for B.SC nursing students

1. Venous system:
Anatomy:

2. Arteries: Veins:
• Distribute blood to various
parts.
• Are deeply situated.
• No superficial arteries.
• Follow definite pathways.
• Only one systemic artery,
the aorta – takes oxy.
Blood away from heart.
• Drain blood from them.
• Superficial or deep.
• Names of superficial doesn’t
correspond to that of arteries.
• More difficult to follow –
connect in irregular
networks.
• 3 systemic veins – coronary
sinus, IVC, SVC – return
deoxy. Blood to the heart.

3. • CORONARY SINUS:
• Main vein of heart.
• Located in coronary sulcus.
• Opens into the right atrium between the orifice of IVC
and tricuspid valve.
• Wide venous channel into which 3 veins drain:
• 1. Great cardiac vein: ant. Interventricular sulcus –
joins at the left end.
• 2. middle cardiac vein: (PIVS) and
• 3. small cardiac vein on its right end.
• Ant. Cardiac veins – open directly into the right
atrium

5. • IVC:
• Largest vein of the body.
• Begins ant. To L5 by the union of CIV – ascends
behind the peritoneum to the right of midline –
pierces the caval opening of diaphragm at T8 – enters
inferior part of right atrium.
• Drains abdomen, pelvis and lowerlimbs.
• Compressed during later stages of preg. By enlarging
uterus – produces edema of ankles and feet and
temporary varicose veins.

7. • SVC:
• Empties blood into superior part of right atrium.
• Begins posteriorly to the right first costal cartilage by
the union of right and left brachiocephalic veins and
ends at level of 3rd costal cartilage – enters right
atrium.
• Drains head, neck, chest and upper limbs.

9. Veins of head and neck:
• Most blood draining from the head passes into 3 pairs
of veins – internal jugular, external jugular, and
vertebral veins.
• Within the brain, all veins drain into dural venous
sinuses and then into the int. jugular veins.
• Dural venous sinuses are endothelial lined venous
channels between layers of cranial dura matter.

11. • INTERNAL JUGULAR VEINS:
• Flow of blood from the dural venous sinuses into the
internal jugular veins:
• ‘superior sagittal sinus’ – begins at the frontal
bone, where is receives a vein from the nasal cavity,
and passes posteriorly to the occipital bone.
• Along its course, it receives blood from the superior,
medial, and lateral aspects of the cerebral
hemispheres, meninges, and cranial bones.
• SSS turns to the right and drains into the right
transverse sinus.
• Inferior sagittal sinus – much smaller.
• Begins posterior to the attachment of falx cerebri and
receives great cerebral vein – becomes straight sinus.

13. • Great cerebral vein drains the deeper parts of the
brain.
• Along its course the inferior sagittal sinus also receives
tributaries from the superior and medial aspects of the
cerebral hemispheres.
• Straight sinus – runs in tentorium cerebelli –
formed by union of the inferior sagittal sinus and the
great cerebral vein.
• Also receives blood from the cerebellum and usually
drains into the left transverse sinus.
• Transverse sinuses – begin near occipital bone –
pass laterally and anteriorly, and become sigmoid
sinuses near the temporal bone.

15. • Receive blood from cerebrum, cerebellum and cranial
bones.
• Sigmoid sinus – located along the temporal bone.
• Pass through the jugular foramina – terminate in the
‘internal jugular veins’.
• Drain the transverse sinus.
• Cavernous sinus – located on either side of the
sphenoid bone.
• Receive blood from the ophthalmic veins from the
orbits, and from the cerebral veins from the cerebral
hemispheres.
• Ultimately empty into the transverse sinuses and
internal jugular veins.

17. • Unique because they have nerves and a major blood
vessel passing through them on their way to the orbit
and face.
• Occulomotor nerve, trochlear nerve, and ophthalmic
and maxillary branches of the trigeminal nerve as well
as the internal carotid arteries pass through the
cavernous sinuses.
• Right and left internal jugular veins – pass
inferiorly on either side of the neck lateral to the
internal carotid and common carotid arteries.
• Unite with the subclavian veins posterior to the
clavicles at the sternoclavicular joints to form the right
and left brachicephalic veins.

18. • From here blood flows into the SVC.
• General structures drained by the internal jugular
veins are the brain, face and neck.

