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CARDIOVASCULAR SYSTEM
Chapter 11
CIRCULATORY SYSTEM2 interconnected circuits
connected at the heart; also
contains arteries, capillaries,
veins, and blood
 ARTERIES- blood vessels
going away from the heart
 VEINS- blood vessels going
toward the heart
 CAPILLARIES- smallest vessels
exchange materials between
the blood and interstitial fluid
1. SYSTEMIC CIRCUIT- exits
the LEFT side of heart and
travels to BODY (hi O2)
2. PULMONARY CIRCUIT –
exits the RIGHT side of the
heart and travels to LUNGS
(low O2)
HEART
- located in the thoracic cavity
- size of a persons fist
- 4 chambers
- 2/3 of the heart lies to the
left of the sternum
APEX- points to the left hip and is
lies on the diaphragm
BASE- where blood vessels
emerge- point toward the right
shoulder and lies beneath
second rib
MEDIASTINUM- opening between
the lungs
HEART WALL- 3 LAYERS
1. ENDOCARDIUM- (white) inner most
layer- slick decreasing friction to allow
blood flow
2 MYOCARDIUM-- thick cardiac muscle3. EPICARDIUM (visceral pericardium)slick outer covering which decreases
friction on the heart
PERICARDIUM-double layered sac that gives heart room to
move, but resists over-expansion
1. VISCERAL PERICARDIUM lines the outside of
the heart
2. PARIETAL PERICARDIUM- protects heart and
anchors it to diaphragm
3. PERICARDIAL FLUIDSerous fluid- which
reduces friction found in the PERICARDIAL
CAVITY (space between the layers)
HEART
BICUSPID (2) – located on
left side (blood returned
from lungs)
TRICUSPID (3)- located on
right side ( blood
returned from body)
CHORDAE TENDINAE- thin
strands of connective
tissue
Cuspid Valve between atria and
ventricles
CONTROL- Chordae tendinae- pull valves close
during ventricular contraction- prevents
backflow of blood to the atria
When ventricle is relaxed valve is open
SEMILUNAR VALVES3 cusps which close tightly
by the backflow of blood
-contraction by the
ventricles forces them
open
AORTIC SEMILUNAR VALVEleaves the left ventricleleads to aorta and
systemic circuit
PULMONARY SEMILUNAR
VALVE- leaves the right
ventricle- leads to
pulmonary artery and
pulmonary circuit
DIFFERENCES BETWEEN VEINS AND
ARTERIES
ARTERIES-carry blood away from the heart
1. Walls of ARTERIES are much thicker than
veins
- much more tunica media-(muscle) and
less lumen (opening)
-needs to be able to expand and contract
- if near the heart will have hi blood
pressure
DIFFERENCES BETWEEN VEINS AND
ARTERIES
VEINS- carry blood back to the heart
2. VEINS- have much larger lumen and very little tunica
media
- away from the heart will have low blood pressure (no
need to expand)
-skeletal muscle aides in helping blood return by
contracting the veins
- larger veins have venous valves that close preventing
backflow due to gravity
VARICOSE VEINS- veins inefficient in blood return- blood
pools
STRUCTURE OF BLOOD VESSELS
ARTERIES ARTERIOLESCAPILLARIESVENULES
VEINS
WALLS OF BLOOD VESSELS HAVE 3 LAYERS (except
capillaries)- that surround the LUMEN (opening)
1. TUNICA INTERNA- innermost (one cell thick) slick
surface
2. TUNICA MEDIA-bulky, middle coat of smooth muscle
3. TUNICA EXTERNA- outermost composed of fibrous
connective tissue ; supports and protects the blood
vessels
CAPILLARIES AND CAPILLARY BEDS
(pg 342)
CAPILLARY- have only 1 layer of cells
(TUNICA INTERNA)
- thin walls permit the exchange of materials
between the blood and interstitial fluid
CAPILLARY BEDSnetworks of tiny capillaries intertwined that
typically contains 2 types of vessels (1
vascular shunt and 10-100 true capillaries)
VASCULAR SHUNT- vessel that directly
connects arterioles and venulesprecapillary sphincters will close and direct
the blood straight to venules when needed
(cold)
CAPILLARY BEDSTRUE CAPILLARIES- when precapillary
sphincters are open blood will take part in
exchange with local cell tissue
- CAPILLARIES are the only type of
blood vessel that can redirect bloodflow
HEART CHAMBERS (4 TOTAL)
LEFT AND RIGHT ATRIA (atrium sing.)
-Located superior
-smaller and less muscular
-atrial contraction forces blood into
ventricles
- receive return blood flow from:
1.
SYSTEMIC CIRCUIT- dumps into right atrium
2.
PULMONARY CIRCUIT- dumps into left
atrium
-
LEFT AND RIGHT VENTRICLES
located inferior
- Much larger and more
muscle
- receive blood from
atria
- contract to send blood
out:
LEFT VENTRICLEOUT to systemic
circuit
RIGHT VENTRICLEOUT to pulmonary
circuit
-
CIRCULATION THROUGH THE HEART
Beginning in the right atrium trace a drop of blood
through the pulmonary circuit , back to the heart and
out the aorta. Identify where it is oxygenated and
deoxygenated.
1. _Right atrium (deoxygenated 7._pulmonary vein_
2.
Tricuspid valve ________8.__left atrium______
3.______right ventricle_______9.____bicuspid valve___
4._pulmonary semilunar valve__10.___left ventricle__
5._pulmonary artery_____
11. __aortic semilunar valve
6.__lungs_________
12. aorta
13. body
14 vena cava

