Patho: Chapter 26 (Disorders of Blood flow and Blood Pressure)

What are the tunica layers of blood vessels?

• Tunica Adventitia (Tunica Externa)

• Tunica Media

• Tunica Intima (Tunica Interna)

What is the Tunica Adventitia (Tunica Externa)?

The outermost layer of a blood vessel

What does the Tunica Adventitia (Tunica Externa) contain?

• Collagen fibers

• Elastic fibers

• Connective tissue

What is the function of the Tunica Adventitia (Tunica Externa)?

• Provides structural support to the blood vessel

• Helps protect the vessel from overstretching

• Help anchor the vessel to surrounding tissues

What is the Tunica Media?

The middle layer of a blood vessel wall

What does the Tunica Media contain?

• Smooth muscle

• Elastin

What is the function of the Tunica Media?

Smooth muscle contracts and stretches to accommodate pressure changes in blood vessels.

What is the Tunica Intima (Tunica Interna)?

The innermost layer of a blood vessel

What does the Tunica Intima (Tunica Interna) contain?

Endothelium

What is the function of the Tunica Intima (Tunica Interna)?

• Allows food and oxygen to pass from the blood into tissues

• Allows waste products and carbon dioxide to pass from tissues into blood

• Produces compounds that stimulate vasodilation, vasoconstriction, inflammation, and clot formation.

What is vascular endothelium?

The endothelial lining of blood vessels found in the tunica intima.

What is hyperlipidemia?

An abnormally high level of lipids (cholesterol and/or triglycerides) in the blood

What causes hyperlipidemia?

• Increased LDL cholesterol

• Increased triglycerides

• Abnormal lipid transport and metabolism

What are the characteristics/manifestations of hyperlipidemia?

• Elevated cholesterol and/or triglycerides in the blood

• Increased risk of atherosclerosis

• LDL can be oxidized and deposited in the arteries

How do lipids travel in plasma?

They are encapsulated by lipoproteins

What are the 5 main types of lipoproteins?

• Chylomicrons

• Very Low-Density Lipoproteins (VLDL)

• Intermediate-Density Lipoproteins (IDL)

• Low-Density Lipoproteins (LDL)

• High-Density Lipoproteins (HDL)

What is the function of Chylomicrons?

Deliver dietary triglycerides to adipose and skeletal muscle tissue

What is the function of Very Low-Density Lipoproteins (VLDL)?

Transport triglycerides from the liver to tissues.

What is the function of Intermediate-Density Lipoproteins (IDL)?

Serve as an intermediate lipoprotein between VDL and LDL

What is the function of Low-Density Lipoproteins (LDL)?

Main carrier of cholesterol that transports cholesterol from the liver to cells throughout the body.

What is the function of High-Density Lipoproteins (HDL)?

It picks ups excess cholesterol from tissues and transports it back to the liver.

Which lipoprotein is the main carrier of cholesterol?

Low-Density Lipoproteins (LDL)

Which cholesterol is considered “bad cholesterol”?

Low-Density Lipoproteins (LDL)

Which cholesterol is considered “good cholesterol”?

High-Density Lipoproteins (HDL)

Does HDl carry a lot of cholesterol and triglycerides?

No, HDL is about 50% protein and carries less cholesterol and little triglyceride than LDL.

What is the lipoprotein structure?

Particles made of lipids and proteins that transport lipids through the blood.

What are the layers of a lipoprotein?

• Outer layer

• Center

What does the outer layer of a lipoprotein contain?

Phospholipids and proteins (apolipoproteins)

What does the center of a lipoprotein contain?

Cholesterol and triglycerides

What is the function of lipoproteins?

• Encapsulate lipids so they can travel in plasma (blood)

• Transport cholesterol and triglycerides throughout the body

What are the 3 different stages or subtypes of lesions that are associated with atherosclerosis?

• Fatty streaks

• Fibrous atheromatous plaques

• Complicated lesions

What are the characteristics of Fatty Streaks?

• Earliest stage of atherosclerosis

• Thin, fat, yellow intimal discolorations

• Consists of foam cells (fat-filled macrophages) and fat-filled smooth muscle cells

What are the characteristics of Fibrous Atheromatous Plaques?

• Develop from fatty streaks

• Larger, thicker plaques

• Narrow the artieries

What are the characteristics of Complicated lesions?

• May contain hemorrhage

• Scar tissue forms

• Plaque may rupture

• Can lead to thrombosis

The first evidence of atherosclerosis is _________.

Fatty streak

The fatty streak can develop into __________.

Fibrous atheormatous plaque

What is the basic lesion of clinical atherosclerosis?

Fibrous atheromatous plaque

What are the early steps in the development of atherosclerosis?

