Blood and Blood
Vessels
Module 17.3: Red blood cell production and recycling
• RBC production and recycling
• Events occurring in red bone marrow
• Blood cell formation (erythropoiesis) occurs only in red bone marrow
(myeloid tissue)
• Located in vertebrae, ribs, sternum, skull, scapulae, pelvis, and proximal limb
bones
• Fatty yellow bone marrow can convert to red bone marrow in cases of
severe, sustained blood loss
• Developing RBCs absorb amino acids and iron from bloodstream and
synthesize Hb
Module 17.3: Red blood cell production and
recycling
• Stages
• Proerythroblasts
• Erythroblasts
• Actively producing Hb
• After four days becomes normoblast
• Reticulocyte (80% of mature cell Hb)
• Ejects organelles including nucleus
• Enters bloodstream after two days
• After 24 hours in circulation, is mature RBC
Module 17.3: Red blood cell production and
recycling
• Events occurring at macrophages
• Engulf old RBCs before they rupture (hemolyze)
• Hemoglobin recycling
• Iron
• Stored in phagocyte
• Released into bloodstream attached to plasma protein (transferrin)
• Globular proteins disassembled into amino acids for other uses
• Heme  biliverdin  bilirubin  bloodstream
• Hemoglobin not phagocytized breaks down into protein chains and
eliminated in urine (hemoglobinuria)
Module 17.3: Red blood cell
production and recycling
• Events occurring at liver
• Bilirubin excreted into bile
• Accumulating bile due to diseases or disorders can lead to yellowish
discoloration of eyes and skin (jaundice)
• Events occurring at the large intestine
• Bacteria convert bilirubin to urobilins and stercobilins which
become part of feces
• Give feces yellow-brown or brown coloration
Module 17.3: Red blood cell
production and recycling
• Events occurring at kidneys
• Excrete some hemoglobin and urobilins
• Give urine its yellow color
• Presence of intact RBCs in urine (hematuria)
• Only after urinary tract damage
Events Occurring in the Red Bone Marrow
Start
Developing RBCs absorb amino
acids and Fe2+ from the bloodstream
and synthesize new Hb molecules.
Proerythroblasts then differentiate
into various stages of cells called
erythroblasts, which actively
synthesize hemoglobin.
Erythroblasts are named
according to total size, amount of
hemoglobin present, and size and
appearance of the nucleus.
Events in the life cycle of RBCs
Events Occurring in
Macrophages
Macrophages in liver,
spleen, and bone marrow
Fe2+
Fe2+ transported in circulation
RBC
formation
by transferrin
Heme
Amino acids
Average life span of
RBC is 120 days
90%
Biliverdin
Bilirubin
10%
Bilirubin bound
to albumin in
bloodstream
Cells destines to become RBCs first
differentiate into proerythroblasts.
Old and
damaged
RBCs
In the bloodstream,
the rupture of RBCs
is called hemolysis.
Hemoglobin that is not phagocytized
breaks down, and the alpha and beta
chains are eliminated in urine. When
abnormally large numbers of RBCs
break down in the bloodstream, urine
may turn red or brown. This condition
is called hemoglobobinuria.
Ejection of
nucleus
After roughly four days of differentiation, the
erythroblast, now called a normoblast, sheds
its nucleus and becomes a reticulocyte
(re-TIK-ū-lō-sīt), which contains 80 percent of
the Hb of mature RBC.
After two days in the bone marrow,
reticulocytes enter the bloodstream. After 24
hours in circulation, the reticulocytes
complete their maturation and become
indistinguishable from other mature RBCs.
New RBCs
released into
circulation
Liver
Bilirubin
Events Occurring in the Kidney
Absorbed into the circulation
Excreted
in bile
Hb
Events Occurring in
the Liver
Bilirubin
Urobilins
Urobilins,
sterconilins
Events Occurring in the Large Intestine
Eliminated
in feces
Eliminated
in urine
Figure17.3
Module 17.3 Review
a. Define hemolysis.
b. Identify the products formed during the breakdown of heme.
c. In what way would a liver disease affect the level of bilirubin in
the blood?
Module 17.4: Blood types
•
Blood types
•
Determined by presence or absence of cell surface markers
(antigens)
•
•
•
•
Are genetically determined glycoproteins or glycolipids
Can trigger a protective defense mechanism (immune response)
Identify blood cells as “self” or “foreign” to immune system
More than 50 blood cell surface antigens exist
•
Three particularly important
• A, B, Rh (or D)
Module 17.4: Blood types
•
Four blood types (AB antigens)
1.
Type A (A surface antigens)
•
2.
Anti-B antibodies in plasma
Type B (B surface antigens)
•
3.
Anti-A antibodies in plasma
Type AB (Both A and B surface antigens)
•
4.
No anti-A or anti-B antibodies in plasma
Type O (no A or B surface antigens)
•
Both anti-A and anti-B antibodies in plasma
The characteristics of blood for each of the four blood types
Type A
Type B
Type A blood has RBCs
with surface antigen A only.
Type B blood has RBCs
with surface antigen B only.
Surface
antigen A
If you have Type A blood,
your plasma contains anti-B
antibodies, which will attack
Type B surface antigens.
Type AB
Type O
Type AB blood has RBCs
with both A and B surface
antigens.
Type O blood has RBCs
lacking both A and B
surface antigens.
If you have Type AB blood,
your plasma has neither
anti-A nor anti-B antibodies.
If you have Type O blood,
your plasma contains both
anti-A and anti-B antibodies.
Surface
antigen B
If you have Type B blood,
your plasma contains anti-A
antibodies.
Figure17.4 1
Module 17.4: Blood types
•
Rh surface antigens
•
•
•
Separate antigen from A or B
Presence or absence on RBC determines positive or negative
blood type respectively
Examples: AB+, O–
Figure17.4 3
Module 17.4 Review
a. What is the function
of surface antigens
on RBCs?
b. Which blood type(s)
can be safely
transfused into a
person with Type O
blood?
CLINICAL MODULE 17.5:
Newborn hemolytic disease
•
Newborn hemolytic disease
•
Genetically determined antigens mean that a child can have a
blood type different from either parent
During pregnancy, the placenta restricts direct transport between
maternal and infant blood
•
•
•
Anti-A and anti-B antibodies are too large to cross
Anti-Rh antibodies can cross
• Can lead to mother’s antibodies attacking fetal RBCs
CLINICAL MODULE 17.5:
Newborn hemolytic disease
•
First pregnancy with Rh– mother and Rh+ infant
•
During pregnancy, few issues occur because no anti-Rh antibodies
exist in maternal circulation
During birth, hemorraging may expose maternal blood to fetal Rh+
cells
•
•
Leads to sensitization or activation of mother’s immune system to
produce anti-Rh antibodies
Rh–
mother
First Pregnancy of an Rh– Mother
with an Rh+ infant
Rh+
fetus
The most common form of hemolytic disease of
the newborn develops after an Rh– women has
carried an Rh+ fetus.
During First Pregnancy
Problems seldom develop during a
Maternal blood supply
first pregnancy, because very few fetal
and tissue
cells enter the maternal circulation
then, and thus the mother’s immune
system is not stimulated to produce
anti-Rh antibodies.
Placenta
Fetal blood supply
and tissue
Exposure to fetal red blood cell
antigens generally occurs during
delivery, when bleeding takes place at
the placenta and uterus. Such mixing
of fetal and maternal blood can
stimulate the mother’s immune system
to produce anti-Rh antibodies, leading
to sensitization.
Hemorrhaging at Delivery
Maternal blood supply
and tissue
Fetal blood supply
and tissue
Roughly 20 percent of Rh– mothers
who carried Rh+ children become
sensitized within 6 months of delivery.
Because the anti-Rh antibodies are not
produced in significant amounts until
after delivery, a woman’s first infant is
not affected.
Rh antigen on
fetal red blood cells
Maternal Antibody Production
Maternal blood supply
and tissue
Maternal antibodies
to Rh antigen
Figure17.5
CLINICAL MODULE 17.5:
Newborn hemolytic disease
•
Second pregnancy with Rh– mother and Rh+ infant
•
Subsequent pregnancy with Rh+ infant can allow maternal anti-Rh
antibodies to cross placental barrier
•
Attack fetal RBCs and cause hemolysis and anemia
•
•
= Erythroblastosis fetalis
Full transfusion of fetal blood may be necessary to remove
maternal anti-Rh antibodies
Prevention
•
•
RhoGAM antibodies can be administered to maternal circulation at
26–28 weeks and before/after birth
•
•
Destroys any fetal RBCs that cross placenta
Prevents maternal sensitization
Rh–
mother
Second Pregnancy of an Rh– Mother
with an Rh+ Infant
Rh+
fetus
If a subsequent pregnancy involves an Rh+ fetus,
maternal anti-Rh antibodies produced after the
first delivery cross the placenta and enter the
fetal bloodstream. These antibodies destroy
fetal RBCs, producing a dangerous anemia.