19. • EXTERNAL JUGULAR VEINS:
• Right and left ext. jugular veins begin in the parotid
glands near the angle of the mandible.
• Superficial veins that descend through the neck across
the SCM muscles.
• Terminate at a point opposite the middle of the
clavicles, where they empty into the subclavian veins.
• Drain structures external to the cranium, such as scalp
and superficial and deep regions of the face.
• When venous pressure rises, during heavy coughing or
straining or in cases of heart failure, the EJV become
very prominent along the side of the neck.

21. • VERTEBRAL VEINS:
• Right and left vertebral veins originate inferior to the
occipital condyles.
• Descend through successive transverse foramina of
the first 6 cervical vertebrae and emerge from the
foramina of the 6th cervical vertebra to enter the
brachicephalic veins in the root of the neck.
• Drain deep structures in the neck such as the cervical
vertebrae, cervical spinal cord, and some neck
muscles.

23. Veins of the upper limbs:
• Both superficial and deep veins return blood from the
upper limbs to the heart.
• Superficial veins are located just deep to the skin and
are often visible.
• Anastomose extensively with one another and with
deep veins, and they don’t accompany arteries.
• Superficial veins are larger than deep veins and return
most of the blood from the upper limbs.
• Deep veins are located deep in the body.
• Usually accompany arteries and have the same names
as the corresponding arteries.
• Both have valves; more numerous in deep veins.

25. • Superficial veins:
• 1. Cephalic veins:
• Principal superficial veins that drain upper limbs are
cephalic and basilic veins.
• Originate in the hand and convey blood from the
smaller superficial veins into the axillary veins.
• Cephalic veins begin on the lateral aspect of the ‘dorsal
venous arches’. (networks of veins on the dorsum of
the hands formed by the ‘dorsal metacarpal veins’.)
• These veins in turn drain the ‘dorsal digital veins’ –
which pass along the sides of the fingers.
• Following their formation from dorsal venous arches,
arch around the radial side of the forearms to the ant.
Surface and ascend through the entire limbs.

27. • End where they join the axillary veins, just inferior to
the clavicles.
• Accessory cephalic veins originate either from a
venous plexus on the dorsum of the forearms or from
the medial aspects of the dorsal venous networks of
the hands, and unite with cephalic veins just inferior
to the elbow.
• Drain blood from the lateral aspect of the upper limbs.
• Basilic veins:
• Begin on the medial aspects of the dorsal venous arch
and ascend along the posteromedial surface of the
forearm and anteromedial surface of the arm.

29. • Drain blood from the medial aspects of the upper
limbs.
• Ant. To the elbow, basilic veins are connected to the
cephalic veins by the ‘median cubital veins’, which
drain the forearm.
• If veins must be punctured for an injection,
transfusion, or removal of a blood sample, the medial
cubital veins are preferred.
• After receiving median cubital veins, basilic veins
continue ascending until they reach the middle of the
arm.
• Penetrate the tissues deeply and run alongside the
brachial arteries until they join the brachial veins.

31. • As the basilic and brachial veins merge in the axillary
area, they form the axillary veins.
• Median antebrachial veins:
• Begin in the palmar venous plexuses (network of veins
on the palms).
• Drain the palmar digital veins in the fingers.
• Median ante brachial veins ascend anteriorly in the
forearms to join the basilic or median cubital veins,
sometimes both.
• Drain the palms and forearms.

33. • Deep veins:
• Radial veins:
• Paired radial veins begin at the deep palmar venous
arches.
• Arches drain the palmar metacarpal veins in the
palms.
• Drain lateral aspects of forearms and pass alongside
the radial arteries.
• Just inferior to the elbow joint, the radial veins unite
with the ulnar veins to form brachial veins.
• Ulnar veins:
• Paired – larger than the radial veins – begin at the
superficial palmar venous arches.

35. • Drain the common palmar digital veins and the proper
palmar digital veins in the fingers.
• Ulnar veins drain the medial aspect of the forearms,
pass alongside the ulnar arteries, and join with the
radial veins to form the brachial veins.
• Brachial veins:
• Paried – accompany brachial arteries.
• Drain forearms, elbow joints, arms and humerus.
• Join with the basilic veins to form axillary veins.
• Axillary veins:
• Ascend to the outer borders of the first ribs – become
subclavian veins.
• Tributaries: correspond with branches of axillary a.

37. • Drain the arms, axillas, and superolateral chest wall.
• Subclavian veins:
• Continuations of the axillary veins that terminate at
the sternal end of the clavicles – unite with the
internal jugular veins to form the brachiocephalic
veins.
• Subclavian veins drains the arms, neck, and thoracic
wall.
• Thoracic duct of the lymphatic system delivers lymph
into the junction between the left subclavian and the
left internal jugular veins.
• Right lymphatic duct delivers lymph into the junction
between right subclavian and right internal jugular
veins.

