Blood Vessels
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Intracellular Fluid (ICF): Fluid located
within the cell; cytosol
Extracellular Fluid (ECF): Fluid outside of
body cells; plasma and interstitial fluid
Interstitial Fluid (IF): The portion of
extracellular fluid that fills the microscopic
spaces between the cells of tissues; tissue
fluid
Bulk Flow
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Filtration and reabsorption of fluids due to
pressure (osmotic/hydrostatic) differences
Balance of pressures = net filtration
pressure (NFP)
Starling's Law of the Capillaries movement of fluid between plasma and
the interstitial fluid is in a state of near
equilibrium at the arterial and venous
ends of a capillary
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Blood hydrostatic pressure (BHP)=
pressure of blood acting against the
capillary walls forcing fluids out of
capillaries
Interstitial fluid hydrostatic pressure
(IFHP) = pressure acting outside the
capillaries pushing fluid in
Blood colloid osmotic pressure (BCOP)=
pressure as a result of moving fluid into
capillaries due to attraction to non
diffusible solutes (i.e. plasma proteins)
Edema - filtration exceeds reabsorption
resulting in increased interstitial fluid
volume; causes include:
 Increased blood hydrostatic pressure in
capillaries (cardiac failure, blood clots)
 Decreased concentration of plasma
proteins (burns, malnutrition, kidney dis.)
 Increased permeability of capillaries
 Increased extracellular fluid volume
 Blockage of lymphatic vessels (radical
mastectomy)
Edema is not detectable in tissues until IF is
increased 30% above normal
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Blood flows from high pressure (arterial)
to low pressure (venous).
Arteries-arterioles-capillaries-venules-veins
Pressure: aorta: 90-130mmHg
arteries: 80-120
arterioles: 60-80
capillaries: 20-40
venules: 10-20
veins: 5-10
vena cava: 0-5
NFP = (BHP+IFOP) - (BCOP+IFHP)
Arterial end:
NFP=(35+1)-(26+0)=(36)-(26)=10 mmHg
Venous end:
NFP=(16+1)-(26+0)=(17)-(26)= -9 mmHg
Definition of Terms
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Resistance =the opposition to flow and is a
measure of the amount of friction blood
encounters as it passes through vessels.
Blood viscosity
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Total blood vessel length
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Blood vessel diameter
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Blood Pressure =the force per unit area
exerted on a vessel wall by the blood
contained within it (expressed in mm Hg).
Arterial blood pressure
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Systolic pressure
Diastolic pressure
Pulse pressure
Mean arteriole pressure
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Capillary blood pressure
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Venous blood pressure
Venous Blood Pressure
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Muscular pump
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Respiratory pump
Factors affecting Blood
Pressure
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Cardiac Output
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Peripheral Resistance
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Increased CO = increased BP
Decreased CO = decreased BP
Increased vasoconstriction = increased BP
Increased vasodilation = decreased BP
Blood Volume
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Increased blood volume = increased BP
Decreased blood volume = decreased BP
Maintaining BP
(Short-term: neural)
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Vasomotor center
Baroreceptors
Chemoreceptors
Hypothalamus and
cerebral cortex
Peripheral chemoreceptors
Maintaining BP
(Short-term: chemical)
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Adrenal medulla
hormone (Adrenalin)
Atrial natriuretic
peptide (ANP)
Antidiuretic hormone
(ADH)
Angiotensin II
Nitric oxide
Alcohol
Endothelin
Maintaining BP (Long-term)
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Renal Regulation
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High blood pressure due to increased blood
volume causes decreased reabsorption in
kidneys resulting in a decrease in blood
volume and a lowering of blood pressure.
Renin-angiotensin II mechanism=when artery
blood pressure drops, renin triggers
angiotensin II production which causes
vasoconstriction and increased blood
pressure
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Blood flow =the volume of blood flowing
through a vessel, an organ, or the entire
circulation in a given period
Blood pressure:
Heart pumps blood through vessels. Blood flow is
under pressure due to resistance in the system
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F=
P
R
F= blood flow
P= pressure
R= resistance
Blood flow is directly proportional to changes in
blood pressure.
Blood flow is inversely proportional to peripheral
resistance.
Systolic: Ventricles ejecting blood into the
aorta
Diastole:: ventricles relaxing, pressure drops
in aorta
Difference between the two is called pulse
pressure.
What is the pulse pressure on a normal BP
of 120/80?
40mm/Hg
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Pulse pressure is increased in conditions
like arteriosclerosis.
Total peripheral resistance is controlled by
arterioles. BP is controlled by arterioles.
Arteries and veins
1- Tunica intima: inside layer of the vessel.
in veins= valves
2- Tunica media: smooth muscle is thicker
in arteries and thinner in
veins. Can dilate and
constrict.
