Basic Tissues and Proteoglycans Quiz

Block 1.3 Lectures - 2024-2025

• The lecture is on the microscopic structure of the cardiovascular system (CVS).
• The writer is Danial Abdulfattah.
• The reviewer is Ahmed Al-Ahmed.
• The notes include 221-222-223 notes.
• The notes cover the circulatory and lymphatic systems.

Circulatory System

• The circulatory system is composed of the cardiovascular and lymphatic systems.
• The cardiovascular system includes the heart and blood vessels.
• The lymphatic system includes lymph, lymph vessels, and lymph nodes.

Cardiovascular System

• The cardiovascular system is a part of the circulatory system.
• It is composed of the heart and blood vessels.
• Blood vessels are of two types: arterial bunches and venous bunches.
• These two types of vessels meet in capillary beds.

Blood Vessel Wall Structure

• Blood vessels consist of three layers: tunica intima, tunica media, and tunica adventitia.
• The tunica intima is the innermost layer.
• The tunica media is the middle layer, mainly composed of smooth muscle.
• The tunica adventitia is the outermost layer, containing connective tissue and collagen.

Tunica Intima

• The tunica intima consists of three layers: endothelium, subendothelial connective tissue, and internal elastic lamina(in arteries only).
• Endothelium is a single layer of squamous epithelium.
• Subendothelial tissue is loose connective tissue.
• The internal elastic lamina is a layer of elastic tissue found only in arteries.

Tunica Media

• Tunica media is mainly composed of smooth muscle arranged helically.
• It contains other structures such as elastic fibers, lamellae, reticular fibers, and proteoglycans.
• NO fibroblast secretes the proteoglycans.
• There is an external elastic lamina in large arteries (e.g., aorta, pulmonary).
• In capillaries, the media is replaced by pericytes.

Tunica Adventitia

• The tunica adventitia is the outermost layer of the blood vessel wall.
• It is largely composed of connective tissue containing fibroblasts, collagen type I, and elastic fibers.
• Vasa vasorum (vessels of the vessel) are found in large vessels, especially veins.

Types of Capillaries

• Capillaries are the smallest blood vessels.
• Three types of capillaries are continuous, fenestrated, and discontinuous.
• Continuous capillaries are completely closed, allowing minimal leakage between the inside and outside of the vessel.
• Fenestrated capillaries have pores (fenestrae) allowing rapid exchange of substances.
• Discontinuous/sinusoidal capillaries have large pores and intercellular clefts allowing the largest substances to pass through.

Arteries and Veins

• Arteries carry oxygenated blood away from the heart.
• Veins carry deoxygenated blood toward the heart.
• Arteries have thicker walls compared to veins, particularly the tunica media.
• Veins have thinner tunica media, but larger, more prominent tunica adventitia.
• Veins have valves to prevent backflow and maintain blood flow towards the heart, whereas arteries do not have valves.

Venules

• Venules drain capillary beds.
• Postcapillary venules are similar to capillaries with porous endothelium.
• Collecting venules have more contractile cells.
• Muscular venules have 2-3 layers of smooth muscle cells.

Medium-Sized Veins

• Thin walls and few smooth muscle fibers.
• Prominent tunica adventitia and vasa vasorum.
• Have valves to prevent backflow.
• A thinner tunica media, compared to muscular arteries.
• It normally has no smooth muscles in the tunica adventitia (but can be found here), very thick vasa vasorum.

Large Veins

• The tunica intima is thinner.
• The tunica media is thinner.
• The tunica adventitia is thicker containing more collagen fibers

Lymphatic System

• The lymphatic system parallels the cardiovascular system.
• Lymphatic vessels collect excess interstitial fluid(lymph) and return it to the blood.
• Lymphatic capillaries are closed-ended vessels, lack pericytes, and have incomplete basal laminae.
• Large lymphatic vessels are similar to veins

Heart Structure

• The heart wall consists of three layers: the endocardium, myocardium, and epicardium.
• The endocardium is the inner lining.
• The myocardium is the middle layer composed of cardiac muscle fibers arranged in layers.
• The epicardium (visceral pericardium) is the outer layer

Heart Fibrous Skeleton

• Serves as a base and attachment of the cardiac muscle.
• Supports the heart valves.
• Coordinates heartbeats.

Further Studying

• Lymphatic capillaries drain interstitial fluid.
• Microvasculature is composed of arterioles, capillaries, and venules.

Test your knowledge on basic tissues and their functions, including the role of proteoglycans and fibroblasts. The quiz also covers the different types of tissues present in various locations, and unique characteristics of epithelial tissue. Enhance your understanding of tissue structures and their physiological roles.