39. • In a procedure called ‘central line placement’, the right
subclavian vein is frequently used to administer
nutrients and medication and measure venous
pressure.

40. Veins of thorax:
• Brachiocephalic veins drain some portions of the
thorax, most thoracic structures are drained by a
network of veins, called the azygous system – runs on
either side of the vertebral column.
• System consists of 3 veins – azygos, hemiazygous, and
accessory hemiazygous veins.
• Ultimately they empty into the SVC.

42. • Brachiocephalic vein:
• Right and left brachiocephalic veins – formed by the
union of the subclavian and internal jugular veins –
drain blood from the neck, upper limbs, mammary
glands, and superior thorax.
• BCV unite to form the SVC.
• Azygous system:
• Collects blood from the thorax and the abd. Wall.
• Serves as a bypass for the IVC that drains blood from
the lower body.
• Several small veins directly link the azygous system
with the IVC.

44. • Large veins that drain the lower limbs and abdomen
conduct blood into the azygous system.
• If the IVC or portal system becomes obstructed, the
azygous system can return blood from lower body to
the SVC.
• 1. azygous vein: ant. To the vertebral column.
• Slightly to the right of the midline.
• Begins at the junction of left ascending lumbar and
right subcostal veins near the diaphragm.
• At the level of T4, it arches over the root of right lung
to end in SVC.
• Azygous vein drains the right side of thoracic wall,
thoracic viscera, and abd. Wall.

46. • Receives blood from right posterior intercostal,
hemiazygous, esophageal, acc. Hemiazygous,
mediastinal, pericardial, and bronchial veins.
• 2. hemiazygous vein:
• Ant. Of vertebral column.
• Slightly to the left of the midline.
• Often brings at the junction of left asccending lumbar
and left subcostal veins.
• Terminates by joining azygous vein at about the level
of T9.
• Drains the left side of thoracic wall, thoracic viscera,
and abdominal wall.
• Receives blood from 9th to 11th left post. Intercostal,
esophageal, mediastinal, and acc. Hemiazygous veins.

48. • 3. accessory hemiazygous vein:
• Also anterior to the vertebral column.
• Left of the midline.
• Begins at the 4th or 5th intercostal space.
• Descends from the 5th to 8th thoracic vertebra or ends
in the hemiazygous vein.
• Terminates by joining the azygous vein at about the
level of the 8th thoracic vertebra.
• Drains the left side of the thoracic wall.
• Receives blood from the 4th to 8th left posterior
intercostal veins, left bronchial, and mediastinal veins.

50. Veins of the abdomen and pelvis:
• Blood from the abdominal and pelvic viscera and
abdominal wall returns to the heart via the IVC.
• Most carry return flow from parietal branches of the
abdominal aorta, and their names correspond to those
of arteries.
• IVC doesn’t receive veins directly form the GIT,
spleen, pancreas, and GB.
• These organs pass their blood into a common vein, the
hepatic portal vein, which delivers the blood to the
liver.
• Superior mesenteric and splenic veins unite to form
the hepatic portal vein.

52. • Special flow of venous blood called the ‘hepatic portal
circulation’.
• After passing through the liver for processing, blood
drains into the hepatic veins, which empty into the
IVC.
•
• IVC:
• 2 common iliac veins that drain the lower limbs,
pelvis, and abdomen unite to form the IVC.
• Extends superiorly through the abdomen and thorax
to the right atrium.

53. • COMMON ILIAC VEINS:
• Formed by union of the internal and external iliac
veins ant. To the sacroiliac joint.
• Represent the distal continuation of the IVC at their
bifurcation.
• Right is shorter than left.
• Drain the pelvis, external genitals, and lower limbs.
• INTERNAL ILIAC VEINS:
• Begin near the superior portion of the greater sciatic
notch and run medial to their corresponding arteries.
• Drain thigh, buttocks, external genitals and pelvis.

55. • EXTERNAL ILIAC VEINS:
• Companions of the internal iliac arteries.
• Begin at the inguinal ligaments as continuations of the
femoral veins.
• End anterior to the sacroiliac joint where they join
with the internal iliac veins to form the common iliac
veins
• Drain lower limbs, cremaster muscle in males, and the
abdominal wall.
• LUMBAR VEINS:
• Series of parallel veins – 4 on each side –drain blood
from both sides of post. Abd. Wall, vertebral canal,
spinal cord, and meninges.

