BLOOD VESSELS = VASCULAR
I. Arteries
A. Lumen
B. Wall
1. Tunica interna
2. Tunica media
3. Tunica externa
C. Pulse
II. Arterioles
Tiny arteries, primary resistance blood vessel
III. Capillaries
Thin wall, diffusion
IV. Venules
Tiny veins
V. Veins
A. Low pressures (6-8mmHg)
B. Valves
C. Skeletal muscle
D. Breathing
VI.Sinuses
VII. Blood reservoirs
Veins & sinuses
VIII. Blood Velocity
Inversely related to total cross sectional area of a vessel, thus velocity is lowest in capillaries.
IX. Blood Flow
volume of blood passing through a vessel, F = P/R
X. Pressure
Pressure is the force that drives blood through vessels due to pumping of heart, so highest in aorta, lowest in vena cava. As arterial pressure increases, arteries expand; as arterial pressure decreases, arteries recoil; you can feel this change in certain areas as a pulse.
XI. Resistance
A. Blood viscosity
The thicker the blood, the higher the viscosity, the more resistance and thus less flow
B. Vessel length
The longer the vessels, the higher the resistance, but this is a constant in the body
C. Vessel radius
1. Resistance = 1/radius4
2. Arterioles
XII. Relationships [F=P/R; Mean Art. Press = CO x TPR]
XIII. Arterial pressure
A. Neural controls
1. Vasomotor fibers
a. Sympathetic efferents
b. Vasodilator
c. Vasoconstrictor
2. Vasomotor center
In brainstem
3. Cardiac center
Cardiac changes effects pressure
4. Baroreceptors
Pressure receptors in aortic arch and carotid sinus that monitor stretch of artery
5. Aortic & Carotid bodies
Chemoreceptors for oxygen, carbon dioxide, hydrogen
B. Chemicals/hormones
1. Angiotensin
Powerful vasoconstrictor
2. Epinephrine
3. ADH (Vasopressin)
Stimulates water reabsorption from kidneys and vasoconstriction
C. Blood volume
Increased blood volume leads to increased arterial pressure; body strives towards volume homeostasis
D. Measurement of arterial pressure {120/80}
Systolic pressure represents contraction of ventricles and is the first sound heard as pressure is released from sphygmomanometer -120mmHg
Diastolic pressure represents the arterial pressure when the ventricles are relaxing and is the last sound heard as pressure is released from sphygmomanometer – 80 mmHg
XIV. Venous Return
A. Low pressures
B. Peripheral venous pressure
C. Skeletal muscle contraction helps in venous return
D. One way valves help with venous return
E. Breathing works as a thoracoabdominal pump to promote venous return
XV. Gravity
A. Increased pressure in lower body
B. Increased capillary filtration which decreases circulating blood volume
C. Compensatory mechanisms
1. Baroreceptors
1. Skeletal muscle [90-25 mm Hg drop just by walking ]
XVI. CV adjustments during exercise
A. Skeletal muscle vasodilation
1. CNS sympathetic vasodilator fibers
2. Local autoregulatory response
a. Decreased O2 level
b. Increased local vasodilator substances
3. Decreased TPR
B. Visceral vasoconstriction
C. Increased sympathetic stimulation to heart
D. Increased venous return
E. HR, SV, CO increase
F. Mean arterial pressure increases
XVII. HYPERTENSION – If time {140/90}Not on test
A. Causes
1. Adrenal tumor
2. Kidney disease
3. Volume loading
4. 90% unknown
B. Sequelae
1. Heart, angina, enlarged heart
2. Aneurysm
3. Sclerosis
4. Rupture
5. Kidney disease
C. Treatment
a. Lose weight, exercise
b. Decrease salt, diuretics
c. Stop smoking, alcohol, caffeine
d. Biofeedback
e. Vasodilators (isoproteronol)
XVIII. CIRCULATORY ROUTES (Refer to Blood Vessel Objectives for illustrations of circulatory routes.)
A. Pulmonary circuit
B. Systemic circuit
C. Fetal circulation
1. Placenta
2. Umbilical cord