FEATURES OF THE HEART
INTERVENTRICULAR
SEPTUM- thick muscle
(myocardium) that
divides ventricles
INTERVENTRICULAR
SULCUS- line on outside
that divides ventricles
INTERATRIAL SEPTUMmuscle that divides atria
INTERATRIAL SULCUS- line
on outside that divides
atria
FEATURES OF THE HEART
ATRIOVENTRICULAR SULCUS- line on
surface of heart that separates atria from
ventricles
ATRIOVENTRICULAR VALVES- (AV valves)
valves between the atria and ventricles
FUNCTION OF CIRCULATORY
SYSTEM
Transports
1.
2.
3.
4.
OXYGEN
NUTRIENTS
WASTES
HORMONES
CARDIAC CYCLE

CARDIAC CYCLE- one complete series of
heart contractions which constitutes a
single heartbeat.
CARDIAC CYCLE
The heart beats in a rhythmic “Lub-Dub”
due to the coordinated contractions of
both atria and both ventricles.
 Heart sounds are produced by the closing
of heart valves !!!!
 ATRIAL CONTRACTION increases the
pressure and forces blood into the
Ventricles ( which are relaxed at that time)
no sound

CARDIAC CYCLE
VENTRICULAR CONTRACTION- increases
pressure forcing the atrioventricular valves
closed preventing backflow to atria (Lub
sound) while also forcing the semilunar
valves open to allow blood to arteries
 VENTRICULAR RELAXATION allows
semilunar valves to close to prevent
backflow into the ventricles (Dub sound)

Heart Electrical Conduction SystemCardiac cells have an inherent ability to
contract in a rhythmic manner. Specific
pace-setting cardiac cells can send out
electrical signals to adjacent cells causing
simultaneous contraction. INTERCALATED
DISCS allow all the proper cells to contract
together.
Heart Electrical Conduction SystemSINOATRIAL NODE- (SA NODE) group of PACEMAKER cells
located in the wall of the right atrium which set the pace
for the entire cardiac cycle. They send out impulses to
both atria to allow cause them to contract.
ATRIOVENTRICULAR NODE (AV NODE)- group of cells
located in the inferior part of the right atrium near the
interatrial septum which receive impulses from the SA
NODE pause for a while to allow the atria to empty and
then send the impules down to the ventricles via the
ATRIOVENTRICULAR BUNDLE (Bundles of His) and the
PURKINJE FIBERS
Heart Electrical Conduction SystemATRIOVENTRICULAR BUNDLE- special muscle
fibers located in the interventricular septum
which pass the electrical signal down to the
Purkinje fibers and cause the ventricles to
contract simultaneously.
 PURKINJE FIBERS- located at the APEX of the
heart and expands up the outer walls of each
ventricle cause the simultaneous contraction.