57. • Run horizontally with the lumbar arteries.
• Connect at right angles with the right and left
ascending lumbar veins – form the origin of the
corresponding azygous or hemiazygous vein.
• Drain blood into the ascending lumbars and then run
into the IVC.
• GONADAL VEINS:
• Ascend with gonadal arteries along the posterior abd.
Wall.
• In males – ka testicular veins.
• Left testicular vein drains into left renal vein.
• Right drains into IVC.

59. • Females – ka ovarian veins.
• Drain ovaries.
• Left ovarian vein empties into the left renal vein.
• Right – into IVC.
• RENAL VEINS:
• Large renal veins pass anterior to the renal arteries.
• Left is longer than right.
• Left receives left testicular vein (or ovarian vein),
inferior phrenic vein, usually left suprarenal veins.
• Right renal vein empties into the IVC posterior to the
duodenum.
• Drain kidneys.

61. • SUPRARENAL VEINS: 2 in no.
• Drain adrenal glands.
• INFERIOR PHRENIC VEINS:
• Drain diaphragm.
• HEPATIC VEINS:
• Drain liver.

62. Veins of the lower limbs:
• Blood is drained from lower limbs by superficial and
deep veins.
• Superficial veins often anastomose with one another
and with deep veins along their length.
• Deep veins have the same names as corresponding
arteries.
• All veins of the lower limbs have valves – which are
more numerous than in veins of the upper limbs.

64. • Superficial veins:
• 1. great saphenous veins:
• Longest veins in the body – ascend from the foot to
the groin in the subcutaneous layer.
• Begin at the medial end of the dorsal venous arches of
the foot.
• Dorsal venous arches are networks of veins on the
dorsum of the foot formed by the ‘dorsal digital veins’
– which collect blood from the toes, and then unite in
pairs to form the ‘dorsal metatarsal veins’, which
parallel the metatarsals.
• As the dorsal metatarsal veins approach the foot, they
combine to form the dorsal venous arches.

65. • Great saphenous veins pass ant. To the
medial malleolus of the tibia and then
superiorly along the medial aspect of the
leg and thigh just deep to the skin.
• Receive tributaries from superficial
tissues and connect with the deep veins
as well.
• Empty into the femoral veins at groin.
• Drain mainly the medial side of the leg
and thigh, groin, ext. genitals and abd.
Wall.
• Along their length, great saphenous
veins have 10-20 valves – more in leg
than in thigh.

66. • These veins are more likely
to be subject to varicosities
than other veins in the lower
limbs because they must
support a long column of
blood and aren’t well
supported by skeletal
muscles.
• Are often used for prolonged
administration of IVF.
• Important in very young
children and in patients of
any age who are in shock
and whose veins are
collapsed.

68. • Coronary bypass grafting – if
multiple blood vessels need
to be grafted, sections of great
saphenous vein are used
along with atleast one artery
as a graft.
• After the vein is removed and
divided into sections, they are
used to bypass the blockages.
• Vein grafts are reversed so
that valves don’t obstruct the
blood flow.

69. • Small saphenous veins:
• Begin at the lateral aspect of the dorsal venous arches
of the foot.
• Pass posterior to the lateral malleolus of the fibula and
ascend deep to the skin along the posterior aspect of
the leg.
• Empty into popliteal veins in the popliteal fossa, post.
To the knee.
• Drain foot and posterior aspect of the leg.
• May communicate with the great saphenous veins in
the proximal thigh.

71. • Deep veins:
• Posterior tibial veins:
• Plantar digital veins on the plantar surfaces of the toes
unite to form the plantar metatarsal veins, which
parallel the metatarsals.
• In turn unite to form the deep plantar venous arches.
• From each arch emerges the medial and lateral plantar
veins.
• Medial and lateral plantar veins, posterior to the
medial malleolus of the tibia, form the paired
posterior tibial veins, which sometimes merge into a
single vessel.
• Accompany the posterior tibial artery through the leg.

72. • Ascend deep to the muscles in the posterior aspect of
the leg and drain the foot and posterior compartment
muscles.
• 2/3rds of the way up the leg, the posterior tibial veins
drain blood from the fibular veins, which drain lateral
and posterior leg muscles.
• Posterior tibial veins unite with the anterior tibial
veins just inferior to the popliteal fossa to form the
popliteal veins.