The fetal demand for blood cells increases,
and they begin leaving the bone marrow and
entering the bloodstream before completing
their development. Because these immature
During Second Pregnancy
RBCs are erythroblasts, HDN is also known
as erythroblastosis fetalis. Fortunately, the
Maternal blood supply
mother’s anti-Rh antibody production can
and tissue
be prevented if such antibodies (available
under the name RhoGAM) are administered
to the mother in weeks 26–28 of pregnancy
and during and after delivery. These
antibodies destroy any fetal RBCs that
cross the placenta before they can stimulate
Fetal blood supply
a maternal immune response. Because
and tissue
maternal sensitization does not occur, no
anti-Rh antibodies are produced.
Hemolysis of
fetal RBCs
Maternal anti-Rh
antibodies
Figure17.5
CLINICAL MODULE 17.5
Review
a. Define hemolytic disease of the newborn (HDN).
b. Why is RhoGAM administered to Rh– mothers?
Module 17.6: White blood cells
• White blood cells (leukocytes)
• Spend only a short time in circulation
• Mostly located in loose and dense connective tissues where infections often
occur
• Can migrate out of bloodstream
•
•
•
•
•
Contact and adhere to vessel walls near infection site
Squeeze between adjacent endothelial cells
= Emigration
Are attracted to chemicals from pathogens, damaged tissues, or other WBCs
= Positive chemotaxis
Module 17.6: White blood cells
• White blood cell types
1.
Granular leukocytes (have cytoplasmic granules)
•
•
•
Neutrophil
Eosinophil
Basophil
2. Agranular leukocytes (lacking cytoplasmic granules)
•
•
Monocyte
Lymphocyte
• Changing populations of different WBC types
associated with different conditions can be seen in a
differential WBC count
Module 17.6: White blood cells
• Granular leukocytes
• Neutrophils
• Multilobed nucleus
• Phagocytic cells that engulf pathogens and debris
• Eosinophils
• Granules generally stain bright red
• Phagocytic cells that engulf antibody-labeled materials
• Increase abundance with allergies and parasitic infections
• Basophils
• Granules generally stain blue
• Release histamine and other chemicals promoting
inflammation
The structure and function of white
blood cells (leukocytes)
GRANULAR LEUKOCYTES
Neutrophil
Eosinophil
Basophil
WBCs can be
divided into
two classes
Shared Properties of WBCs
• WBCs circulate for only a short portion of their
life span, using the bloodstream primarily to
travel between organs and to rapidly reach
areas of infection or injury. White blood cells
spend most of their time migrating through
loose and dense connective tissues throughout
the body.
AGRANULAR LEUKOCYTES
Monocyte
Lymphocyte
• All WBCs can migrate out of the bloodstream.
When circulating white blood cells in the
bloodstream become activated, they contact
and adhere to the vessel walls and squeeze
between adjacent endothelial cells to enter the
surrounding tissue. This process is called
emigration, or diapedesis (dia, through;
pedesis, a leaping).
• All WBCs are attracted to specific chemical
stimuli. This characteristic, called postive
chemotaxis (kē-mō-TAK-sis), guides WBCs to
invading pathogens, damaged tissues, and
other active WBCs.
• Neutrophils, eosinophils, and monocytes are
capable of phagocytosis. These phagocytes can
engulf pathogens, cell debris, or other
materials. Macrophages are monocytes that
have moved out of the bloodstream and have
become actively phagocytic.
Figure17.6
Module 17.6: White blood cells
• Agranular leukocytes
• Monocytes
• Large cells with bean-shaped nucleus
• Enter tissues and become macrophages (phagocytes)
• Lymphocytes
• Slightly larger than RBC with large round nucleus
• Provide defense against specific pathogens or toxins
Module 17.6 Review
a. Identify the five
types of white blood
cells.
b. How do basophils
respond during
inflammation?
Module 17.7: Formed element production
•
•
Formed elements
•
Appropriate term since
platelets are cell
fragments
Platelets
•
•
•
Structure: flattened
discs that appear
round when viewed
from top but
spindle-shaped in
blood smear
Function: clump
together and stick
to damaged vessel
walls where they
release clotting
chemicals
Immediate
precursor cell is
megakaryocyte
(mega-, big + karyon,
nucleus + -cyte, cell)
Module 17.8: Hemostasis
• Hemostasis (haima, blood + stasis, halt)
• Stops blood loss from damaged blood vessel walls
• Establishes framework for tissue repairs
Fig. 18.1
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Monocyte
Small
lymphocyte
Neutrophil
Platelets
Eosinophil
Small
lymphocyte
Erythrocyte
Young (band)
neutrophil
Neutrophil
Monocyte
Large
lymphocyte
Neutrophil
Basophil
Section 2: Functional Anatomy
of Blood Vessels
•
•
Blood vessels conduct blood between heart and peripheral
tissues
Two circuits
1.
2.
•
Pulmonary circuit (to and from lungs)
Systemic circuit (to and from rest of body)
Each circuit begins and ends with heart
•
Occur in sequence
Section 2: Functional Anatomy
of Blood Vessels
•
Specific vessels
•
•
•
Arteries (transport blood away from heart)
Veins (transport blood to the heart)
Capillaries (exchange substances between blood and tissues)
•
Interconnect smallest arteries and smallest veins
Section 2: Functional Anatomy
of Blood Vessels
•
General circulation pathway through circuits
1.
Right atrium (entry chamber) from systemic circuit to right ventricle,
to pulmonary circuit
Pulmonary circuit
2.
•
3.
Pulmonary arteries to pulmonary capillaries to pulmonary veins
Left atrium from pulmonary circuit to left ventricle, to systemic
circuit
Systemic circuit
4.
•
Systemic arteries to systemic capillaries to systemic veins
Figure17 Section2
Module 17.10: Arteries and
veins
•
Both arteries and veins have three layers
1.
Tunica intima (tunica interna)
•
•
Innermost layer
Endothelial cells with connective tissue with elastic fibers
•
2.
In arteries, outer margin has layer of elastic fibers (internal elastic
membrane)
Tunica media
•
•
Middle layer
Contains concentric sheets of smooth muscle
•
•
Capable of vasoconstriction or vasodilation
Collagen fibers connect tunica media to other layers
Module 17.10: Arteries and
veins
•
Both arteries and veins have three layers (continued)
3.
Tunica externa
•
•
•
•
Outermost layer
Connective tissue sheath with collagen and elastic fibers
Generally thicker in veins
Anchor vessel to surrounding tissues
A photomicrograph of an artery
and an adjacent vein
Artery
Vein
LM x 60
Figure17.10 1
The structure of the wall of an artery
Artery
Tunica intima
Smooth
muscle
Internal elastic
membrane
External
elastic
membrane
Tunica media
Endothelium
Elastic fiber
Tunica externa
Figure17.10 1
The structure of the
wall of a vein
Vein
Endothelium
Smooth muscle
Tunica intima
Tunica media
Tunica externa
Figure17.10 1
Module 17.10: Arteries and
veins
•
Five general blood vessel classes
1.
Arteries
•
•
2.
Elastic arteries (large vessels close to the heart that stretch
and recoil when heart beats)
Muscular arteries (medium-sized arteries, distribute blood
to skeletal muscles and internal organs)
Arterioles
•
3.
Poorly defined tunica externa and tunica media only 1–2
smooth muscle cells thick
Capillaries
•
Thin, exchange vessels
Module 17.10: Arteries and
veins
•
Five general blood vessel classes (continued)
4.
Venules (small veins lacking tunica media, collect blood from
capillaries)
Veins
5.
•
•
Medium-sized veins (tunica media is thin but tunica externa is thick
with longitudinal collagen and elastic fibers)
Large veins (superior and inferior venae cavae and tributaries
having thin tunica media)
The five general classes of blood vessels:
arteries, arterioles, capillaries, venules, and veins
Large Veins
Elastic Arteries
Include the superior and inferior venae cavae
and their tributaries; contain all three vessel
wall layers; have a slender tunica media
composed of a mixture of elastic and
collagen fibers
Large vessels that transport blood away from
the heart; include the pulmonary trunk and
the aorta and its major branches; are resilent,
elastic vessels capable of stretching and
recoiling as the heart beats
and arterial pressures
change
Tunica externa
Tunica media
Tunica intima
Internal elastic layer
Tunica intima
Tunica media
Tunica externa
Medium-sized Veins
Muscular Arteries
Range from 2 to 9 mm in internal diameter;
the tunica media is thin and contains
relatively few smooth muscle cells; the
thickest layer is the tunica externa, which
contains longitudinal bundles of
elastic and collagen fibers
Medium-sized arteries that distribute blood
to the body’s skeletal muscles and internal
organs
Tunica externa
Tunica media
Tunica intima
Tunica externa
Tunica media
Tunica intima
Venules
Arterioles
Collect blood from capillary beds and are the
smallest venous vessels; those smaller than
50 μm lack a tunica media and
resemble expanded capillaries
Have a poorly defined tunica externa, and
the tunica media consists of only
one or two layers of smooth muscle
cells
Smooth muscle cells
Endothelium
Tunica externa
Endothelium
Capillaries
Pores
Endothelial cells
Basal lamina
The only blood vessels whose walls permit exchange
between the blood and the surrounding interstitial
fluids due to thin walls and short
diffusion distances
Endothelial cells
Basal lamina
Figure17.10 2
Module 17.10 Review
a. List the five general
classes of blood
vessels.
b. Describe a capillary.
c. A cross section of
tissue shows several
small, thin-walled
vessels with very little
smooth muscle tissue
in the tunica media.
