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Essentials of Human Anatomy

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Essentials of Human Anatomy Blood Vessels Dr Fadel Naim Ass. Prof. Faculty of Medicine IUG * Arteries to Thoracic Wall Arteries to Pelvic Region Arteries to the Lower ... – PowerPoint PPT presentation

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Title: Essentials of Human Anatomy


1
Essentials of Human Anatomy
Blood Vessels
Dr Fadel Naim Ass. Prof. Faculty of Medicine IUG
1
2
Blood Vessels
  • An efficient mode of transport for oxygen,
    nutrients, and waste products to and from body
    tissues.
  • Heart is the mechanical pump that propels the
    blood through the vessels.
  • Heart and blood vessels form a closed-loop
    system.
  • Blood is continuously pumped to and from the
    tissues.
  • Are not rigid and immobile.
  • Can pulsate and change shape in accordance with
    the bodys needs.

3
Blood Vessels
  • Arteries
  • Carry blood away from ventricles of heart
  • Arterioles
  • Receive blood from arteries
  • Carry blood to capillaries
  • Capillaries
  • Sites of exchange of substances between blood
    and body cells
  • Venules
  • Receive blood from capillaries
  • Veins
  • Carry blood toward atrium of heart

4
Three Main Classes of Blood Vessels
  • Arteries become progressively smaller as they
    divide and get further from the heart.
  • Veins become progressively larger as they merge
    and get closer to the heart.
  • Anastomosis Site where two or more vessels
    merge to supply the same body region.
  • arterial anastomoses alternate route
  • Veins tend to form many more anastomoses than do
    arteries.

5
Three Main Classes of Blood Vessels
  • End arteries
  • Arteries that do not form anastomoses
  • Only one route
  • E.g. renal artery, splenic artery
  • Functional end arteries
  • Have small anastomoses
  • E.g. coronary arteries

6
Blood Vessel Tunics
  • Tunica Intima, or Tunica Interna
  • innermost layer
  • composed of
  • an endothelium (simple squamous epithelium)
  • subendothelial layer (areolar CT)
  • Tunica Media
  • middle layer of the vessel wall
  • composed of
  • circularly arranged smooth muscle cells
  • Sympathetic innervation
  • Increase vasoconstriction (narrowing of the
    blood vessel lumen)
  • Decrease vasodilation (widening of the blood
    vessel lumen)

7
Blood Vessel Tunics
  • Tunica Externa, or Tunica Adventitia
  • outermost layer
  • composed of
  • areolar connective tissue that contains elastic
    and collagen fibers
  • helps anchor the vessel to other tissues
  • Term adventitia is used to specify outer layer in
    blood vessels that are buried in CT
  • Vasa vasorum blood vessels that supply large
    blood vessels
  • In the externa
  • Arteries vs Veins
  • Media largest in arteries, externa largest in
    veins
  • Lumen is smallest in arteries
  • Artery wall have more elastic and collagen fibers
  • Capillaries only the Interna

8
Arteries
  • In the systemic circulation, carry oxygenated
    blood to the body tissues.
  • Pulmonary arteries carry deoxygenated blood to
    the lungs.
  • Three basic types of arteries
  • elastic arteries, muscular arteries, and
    arterioles
  • as an arterys diameter decreases
  • corresponding decrease in the amount of elastic
    fibers
  • relative increase in the amount of smooth muscle

9
Capillaries
  • Contain only the tunica intima, but this layer
    consists of a basement membrane and endothelium
    only.
  • Allow gas and nutrient exchange between the blood
    and the body tissues to occur rapidly.
  • Smallest blood vessels, connect arterioles to
    venules.
  • Are called the functional units of the
    cardiovascular system.
  • A group of capillaries (10100) functions
    together and forms a capillary bed.

10
The Three Basic Kinds of Capillaries
  • Continuous capillaries
  • the most common type
  • Fenestrated capillaries
  • Sinusoids, or discontinuous capillaries

11
Regulation of Capillary Blood Flow
  • Precapillary sphincters
  • may close a capillary
  • respond to needs of the cells
  • low oxygen and nutrients cause sphincter to relax

12
Veins
  • Drain capillaries and return the blood to the
    heart.
  • Walls are relatively thin and the vein lumen is
    larger.
  • Systemic veins carry deoxygenated blood to the
    right atrium of the heart, while pulmonary veins
    carry oxygenated blood to the left atrium of the
    heart.
  • Blood pressure is substantially reduced by the
    time blood reaches the veins.
  • Hold about 60 of the bodys blood at rest.
  • Veins function as blood reservoirs.

13
From Venules to Veins
  • Venules merge to form veins.
  • Venule becomes a vein when its diameter is
    greater than 100 micrometers.
  • Blood pressure in veins is too low to overcome
    the forces of gravity.
  • To prevent blood from pooling in the limbs, most
    veins contain one-way numerous valves to prevent
    blood backflow in the veins.
  • As blood flows superiorly in the limbs, the
    valves close to prevent backflow.
  • Numerous valves along its length to assist in
    moving blood back to the heart.

14
From Venules to Veins
  • Many deep veins pass between skeletal muscle
    groups.
  • As the skeletal muscles contract, veins are
    squeezed to help pump the blood toward the heart.
  • This process is called the skeletal muscle pump.