73. • Anterior tibial veins:
• Paired.
• Arise in the dorsal venous arch and accompany the
ant. Tibial artery.
• Ascend in the interosseous membrane between the
tibia and fibula and unite with the posterior tibial
veins to form the popliteal vein.
• Drains ankle joint, knee joint, tibiofibular joint, and
ant. Portion of the leg.

75. • Popliteal veins:
• Formed by union of the ant. And post. Tibial veins.
• Also receive blood from the small saphenous veins and
tributaries that correspond to branches of the
popliteal artery.
• Drain knee joint, and the skin, muscles, bones of
portions of the calf and thigh around the knee joint.
• Femoral veins:
• Accompany femoral arteries and are the continuation
of popliteal veins just superior to the knee.
• Extend up the post. Surface of thighs and drains the
muscles of the thigh, femurs, ext. genitals, and
superficial LNs.

77. • Largest tributaries: deep veins of the thigh.
• Just before penetrating the abd. Wall, they receive
deep femoral and great saphenous veins.
• After entering the pelvic cavity – external iliac veins.
• In order to take blood samples or pressures recordings
from the right side of the heart, a catheter is inserted
into the femoral vein as it passes through the femoral
triangle.
• Catheter passes through the external and common
iliac veins and IVC into the right atrium.

78. Hepatic portal circulation:
• Carries venous blood from the GIT organs and spleen
to the liver.
• A vein that carries blood from one capillary network to
another is called a ‘portal vein’.
• Hepatic portal vein receives blood from capillaries of
GIT organs and the spleen and delivers it to the
sinusoids of the liver.
• After a meal, hepatic portal blood is rich in nutrients
absorbed from the GIT.
• Liver stores some of them and modifies others before
they pass into the general circulation.

79. • E.g: liver converts glucose into glycogen for storage,
reducing blood glucose level shortly after a meal.
• Also detoxifies harmful substances, such as alcohol,
that have been absorbed from the GIT and destroys
bacteria by phagocytosis.
• Superior mesenteric and splenic veins unite to form
the hepatic portal vein.
• Superior mesenteric vein drains blood from the small
intestine and portions of the large intestine, stomach,
and pancreas through the jejunal, ileal, ileocolic, right
colic, middle colic, pancreaticoduodenal, and right
gastroepiploic veins.

81. • Splenic vein drains blood from the stomach, pancreas,
and portions of the large intestine through short
gastric, left gastroepiploic, pancreatic, and inferior
mesenteric veins.
• Inferior mesenteric vein – which passes into the
splenic vein, drains portions of the large intestine
through the superior rectal, sigmoidal, and left colic
veins.
• Right and left gastric veins, which open directly into
the hepatic portal vein, drain the stomach.
• Cystic vein, which also opens into the hepatic portal
vein, drains the gall bladder.

82. • At the same time the liver is receiving nutrient rich but
deoxygenated blood via the hepatic portal vein, it also
is receiving oxygenated blood via the hepatic artery.
• Oxygenated blood mixes with the deoxygenated blood
in sinusoids.
• Blood leaves the sinusoids of the liver through the
hepatic veins, which drain into the IVC.

83. Pulmonary circulation:
• Carries deoxygenated blood from the right ventricle to
the air sacs within lungs and returns oxygenated blood
from the air sacs to the left atrium.
• Pulmonary trunk emerges from the right ventricle and
passes superiorly, posteriorly, and to the left.
• Then divides into 2 branches: right pulmonary artery
to the right lung and the left pulmonary artery to the
left lung.
• After birth, pulmonary arteries are the only arteries
that carry deoxygenated blood.
• On entering the lungs, the branches divide and
subdivide until finally they form capillaries around the
air sacs within the lungs.

84. • CO2 passes from the blood into the air sacs and is
exhaled.
• Inhaled O2 passes from the air within lungs into the
blood.
• Pulmonary capillaries unite to form venules and
eventually pulmonary veins, which exit the lungs and
carry the oxygenated blood to the left atrium.
• 2 left and 2 right pulmonary veins enter the left
atrium.
• After birth, the pul. Veins are the only veins that carry
oxygenated blood.
• Contractions of the left ventricle then eject the
oxygenated blood into the systemic circulation.

85. Fetal circulation:
• Circulatory system of a fetus.
• Exists only in fetus and contains special structures
that allow the developing fetus to exchange materials
with its mother.
• Differs from the postnatal circulation because the
lungs, kidneys, and GIT don’t begin to function until
birth.
• Fetus obtains O2 and nutrients from and eliminates
CO2 and other wastes into the maternal blood.