Which type of vessels
are these?
Module 17.11: Capillaries
•
Typical capillary consists of tube of endothelial cells with
delicate basal lamina
•
•
•
Neither tunica intima nor externa are present
Average diameter = 8 µm
•
About the same as an RBC
Two major categories
1.
2.
Continuous capillaries
Fenestrated capillaries
Module 17.11: Capillaries
•
Continuous capillaries
•
•
Endothelium is a complete lining
Located throughout body in all tissues except epithelium and
cartilage
Permit diffusion of water, small solutes, and lipid-soluble materials
•
•
•
•
Prevent loss of blood cells and plasma proteins
Some selective vesicular transport
Some capillaries have endothelial tight junctions
•
Restricted and regulated permeability
Module 17.11: Capillaries
•
Fenestrated capillaries
•
•
•
Contain windows or pores penetrating endothelium
Permit rapid exchange of water and larger solutes
Examples: capillaries in brain and endocrine organs, absorptive
areas of GI tract, kidney filtration sites
The two major types of capillaries:
continuous capillaries and fenestrated capillaries
Basal lamina
Endothelial cell
Nucleus
A continuous capillary
A fenestrated capillary
Fenestrations,
or pores
Vesicles containing
materials transported
across the endothelial cell
Basal
lamina
Boundary
between
endothelial
cells
Boundary
between
endothelial
cells
Basal
lamina
Figure17.11 1 – 2
Module 17.11: Capillaries
•
Sinusoids
•
•
•
•
•
Resemble fenestrated capillaries that are flattened and irregularly
shaped
Commonly have gaps between endothelial cells
Basal lamina is thin or absent
Permit more water and solute (plasma proteins) exchange
Occur in liver, bone marrow, spleen, and many endocrine organs
A sinusoid
Gap between
adjacent cells
Figure17.11 3
Module 17.11: Capillaries
•
Capillary bed
•
•
•
Network of capillaries with several connections between
arterioles and venules
Can have collateral arteries (functionally redundant) fusing to
one arteriole (forming an arterial anastomosis) leading to
capillary bed
Can be bypassed by arteriovenous anastomosis that directly
connects arteriole to venule
Module 17.11: Capillaries
•
Capillary bed (continued)
•
Thoroughfare channels (direct passages through capillary bed)
•
•
Begin with metarteriole segment that can constrict or dilate to control
flow
Has multiple capillaries connecting to venules
•
Have bands of smooth muscle (precapillary sphincters) to control flow
into capillary bed
•
Vasomotion (cycling contraction and relaxing changing capillary bed flow)
A capillary bed
Collateral arteries
Vein
Venule
Arteriole
Metarteriole
Smooth
muscle cells
Thoroughfare
channel
Capillaries
Precapillary
sphincter
Small
venules
Arteriovenous
anastomosis
Precapillary sphincters
KEY
Continuous
blood flow
Variable
blood flow
Figure17.11 4
Module 17.11 Review
a. Identify the two types
of capillaries.
b. At what sites in the
body are fenestrated
capillaries located?
c. Why do capillaries
permit the diffusion of
materials, whereas
arteries and veins do
not?
Module 17.12: Venous
functional anatomy
•
Venous functional anatomy and pressure
•
Blood pressure in venules and medium veins is <10% of that in
ascending aorta (largest artery)
These vessels contain valves (folds of tunica intima) that ensure
one-way flow of blood toward heart
•
•
Malfunctioning valves can lead to varicose veins (enlarged
superifical thigh and leg veins) or distortion of adjacent tissues
(hemorrhoids)
Figure17.12 1
Module 17.12: Venous
functional anatomy
•
Increasing venous blood flow
•
•
Skeletal muscle contractions squeezing veins with valves
Sympathetically controlled constriction of veins
(venoconstriction)
•
Venoconstriction can maintain arterial blood volume despite
hemorrhaging
Figure17.12 2
• Total blood volume
distribution
• Unevenly distributed
between arteries,
veins, and capillaries
• Systemic venous
system contains
nearly 2/3 of total
blood volume (~3.5 L)
• Of that , ~1 L is in
venous networks of
liver, bone marrow,
and skin
venous
The distribution of blood volume within the body
Systemic
venous
system Pulmonary
circuit
Heart
Systemic
arterial
system
Systemic
capillaries
Module 17.12 Review
a. Define varicose
veins.
b. Why are valves
located in veins, but
not in arteries?
c. How is blood
pressure maintained
in veins to counter
the force of gravity?
Module 17.13: Pulmonary
circuit
•
Arteries of pulmonary circuit differ from those in systemic
circuit
•
Pulmonary arteries carry deoxygenated blood
Right ventricle 
pulmonary trunk (large artery) 
pulmonary arteries 
pulmonary arterioles 
pulmonary capillaries (surrounded by alveoli, where gas
exchange occurs) 
pulmonary venules 
pulmonary veins 
left atrium
Fig. 19.1
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
CO2
O2
Pulmonary circuit
O2-poor,
CO2-rich
blood
O2-rich,
CO2-poor
blood
Systemic circuit
CO2
O2
The path of blood flow through the pulmonary circuit
Aortic arch
Ascending aorta
Pulmonary trunk
Superior vena cava
Left lung
Left
pulmonary
arteries
Right lung
Right
pulmonary
arteries
Left
pulmonary
veins
Right
pulmonary
veins
Alveolus
Capillary
Inferior vena cava
Descending aorta
Figure17.13 3
Module 17.13: Pulmonary
circuit
•
Major patterns of blood vessel organization
1.
Peripheral arteries and veins are generally identical between left and
right sides except near heart
Vessels change names as they branch or move into new areas
Tissues and organs are usually served by many arteries and veins
2.
3.
•
Anastomoses reduce impact of potential blockages (occlusions)
Module 17.13 Review
a. Identify the two
circulatory circuits of
the cardiovascular
system.
b. Briefly describe the three
major patterns of blood
vessel organization.
c. Trace a drop of blood
through the lungs,
beginning at the right
ventricle and ending at
the left atrium.
Module 17.14: Systemic
vessels
•
Systemic vessels
•
Arterial system
•
•
Originates from aorta (largest elastic vessel exiting left ventricle)
Venous system
•
All drain into:
• Superior vena cava (upper limbs, head, and neck)
• Inferior vena cava (trunk and lower limbs)
An overview of the systemic arterial system
Vertebral
Common carotid
Subclavian
Brachiocephalic
trunk
Axillary
Aortic arch
Ascending
aorta
Descending aorta
Diaphragm
Brachial
Celiac trunk
Renal
Gonadal
Lumbar
Common iliac
Radial
Internal iliac
Ulnar
Digital
arteries
External iliac
Palmar
arches
Deep
femoral
Femoral
Popliteal
Posterior tibial
Anterior tibial
Fibular
Dorsalis pedis
Plantar arch
Figure17.14 1
An overview of the systemic venous system
Vertebral
External jugular
Internal jugular
Subclavian
Brachiocephalic
Axillary
Superior vena cava
Brachial
Cephalic
Diaphragm
Basilic
Inferior vena cava
Renal
Gonadal
Lumbar
Radial
Median
antebrachial
Ulnar
Common iliac
Internal
iliac
External
iliac
Palmar
venous
arches
Digital
veins
Deep
femoral
Femoral
Great saphenous
Popliteal
Small saphenous
Fibular
Plantar venous arch
Dorsal venous arch
Posterior tibial
Anterior tibial
KEY
Superficial veins
Deep veins
Figure17.14 2
Module 17.14: Systemic
vessels
•
Systemic vessels
•
•
Arteries and veins are usually similar on both sides of body
One significant difference between arteries and veins is
distribution in the neck and limbs
•
•
Arteries: deep in skin, protected by bones and soft tissues
Veins: generally two sets, one deep and one superficial
•
Important in controlling body temperature
•
Venous blood flows superficially in hot weather to
radiate heat
•
Venous blood flows deep in cold weather to conserve
heat
Module 17.14 Review
a. Name the two large
veins that collect
blood from the
systemic circuit.
b. Identify the largest
artery in the body.
c. Besides containing
valves, cite another
major difference
between the arterial
and venous systems.
