the output of blood by
the heart per minute; determined by the
stroke volume and the heart rate
 Heart rate = the frequency with which
blood is ejected from the heart; as the
heart rate increases, cardiac output
tends to increase
 Stroke volume = the amount of blood
pumped by the left ventricle of the heart
in one contraction; this is not all the
blood contained in the ventricle
The Heart (cont’d)
The physiology of cardiac output –
 Preload = the amount of blood that the
heart must pump with each beat at the
end of diastole; measured by central
venous pressure or “pulmonary wedge
pressure”
 Afterload = the pressure or tension that
impedes the flow of blood out of the heart
 Cardiac contractility = the ability of
muscle tissue to contract when its thick
(myosin) and thin (actin) filaments slide
past each other
The Heart (cont’d)
Heart rate regulation –
 Autonomic regulation of cardiac
function
◦ Parasympathetic nervous system
 Regulates heart rate through the vagus nerve:
increased vagal activity produces a slowing of
the heart rate
 Acts to conserve energy, promote bowel/bladder
elimination, pupil contraction, etc
◦ Sympathetic nervous system
 Excitatory influence on heart rate and
contractility
 Increases blood pressure and blood sugar,
dilates bronchioles and pupils (i.e. “fight-orflight” response)
The Heart (cont’d)
Heart rate regulation –
 Electrolytes
◦ Sodium
 Due to fluid retention in the blood vessels from high
levels of sodium (hypernatremia), the heart has to
work harder to pump blood to the body
◦ Potassium
 Both hypo- and hyperkalemia can have profound
effects on cardiac contractility
 High levels of serum potassium can result in
tachycardia, then bradycardia, and death
 Low levels of serum potassium can result in
bradycardia and death
 Important electrolyte for patients on diuretics or
heart medications
The Heart (cont’d)
Heart rate regulation –
 Electrolytes
◦ Calcium
 Necessary for muscle contractility, cardiac function,
neural transmission, and blood clotting

Body Temperature
◦ Hyperthermia can lead to tachycardia, cardiac
dysrhythmias, labile blood pressure, postural
instability
◦ Hypothermia can result in a gradual decline in
heart rate and cardiac output
 Blood pressure initially rises, then falls
 Dysrhythmias
 Ventricular fibrillation
The Heart (cont’d)
Heart rate regulation –
 Emotions: the average person’s heart rate
increases with any intense emotion,
including anger, fear, happiness, and
anxiety
 Gender: a woman’s heart rate is typically
higher than that of a man because the
female heart is smaller, requiring more
beats to pump the same amount of blood
 Age: the heart rate decreases with age;
the average heart rate is 60-80 beats per
minute, whereas an infant’s is much
faster and an elderly person’s is slower
The Heart (cont’d)
Veins and arteries –
What is the Difference?
 Arteries take blood away from the heart,
whereas veins bring blood back to the
heart; generally speaking, blood found in
arteries is oxygenated, and blood found in
veins is deoxygenated; the exception is
the pulmonary arteries, which carry
deoxygenated blood from the heart to the
lungs, and the pulmonary veins, which
carry oxygenated blood from the lungs to
the heart
The Heart (cont’d)
Veins and arteries –
 Arteries
◦ Tough, elastic tubes that divide into smaller
vessels as they move away from the heart
◦ Must be able to withstand immense pressure
as they receive blood directly from the heart
◦ The largest artery in the body is the aorta,
which originates from the heart and branches
out into smaller arteries
◦ The smallest arteries are termed arterioles
◦ Intra-arterial pressure is the force applied
against the walls of the arteries as the heart
pumps blood through the body
The Heart (cont’d)
Veins and arteries –
 Veins
◦ Elastic vessels that transport blood to the heart
◦ The smallest veins in the body are called
venules
◦ Venules receive blood from the arteries via
arterioles and capillaries, then branch into
larger veins which carry the blood to the largest
vein in the body, the vena cava
◦ The vena cava transports blood directly to the
right atrium of the heart
◦ Intravenous pressure is the pressure in the
veins and is difficult to measure noninvasively
Veins
Arteries
The Heart (cont’d)
Veins and arteries –
 Venous and arterial walls
◦ The walls of both the arteries and the veins
consist of 3 layers, the tunica adventitia, tunica
media, and tunica intima
◦ In arteries, the tunica intima has an elastic
membrane lining
◦ In most veins, the tunica intima contains valves,
which are flap-like structures that allow blood to
flow in only one direction

Capillaries are located within the tissues of
the body and transport blood from the
arterioles to the venules; walls are very thin
Identify the location of veins in the upper
torso commonly used for central line and
peripheral line insertion:
Jugular
Subclavian
Superior Vena Cava
Basilic
Cephalic
Dorsal Metacarpal
1)
2)
3)
4)
5)
Digital dorsal vein
Dorsal metacarpal vein
Dorsal venous network
Cephalic vein
Basilic vein
The Lungs
The Lungs
The respiratory system consists of air
passages where gas exchange takes place
 Air passages are divided into conducting
airways and respiratory tissues