87. • Exchange of materials between fetal and maternal
circulations occurs through the ‘placenta’, which forms
inside the mother’s uterus and attaches to the
umbilicus of the fetus by the ‘umbilical cord’.
• Placenta communicates with the mother’s
cardiovascular system through many small blood
vessels that emerge from the uterine wall.
• Umbilical cord contains blood vessels that branch into
capillaries in the placenta.
• Wastes from the fetal blood diffuse out of capillaries,
into spaces containing maternal blood in the placenta,
and finally into the mother’s uterine veins.

88. • Nutrients travel in the opposite route – from the
maternal blood vessels to the intervillous spaces to the
fetal capillaries.
• Normally, there is no direct mixing of maternal and
fetal blood because all exchanges occur by diffusion
through capillary walls.
• Blood passes from the fetus to the placenta via two
umbilical arteries.
• These branches of the internal iliac arteries are within
the umbilical cord.
• At the placenta, fetal blood picks up O2 and nutrients
and eliminates CO2 and wastes.

89. • Oxygenated blood returns from the placenta via a
single umbilical vein.
• This vein ascends to the liver of the fetus, where it
divides into 2 branches.
• Some blood flows through branch that joins the
hepatic portal vein and enters the liver, but most of the
blood flows into the second branch, the ductus
venosus, which drains into the IVC.
• Deoxygenated blood returning from lower body
regions of the fetus mingles with oxygenated blood
from the ductus venosus in the IVC.
• Mixed blood then enters the right atrium.

91. • Deoxygenated blood returning from upper body
regions of the fetus enters the SVC and also passes
into the right atrium.
• Most of the fetal blood doesn’t pass from the right
ventricle to the lungs, as it does in post natal
circulation, because an opening called the ‘foramen
ovale’ exists in the septum between right and left atria.
• Most of the blood that enters the right atrium passes
through the foramen ovale into the left atrium and
joins the systemic circulation.
• Blood that does pass into the right ventricle is pumped
into the pulmonary trunk, but little of this blood
reaches the nonfunctioning fetal trunk.

93. • Instead, most is sent through the ductus arteriosus, a
vessel that connects the pulmonary trunk with the
aorta.
• Blood in the aorta is carried to all fetal tissue through
the systemic circulation.
• When the common iliac arteries branch into the
external and internal iliacs, part of the blood flows
into the internal iliacs, into the umbilical arteries, and
back to the placenta for another exchange of materials.

94. • After birth, when pulmonary, renal and digestive
functions begin, the following vascular changes occur:
• 1. when the umbilical cord is tied off, blood no longer
flows through the umbilical arteries, they fill with
connective tissue, and the distal portions of the
umbilical arteries become fibrous cords called –
‘medial umbilical ligaments’.
• Although the arteries are closed functionally only a
few minutes after birth, complete obliteration of the
lumens may take 2 to 3 months.
• 2. umbilical vein collapses but remains as the
‘ligamentum teres’ (round ligament), a structure that
attaches the umbilicus to the liver.

96. • 3. ductus venosus collapses but remains as the
ligamentum venosum, a fibrous cord on the inferior
surface of the liver.
• 4. placenta is expelled after child birth.
• 5. foramen ovale normally closes shortly after birth to
become the ‘fossa ovalis’, a depression in the
interatrial septum. When an infant takes its first
breath, the lungs and blood flow tot the lungs
increases.
• Blood returning from the lungs to the heart increases
pressure in the left atrium.
• This closes the foramen ovale by pushing the valve
that guards it against the interatrial spetum.
• Permanent closure occurs in about an year.

98. • 6. ductus arteriosus closes by vasoconstriction almost
immediately after birth and becomes the ‘ligamentum
arteriosum’.
• Complete anatomical obliteration of the lumen takes
1-3 months.

99. Development of blood vessels and blood:
• Development of blood cells and the formation of blood
vessels begins outside the embryo as early as 15 to 16
days in the ‘mesoderm’ of the wall of the yolk sac,
chorion and connecting stalk.
• About 2 days later, blood vessels form within the
embryo.
• Early formation of the CVS is linked to the small
amount of yolk in the ovum and yolk sac.
• As the embryo develops rapidly during the 3rd week,
there is a greater need to develop a CVS to supply
sufficient nutrients to the embryo and remove wastes
from it.