Module 17.15: Upper limb
vessels
• Upper limb vessels
•
Arteries
•
Branches of aortic
arch
•
Brachiocephalic
trunk
• Right subclavian (right
arm)
• Right common carotid
artery (right side head
& neck)
•
•
Left common
carotid artery
(left side head &
neck)
Left subclavian
artery (left arm)
Module 17.15: Upper limb
vessels
•
Arteries (continued)
•
Right subclavian
artery branches
•
•
•
Internal thoracic
artery (pericardium,
anterior chest wall)
Vertebral artery
(brain, spinal cord)
Arteries of the arm
•
•
Axillary artery
(through axilla)
Brachial artery
(upper limb)
Module 17.15: Upper limb
vessels
•
Arteries (continued)
•
Arteries of the forearm
•
•
•
•
Radial artery (follows radius)
Ulnar artery (follows ulna)
Palmar arches (hand)
Digital arteries (thumb and fingers)
The branches of the aortic arch and the
arteries they give rise to
Branches of the Aortic Arch
Start
Brachiocephalic
trunk
Left common
carotid artery
Left subclavian
artery
The Right Subclavian Artery
Vertebral
Internal
thoracic
Major branches of the
subclavian artery
Aortic arch
Axillary
Ascending
aorta
Deep
brachial
Arteries of the Arm
Heart
Brachial
Ulnar
collateral
arteries
Arteries of the Forearm
Descending
aorta
Radial
Ulnar
Deep palmar arch
Superficial palmar arch
Digital arteries
Figure17.15
Veins of the Neck
The veins that drain into the superior vena cava
External
jugular vein
Internal
jugular vein
Vertebral vein
Brachiocephalic vein
The Right Subclavian Vein
Veins of the Arm
Axillary vein
Cephalic vein
Veins of the Forearm
Median cubital vein
Superior vena cava
Brachial
Basilic
Superior vena cava
Median antebrachial vein
KEY
Cephalic
Superficial veins
Deep veins
Radial
Basilic
Ulnar
Digital veins
Deep palmar arch
Start
Superficial
palmar arch
Figure17.15
Module 17.15: Upper limb
vessels
•
Veins
•
•
Digital veins (empty from thumb and fingers)
Veins of the forearm
•
•
•
•
•
Superficial palmar arch (hand)
Median antebrachial vein (anterior forearm)
Cephalic vein
Basilic vein
Median cubital vein (interconnects cephalic and basilic veins)
•
Venous samples usually collected here
Module 17.15: Upper limb
vessels
•
Veins (continued)
•
Veins of the arm
•
•
•
•
Cephalic vein (lateral side of arm)
Basilic vein (median side of arm)
Brachial vein (median area of arm)
Right subclavian vein
•
Merging of axillary vein and cephalic vein
Module 17.15: Upper limb
vessels
•
Veins (continued)
•
Veins of the neck
•
•
•
•
External jugular vein (drains superficial head & neck)
Internal jugular vein (drains deep head & neck)
Vertebral vein (cervical spinal cord and posterior skull)
Veins draining into superior vena cava (SVC)
•
•
Internal thoracic vein (intercostal veins)
Brachiocephalic vein (jugular, axillary, vertebral, and internal thoracic
veins)
Module 17.15 Review
a. Name the two arteries formed by the division of the
brachiocephalic trunk.
b. A blockage of which branch from the aortic arch would interfere
with blood flow to the left arm?
c. Whenever Thor gets angry, a large vein bulges in the lateral region
of his neck. Which vein is this?
Module 17.16: Head and neck
vessels
•
Head and neck vessels
•
Arteries
•
Common carotid artery (head and neck)
• Palpated alongside trachea (windpipe)
• Contains carotid sinus (with baroreceptors monitoring blood pressure)
•
Branches of common carotid artery
• External carotid artery (neck, esophagus, pharynx, larynx, lower jaw, cranium,
and face on that side)
• Internal carotid artery (brain and eyes)
•
Vertebral artery (enters cranium and fuses with basilar artery along
ventral medulla oblongata)
Areas supplies by the external carotid, internal carotid, and vertebral arteries
Carotid canal
Basilar
Superficial
temporal
Maxillary
Occipital
Branches of the
External Carotid
Facial
Internal carotid
artery
Lingual
External
carotid
Vertebral artery
Carotid sinus
Common carotid artery
Axillary
Subclavian
Brachiocephalic trunk
Figure17.16 1
Module 17.16: Head and neck
vessels
•
Veins
•
•
•
External jugular vein (cranium, face, lower jaw, and neck on
that side)
Internal jugular vein (various cranial venous sinuses)
Vertebral vein (cervical spinal cord and posterior skull)
Areas drained by the external and internal jugular veins
Dural sinuses
draining the brain
Temporal
Maxillary
Jugular foramen
Facial
Branches of the
External Jugular
Occipital
External
jugular
Vertebral vein
Internal jugular vein
Clavicle
Right brachiocephalic
Left brachiocephalic
Axillary
Right
subclavian
Superior
vena cava
Figure17.16 2
Module 17.16 Review
a. Name the arterial structure that contains baroreceptors.
b. Identify branches of the external carotid artery.
c. Identify the veins that combine to form the brachiocephalic
vein.
Module 17.18: Vessels of the
trunk
•
Vessels of the trunk
•
Arteries
•
Somatic branches of thoracic aorta
• Intercostal arteries (chest muscles and vertebral column)
• Superior phrenic artery (superior diaphragm)
•
Visceral branches of thoracic aorta
•
•
•
•
Bronchial arteries (lung tissues not involved in gas exchange)
Esophageal arteries (esophagus)
Mediastinal arteries (tissues of mediastinum)
Pericardial arteries (pericardium)
Module 17.18: Vessels of the
trunk
• Arteries (continued)
•
Major paired abdominal aorta branches
•
•
•
•
•
Inferior phrenic arteries (inferior diaphragm and esophagus)
Adrenal arteries (adrenal glands)
Renal arteries (kidneys)
Gonadal arteries (gonads)
Lumbar arteries (vertebrae, spinal cord, abdominal wall)
Module 17.18: Vessels of the
trunk
•
Arteries (continued)
•
Major unpaired branches of abdominal aorta
•
Celiac trunk (three branches)
1.
2.
3.
•
•
Left gastric artery (stomach and inferior esophagus)
Splenic artery (spleen and stomach arteries)
Common hepatic artery (arteries to liver, stomach, gallbladder, and proximal
small intestine)
Superior mesenteric artery (pancreas, duodenum, most of large
intestine)
Inferior mesenteric artery (colon and rectum)
The branches of the thoracic aorta and the abdominal aorta
Aortic arch
Internal thoracic
Thoracic aorta
Somatic Branches of
the Thoracic Aorta
Visceral Branches of
the Thoracic Aorta
Bronchial arteries
Esophageal arteries
Intercostal arteries
Mediastinal artery
Superior phrenic artery
Pericardial artery
Diaphragm
Inferior phrenic
Adrenal
Renal
Gonadal
Lumbar
Common iliac
Celiac trunk
Left gastric
Splenic
Common
hepatic
Branches of
the celiac
trunk
Superior mesenteric
Abdomial aorta
Inferior mesenteric
Figure17.18 1
Module 17.18: Vessels of the
trunk
•
Veins
•
Azygos and hemiazygos veins (most of thorax)
1.
2.
3.
4.
Intercostal veins (chest muscles)
Esophageal veins (inferior esophagus)
Bronchial veins (passageways of lungs)
Mediastinal veins (mediastinal structures)
Module 17.18: Vessels of the
• Veins (continued)
trunk
•
Major tributaries of inferior vena cava
•
•
•
•
•
•
Lumbar veins (lumbar portion of abdomen)
Gonadal veins (gonads)
Hepatic veins (liver)
Renal veins (kidneys)
Adrenal veins (adrenal glands)
Phrenic veins (diaphragm)
The major tributaries of the superior and inferior venae cavae
Brachiocephalic
The Azygos and
Hemiazygos Veins
Superior vena cava
Azygos vein
Hemiazygos vein
Internal thoracic
Tributaries:
Esophageal, bronchial,
and mediastinal veins
Intercostal veins
Inferior vena cava
Hepatics
Phrenic
Adrenal
Renal
Gonadal
Lumbar
Common iliac
Major Tributaries of the Inferior Vena Cava
• Lumbar veins drain the lumbar portion of the abdomen,
including the spinal cord and muscles of the body wall.