Heart Electrical Conduction SystemELECTROCARDIOGRAM- measures the
electrical events that occur during a cardiac
cycle
 P WAVE Sino atrial node firing- (then a
pause)


QRS COMPLEX- AV bundle and Purkinje fibers
fire (much larger amount of electricity needed)

T WAVE- ventricles repolarizing (atria
depolarize during QRS so it is masked)
BLOOD PRESSURE
BLOOD PRESSURE- the primary force that
pushes blood through arteries and
arterioles.

It is influenced by cardiac output,
peripheral resistance and blood volume.
Blood pressure is regulated by the nervous
system, hormones, and kidneys.

FINDING BLOOD PRESSURE
SPHYGMOMANOMETER- blood pressure cuff which is wrapped around
the arm and finds the pressure on the BRACHIAL ARTERY.
How to use a sphygmomanometer along with a stethoscope to find
blood pressure
1.
Pump up the cuff so that the artery becomes compressed and
blood can not pass through.
2.
Slowly open the release valve allowing cuff pressure to drop.

3.Using a stethoscope listen below the cuff for the first sounds of
blood squeezing through the cuff. When you hear a tapping sound
this is the SYSTOLIC PRESSURE.

4.Allow pressure to decrease until no tapping sound is heard.
The moment it becomes inaudible is the DIASTOLIC PRESSURE.
Factors affecting Blood pressure
1. PERIPHERAL RESISTANCE- the friction of
blood rubbing against the vessels. Peripheral
resistance is affected by the viscosity of the
blood and the size of the lumen (opening)

2. BLOOD VOLUME- (about 5 liters) When blood volume or blood pressure rises the
kidneys respond by removing more water from
the body as urine. When blood pressure is low
kidneys reduce the amount of urine produced.

3. CARDIAC OUTPUT
CARDIAC OUTPUT = Heart rate x
Stroke Volume
The average heart rate at rest is 75
beats/minute and the average stroke
volume is 70 mL per beat
 STROKE VOLUME- volume of blood
ejected by the contraction of ventricles.

CARDIAC OUTPUT
MEDULLA OBLONGATA (of the brain) controls the cardiac cycle by sending
signals to the SINOATRIAL NODE
 ARTERIAL BLOOD PRESSURE
SYSTOLIC PRESSURE (typically 120 mmHg).highest value when ventricles contract
DIASTOLIC PRESSURE (typically 70-80
mmHg) lowest value when ventricles are
relaxed
Factors affecting Blood pressure
4. NERVOUS SYSTEMVASOCONSTRICTION- making the arteries smallerif blood pressure levels are too low or oxygen levels are
too low
VASODILATION- opening up the arteries
5. HORMONAL CONTROLSEPINEPHRINE and NOREPINEPHRINE- produced by
adrenal glands in fight or flight- increases cardiac output
and constricts blood vessels
Drugs which increase blood pressure- antidiuretics and
nicotine ANTIDIURETIC- stimulates kidneys to conserve
water
Major Veins
SUPERIOR VENA CAVA- enters the top of
the right atrium
INFERIOR VENA CAVA- enters the bottom of
the right atrium
PULMONARY VEIN- enters the left atrium
MAJOR ARTERIES
AORTA- exits the left ventricle has large
curve (AORTIC ARCH)
PULMONARY ARTERY- exits right ventricle
and branches under aortic arch to each
lung