15
Venous flow occurs by1. muscle contraction2.
respiratory pump3. valve assistance4.
Ventricular relaxation
16
Arteriole
  • smallest arterioles only have a few smooth
    muscle fibers
  • capillaries lack muscle fibers

17
Pulse
  • alternate expanding and recoiling of the
    arterial wall that can be felt

18
Usually occur at the bifurcations and branches of
the large arteries located at the Circle of
Willis
Cerebral aneurysms
19
Varicose Veins
  • Twisted, dilated superficial veins
  • caused by leaky venous valves
  • congenital or mechanically stressed from
    prolonged standing or pregnancy
  • allow backflow and pooling of blood
  • extra pressure forces fluids into surrounding
    tissues
  • nearby tissue is inflamed and tender
  • Deeper veins not susceptible because of support
    of surrounding muscles

20
GREAT SAPHENOUS VEIN CUT DOWN
  • Usually performed at the ankle
  • Disadvantage that phlebitis is a potential
    complication
  • Also at the groin in the femoral triangle,
  • Phlebitis is relatively rare
  • Larger diameter of the vein
  • Use of large-diameter catheters
  • Rapid infusion of large volumes of fluids.

21
The Great Saphenous Vein In Coronary Bypass
Surgery
  • In occlusive coronary disease caused by
    atherosclerosis, the diseased arterial segment
    can be bypassed by inserting a graft consisting
    of a portion of the great saphenous vein.
  • The venous segment is reversed so that its valves
    do not obstruct the arterial flow.
  • The great saphenous vein can also be used to
    bypass obstructions of the brachial or femoral
    arteries

22
Venipuncture of the Upper Limb
  • Because of the prominence and accessibility of
    the superficial veins of the upper limb, they are
    commonly used for venipuncture
  • These veins may be embedded with the subcutaneous
    tissue (fat), making them difficult to see
  • By applying a tourniquet to the arm, the venous
    return is occluded and the veins distend and are
    usually visible and/or palpable.

23
Venipuncture of the Upper Limb
  • The median cubital vein is commonly used for
    venipuncture for
  • Drawing blood
  • Inserting a catheter for right cardiac
    catheterization
  • The dorsal venous network and the cephalic and
    basilic veins arising from it are commonly used
    for intravenous feeding

24
FEMORAL ARTERY CATHETERIZATION
  • A long, fine catheter can be inserted into the
    femoral artery as it descends through the femoral
    triangle.
  • The catheter is guided under fluoroscopic view
    along the external and common iliac arteries into
    the aorta.
  • The catheter can then be passed into the inferior
    mesenteric, superior mesenteric, celiac arteries,
    or renal arteries.
  • Contrast medium can then be injected into the
    artery under examination and a permanent record
    obtained by taking a radiograph.
  • Pressure records can also be obtained by guiding
    the catheter through the aortic valve into the
    left ventricle.

25
Measuring Blood Pressure
  • Arterial blood pressure measurement using
    sphygmomanometer.
  • A cuff is placed around the arm and inflated with
    air until it compresses the brachial artery
    against the humerus and occludes it.
  • A stethoscope is placed over the artery in the
    cubital fossa, the pressure in the cuff is
    gradually released
  • The examiner detects the sound of blood beginning
    to spurt through the artery.
  • The first audible spurt indicates systolic blood
    pressure.
  • As the pressure is completely released, the point
    at which the pulse can no longer be heard is the
    diastolic blaod pressure.

26
Major Vessels of Arterial System
27
Major Branches of the Aorta
  • Coronary arteries
  • Brachiocephalic
  • Left common carotid
  • Left subclavian
  • Celiac
  • Superior mesenteric artery
  • Renals
  • Ovarian / testicular
  • Inferior mesenteric

28
Minor Branches of the Aorta
  • Pericardial Thoracic
  • Bronchial Lumbar
  • Esophageal Suprarenal
  • Mediastinal
  • Intercostal
  • Phrenic

29
Major Blood Vessels of the Heart
30
Abdominal Aorta and Its Major Branches
31
Arteries to Neck, Head, and Brain
32
Cerebral Arterial Circle
  • Circle of Willis
  • formed by anterior and posterior cerebral
    arteries, which join the internal carotid arteries

33
Arteries to Shoulder and Upper Limb
34
Arteries to Thoracic Wall
35
Arteries to Pelvic Region
36
Arteries to the Lower Limb
37
Major Vessels of the Venous System
38
Major Veins of the Brain, Head and Neck
39
Veins from the Upper Limb and Shoulder
40
Veins That Drain the Thoracic Wall
41
Veins That Drain the Abdominal Viscera
42
Veins of the Lower Limb and Pelvis
43
Hepatic Portal System
  • A venous network that drains the GI tract and
    shunts the blood to the liver for processing and
    absorption of transported materials.
  • Blood exits the liver through hepatic veins that
    merge with the inferior vena cava.
  • Is needed because the GI tract absorbs digested
    nutrients, and these nutrients must be processed
    and/or stored in the liver.

44
(No Transcript)
45
THE END
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