Transcript Ch 21 Student_Bloodvessels Lab

Chapter 21
Blood
Vessels and
Circulation
STRUCTURE AND FUNCTION
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Blood vessels form a network in our body taking the blood
from the heart to the tissues of the body and returning it back
to the heart.
Classified by size and histological organization
The direction of the flow of the blood in different vessels of the
body is:
 Heart  Arteries  Arterioles  Capillaries 
Venules Veins  Heart
Anatomy of Blood Vessels
• 60,000 miles of blood vessels in the
body!! ONLY 1 MILE of those is
actually visible to the eye. To put that
in perspective, the distance around the
earth is about 25,000 miles, making the
distance your blood vessels could travel
if laid end to end more than 2x around
the earth.
• Arteries carry blood AWAY FROM
heart
• Heart, arteries, and capillaries
contain approximately 30-35% of
the blood at any given time.
• Veins carry blood BACK TO heart
• Veins contain 60-65% of the blood
• About 1/3 of the blood in the veins is
circulating in the liver, bone marrow
and skin.
• Capillaries connect smallest arteries
to veins
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Pulse Pressure-Pulse
• Difference between systolic and diastolic pressures is called the
PULSE PRESSURE. (EX: 120-80 pp = 40)
– Measures maximum force generated on small arteries
– Pulse pressure is felt as a throbbing pulsation in an artery
(pulse) during systole as the elastic arteries are expanded by the
blood being forced into them by ventricles. (Strongest in the
arteries close to the heart, becomes weaker in arterioles and
disappears in capillaries and veins.)
• Pulse is routinely measured in the radial, common carotid,
brachial, femoral, temporal arteries. Pulse rate is generally the
same as heart rate between 70 and 80 beats/min.
– Pulse is the temporary increase in arterial pressure that can be
felt throughout the body. Pulse rate can be used to measure heart
rate for a normal, healthy heart and can be an indicator of heart
health. A very weak contraction may NOT register a pulse rate.
– Heart rate is the rate at which the heart beats or contracts. Any
contraction, even if weak, is part of the heart rate.
– Rapid resting pulse rate is called tachycardia and a slow pulse
rate is termed bradycardia.
Evaluating Circulation
• BP is usually measured in the left brachial artery using
an instrument known as Sphygmomanometer.
• Systolic blood pressure is the force of blood recorded
during ventricular contraction. Diastolic blood
pressure is the force of blood recorded during
ventricular relaxation.
• The various sounds that are heard while taking blood
pressure are called Korotkoff sounds.
Vessel Structure
Blood vessels that take the blood away
from the heart.
The wall of arteries and veins consists
of 3 major layers
Tunica intima – innermost layer lines
the blood vessel; exposed to blood
Tunica media – middle layer
– smooth muscle, collagen, and
elastic tissue (strengthens vessel
prevents rupture).
– Capable of vasoconstriction and
vasodilation
Tunica externa – outermost layer
– mainly composed of collagen
– that anchorsanchors vessel to nearby
organs, giving it stability.
Arteries and Arterioles
ARTERIES
Elastic (CONDUCTING) arteries
• Found CLOSER TO THE HEART; able to receive blood under
HIGHER pressure
Muscular (DISTRIBUTING) arteries
• Found CLOSER TO THE ORGANS AND TISSUES.
• Distribute blood to the body's skeletal muscle and internal
organs. Most of the arterial system vessels are muscular
arteries.
ARTERIOLES small microscopic
arteries delivering blood to
capillaries. Contain 3 tunica
layers
• regulate the amount of
blood entering into the
capillaries through
vasoconstriction and
vasodilation
Veins and Venules
VEINS
• Same three tunics; flexible, thinner walled –Low BP- collapse
when empty; expand easily to accommodate increased blood flow
• Contain VALVES to prevent the backflow of blood.
• Lumen is larger than arteries.
• Operate as blood reservoirs
VENULES
• Formed by joining of small capillaries.
• Contain tunica interna and media
– NO TUNICA EXTERNA
• Collect blood from capillaries and drain it into veins.