• Gonadal (ovarian or testicular) veins drain the ovaries of
testes. The right gonadal vein empties into the inferior vena
cava; the left gonadal vein generally drains into the left renal
vein.
• Hepatic veins drain the sinusoids of the liver.
• Renal veins, the largest tributaries of the inferior vena
cava, collect blood from the kidneys.
• Adrenal veins drain the adrenal glands. In most
individuals, only the right adrenal vein drains into the
inferior vena cava; the left adrenal vein drains into the left
renal vein.
• Phrenic veins drain the diaphragm. Only the right phrenic
vein drains into the inferior vena cava; the left drains into
the left renal vein.
Figure17.18 2
Module 17.18 Review
a. Which vessel collects most of the venous blood inferior to the
diaphragm?
b. Identify the major tributaries of the inferior vena cava.
c. Grace is in an automobile accident, and her celiac trunk is ruptured.
Which organs will be affected most directly by this injury?
Module 17.19: Vessels of the
viscera
•
Vessels of the viscera
•
Arteries
•
Branches of common hepatic artery
•
•
•
•
•
•
Hepatic artery proper (liver)
Cystic (gallbladder)
Gastroduodenal (stomach and duodenum)
Right gastric (stomach)
Right gastroepiploic (stomach and duodenum)
Superior pancreaticoduodenal (duodenum)
Module 17.19: Vessels of the
viscera
• Arteries (continued)
•
Superior mesenteric artery
•
•
•
•
•
Inferior pancreaticoduodenal (pancreas and duodenum)
Right colic (large intestine)
Ileocolic (large intestine)
Middle colic (large intestine)
Intestinal arteries (small intestine)
Module 17.19: Vessels of the
viscera
• Arteries (continued)
•
Inferior mesenteric artery
•
•
•
•
Left colic (colon)
Sigmoid (colon)
Rectal (colon)
Branches of the splenic artery
•
•
Left gastroepiploic (stomach)
Pancreatic (pancreas)
The locations of the celiac trunk, the superior and inferior mesenteric arteries, and their branches
The Celiac Trunk
Common hepatic artery
Left gastric artery
Splenic artery
The celiac trunk
Branches of the
Common Hepatic Artery
Hepatic artery proper (liver)
Cystic (gallbladder)
Liver
Branches of the
Splenic Artery
Gastroduodenal (stomach
and duodenum)
Right gastric (stomach)
Stomach
Pancreatic (pancreas)
Right gastroepiploic
(stomach and duodenum)
Superior pancreaticoduodenal (duodenum)
Ascending colon
Left gastroepiploic
(stomach)
Spleen
Panceas
Inferior Mesenteric
Artery
Superior Mesenteric
Artery
Left colic (colon)
Sigmoid (colon)
Inferior
pancreaticoduodenal
(pancreas and
duodenum)
Right colic (large
intestine)
Ileocolic (large
intestine)
Middle colic (cut)
(large intestine)
Rectal (rectum)
Small intestine
Sigmoid colon
Rectum
Intestinal arteries (small
intestine)
Figure17.19 1
Module 17.19: Vessels of the
viscera
•
Veins
•
Hepatic portal vein tributaries
•
Superior mesenteric vein and tributaries
•
•
•
•
•
Pancreaticoduodenal
Middle colic (transverse colon)
Right colic (ascending colon)
Ileocolic (Ileum and ascending colon)
Intestinal (small intestine)
Module 17.19: Vessels of the
viscera
•
Veins (continued)
•
Hepatic portal vein tributaries (continued)
•
Splenic vein and tributaries
•
•
•
•
Left gastroepiploic (stomach)
Right gastroepiploic (stomach)
Pancreatic
Inferior mesenteric vein and tributaries
•
•
•
Left colic (descending colon)
Sigmoid (sigmoid colon)
Superior rectal (rectum)
The veins (and their tributaries) that form the hepatic portal vein
Inferior vena cava
Left gastric
Right gastric
Hepatic
Liver
Splenic Vein and Its
Tributaries
Stomach
Cystic
Hepatic portal
Spleen
Superior Mesenteric
Vein and Its Tributaries
Left gastroepiploic
(stomach)
Right gastroepiploic
(stomach)
Pancreatic
Pancreas
Pancreaticoduodenal
Middle colic (from
transverse colon)
Right colic (ascending
colon)
Ileocolic (ileum and
ascending colon)
Intestinal (small intestine)
Descending colon
Inferior Mesenteric
Vein and Its
Tributaries
Left colic (descending
colon)
Sigmoid
(sigmoid colon)
Superior rectal (rectum)
Tributaries of the Hepatic Portal Vein
• The inferior mesenteric vein collects blood from capillaries
along the inferior portion of the large intestine. It drains the
left colic vein and the superior rectal veins, which collect
venous blood from the descending colon, sigmoid colon,
and rectum.
• The splenic vein is formed by the union of the inferior
mesenteric vein and veins from the spleen, the lateral border
of the stomach (left gastroepiploic vein), and the pancreas
(pancreatic veins).
• The superior mesenteric vein collects blood from veins
draining the stomach (right gastroepiploic vein), the small
intestine (intestinal and pancreaticoduodenal veins), and
two-thirds of the large intestine (ileocolic, right colic, and
middle colic veins).
Figure17.19 2
Module 17.19 Review
a. List the unpaired branches of the abdominal aorta that supply
blood to the visceral organs.
b. Identify the three veins that merge to form the hepatic portal
vein.
c. Identify two veins that carry blood away from the stomach.
Module 17.20: Lower limb
vessels
•
Lower limb vessels
•
Arteries
•
Common iliac artery
•
•
•
•
•
Internal iliac artery (bladder, pelvic walls, external genitalia, medial
side of thigh, in females, uterus and vagina)
Lateral sacral artery
Internal pudendal artery
Obturator artery
Superior gluteal artery
Module 17.20: Lower limb
vessels
•
Arteries (continued)
•
Common iliac artery (continued)
•
External iliac artery
•
Femoral artery
•
•
•
•
•
Deep femoral artery
Femoral circumflex arteries (ventral and lateral skin and deep muscles of thigh)
Popliteal artery (posterior knee)
Posterior and anterior tibial arteries (leg)
Fibular artery (lateral leg)
Module 17.20: Lower limb
vessels
•
Arteries (continued)
•
Arteries of the foot
•
•
•
•
•
Dorsalis pedis
Dorsal arch
Plantar arch
Medial plantar
Lateral plantar
The arteries that supply the pelvis and lower limb
Anterior View
Internal Iliac and Its Branches
Common iliac
Posterior View
Internal iliac
External iliac
Femoral
Deep femoral
Right external
iliac
Lateral sacral
Internal pudendal
Obturator
Femoral circumflex
Deep femoral
Femoral
circumflex
Superior gluteal
Femoral
Descending genicular artery
Popliteal
Popliteal
Anterior tibial
Posterior tibial
Anterior tibial
Posterior tibial
Fibular
Arteries of the Foot
Fibular (peroneal)
Dorsalis pedis
Medial plantar
Lateral plantar
Dorsal arch
Plantar arch
Figure17.20 1
Module 17.20: Lower limb
vessels
•
Veins
•
•
•
External iliac veins (lower limbs, pelvis, and lower abdomen)
Internal iliac veins (pelvic organs)
External and internal iliac fuse to form common iliac veins
The veins that drain the pelvis and lower limb
Anterior View
Common iliac
Posterior View
External iliac
Internal iliac
Gluteal
Internal pudendal
Lateral sacral
Obturator
Femoral
Femoral circumflex
Deep femoral
Convergence of the great
saphenous, the deep
femoral, and the femoral
circumflex veins
Femoral
Great saphenous
Femoral
Popliteal
Small saphenous
Anterior tibial
Posterior tibial
Fibular
Dorsal venous arch
Plantar venous
arch
Digital
Figure17.20 2
Module 17.20 Review
a. Name the first two divisions of the common iliac artery.
b. The plantar venous arch carries blood to which three veins?
c. A blood clot that blocks the popliteal vein would interfere with
blood flow in which other veins?
