Outline-2, BIO 2320, Blood Vessels


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


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

Neural Control of Blood Pressure Video