Vessel Histology & Comparisons
What are the three tunics (layers) that make up the walls of most blood vessels from deep to superficial?
→ Tunica intima, tunica media, tunica externa (Slide 5)
Which tunic is present in capillaries?
→ Only the tunica intima (endothelium + basement membrane) (Slide 8)
What percentage of blood is typically held in systemic veins at rest?
→ About 55% (Slide 14)
What is the primary mechanism by which oxygen and carbon dioxide move across capillary walls?
→ Diffusion (Slide 20)
What term describes the growth of new blood vessels in tissues?
→ Angiogenesis (Slide 26–27)
Which vessel type has the thickest tunica media?
→ Arteries (Slide 5)
List the types of capillaries from most permeable to least permeable.
→ Sinusoid, Fenestrated, Continuous (Slide 10)
Which vessels collect blood directly from capillary beds before merging into veins?
→ Venules (Slide 15)
What is bulk flow?
→ The movement of large amounts of fluid and dissolved substances down a pressure gradient (Slide 21)
Which tissues have high vascularization, and which have low?
→ High: skeletal muscle, heart, brain, liver; Low: tendons, ligaments, cartilage, cornea, lens (Slide 26)
Which vessel type contains only the tunica intima?
→ Capillaries (Slide 5, 8)
Which type of capillary has large gaps that allow passage of formed elements and plasma proteins?
→ Sinusoid capillary (Slide 9)
What structures in veins prevent the backflow of blood?
→ Venous valves (Slide 15)
During filtration, fluid moves ______ a capillary. During reabsorption, fluid moves ______ a capillary.
→ Out of; into (Slide 21)
What happens to blood vessel density in adipose tissue with weight gain versus weight loss?
→ Weight gain increases vascularization; weight loss reduces it (Slide 27)
What structural difference explains why veins can act as blood reservoirs while arteries cannot?
→ Veins have thinner walls and larger lumens, allowing them to hold more blood (Slide 6)
Which type of capillary has continuous endothelial lining with tight junctions, allowing only small molecules to pass?
→ Continuous capillary (Slide 9)
Why do veins have thinner walls and larger lumens than arteries?
→ To allow them to function as blood reservoirs and operate under lower pressure (Slide 14–15)
Which two forces primarily determine the direction of bulk flow?
→ Hydrostatic pressure and colloid osmotic pressure (Slide 21)
Why is angiogenesis important in athletes who undergo endurance training?
→ Increases capillary density to improve oxygen and nutrient delivery (Slide 27)
Which layer in the walls of vessels contains the Elastic Laminae?
→ The Tunica Media (Slide 5)
Which type of capillary has small pores to allow movement of larger substances like hormones or nutrients?
→ Fenestrated capillary (Slide 9)
How does the skeletal muscle pump assist venous return?
→ Muscle contraction compresses veins, pushing blood toward the heart (Slide 16)
At the arterial end of a capillary, which pressure is greater: hydrostatic or osmotic? What is the result?
→ Hydrostatic pressure is greater, leading to net filtration (Slide 22)
What is tumor angiogenesis?
→ The growth of new blood vessels that supply nutrients to tumors (Slide 28)
List the 3 types of each of kind of Veins and Arteries starting from the capillaries.
→ Veins: Venule, small to medium-sized veins, Large Veins. Arteries: Arteriole, muscular artery, Elastic Artery (Slide 6)
How is blood through the capillary bed regulated?
→ Contraction and Relaxation of precapillary sphincters (Slide 11)
How does the respiratory pump aid venous return?
→ Inhalation decreases thoracic pressure and increases abdominal pressure, moving blood toward the heart (Slide 17)
At the venous end of a capillary, which pressure is greater: hydrostatic or osmotic? What is the result?
→ Colloid osmotic pressure is greater, leading to net reabsorption (Slide 22)
Why is tumor angiogenesis dangerous for cancer progression?
→ It provides tumors with oxygen and nutrients, enabling growth and metastasis (Slide 28)
How does the thickness of vessel walls affect resistance and blood pressure in arteries vs. veins?
→ Thicker arterial walls maintain high pressure and resistance; thinner venous walls create low resistance and low pressure (Slides 5–7)
Why are continuous capillaries abundant in the brain and lungs?
→ To tightly regulate exchange and protect sensitive tissues (Slide 9, 11)
What would happen to venous return if valves in leg veins became incompetent?
→ Blood would pool in the legs, causing varicose veins and reduced venous return (Slide 15, Supplemental reasoning)
In hypertension, why is filtration favored across more of the capillary length?