CLINICAL MODULE 17.21: Fetal
circulation and defects
•
Unique fetal circulation structures
•
•
•
Umbilical arteries (internal iliac arteries to placenta)
Umbilical vein (placenta to ductus venosus)
Ductus venosus (drains liver and umbilical vein into inferior vena
cava)
Ductus arteriosus (pulmonary trunk to aorta)
•
•
•
Sends blood from right ventricle to systemic circuit
Foramen ovale (right to left atrium)
•
Has one-way valve to prevent backflow
The path of blood flow in a full-term fetus before birth
Foramen ovale
Ductus arteriosus
Aorta
Placenta
Pulmonary
trunk
Liver
Umbilical vein
Inferior vena cava
Ductus venosus
Umbilical
cord
Umbilical arteries
Figure17.21 1
CLINICAL MODULE 17.21: Fetal
circulation and defects
•
At birth, fetal circulation changes due to activated pulmonary
circulation
•
Resulting pressure closes foramen ovale
•
•
Fossa ovalis (shallow depression, adult remnant)
Rising oxygen levels cause ductus arteriosus to constrict and
close
•
Ligamentum arteriosum (fibrous adult remnant)
The flow of blood through the heart upon the closing
of the ductus arteriosus and foramen ovale at birth
Ductus arteriosus
(closed)
Pulmonary trunk
Left atrium
Foramen ovale
(closed)
Right atrium
Left ventricle
Right ventricle
Inferior
vena cava
Figure17.21 2
CLINICAL MODULE 17.21: Fetal
circulation and defects
•
Congenital cardiac defects
•
Ventricular septal defects
•
•
Openings in interventricular septum
Patent foramen ovale
•
•
•
Passageway remains open
Left ventricle must work harder to provide adequate systemic flow
Patent ductus arteriosus
•
•
Passageway remains open
Blood is not adequately oxygenated and skin bluish
CLINICAL MODULE 17.21
Review
a. Describe the pattern of fetal blood flow to and from the placenta.
b. Identify the six structures that are necessary in the fetal circulation
but cease to function at birth, and describe what becomes of
these structures.
Module 18.4: Coronary
circulation
• Coronary circulation
•
•
•
Provides cardiac muscle
cells with reliable
supplies of oxygen and
nutrients
During maximum
exertion, myocardial
blood flow may increase
to 9× resting levels
Blood flow is continuous
but not steady
• With left ventricular
relaxation, aorta walls recoil
(elastic rebound), which
pushes blood into coronary
arteries
Module 18.4: Coronary
circulation
•
Coronary arteries
•
Right coronary artery (right atrium, portions of both
ventricles and conduction system of heart)
•
•
•
Marginal arteries (right ventricle surface)
Posterior interventricular artery (interventricular septum and
adjacent ventricular portions)
Left coronary artery (left ventricle, left atrium, and
interventricular septum)
•
•
Circumflex artery (from left coronary artery, follows coronary
sulcus to meet right coronary artery branches)
Anterior interventricular artery (interventricular sulcus)
The locations of the arterial supply to the heart
Pulmonary
trunk
Aortic
arch
An anterior view of the coronary arteries
Left Coronary Artery
Left
atrium
Left coronary artery
Circumflex artery
Right
atrium
Right Coronary Artery
Anterior
interventricular
artery
Right
ventricle
Right coronary artery in the coronary sulcus
Left
ventricle
Marginal arteries
Anterior view
Arterial anastomoses
between the anterior
and posterior
interventricular arteries
The branches of the coronary arteries
on the posterior surface of the heart
Circumflex artery
Left
atrium
Marginal
artery
Right
atrium
Left
ventricle
Posterior
interventricular
artery
Right
ventricle
Posterior view
Right coronary
artery
Figure18.4 1 – 2
Module 18.4: Coronary
circulation
•
Coronary veins
•
•
Great cardiac vein (drains area supplied by anterior
interventricular artery, empties into coronary sinus on
posterior)
Anterior cardiac veins (drains anterior surface of right ventricle,
empties into right atrium)
The major collecting
vessels on the anterior
surface of the heart
Aortic
arch
Left
atrium
Right
atrium
Anterior cardiac veins
Great
cardiac
vein
Right
ventricle
Left
ventricle
Anterior view
Figure18.4 3
Module 18.4: Coronary
circulation
• Coronary veins (continued)
•
•
•
•
Coronary sinus (expanded vein, empties into right atrium)
Posterior cardiac vein (drains area supplied by circumflex artery)
Small cardiac vein (drains posterior right atrium and ventricle,
empties into coronary sinus)
Middle cardiac vein (drains area supplied by posterior
interventricular artery, drains into coronary sinus)
The major collecting vessels on
the posterior surface of the heart
Great
cardiac vein
Left
atrium
Coronary sinus
Right
atrium
Left
ventricle
Posterior
cardiac vein
Small
cardiac
vein
Right
ventricle
Posterior view
Middle
cardiac
vein
Figure18.4 4
Module 18.4 Review
a. List the arteries and veins of the heart.
b. Describe what happens to blood flow during elastic rebound.
c. Identify the main vessel that drains blood from the myocardial
capillaries.
Module 18.5: Internal heart
anatomy
• Internal heart anatomy
•
Four chambers
•
•
Two atria (left and right separated by interatrial septum)
Two ventricles (left and right separated by interventricular
septum)
• Left atrium flows into left ventricle
• Right atrium flows into right ventricle
Module 18.5: Internal heart
anatomy
•
Right atrium
•
•
•
•
Receives blood from superior and inferior venae cavae and
coronary sinus
Fossa ovalis (remnant of fetal foramen ovale)
Pectinate (pectin, comb) muscles (muscular ridges on anterior
atrial and auricle walls)
Left atrium
•
Receives blood from pulmonary veins
Module 18.5: Internal heart
anatomy
•
Right ventricle
•
Receives blood from right atrium through right atrioventricular (AV)
valve
•
Also known as tricuspid (tri, three)
•
•
Has three flaps or cusps attached to tendinous connective fibers
Fibers connect to papillary muscles
•
•
Innervated to contract through moderator band which keeps “slamming” of AV
cusps
Prevents backflow of blood to atrium during ventricular contraction
Module 18.5: Internal heart
anatomy
•
Left ventricle
•
Receives blood from left atrium through right atrioventricular
valve
•
•
•
•
Also known as bicuspid and mitral (mitre, bishop’s hat) valve
Prevents backflow of blood to atrium during ventricular
contraction
Has paired flaps or cusps
Trabeculae carneae (carneus, fleshy)
•
•
Muscular ridges on ventricular walls
Aortic valve
•
Allows blood to exit left ventricle and enter aorta
The internal anatomy of the heart and
the direction of blood flow between
the chambers
Ascending
aorta
Pulmonary
trunk
Superior
vena cava
Left Atrium
Right Atrium
Aortic arch
Receives blood from the superior
and inferior venae cavae and from
the cardiac veins through the
coronary sinus
Receives blood from
the pulmonary veins
Left pulmonary veins
Fossa ovalis
Pectinate muscles on the inner
surface of the auricle
Opening of the coronary sinus
Left Ventricle
Right Ventricle
Thick wall of left ventricle
Right atrioventricular (AV)
valve (tricuspid valve)
Chordae tendineae
Papillary muscle
Pulmonary valve (pulmonary
semilunar valve)
Left atrioventricular (AV)
valve (bicuspid valve)
Inferior
vena cava
Trabeculae carneae
Interventricular
septum
Moderator
band
Aortic valve
Figure18.5 1
Module 18.5: Internal heart
anatomy
•
Ventricular comparisons
•
Right ventricle has relatively thin wall
•
•
•
Ventricle only pushes blood to nearby pulmonary circuit
When it contracts, it squeezes against left ventricle wall forcing
blood out pulmonary trunk
Left ventricle has extremely thick wall and is round in cross
section
•
•
Ventricle must develop 4–6× as much pressure as right to push
blood around systemic circuit
When it contracts
1.
2.
Diameter of chamber decreases
Distance between base and apex decreases
A sectional view of the heart showing
the thicknesses of the ventricle walls
and the shapes of the ventricular
chambers
Posterior
interventricular sulcus
The left ventricle has
an extremely thick
muscular wall and is
round in cross section.
The relatively thin wall
of the right ventricle
resembles a pouch
attached to the massive
wall of the left ventricle
Fat in anterior
interventricular sulcus
Figure18.5 2
The changes in ventricle
shape during ventricular
contraction
Right
ventricle
Left
ventricle
Dilated (relaxed)
Contraction of left ventricle
decreases the diameter of the
ventricular chamber and reduces
the distance between the base
and apex
Contraction of right
ventricle squeezes
blood against the thick
wall of the left ventricle.
Contracted
Figure18.5 3
Module 18.5 Review
a. Damage to the semilunar valves on the right side of the heart
would affect blood flow to which vessel?
b. What prevents the AV valves from swinging into the atria?
c. Why is the left ventricle more muscular than the right ventricle?