100. • Blood vessels and blood cells develop from the same
precursor cell, called a ‘hemangioblast’.
• Once mesenchyme develops into hemangioblasts, they
can give rise to cells that produce blood vessels or cells
that produce blood cells.
• Blood vessels develop form ‘angioblasts’, which are
derived from hemangioblasts.
• Angioblasts aggregate to form isolated masses and
cords throughout the embyronic discs called ‘blood
islands’.
• Spaces soon appear in the islands and become the
lumens of the blood vessels.
• Some of the angioblasts immediately around the
spaces give rise to the endothelial lining of BVs.

102. • Angioblasts around the endothelium form the tunics of the
larger blood vessels.
• Growth and fusion of the blood islands form an extensive
network of blood vessels throughout the embryo.
• By continuous branching, blood vessels outside the
embryo connect with those inside the embryo, linking the
embryo with the placenta.
• Blood cells develop from ‘pluripotent stem cells’ derived
from hemangioblasts.
• This development occurs in the walls of blood vessels in
the yolk sac, chorion, and allantois at about 3 weeks after
fertilization.
• Blood formation in the embryo itself begins at about the
5th week in the liver and the 12th week in the spleen, red
bone marrow and thymus.

103. Aging and the CVS:
• General changes include: decreased compliance of the
aorta, reduction in cardiac muscle fiber size,
progressive loss of cardiac muscular strength, reduced
CO, a decline in max. HR, and an increase in SBP.
• Total blood cholesterol tends to increase with age, as
does LDL.
• HDL tends to decrease.
• Increase in the incidence of CAD – major cause of
heart disease and death in older people.
• Cong. Heart failure – associated with impaired
pumping of the heart, is also prevalent in older
community.

104. • Changes in the blood vessels that serve brain tissue –
atherosclerosis – reduce nourishment to the brain
cells and result in malfunction or death of brain cells.
• By age 80, cerebral blood flow is 20% less and renal
blood flow is 50% less than in the same person at age
30.

105. Homeostatic imbalances:

106. Hypertension:
• Most common disorder affecting the heart and blood
vessels and is major cause of heart failure, kidney
disease and stroke.
• New guidelines:
Category: Systolic: Diastolic:
Normal Less than 120 Less than 80
Prehypertension 120-139 80-89
Stage 1 HTN 140-159 90-99
Stage 2 HTN Greater than 160 Greater than 100

107. • Types of HTN:
• 90-95% of all cases of HTN are ‘primary HTN’ –
persistently elevated BP that cannot he attributed to
any identifiable cause.
• Remaining 5-10% cases are ‘secondary HTN’ – has an
identifiable underlying cause.
• Disorders causing sec. HTN:
• 1. obstruction of renal blood flow or disorders that
damage renal tissue may cause the kidneys to release
excessive amounts of renin into blood.
• Resulting high level of AT-II causes VC, increasing
systemic vascular resistance.

108. • 2. hypersecretion of aldosterone:
• Resulting from a tumor of the adrenal cortex –
stimulates excess reabsorption of salt and water by the
kidneys, which increases the volume of body fluids.
• 3. hypersecretion of E and NE by a
‘pheochromocytoma’ – a tumor of the adrenal
medulla.
• E and NE increase HR and contractility and increase
SVR.

109. • Damaging effects of untreated HTN:
• High BP – ‘silent killer’ – can cause considerable
damage to the blood vessels, heart, brain, and kidneys
before it causes pain or other noticeable symptoms.
• Major risk factor for the no.1 heart disease and no. 3
stroke death cases.
• Blood vessels: causes thickening of the tunica media,
accelerates development of atherosclerosis and CAD,
and increases SVR.
• Heart: HTN increases afterload – forces ventricles to
work harder and eject blood.
• Normal response to increased work load –
hypertrophy of the myocardium, esp. in left ventricle
wall.

110. • Myocardial hypertrophy is accompanied by muscle
damage and fibrosis.
• As a result, left ventricle enlarges, weakens, and
dilates.
• Arteries in the brain are usually less protected by
surrounding tissues than are the major arteries in
other parts of the body, prolonged HTN can eventually
cause them to rupture, resulting in a stroke.
• HTN also damages kidney arterioles, causing them to
thicken, which narrows the lumen, because the blood
to the kidneys is thereby reduced, the kidneys secrete
more renin, which elevates the BP even more.

111. • Life style changes to reduce HTN:
• 1. lose weight: best treatment for high BP.
• Losing few pounds helps reduce BP in overweight
hypertensive individuals.
• 2. limit alcohol intake:
• Drinking in moderation may lower risk of CHD,
mainly among males over 45 and females over 55.
• Moderation: no more than 12 0z beer (355ml) per day
for females and no more than 2 12-oz beer per day for
males.
• 3. exercise: moderate activity, several times a week for
30-45minutes can lower SBP by about 10mmHg.

