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• Short term regulation via changes in peripheral resistance
• Cause increased blood pressure
o Epinephrine and norepinephrine from adrenal medulla
o Increased CO and vasoconstriction, respectively
o Angiotensin II stimulates vasoconstriction
o High ADH levels cause vasoconstriction
• Cause lowered blood pressure
o Atrial natriuretic peptide causes decreased blood volume by
antagonizing aldosterone and promoting vasodilation
• Long term mechanisms: renal regulation
o Baroreceptors quickly adapt to chronic high or low BP so are
ineffective
o Long-term mechanisms control BP by altering blood volume via
kidneys
o Kidneys regulate arterial blood pressure
§ Direct renal mechanism
§ Indirection renal (renin-angiotensin-aldosterone)
mechanism
o Direction Renal Mechanism
§ Alters blood volume independently of hormones
• Increased BP or blood volume causes elimination of
more urine, thus reducing blood volume and
therefore BP
• People with high BP often prescribed diuretics to
help reduce BP
• Decreased BP or blood volume causes kidneys to
conserve water, and BP rises

o Indirect mechanism
§ The renin-angiotensin-aldosterone mechanism
• Arterial blood pressure down à release of renin (an
enzyme)
• Renin catalyzes conversion of angiotensinogen (from
liver) to angiotensin I
• Angiotensin converting enzyme (ACE, especially from
lungs) converts to angiotensin I to angiotensin II
• “Angio” = blood vessel
• “Ten” = stretch
§ Functions of Angiotensin II
• Increases blood volume
o Stimulates aldosterone secretion
o Causes ADH release
o Triggers hypothalamic thirst center
• Increases vasoconstriction directly increasing blood
pressure
o Monitoring circulatory efficiency
§ Vital signs: pulse and blood pressure, along with
respiratory rate and body temperature
§ Pulse: pressure wave caused by expansion and recoil of
arteries
§ Radial pulse (taken at wrist) routinely used
§ Pressure points where arteries pass close to body surface
• Can be compressed to stop blood flow
o Capillary exchange of respiratory gases and nutrients

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§ Capillary exchange is movement of substances between
blood and ISF
§ Diffusion down concentration gradients
• O2 and nutrients from blood to tissues
• CO2 and metabolic wastes from tissues to blood
§ Routes in/out capillaries
• Diffusion through plasma membrane
o Must be small and lipid-soluble (respiratory
gases)
• Diffusion through intercellular clefts
o Must be small and water-soluble (glucose,
monosaccharides, single amino acids)
• Diffusion through fenestrations
o For larger water-soluble substances
(disaccharides, dipeptides, hormones, immune
cells)
• Active transport
o Larger molecules, such as proteins, are actively
transported in pinocytotic vesicles
§ Fluid movements: bulk flow
• Movement of fluid separate from solute
• Fluid leaves capillaries at arteriole end; most return
to blood at venule end
o Extremely important in determining blood
volume and ISF volume
o Edema- abnormal increases in ISF volume;
occurs when bulk fluid movement is disturbed

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• Direction and amount of fluid flow depend on two
opposing forces
o 1
...
Colloid osmotic pressure
§ capillary colloid osmotic pressure
(oncotic pressure)
§ pressure exerted by large plasma
proteins and other non-diffusible
molecules that pull water back into
capillary
§ highest at venule end
• Circulatory shock
o Any condition in which blood vessels
inadequately filled or blood cannot circulate
normally
o Hypovolemic: results from large-scale blood
loss
o Vascular: results from extreme vasodilation
and decreased peripheral resistance
o Cardiogenic: results when an inefficient heart
cannot sustain adequate circulation
o Circulatory pathways: blood vessels of the body
§ Two main circulations

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• Pulmonary circulation: short loop that runs from
heart to lungs and back to heart
• Systemic circulation: long loop to all parts of body
and back to heart
o L ventricle à
§ Ascending aorta
• L&R coronary arteries
o Ascending aorta à
§ Brachiocephalic (R)
§ L common carotid (L)
§ L subclavian (L)
o Brachiocephalic becomes à
§ R subclavian, becomes à
§ R axillary à arteries of R upper limb
§ R vertebral (branch off R subclavian)
o R common carotid (branch off brachiocephalic)
à
§ R external carotid
§ R internal carotid
o L common carotid à
§ L external carotid
§ L internal carotid
o L subclavian becomes à
§ L axillary à arteries of L upper limb
§ L vertebral (branch off L subclavian)
o External carotid arteries branch (inferior to
superior) à

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§ Thyroid
§ Lingual
§ Facial
§ Occipital
§ Maxillary
§ Superficial temporal
o Internal carotid arteries à (inferior to
superior)
§ Opthalmic
§ Cerebral
o Axillary artery becomes brachial
o Brachial splits
§ Radial
§ Ulnar
§ Branches anastomose to form superficial
and deep palmar arches which feed the
digital arteries
o Aortic arch becomes à descending aorta
§ Thoracic aorta à
• Visceral branches (esophageal,
bronchial, pericardial)
• Parietal branches (intercostals,
diaphragm)
§ Diaphragm à abdominal aorta
o Abdominal aorta (superior to inferior)
§ Celiac trunk –liver, gallbladder, spleen,
stomach, esophagus, duodenum

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§ Suprarenal- adrenal gland
§ Superior mesenteric artery – SI and colon
§ Renal artery – kidneys
§ Gonadal
§ Inferior mesenteric artery – SI and colon
o Celiac trunk branches immediately into:
§ Common hepatic
• Stomach, duodenum, pancreas,
liver
§ Splenic
• Stomach, pancreas, spleen
§ L Gastric
• Stomach, inferior esophagus
o Abdominal aorta
§ Splits R&L common iliac becomes
external iliac
• External iliac becomes (internal
iliac branches off common iliac)
• Femoral becomes
• Popliteal splits
o Anterior tibial
o Posterior tibial
• Anterior tibial becomes
o Dorsali pedis which feeds
o Metatarsal arteries
• Posterior tibial

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o Fibular branches off
o Digital veins feed à
o Superficial palmar venous arch, feeds
§ Radial vein
§ Ulnar vein
o Median cubital connects cephalic and basilic
veins
o Basilic, brachial and cephalic veins merge to
form à
o Axillary vein à subclavian à brachiocephalic
à superior vena cava





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