• Endothelium is damaged

• LDL enters the damaged area

• Monocytes enter and become macrophages

How do foam cells form in atherosclerosis?

• Macrophages oxidize LDL

• Macrophages ingest oxidized LDL

• Macrophages become foam cells

How do plaques and complicated lesions develop?

• Chemicals promote plaque formation

• Plaques enlarge and block arteries

• Hemorrhage, scar tissue, plaque rupture, and thrombosis may occur

What is atherosclerosis?

The hardening and narrowing of the arteries caused by the buildup of fatty lesions (plaques) in the intimal lining of arteries.

What causes atherosclerosis?

• Endothelial damage

• LDL entering the damaged area

• Macrophages ingesting oxidized LDL and becoming foam cells

• Plaque formation development in the artery wall

What are the characteristics/manifestations of athersclerosis?

• Fatty streaks

• Fibrous atheromatous plaques

• Complicated lesions

• Narrowing of arteries

• Increased risk of thrombosis, heart attack, and stroke

What are foam cells?

Macrophages that have ingested oxidized LDL (bad cholesterol) and become filled with fat.

What are the characteristics/manifestations of foam cells?

• Fat-filled macrophages

• Found in fatty streaks

• Contribute to plaque formation in atherosclerosis

What role do macrophages play in atherosclerosis?

They ingest oxidized LDL (bad cholesterol) and become foam cells, contributing to plaque formation.

How are unstable plaques formed?

From lipids released by necrotic foam cells, which accumulate and form unstable plaques.

What are the characteristics/manifestations of unstable plaques?

• Very thin fibrous caps

• Can rupture easily

• Can lead to thrombosis formation

• May completely block an artery

• May break free and become an embolus

What immediate threat do the unstable plaques present?

All of the above

What are Peripheral Vascular Disorders?

Vascular disorders that occur in the peripheral structures or extremities.

What are examples of Peripheral Vascular Disorders?

• Peripheral Arterial Disease (PAD)

• Raynaud Phenomenon

• Aneurysms

What are the characteristics/manifestations of Peripheral Vascular Disorders?

• Affect blood vessels in the extremities

• May be caused by atherosclerosis, embolism, or thrombus formation

• Can impair blood flow to tissues

What is Peripheral Arterial Disease (PAD)?

A type of peripheral vascular disorder that affects the large arteries (non-coronary, aortic arch, or brain arteries).

What causes Peripheral Arterial Disease (PAD)?

• Atherosclerosis

• Inflammatory responses

• Embolism

• Thrombus formation

What are the risk factors for Peripheral Arterial Disease (PAD)?

• Smoking cigarettes

• Diabetes mellitus

What are the characteristics/manifestations of Peripheral Arterial Disease (PAD)?

• Atherosclerotic blockages

• Reduced blood flow to peripheral tissues

What is Raynaud Phenomenon?

An intense vasospasm of the arteries and arterioles in the toes and especially the fingers.

What causes Raynaud Phenomenon?

• Cold temperatures

• Emotional stress

What are the characteristics/manifestations of Raynaud Phenomenon?

• Intense vasospasm

• Affects arteries and arterioles

• Primarily affects the fingers and toes

• Triggered by cold temperatures or emotional stress

What is an aneurysm?

An abnormal localized dilation of a blood vessel caused by weakening and stretching of the vessel wall

What causes an aneurysm?

• Congenital disorders

• Trauma

• Infections

• Atherosclerosis

What are the characteristics/manifestations of an aneurysm?

• Localized dilation (bulging) of a blood vessel

• Vessel wall becomes weakened and stretched

• Most commonly occurs in the aorta

• Can rupture, causing hemorrhage and clot formation

Can an untreated aneurysm rupture?

Yes

What is a true aneurysm?

An aneurysm in which the vessel wall remains intact (complete vessel wall) and the blood remains within the vascular compartment.

What are the characteristics/manifestations of a true aneurysm?

• Complete vessel wall remains intact

• Blood remains within the vessel

• Vessel bulges outward like a balloon

What is a false aneurysm?

A localized tear in the vessel wall that allows blood to leak out and from a cavity or pocket.

What are the characteristics/manifestations of a false aneurysm?

• Tear in the vessel wall

• Blood leaks out of the vessel

• Forms a blood-filled cavity or pocket

• Includes dissecting aneurysms

What is a Berry Aneurysm?

A true aneurysm consisting of a small spherical (“berry-like”) dilation of a blood vessel at a point of bifurcation. It is commonly found in the Circle of Willis in the brain.

What are the characteristics/manifestations of a Berry Aneurysm?

• True aneurysm

• Small, round (“berry-like”) bulge

• Occurs at vessel bifurcations

• Common in the brain (Circle of Willis)

What is a Dissecting Aneurysm?