112. • 4. reduce intake of sodium: half of people with HTN
are ‘salt sensitive’.
• In them, high salt diet appears to promote HTN, a low
salt diet can lower their BP.
• 5. maintain recommended dietary intake of potassium,
calcium, and magnesium: high levels are associated
with a lower risk for HTN.
• 6. don’t smoke: devastating effects on the heart and
can augment the damaging effects of high BP by
promoting vasoconstriction.
• 7. manage stress: meditation helps in reducing high
BP. Work by decreasing the daily release of
epinephrine and norepinephrine by the adrenal
medulla.

113. • Drug treatment:
• Many diff. classes of drugs work in different pathways.
• 1. diuretics: decrease BP by decreasing the blood
volume – increase elimination of water and salt in the
urine.
• 2. ACE inhibitors: block formation of AT-II and
thereby promote vasodilation and decrease the
secretion of aldosterome.
• 3. beta blockers: reduce BP by inhibiting the secretion
of renin and by decreasing HR and contractility.
• 4. vasodilators: relax smooth muscle in arterial walls,
causing vasodilation and lower BP by lowering SVR.

114. • 5. CCBs: slow the inflow of Ca2+ into vascular
smooth muscle cells.
• Reduce heart workload by slowing Ca2+ entry
into pacemaker cells and regular myocardial
fibers – decreasing HR and force of myocardial
contraction.

115. Med. Terminologies:
• Aneurysm:
• Thin, weakened section of the wall of an artery or a
vein that bulges outward, forming a balloon like sac.
• Common causes are atherosclerosis, syphilis,
congenital blood vessel defects, and trauma.
• If untreated, the aneurysm enlarges and the blood
vessel wall becomes so thin that it bursts.
• Result is massive h’gge with shock, severe pain, stroke
or death.
• Rx: surgery in which the weakened area of the blood
vessel is removed and replaced with graft of synthetic
material.

117. • Aortography:
• Examination of the aorta and its main branches after
injection of a radio-opaque dye.
• Carotid endarterectomy:
• Removal of atherosclerotic plaque from the carotid
artery to restore greater blood flow to the brain.
• Claudication:
• Pain and lameness of limping caused by defective
circulation of the blood in the vessels of the limbs.

119. • Deep venous thrombosis:
• Presence of a thrombus in a deep vein of the lower
limbs. may lead to:
• 1. pul. Embolism, if the thrombus dislodges and then
lodges within the pul. Arterial blood flow
• 2. postphlebitic syndrome – consists of edema, pain
and skin changes due to destruction of venous valves.

121. • Doppler ultrasound scanning:
• Imaging technique commonly used to measure blood
flow.
• Transducer is placed on the skin and an image is
displayed on a monitor that provides the exact
position and severity of a blockage.

122. • Femoral angiography:
• Imaging technique in which a contrast medium is
injected into the femoral artery and spreads to other
arteries in the lower limbs, and then a series of
radiographs are taken of one or more sites.
• Used to diagnose narrowing or blockage of arteries in
the lower limbs.

123. • Hypotension:
• Low BP.
• Most commonly used to describe an acute drop in BP,
as occurs during excessive blood loss.
• Normotensive: normal BP
• Occulsion:
• Closure or obstruction of the lumen of a structure such
as a blood vessel.
• E.g: atherosclerotic plaque in an artery.
• Phlebitis:
• Inflammation of a vein, often in a leg.
• Thrombectomy:
• Operation to remove a blood clot from a blood vessel.

125. • Orthostatic hypotension:
• Excessive lowering of systemic BP when a person
assumes an erect posture – usually a sign of a disease.
• May be caused by excessive fluid loss, certain drugs,
and cardiovascular or neurogenic factors.
• Also called ‘postural hypotension’.
• Venipuncture:
• Puncture of a vein, usually to withdraw blood for
analysis or introduce a solution – antibiotic.
• Median cubital vein is frequently used.

126. • Thrombophlebitis:
• Inflammation of a
vein involving clot
formation.
• Superficial
thrombophlebitis
occurs in veins
under the skin,
esp. in the calf.

127. • White coat hypertension:
• Stress induced syndrome found in patients who
have elevated BP when being examined by
health-care personnel, but otherwise have
normal BP.