Module 18.6: Heart valves
• Semilunar (half-moon shaped) valves
• Aortic and pulmonary semilunar valves
• Allow blood to exit ventricles and enter aorta or pulmonary trunk
• Do not require muscular braces because cusps are stable
• All three symmetrical cusps support each other
Module 18.6: Heart valves
• Valve action during atrial contraction and ventricular relaxation
• AV valves
• Open
• Blood pressure from contracting atria pushes cusps apart
• Chordae tendineae are loose, offering no resistance
• Semilunar valves (aortic and pulmonary)
• Closed
• Little pressure from ventricles
• Blood pressure from aorta and pulmonary arteries keep closed
The positions of the valves and associated
structures when the ventricles are relaxed
Pulmonary
veins
Left
atrium
Right
ventricle
Aortic valve (closed)
Left AV (bicuspid)
valve (open)
Left ventricle
(dilated)
Right AV (tricuspid)
valve (open)
Aortic valve (closed)
Superior view
of cardiac valves
Pulmonary valve (closed)
Chordae tendineae
(loose)
Papillary muscles
(relaxed)
KEY
Oxygenated
blood
Deoxygenated
blood
Figure18.6 1
Module 18.6: Heart valves
• Valve action during atrial relaxation and ventricular contraction
• AV valves
• Closed
• Blood pressure from contracting ventricles pushes cusps together
• Papillary muscles tensing prevent cusps from swinging into atria (would
allow backflow or regurgitation)
• Semilunar valves (aortic and pulmonary)
• Open
• High blood pressure from ventricles overcome blood pressures from aorta
and pulmonary arteries
Animation: The Heart: Valves
KEY
Aortic sinus
Oxygenated
blood
The positions of the valves and associated
structures when the ventricles contract
Aorta
Left
atrium
Deoxygenated
blood
Aortic valve (open)
Left AV (bicuspid)
valve (closed)
Left ventricle
(contracted)
Right AV (tricuspid)
valve (closed)
Chordae tendineae
(tense)
Papillary muscles
(contracted)
Ventricular contraction
Aortic valve (open)
Superior view
of cardiac valves
Pulmonary valve (open)
Frontal section through
left atrium and ventricle
Figure18.6 2
Module 18.6: Heart valves
• Cardiac skeleton
• Flexible connective tissues in which all valves are encircled and
supported
• Also surrounds aorta and pulmonary trunk
• Separates atrial and ventricular myocardium
• Contains dense bands of tough elastic tissue
A superior view of the heart
showing the cardiac skeleton
Cardiac
skeleton
Figure18.6 3
Module 18.6 Review
a. Define cardiac regurgitation.
b. Compare the structure of the tricuspid valve with that of the
pulmonary valve.
c. What do semilunar valves prevent?
Section 2: The Cardiac Cycle
•
Cardiac cycle
•
Period from one heartbeat to the beginning of next
•
Alternating periods of contraction (systole) and relaxation (diastole)
•
Atria contract as a pair first
•
•
Ventricles contract as a pair next
•
•
As ventricles are relaxed and filling
As atria are relaxed and filling
Cardiac pacemaker system coordinates
•
Typical cardiac cycle lasts 800 msec
A cardiac cycle: a heartbeat (contraction)
followed by a brief period of relaxation
Relaxation
Contraction
Figure18 Section2 1
The sequence of events during a single heartbeat
Relaxation
Atria contract
Ventricles contract
Figure18 Section2 2
Relaxation
The two phases of the cardiac cycle for a
given chamber in the heart: systole
(contraction) and diastole (relaxation)
Start
0
800 msec
msec
100
msec
Cardiac
cycle
370
msec
Figure18 Section2 3
Module 18.8: Cardiac cycle
phases
•
Steps of cardiac cycle (for 75 bpm heart rate)
1.
2.
When cycle begins, all four chambers are relaxed
Atrial systole (100 msec)
•
3.
Contracting atria fill relaxed ventricles with blood
Atrial diastole (270 msec)
•
4.
Concurrent with ventricular systole (2 phases)
Ventricular systole – first phase
•
•
Contracting ventricles push AV valves open but not enough pressure to
open semilunar valves
= Isovolumetric contraction
Module 18.8: Cardiac cycle
phases
• Steps of cardiac cycle (continued)
5.
Ventricular systole – second phase
•
6.
As ventricular pressure rises, semilunar valves open and blood
leaves ventricle (= ventricular ejection)
Ventricular diastole – early
•
•
7.
Ventricles relax and blood pressure in them drops allowing closure
of semilunar valves
Isovolumetric relaxation occurs with AV valves still closed
Ventricular diastole – late
•
•
All chambers relaxed
Ventricles fill passively to roughly 70%
Animation: The Heart: Cardiac Cycle
The phases of the cardiac cycle for a heart rate of 75 beats per minute
Start
Ventricular diastole lasts 530
msec (the 430 msec remaining in
this cardiac cycle, plus the first
100 msec of the next). Throughout
the rest of this cardiac cycle,
filling occurs passively, and both
the atria and the ventricles are
relaxed. The next cardiac cycle
begins with atrial systole and the
completion of ventricular filling.
When the cardiac cycle
begins, all four chambers
are relaxed, and the
ventricles are partially
filled with blood.
0
800
msec
msec
During atrial systole, the
atria contract, completely
filling the relaxed
ventricles with blood.
Atrial systole lasts
100 msec.
100
msec
Atrial systole
ends and atrial
diastole begins
and continues until
the start of the next
cardiac cycle.
As atrial systole ends,
ventricular systole begins.
This period, which lasts
270 msec, can be divided
into two phases.
Ventricular systole—
first phase: Ventricular
contraction pushes the
AV valves closed but
does not create enough
pressure to open the
semilunar valves. This is
known as the period of
isovolumetric
contraction.
Cardiac
cycle
Ventricular diastole
—late: All chambers are
relaxed. The ventricles
fill passively to roughly
70% of their final
volume.
370
msec
Blood flows into the
relaxed atria but the
AV valves remain
closed. This is known
as the period of
isovolumetric
relaxation.
Ventricular systole—
second phase: As
ventricular pressure rises
and exceeds pressure in
the arteries, the semilunar
valves open and blood
is forced out of the
ventricle. This is
known as the period
of ventricular
ejection.
Ventricular diastole—
early: As the ventricles
relax, the pressure in them
drops; blood flows back
against the cusps of the
semilunar valves and forces
them closed.
Figure18.8 1
The pressure changes within the aorta, left atrium, and left ventricle during the cardiac cycle
ATRIAL
ATRIAL
DIASTOLE SYSTOLE
VENTRICULAR
DIASTOLE
ATRIAL
SYSTOLE
ATRIAL DIASTOLE
VENTRICULAR
SYSTOLE
VENTRICULAR DIASTOLE
Aortic valve closes.
120
Aortic valve
opens.
Pressure (mm Hg)
90
Dicrotic notch
KEY
Atrial contraction begins.
Atria eject blood into ventricles.
60
Atrial systole ends; AV valves close.
Left
ventricle
Isovolumetric contraction.
Ventricular ejection occurs.
Semilunar valves close.
30
Isovolumetric relaxation occurs.
Left AV
valve closes.
Left atrium
AV valves open; passive ventricular
filling occurs.
Left AV valve opens.
0
0
100
200
300
400
500
600
700
800
Time (msec)
The correspondence of the heart sounds with events during the cardiac cycle
S1
S4
S2
S3
S4
Heart sounds
“Lubb”
“Dubb”
Figure18.8 2
Module 18.8: Cardiac cycle
phases
• Heart sounds
•
•
•
•
•
•
•
•
S1 (known as “lubb”)
Start of ventricular contraction and closure of AV valves
S2 (known as “dupp”)
Closure of semilunar valves
S3 and S4
Very faint and rarely heard in adults
S3 (blood flowing into ventricles)
S4 (atrial contraction)
Module 18.8 Review
a. Provide the alternate terms for heart contraction and heart
relaxation.
b. List the phases of the cardiac cycle.
c. Is the heart always pumping blood when pressure in the left
ventricle is rising? Explain.
Module 18.9: Cardiac output and
conduction
system
• Conduction system
•
•
Network of specialized cardiac muscle cells
Responsible for initiating and distributing stimulus to contract
•
•
Can do so on their own (= automaticity)
Components
1.
Sinoatrial (SA) node
•
•
2.
Embedded in posterior wall of right atrium
Impulse generated by this pacemaker is distributed through other
components
Internodal pathways
•
Distribute signal to atria on way to ventricles
Module 18.9: Cardiac output and
conduction
system
• Conduction system (continued)
3.
Atrioventricular (AV) node
•
•
•
•
Located at junction of atria and ventricles
Also contains pacemaker cells
If SA node damaged, can maintain heart rate at 40–60 bpm
Can conduct impulses at maximum rate of 230/min
•
4.
= Maximum heart rate
AV bundle and branches
•
•
•
Located in interventricular septum
Normally only electrical connection between atria and ventricles
Branches relay signal to ventricles toward heart apex
Module 18.9: Cardiac output and
conduction system
•
Conduction system (continued)
5.