A false aneurysm caused by a tear in the intimal layer that allows blood to enter the vessel wall and separate its layers, creating a blood-filled cavity.

What are the characteristics/manifestations of a Dissecting Aneurysm?

• False aneurysm

• Tear in the intimal layer

• Blood enters the vessel wall

• Creates a blood-filled cavity between vessel layers

What is a Fusiform Aneurysm?

A true aneurysm that involves the entire circumference of the vessel, with gradual progressive dilation.

What are the characteristics/manifestations of a Fusiform Aneurysm?

• True aneurysm

• Entire vessel circumference bulges

• Gradual, progressive dilation

• Often resembles a balloon-shaped widening

What is blood pressure (BP)?

The force exerted by blood against the walls of blood vessels

How is blood pressure determined?

BP = Cardiac Output (CO) x Total Peripheral Resistance (TPR)

How is blood pressure regulated?

Via the nervous system and the renin-angiotensin-aldosteron (RAA) mechanism.

How does the nervous system respond when blood pressure drops?

1. Baroreceptors detect the drop

2. Signals are sent to the cardiovascular center in the brainstem

3. Sympathetic activity increases

4. Heart beats faster and stronger

5. Blood vessels constrict

6. Blood pressure increases

How does the nervous system respond when blood pressure rises?

1. Baroreceptors detect the increase

2. Signals are sent to the brain stem

3. Parasympathetic (vagal) activity increases

4. Heart rate slows

5. Blood pressure decreases

What is primary (essential) hypertension?

The presence of hypertension without an identifiable cause.

What are risk factors for primary (essential) hypertension?

• Genetics

• Race

• Age

• Insulin resistance

• Diet

• Obesity

• Alcohol use

What is secondary hypertension?

Elevated blood pressure caused by another disease or medical condition.

What causes secondary hypertension?

• Kidney disease

• Adrenal cortical hormone disorders

• Tumors that release catecholamines

• Oral contraceptives

• Other underlying diseases

What are the characteristics/manifestations of secondary hypertension?

• Sustained elevation of blood pressure

• May improve if the underlying condition is treated

What is a hypertensive crisis?

A marked elevation of blood pressure with a systolic pressure greater than 180 mm Hg and/or a diastolic pressure greater than 120 mm Hg.

What causes a hypertensive crisis?

• Severe elevation of blood pressure

• Can occur in patients with hypertension

What are the characteristics/manifestations of a hypertensive crisis?

• Systolic BP > 180 mm Hg

• Diastolic BP > 120 mm Hg

• May be classified as Hypertensive urgency or Hypertensive emergency

What is a hypertensive urgeny?

A marked elevation of blood pressure (systolic > 180 mm Hg and/or a diastolic > 120 mm Hg) without target organ damage.

What causes a hypertensive urgency?

• Severe elevation of blood pressure

• No rapid progression of target organ injury

What are the characteristics/manifestations of a hypertensive urgency?

• Systolic BP > 180 mm Hg and/or diastolic BP > 120 mm Hg

• No target organ damage

• No rapid worsening of the heart, kidneys, brain, or eyes

What is a hypertensive emergency?

A marked elevation of blood pressure (systolic > 180 mm Hg and/or a diastolic > 120 mm Hg) with target organ damage.

What causes a hypertensive emergency?

Severe elevation of blood pressure causing injury to organs.

What are the characteristics/manifestations of a hypertensive emergency?

• Systolic BP > 180 mm Hg and/or diastolic BP > 120 mm Hg

• Target organ damage present

• May affect Heart, kidneys, brain, and eyes.

What can decrease blood pressure?

• Vasodilation

• Ace inhibitors

• Beta-blockers

What is preclampsia?

A multisystem disorder of pregnancy characterized by hypertension that develops after 20 weeks of gestation.

What are the characteristics/manifestations of preeclampsia?

• Hypertension (systolic > 140 mm Hg and/or diastolic > 90 mm Hg)

• Proteinuria (protein in the urine)

• Thromvocytopenia

• Impaired liver function

• Elevated serum creatinine

• Elevated liver enzymes

What is eclampsia?

The development of seizures in a patient with preclampsia

What causes eclampsia?

• Progression of preeclampsia

• Occurs when seizures develop in a patient with preeclampsia

What are the characteristics/manifestations of eclampsia?

• Seizures

• Hypertension

• Proteinuria (protein in the urine)

• Thromvocytopenia

• Impaired liver function

• Elevated serum creatinine

• Elevated liver enzymes

When does gestational hypertension occur?

After 20 weeks of pregnancy and normally resolves by 12 weeks postpartum.

What is a Deep Vein Thrombosis (DVT)?

A blood clot (thrombus) that forms in a deep vein, usually in the lower extremities.