- vasoconstriction and vasodilation
3- Tunica adventitia: outer layer. Thicker in
veins
Capillaries:
- Extensions of the inner layer of the arteriole:
endothelium (simple squamous)
- Continuous: skin, muscles and blood brain
barrier
- Fenestrated: openings called pores that
permeable to fluid and small solutes.
Found in small intestine (absorption), endocrine
glands (hormone release) and kidneys (filtration
of blood)
- Sinusoids: liver, bone marrow and spleen
Very leaky.
Capillary Transport
Mechanisms
Pulse Points
Vascular anatomy:
Arterial:
Major branches off of aorta:
Aortic sinus (ascending): right and left
coronary artery
Arch of aorta:
1- Brachiocephalic trunk which bifurcates
into right subclavian a. and the right
common carotid a.
2- Left common carotid a.
3- Left subclavian a.
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Descending aorta:
Thoracic aorta lies anterior to the vertebral
column and above the diaphragm
Branches are: pericardial a.
esophageal a.
posterior intercostal a.
Abdominal aorta lies below the diaphragm.
Branches are: celiac a.
- left gastric a.
- hepatic a.
- splenic a. (tortuous)
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Phrenic a.: diaphragm
Superior mesenteric a.:
jejunum, ileum, cecum, ascending colon and
transverse colon.
Inferior mesenteric a.:
descending, sigmoid colon and rectum
Renal and suprarenal a.:
supplies blood to the paired kidneys and adrenal
glands
Gonadal a.:
Male: spermatic a. that descend through
the inguinal canal to supply blood to the
testes.
Female: ovarian a.
Middle sacral a.: long slender a. descending
anterior to the lumbar vertebra and
sacrum to supply blood to sacrum and
coccyx.
Abdominal aorta will bifurcate into left and
right common iliac arteries.
- These further divide into:
- internal iliac a.
- external iliac a.
Internal iliac a.:
iliolumbar a.: ilium and back muscles
superior and inferior gluteal a.: buttocks
internal pudendal a.: external genitalia
middle rectal a.: rectum
External iliac a.:
- main blood supply to lower limb
- Between the pubis symphysis and the ASIS it
becomes the femoral a.
Femoral a.:
- superficial circumflex iliac a.: groin
- deep femoral a.: muscles of thigh and
hip
joint
- deep geniculate a.: distal end of thigh
Popliteal a.: knee joint
- Will bifurcate into anterior and posterior tibial a.
Posterior a. branches into fibular a. (largest
branch)
Ant. tibial a. becomes dorsalis pedis a.
(pedal pulse)
Arm, head and neck.
Subclavian a.:
- vertebral a.: through transverse
foramina into brain through foramen
magnum.
- becomes single basilar a. along
the ventral aspect of the
brainstem
- basilar a. divides into two post.
cerebral a.
- becomes part of the Circle of Willis at
base of brain
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- thyrocervical a.: thyroid and parathyroid
glands pharynx and trachea.
Common carotid a.: branch into internal and
external carotid a.
External carotid a.:
- superior thyroid a.
- lingual a.
- facial a.
- occipital a.
Internal carotid a.:
- Ophthalmic a.
- Post. communicating a. (circle of Willis)
Terminate in the anterior and middle
cerebral arteries. These vessels supply
blood to the motor, sensory and speech
cortices of the brain.
Arm:
Subclavian a. give rise to axillary a.
- humoral circumflex a.
Axillary becomes brachial a. (BP)
- deep brachial a. supplies triceps
At the elbow the brachial a. divides into
ulnar and radial a. (pulse).
Major Veins
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Superior vena cava
braciocephalic
external/internal jugular
vertebral
subclavian
axillary
cephalic
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brachial
basilic
median cubital
ulnar
Radial
inferior vena cava
splenic hepatic
renal
superior mesenteric
inferior mesenteric
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common iliac
external/internal iliac
femoral
great saphenous
popliteal
anterior/posterior
tibial
fibular
dorsal digital
Clinical corner
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Aneurysm - a balloon-like outpocketing of an artery wall that
places the artery at risk for rupture
Microangiopathic lesion - an abnormal thickening of a capillary
basement membrane due to the deposit of glycoproteins
Phlebitis - inflammation of a vein accompanied by painful
throbbing and redness of the skin
Hypotension (low BP) and hypertension (high BP)
Angiogenesis - formation of new blood vessels
Claudication - pain and lameness or limping caused by defective
circulation of the blood in vessels of the limbs (Intermittant)
Occlusion - the closure or obstruction of the lumen of a structure
such as a blood vessel
Hypovolemic shock - large-scale blood loss followed by "thready"
pulse
White coat hypertension!!!