◦ Conducting airways are passages through
which air moves as it passes into and out of the
lungs; consists of the mouth, nasal passages,
nasopharynx, larynx, and the tracheobronchial
tree (trachea, bronchi, and bronchioles)
◦ Respiratory tissues are the functional unit of
the lungs; this is where gas exchange actually
occurs; consists of the respiratory bronchioles,
alveoli, and pulmonary capillaries
The Lungs (cont’d)
Conducting airways - Air is warmed, filtered, and humidified as it
passes through the conducting airways
 The trachea divides to form the right and
left primary bronchi
 The primary bronchi divide into secondary
(or lobular) bronchi, which supply each of
the lobes of the lung
 The secondary bronchi branch to form
smaller bronchi, which are named terminal
bronchioles; these are the smallest of the
conducting airways
The Lungs (cont’d)
Respiratory tissues - The lungs are the functional structures of
the respiratory system; they activate
substances such as bradykinin, which is a
potent vasodilator, and convert angiotensin
1 to angiotensin 2 (which is a potent
vasoconstrictor)
 If the lungs are the functional structures of
the respiratory system, then lobules are
the functional units of the lungs; lobules
consist of respiratory bronchioles, alveoli,
and pulmonary capillaries
The Lungs (cont’d)
Respiratory tissues - Oxygen from the alveoli diffuses across the
alveolar capillary membrane into the
blood; carbon dioxide from the blood
diffuses into the alveoli
The Lungs (cont’d)
Inhalation and exhalation - Inhalation (inspiration): the diaphragm,
assisted by external intercostal muscles,
causes the size of the chest cavity to
increase; intrathoracic pressure becomes
more negative; air is drawn into the lungs
 Exhalation (expiration): occurs as the
elastic components of the chest wall and
lung structures that were stretched during
inspiration recoil, which causes the size of
the chest cavity to decrease and the
intrathoracic pressure to increase
The Lungs (cont’d)
Inhalation and exhalation - The act of breathing normally is effortless
and does not require conscious thought
 Normal rate of respiration is usually
between 16-18 breaths per minute, which
is approximately 1 breath for every 4
heartbeats
 In normal breathing, expiration is largely
passive, and is accomplished within 4-6
seconds
 Movements are smooth, with equal
expansion bilaterally
The Lungs (cont’d)
Inhalation and exhalation - Gender plays a role in the act of breathing
◦ In men, respiratory movements are
diaphragmatic
◦ In women, there is greater movement of the
intercostal muscles
When breathing becomes labored, the
accessory muscles of the neck are used,
and nostrils may flare
 The suffix “pnea” refers to breathing

◦ Tachypnea = rapid breathing
◦ Hyperpnea = increased rate/depth of breathing
The Lungs (cont’d)
Inhalation and exhalation –
 Hyperventilation causes excessive intake
of oxygen and excessive elimination of
carbon dioxide; leads to dizziness,
faintness, and numbness to the fingers
and toes
 Hypoventilation is ventilation that is
inadequate for alveolar-capillary exchange
of carbon dioxide and oxygen; causes
increased PaCO2 and hypoxia
The Lungs (cont’d)
Breath sounds - “Normal” breath sounds = bronchial
sounds, bronchiovesicular sounds, and
vesicular sounds
 Abnormal (or adventitious) breath sounds
are those that can not be categorized as
“normal”
◦ Stridor = intense, continuous monophonic
wheezes that are accentuated during
inspiration; stridor can often be heard without
a stethoscope; indicates upper airway
obstruction
The Lungs (cont’d)
Breath sounds –
 Abnormal breath sounds –
◦ Wheezes (or rhonchi) = continuous musical
tones most commonly heard at the end of
inspiration or early expiration; indicate
narrowed airway due to a thickening of reactive
airway walls, or collapse of airways due to
pressure from surrounding pulmonary disease
◦ Pleural friction rub = low-pitched, grating or
creaking sound that occurs when inflamed
pleural surfaces rub together during
respiration; more often heard on inspiration
than expiration; may indicate pleural effusion,
pneumothorax, bacterial pneumonia
The Lungs (cont’d)
Breath sounds –
 Abnormal breath sounds –
◦ Crackles (or rales) = discontinuous, explosive,
popping sounds that originate within the
airways; more common during inspiration than
expiration; indicates accumulation of fluid
secretions or exudate within the airways, or
inflammation and edema in the pulmonary
tissue
 Fine crackles = soft, high-pitched, and very brief
 Course crackles = louder, lower in pitch, and last
longer than fine crackles
The Lungs (cont’d)
Breath sounds - Dyspnea = breathlessness, shortness of
breath; this is a subjective sensation or a
person’s perception of difficulty in
breathing that includes the perception of
labored breathing and the reaction to that
sensation; observed in at least 3 major
cardiopulmonary disease states
◦ Primary lung disease (pneumonia, asthma,
emphysema)
◦ Heart disease (pulmonary congestion)
◦ Neuromuscular disease (muscular dystrophy)
The Lungs (cont’d)
Breath sounds - Cheyne-Stokes respirations: characterized
by apnea, then deep, rapid breathing in a
repeating cycle; results from decreased
sensitivity to concentration of blood gases
Respiratory terms –
 P = pressure
 PO2 = partial pressure of oxygen (partial
pressure = the pressure that one
component of a mixture of gases would
exert if it were alone in a container)
 PCO2 = partial pressure of carbon dioxide
The Lungs (cont’d)
Respiratory terms –
 SpO2 = peripheral oxygen saturation
 SaO2 = arterial oxygen saturation
Monitoring respiratory status –
 Pulse oximetry measures oxygen
saturation (SpO2) and documents
peripheral oxygen availability
 X-ray identifies conditions compromising
respiratory status, such as pneumonia
The Kidneys
The Kidneys
The function of the kidneys is to filter
blood, selectively reabsorb the substances
that are needed to maintain constancy of
body fluid, and excrete metabolic waste
 The kidneys are smaller than a fist,
process approximately 1700L of blood, and
combine its waste products into
approximately 1.5L of urine
 Responsible for long term regulation of
arterial pressure through sodium and
water balance
 Activation of vitamin D (important for
intestinal absorption of calcium)

