Essentials of Pathophysiology
CHAPTER 18
DISORDERS OF BLOOD FLOW AND
BLOOD PRESSURE
PRE-LECTURE QUIZ
True/False
F
HDL is known as the “bad cholesterol.”
T
Most abdominal aneurysms are asymptomatic.
F
Essential (primary) hypertension is characterized by chronic
elevation in blood pressure that results from some other disorder,
such as kidney disease.
F
Orthostatic or postural hypotension is an abnormal rise in blood
pressure that occurs when assuming the standing position from
the supine position.
T
Venous insufficiency leads to tissue congestion and edema in the
lower extremities.
PRE-LECTURE QUIZ
Aortic

Endothelium

Hyperlipidemia

Raynaud

Short

The __________ controls the transfer of molecules across
the vascular wall, plays a role in platelet adhesion and
blood clotting, and functions in the modulation of blood
flow and vascular resistance.
__________, with its associated risk for the development
of atherosclerosis, is a major cause of cardiovascular
disease.
__________ phenomenon is a functional disorder caused
by intense vasospasm of the arteries and arterioles in the
fingers and, less often, in the toes.
__________ dissection is an acute, life-threatening
condition that involves hemorrhage into the vessel wall
with longitudinal tearing or separation of the vessel wall to
form a blood-filled channel.
The body uses neural mechanisms and humoral
mechanisms to effect the __________-term regulation of
blood pressure, which occurs over minutes or hours and is
intended to correct temporary imbalances in blood
pressure.
ARTERY STRUCTURE
Arranged in tunics or
coats
Tunica intima:
Endothelium
Tunica media: smooth
muscle
Tunic adventitia:
collagen and elastic
fibers
ARTERY STRUCTURE
Tunica intima:
endothelium
Tunica media: smooth
muscle
Tunica adventitia:
collagen and elastic
fibers
QUESTION
Which vessel layer can expand to accommodate
pressure changes?
a. Tunica intima
b. Tunica media
c. Tunica adventitia
d. Tunica externa
ANSWER
Tunica media
The tunica media is composed of smooth
muscle, which can stretch/expand to
accommodate changes in blood pressure.
Is this answer arguable?
b.
VASCULAR ENDOTHELIUM
Nutrients and O2 pass into tissues
 Wastes and CO2 pass from tissues into
blood
 Creates compounds that cause
vasodilation or vasoconstriction
 Creates growth factors that can stimulate
smooth muscle
 Forms a smooth lining of the blood vessels
that resists clot formation
 Creates compounds to promote clot
formation in injured areas

ATHEROSCLEROSIS

Lipids get into the vascular endothelium

White blood cells try to clear them away 
foam cells

WBCs and vascular endothelium release
growth factors that promote plaque formation

Plaques block the arteries
LIPOPROTEINS
The more
protein, the
higher the
density
 The more lipid,
the lower the
density

LIPOPROTEINS



The more protein, the
higher the density
The more lipid, the
lower the density
i.e. protein is heavier
than lipids
QUESTION
Tell whether the following statement is true or
false.
LDL is considered to be “good” cholesterol.
ANSWER
False
Rationale: LDL (low-density lipoprotein, which has
more lipids and less protein) is the “bad”
cholesterol. HDL (high-density lipoprotein) has
more protein and less fat, and is considered
“good” cholesterol.
LIPID TRANSPORT IN THE BODY
Dietary lipids absorbed
as chylomicrons
 Adipose and muscle
cells take up lipids
from chylomicrons
 Chylomicron remnants
are intermediatedensity lipoproteins,
IDL

LIPID TRANSPORT IN THE BODY (CONT.)
IDLs become lowdensity
lipoproteins (“bad
cholesterol”)
 These can deliver
fat to the liver and
to other tissues
 LDL receptors are
necessary for the
liver to take them
up
 Some LDLs are
taken up by
scavenger cells
like macrophages

FATTY STREAKS AND ATHEROSCLEROTIC
PLAQUES
FATTY STREAKS AND ATHEROSCLEROTIC
PLAQUES
ATHEROSCLEROSIS

Atherosclerosis develops because scavenger
cells encounter the fatty deposits in the artery
lining and
 Try
º
º
º
to destroy the fats by oxidizing them
Oxidized fats injure the endothelium
Clots form and release growth factors
Smooth muscle grows over the fatty core
 Try
to remove the fats by eating them
 Become
“foam cells” in the core of the plaque
LIPID TRANSPORT IN THE BODY



High-density lipoproteins
(“good cholesterol”) are
made in the liver
They go out to the
peripheral tissues and
pick up lipid
Then they carry it back to
the liver
SCENARIO
A man has several genetic defects in his lipoprotein
receptors…

His liver lacks LDL receptors

His muscle cells lack receptors for the apoproteins
on chylomicrons

His scavenger cells have extra LDL receptors
Question:

Why might he develop atherosclerosis?
STABLE PLAQUES

Have thick fibrous caps

Partially block vessels

Do not tend to form clots or emboli
UNSTABLE PLAQUES

Have thin fibrous caps

Plaque can rupture and cause a clot to form

May completely block the artery

The clot may break free and become an embolus
QUESTION
What immediate threat do unstable plaques
present?
a. Clot formation will increase pressure in the
vessel.
b. Plaque may lead to angina (chest pain).
c. Clots may break loose and block blood flow to
key organs.
d. All of the above constitute immediate threats.
ANSWER
c. Clots may break loose and block blood flow to key
organs.
Rationale: If a clot breaks loose, becoming an
embolus, it may lodge in a blood vessel to the
brain, heart, or lungs. When blood flow is
significantly decreased or blocked altogether, the
result is tissue death—in the examples here,
stroke, heart attack, or pulmonary embolus. The
other choices represent more long-term/chronic
problems.
SCENARIO
A woman complains of pain in her left leg.
 Her foot is cool and pale
 She reports that it is often red and warm when
she is sitting down
 The pain occurs when she is walking to church on
Sundays
 The skin on her left leg is shinier than on her right
leg
Question:
 What could have caused all this? How?
ANEURYSMS



Wall of artery
weakens and
stretches
Risk of rupture and
hemorrhage
Risk of clot
formation
AORTIC ARCH ANEURYSM
CAROTID ARTERY ANEURYSM
DISCUSSION
How would each of the following affect blood
pressure?
 Vasodilation Lower resistance lowers BP
 Decreased stretching of baroreceptors Reflex raises BP
 Hypoxemia Calls for more blood flow raises BP
 Inhibiting angiotensin-converting enzyme
Blocks formation of Angiotesion II
 Beta blockers Slows HR Lowers BP
Lowers BP
 Alpha-2 agonists Decreases Sympathetic response Lowers BP
 Calcium-channel blockers Decreases vascular resistance Lowers
BP
VARICOSE VEINS
SCENARIO
A woman complains of pain in her left leg…
 Her foot is cool and pale
 She reports that it is often red and warm when
she is sitting down
 The pain occurs when she is walking to church on
Sundays
 The skin on her left leg is shinier than on the right
leg
Question:
 What could have caused all this? How?
ANEURYSMS



Wall of artery weakens and
stretches
Risk of rupture and
hemorrhage
Risk of clot formation