• Most WBC immerge from blood thru these
Disorders
ARTERY
Aneurysm- weak point in an artery
or the heart wall
• forms thin-walled, bulging sac where weak spot
in elastic fibers; may rupture at any time causing
hemorrhage also stroke, shock, pain (pressure on
other structures) possible death
VEIN
Deep vein thrombosis (DVT) formation of blood clot
(thrombus) in a deep vein predominantly in the legs.
• Signs may include pain, swelling, redness,
warmness, and engorged superficial veins.
Varicose Veins results in part from the failure of
valves
• Walls of some leg veins lose elasticity and
stretch; valves weaken allowing blood to pool;
veins enlarge, blood stagnates and forms a
clot and edema
• hemorrhoids are varicose veins of the anal
canal
20-10
Circulatory Routes
• Most common route
– heart  arteries  arterioles  capillaries  venules  veins
• Portal system
– blood flows through two CONSECUTIVE capillary networks
before returning to heart
• Hypothalamic hypophyseal portal system - anterior
pituitary
• Hepatic portal system (intestines-liver)
• Anastomoses - branches of two blood vessels merge; provide
alternate routes for blood to reach a tissue or organ.
– arteriovenous (shunt) - artery flows directly into vein
bypasses capillaries
– venous - one vein empties directly into another; Blockage
of vein rarely life threatening
– Arterial - two arteries merge; Common around joints where
movement may temporarily compress vessel
Collateral Circulation
Capillaries
• Microscopic network of vessels which
connect arterioles and venules and
permeate all active tissues
• Composed of TUNICA INTIMA ONLY!
• Primary function - permit the
EXCHANGE OF NUTRIENTS AND
GASES between the blood and the
tissues.
• Blood flow from arterioles feed into
capillaries by ring of smooth muscle
fibers called precapillary sphincters1) open sphincters- high blood
perfusion 2) closed sphincters- blood
moves through thoroughfare
channel to a venule – little fluid
exchange occur.
• 3/4th of capillaries are shut down
at a given time
Major arteries
of the body
Aorta Branches
• Brachiocephalic trunk
• 1 artery - right side only.
• Branches into
• R. subclavian
• Blood to right side
• R. common carotid
• Supplies blood to
the head, neck,
• L. common carotid
• Blood source to the head
• L. subclavian
• Left side of the body
Splenic
Common Carotid Arteries
Each common carotid divides
• External carotid artery supplies blood to most
external head structures of the
neck, lower jaw, and face
– Facial
– Occipital
• Internal carotid artery enters skull delivers blood to
brain
– Divides into three branches
1. Ophthalmic artery
2. Anterior cerebral
artery
3. Middle cerebral artery
4. Posterior cerebral
artery
• Supplies brain with blood
• Supplies meninges and
spinal cord
• Supplies cervical
vertebrae and deep neck
muscles
• Left /right VERTEBRAL
arteries
– Branch from
SUBCLAVIAN arteries
– Enter cranium through
foramen magnum
– Branches fuse to form
basilar artery
• Which branches to
form posterior
cerebral arteries
– Become posterior
communicating
arteries
The Vertebral Arteries
AnastomosesArterial Supply
of Brain
• Paired vertebral
arteries combine to
form basilar artery
on pons
• Cerebral arterial
Circle of Willis on
base of brain formed
from anastomosis of
basilar and internal
carotid arteries
– Circle of Willis brain, internal ear
and orbital
structures
– Basilar artery
supplies
cerebellum, pons,
inner ear
Circle
of
Willis
Flow of Blood
through the
Lungs
Coronary Circulation
Left (LCA) and right (RCA) coronary arteries
Vessel changes names
as they pass to different
regions
• Subclavian- supplies
breast, pericardium
gives rise to axillary
• Axillary - scapular,
pectoral regions,
triceps, deltoid,
latissiumus dorsi to
brachial
• Brachial used for BP
and radial artery for
pulse
• Brachial to Radial and
Ulnar
• Palmar arches to
hand
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• Thoracic aorta supplies
• viscera and body wall
• Bronchial
• Esophageal
• Mediastinal branches
• Phrenic arteries
Abdominal Aorta and Its Branches
Celiac Trunk Branches
Celiac trunk supplies:
Upper abdominal viscera:
1. Diaphragm
• Inferior phrenic
2. Stomach
• Left gastric
3. Spleen
• splenic
4. Liver
• Common hepatic
• Left gastric
5. Indirectly the
Pancreas
• Pancreatic
branches off
splenic
Descending Aorta- Abdominal Aorta
• Divides at terminal segment
of the aorta into:
– Left common iliac artery
– Right common iliac
artery
• Unpaired branches
– Major branches to
visceral organs
• Paired branches
– To body wall
– Kidneys
– Urinary bladder
– Structures outside
abdominopelvic cavity
Mesenteric Arteries
Supply the intestines
Arteries of the
Lower Extremity
branch to the lower limb arise
from externsal iliac branch
of the common iliac artery
Back of Knee
Veins of the
Systemic Circulation
Drain blood from entire
body & return it to
right side of heart
The Systemic Circuit
Veins of the Foot
• Capillaries of the sole
– Drain into a network of plantar veins
• Plantar venous arch
– Drain into deep veins of leg:
• Anterior tibial vein
• Posterior tibial vein
• Fibular vein
– All three join to become popliteal vein
• Dorsal Venous Arch
– Collects blood from: Superior surface of foot/Digital veins
– Drains into two superficial veins
1. Great saphenous vein (drains into femoral vein)
2. Small saphenous vein (drains into popliteal vein)
The Systemic Circuit
• Popliteal Vein
– Becomes the femoral vein
• Before entering abdominal wall, receives blood from:
– Great saphenous vein
– Deep femoral vein
– Femoral circumflex vein
• Inside the pelvic cavity
– Becomes the external iliac vein
• External Iliac Veins
– Are joined by internal iliac veins
• To form right and left common iliac veins
– The right and left common iliac veins
» Merge to form the inferior vena cava
Hepatic portal system
• A portal vein connects two organs without the involvement of
heart in between. The portal veins begin and end with capillaries.
• HPP detours venous blood from GI tract to liver on its way to the
heart. Connects capillaries of intestines and other digestive organs
to modified capillaries of the liver (hepatic sinusoids) causes
blood to pass thru 2 capillary beds before returning to the heart.
• HPP give liver 1st contact with nutrients before the blood
distributes to the body. Liver monitors blood content
– Allows blood to be cleaned of bacteria and other toxins
picked up in GI tract
• Blood enters general circulation through the inferior vena cava via
the hepatic vein.
• The system extends from about the lower portion of the esophagus
to the upper part of the anal canal as well as venous drainage from
the gallbladder, stomach, spleen and pancreas.
Hepatic portal system
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Hepatic portal system
Tributaries of the Hepatic Portal Vein
1. Inferior mesenteric vein
– Drains part of large
intestine
2. Splenic vein
– Drains spleen, part of
stomach, and pancreas
3. Superior mesenteric vein
– Drains part of stomach,
small intestine, and part
of large intestine
4. Left and right gastric veins
– Drain part of stomach
5. Cystic vein
– Drains gallbladder
Veins of Shoulder and
Upper Limb
• Cephalic superficial
empties into the
axillary vein;
• communicates
with the basilic
• Basilic superficial
visible with the naked
eye
Blood will often
be shunted from
superficial to
deep vessels or
vice versa to
maintain stable
body temperature
• Brachial Vein deep
drains Radial and
Ulnar veins into the
axillary
• Axillary –deep brings
blood from thorax,
axilla (armpit), and
upper arm
INTERNAL JUGULAR
vein receives most of
the blood from the
brain.
Drains: Facial vein;
Superficial temporal
EXTERNAL JUGULAR
vein drain the external
structures of the head
Drains: Occipital
Jugulars and upper
limb are drained into
the SUBCLAVIAN vein
Veins of
the Head
and Neck
The Systemic Circuit
• Veins of the Thoracic Cavity
– SUBCLAVIAN veins drain into LEFT AND RIGHT
BRACHIOCEPHALIC VEINS
– The brachiocephalic veins merge to form the
SUPERIOR VENA CAVA (SVC)
• Tributaries of the Superior Vena Cava
– Azygos vein and hemiazygos vein receive blood from:
1. Intercostal veins
2. Esophageal veins
3. Veins of other mediastinal structures