Purkinje fibers
•
Large-diameter conducting cells
•
•
As fast as small myelinated axons
Final part of conduction system that triggers ventricular systole
Animation: The Heart: Conduction System
The components of the conducting system and their specific functions
Each heartbeat begins with an action
potential generated at the sinoatrial
(sī-nō-Ā-trē-al) node, or simply the
SA node. The SA node is embedded
in the posterior wall of the right
atrium, near the entrance of the
superior vena cava. The electrical
impulse generated by this cardiac
pacemaker is then distributed by
other cells of the conducting system.
Purkinje fibers are large-diameter
conducting cells that propagate action
potentials very rapidly—as fast as small
myelinated axons. Purkinje cells are the
final link in the distribution network, and
they are responsible for the depolarization
of the ventricular myocardial cells that
triggers ventricular systole.
In the atria, conducting cells are
found in internodal pathways,
which distribute the contractile
stimulus to atrial muscle cells as the
impulse travels toward the ventricles.
The atrioventricular (AV) node is located at the junction
between the atria and ventricles. The AV node also contains
pacemaker cells, but they do not ordinarily affect the heart
rate. However, if the SA node or internodal pathways are
damaged, the heart will continue to beat because in the
absence of commands from the SA node, the AV node will
generate impulses at a rate of 40–60 beats per minute.
The AV node delivers the stimulus
to the AV bundle, located within the
interventricular septum. The AV bundle is
normally the only electrical connection
between the atria and the ventricles.
Moderator
band
The AV bundle leads to the right and left
bundle branches. The left bundle
branch, which supplies the massive left
ventricle, is much larger than the right
bundle branch. Both branches extend
toward the apex of the heart, turn, and
fan out deep to the endocardial surface.
Figure18.9 3
An action potential is
generated at the SA
node, and atrial
activation begins.
The distribution of the
contractile stimulus, and
how the conducting system
coordinates the contractions
of the cardiac cycle
SA node
Time = 0
The stimulus spreads
across the atrial
surfaces by cell-to-cell
contact within the
internodal pathways
and soon reaches the
AV node.
AV node
Elapsed time = 50 msec
A 100-msec delay
occurs at the AV
node. During this
delay, atrial
contraction begins.
AV
bundle
Bundle
branches
Elapsed time = 150 msec
As atrial contraction
continues, the impulse
travels along the
interventricular septum
within the AV bundle and
the bundle branches to
the Purkinje fibers and, via
the moderator band, to
the papillary muscles of
the right ventricle.
Moderator
band
Elapsed time = 175 msec
The impulse is distributed
by Purkinje fibers and
relayed throughout the
ventricular myocardium.
Atrial contraction is
completed, and
ventricular contraction
begins.
Purkinje fibers
Elapsed time = 225 msec
Figure18.9 4
Module 18.9 Review
a. Define automaticity.
b. If the cells of the SA node failed to function, how would the
heart rate be affected?
c. Why is it important for impulses from the atria to be delayed at
the AV node before they pass into the ventricles?
Module 18.11: Autonomic control
of heart function
• Autonomic control of heart function
• Pacemaker cells in the SA and AV nodes cannot maintain a stable
resting potential
• Always gradual depolarization leading to threshold (= prepotential or
pacemaker potential)
• Fastest rate at SA node (80–100 bpm)
• Brings other conduction system components to threshold
Heart rate under three conditions: at rest, under parasympathetic
stimulation, and under sympathetic stimulation
A prepotential or pacemaker potential
in a heart at rest
+20
Membrane
potential
(mV)
Normal (resting)
Prepotential
(spontaneous
depolarization)
0
–30
Threshold
–60
Heart rate: 75 bpm
0.8
1.6
Time (sec)
2.4
Figure18.11 1
Module 18.11: Autonomic control
of heart function
• Autonomic changes to intrinsic heart rate
• Factors that change rate of depolarization and repolarization will
change time to threshold
• Leads to change in heart rate
• Bradycardia (heart rate slower than normal, <60 bpm)
• Tachycardia (heart rate faster than normal, >100 bpm)
• Parasympathetic stimulation
• Binding of ACh from parasympathetic neurons opens K+ channels, slows
heart rate
• Slows rate of depolarization
• Extends duration in repolarization
Module 18.11: Autonomic control
of heart function
• Autonomic changes to intrinsic heart rate (continued)
• Sympathetic stimulation
• Binding of noepinephrine to beta-1 receptors leads to opening of ion
channels, and increases heart rate
• Increases rate of depolarization
• Shortens duration in repolarization
Heart rate under three conditions: at rest, under parasympathetic
stimulation, and under sympathetic stimulation
A prepotential or pacemaker potential
in a heart at rest
Increased heart rate resulting when
ACh released by parasympathetic
neurons opens chemically gated K+
channels, thereby slowing the rate
of spontaneous depolarization
Parasympathetic stimulation
+20
Membrane
potential
(mV)
0
–30
Threshold
Hyperpolarization
–60
Slower depolarization
Heart rate: 40 bpm
0.8
1.6
2.4
Time (sec)
Figure18.11 2
CLINICAL MODULE 18.14:
Electrocardiograms (ECG)
•
Electrocardiograms record electrical activities of heart from
body surface through time
•
Can be used to assess performance of:
•
•
•
•
Nodes
Conduction system
Contractile components
Appearance varies with placement and number of electrodes or
leads
An electrocardiogram: a standard placement of
leads and the tracing that results
One of the standard
configurations for the
placement of leads for
an ECG
800 msec
The features of a typical electrocardiogram
P wave
QRS complex
T wave
+1
R
+0.5
T
P
0
Millivolts
Q S
–0.5
P–R interval
Q–T interval
Figure18.14 1
CLINICAL MODULE 18.14:
Electrocardiograms (ECG)
•
Typical ECG features
•
P wave (atrial depolarization)
•
•
QRS complex (atrial repolarization and ventricular depolarization)
•
•
•
Atria begin contracting ~25 msec after P wave start
Larger wave due to larger ventricles added to atrial activity
Ventricles begin contracting shortly after R wave peak
T wave (ventricular repolarization)
CLINICAL MODULE 18.14:
Electrocardiograms (ECG)
•
Typical ECG features (continued)
•
P-R interval (start of atrial depolarization to start of ventricular
depolarization)
•
•
>200 msec may indicate damage to conducting pathways or AV
node
Q-T interval (time for ventricles to undergo a single cycle)
•
Starts at end of P-R interval to end of T wave
Module 18.16: Blood pressure
and flow
•
Blood flow (F) is directly proportional to blood pressure
•
•
Increased pressure = increased flow
The pressure gradient (difference from one end of vessel to
other) is more important
•
Large gradient from aorta to capillaries
•
Smaller, more numerous vessels produce more resistance,
reducing pressure and flow
•
•
At aorta: 2.5 cm diameter and 100 mm Hg pressure
At capillaries: 8 µm diameter and 25 mm Hg pressure
Module 18.16: Blood pressure
and flow
•
Arterial pressure is variable
•
•
Rising during ventricular systole (systolic pressure)
Declining during ventricular diastole (diastolic pressure)
•
Commonly written with a “/” between pressures
•
•
Pulse pressure (difference between systolic and diastolic)
•
•
Example: 120/90
Example: 120 – 90 = 30 mm Hg
Mean arterial pressure (MAP)
•
•
Adding 1/3 of pulse pressure to diastolic pressure
Example: 90 + (120 – 90)/3 = 100 mm Hg
The calculation of mean
arterial pressure
Pulse pressure,
the difference
between systolic
and diastolic
pressures
Systolic
120
Mean arterial pressure
(MAP), the sum of the
diastolic pressure and
one-third of the pulse
pressure
100
80
Here, MAP is
Diastolic
60
mm Hg
90 + (120 – 90 )/3
or
90 + 10 = 100 mm Hg
40
20
0
Aorta Elastic Muscular Arterioles Capillaries Venules Medium- Large Venae
sized veins veins cavae
arteries arteries
Figure18.16 4
Module 18.16: Blood pressure
and flow
•
Capillary exchange
•
Involves:
•
Filtration
•
•
•
•
•
Capillary hydrostatic pressure (CHP) provides driving force
Water and small solutes leave capillaries
Larger molecules (like plasma proteins) remain in blood
Diffusion
Osmosis
The effect of capillary
hydrostatic pressure on
water and small solutes
Capillary
hydrostatic
pressure
(CHP)
Amino acid
Blood protein
Glucose
Ions
Interstitial fluid
Small solutes
Hydrogen bond
Water molecule
Endothelial
cell 1
Endothelial
cell 2
Figure18.16 5
Module 18.16 Review
a. Define blood flow, and describe its relationship to blood pressure
and peripheral resistance.
b. In a healthy individual, where is blood pressure greater: in the aorta
or in the inferior vena cava? Explain.
c. For an individual with a blood pressure of 125/70, calculate the mean
arterial pressure (MAP).