The Kidneys
Erythropoietin production (stimulates bone
marrow production of red blood cells)
 Initiates enzymatic processes related to
biochemical synthesis of angiotensin 2,
which is a vasoconstrictor hormone that
increases sodium reabsorption via the
proximal tubule
 Nephrons are the functional unit of the
kidney

◦ There are 1 million nephrons per kidney
◦ Each nephron is divided into 4 segments: the
proximal convoluted tubule, the Loop of Henle,
the distal convoluted tubule, and the collecting
tubule
The Kidneys (cont’d)
The proximal convoluted tubule drains the
Bowman’s capsule
 The Loop of Henle is a thin looped
structure
 The distal convoluted tubule is a distal
coiled portion of the nephron
 The collecting tubule joins with several
tubules to collect the filtrate; urine
concentration occurs in the collecting
tubule under the influence of antidiuretic
hormone

The Kidneys (cont’d)
Antidiuretic hormone (ADH), also known as
vasopressin, increases water retention by
the kidneys, produces vasoconstriction of
blood vessels, and is involved in the stress
response through fluid loss
 ADH maintains extracellular volume by
returning water to the vascular
compartment, producing concentrated
urine by removing water from the tubular
filtrate

The Kidneys (cont’d)
Each nephron consists of a glomerulus,
which is the site of blood filtration,
electrolyte reabsorption, and elimination of
unneeded materials
 The glomerulus consists of a compact tuft
of capillaries encased in a thin, doublewalled capsule called the Bowman’s
capsule
 Blood flows into the glomerular capillaries
from the afferent arteriole, and flows out
of the glomerular capillaries into the
efferent arteriole

The Kidneys (cont’d)
Urine is typically clear and amber-colored,
and consists of approximately 95% water
and 5% dissolved solids
 The kidneys normally produce an average
of 1.5L of urine each day
 Turbidity (cloudiness/haziness) of urine is
clear to slightly hazy
 Urine that is dark in color indicates high
specific gravity with a small output of urine
 Specific gravity compares the density of
urine to that of water; provides information
about hydration status and kidney function

The Kidneys (cont’d)
The specific gravity of urine is 1.010 –
1.025 with normal fluid intake
 Healthy kidneys can produce concentrated
urine with a specific gravity of 1.030 –
1.040
 During periods of marked hydration,
specific gravity can approach 1.000
 Diminished renal function results in a loss
of renal concentration ability, and specific
gravity may fall to levels of 1.006 – 1.010
 Urine pH ranges from 4.5 – 8, with an
average of 6

The Kidneys (cont’d)
Blood chemistry –
 Blood urea nitrogen: 8.0 – 20.0 mg/dL
 Creatinine: 0.7 – 1.5 mg/dL
 Sodium: 135 – 145 mEq/L
 Chloride: 98 – 106 mEq/L
 Potassium: 3.5 – 5.0 mEq/L
 Carbon dioxide: 24 – 29 mEq/L
The Kidneys (cont’d)
Blood chemistry –
 Serum creatinine reflects the glomerular
filtration rate (GFR)
◦ Product of creatine metabolism in muscles
◦ The formation and release of creatinine is
relatively constant and proportional to the
amount of muscle mass
◦ Creatinine clearance declines with age
(decrease in muscle mass)
◦ Indicator of renal function loss (i.e. if creatinine
level doubles, the GFR and renal function has
probably fallen to ½ its normal state)