→ Elevated hydrostatic pressure overwhelms osmotic pull, reducing reabsorption of fluid into the capillary bed, leading to edema (Slide 23)
Which pulse point is commonly used during CPR to check circulation?
→ Carotid artery (Supplemental, from textbook)
Compare the elasticity of elastic arteries vs. muscular arteries.
→ Elastic arteries have more elastic fibers to stretch and recoil; muscular arteries have thicker tunica media with more smooth muscle for distribution and regulation (Slide 7)
List the structures in order from start to finish for capillary beds.
→ Arteriole, metarteriole, thoroughfare channel, true capillaries, postcapillary venule. (Slide 12)
How does venous blood return to the heart despite operating under very low pressure?
→ Assisted by valves, skeletal muscle pump, respiratory pump, and large lumen size (Slides 15–17)
How does low plasma albumin (hypoalbuminemia) affect bulk flow?
→ Reduces colloid osmotic pressure, leading to excessive filtration and edema (Slide 24)
Why is it more reliable to use arteries rather than veins for pulse points?
→ Arteries are under higher pressure, so pulsations are stronger and more palpable (Slide 29, Supplemental reasoning)
Predict what would happen to systemic circulation if veins had the same wall thickness and elasticity as arteries.
→ Veins would lose their reservoir function, venous return would decrease, and blood pressure regulation would be impaired (Slide 6, Supplemental reasoning)
A tissue sample shows sinusoid capillaries. What organs might this tissue have come from, and why?
→ Red bone marrow, Liver, Spleen, some endocrine glands; they allow large substances like formed elements, plasma and plasma proteins to pass through (Slide 9, Supplemental reasoning)
Explain why long periods of standing still may lead to fainting in terms of venous return.
→ Without muscle contractions, skeletal muscle pump is inactive → reduced venous return → decreased cardiac output → reduced cerebral perfusion (Slides 15–16, Supplemental reasoning)
What are the four factors that local blood flow is dependent on?
→ Degree of tissue vascularity, myogenic response, local regulatory factors altering blood flow, total blood flow (Slide 25)
How might reduced angiogenesis contribute to slow wound healing in the elderly?
→ Fewer new vessels form, decreasing delivery of oxygen and nutrients to damaged tissue (Slides 26–27, Supplemental reasoning)
How does the structural difference between arterioles and venules influence their role in regulating capillary blood flow?
→ Arterioles have smooth muscle in the tunica media for constriction/dilation to control flow into capillaries; venules primarily collect blood with minimal resistance (Slide 7, Slide 15)
A tissue sample shows fenestrated capillaries. What organs might this tissue have come from, and why?
→ Kidneys, small intestine, endocrine glands; they allow filtration and hormone/nutrient exchange (Slides 9, 11)
Predict the effect of deep vein thrombosis (DVT) on venous return and systemic circulation.
→ Obstruction decreases venous return, increases venous pressure, and may cause swelling or pulmonary embolism if clot dislodges (Supplemental case application)
How does the lymphatic system complement bulk flow in maintaining fluid balance at the capillary level?
→ It returns the small amount of fluid not reabsorbed by capillaries back to circulation, preventing interstitial fluid buildup (Supplemental – textbook/lecture integration)
A patient with liver cirrhosis has decreased production of plasma proteins. How does this affect oncotic pressure and risk for edema?
→ Decreased oncotic pressure → reduced reabsorption → fluid retention/edema (Slide 24, tied to clinical application)
A biopsy shows a vessel with a very thick tunica media and lots of elastic fibers, near the heart. Identify the vessel and explain its function.
→ Elastic artery; stretches and recoils to buffer pressure changes from the heartbeat (Slide 7)
Compare the functional significance of having continuous capillaries in the blood–brain barrier versus fenestrated capillaries in the kidneys.
→ BBB continuous capillaries protect brain tissue from toxins; fenestrated capillaries in kidneys allow efficient filtration of plasma (Slides 9, 11, Supplemental reasoning)
Compare the importance of the skeletal muscle pump in the legs versus the arms.
→ Legs rely heavily on the pump due to gravity and distance from the heart; arms are closer and less dependent (Slides 15–16, Supplemental reasoning)
Compare how bulk flow contributes to nutrient/waste exchange versus fluid balance in tissues.
→ Nutrient/waste exchange relies mostly on diffusion; bulk flow maintains fluid balance by distributing plasma and interstitial fluid (Slides 20–22, integrated reasoning)
Explain why detecting a weak pedal pulse in the foot could be clinically significant.
→ It may indicate peripheral artery disease or reduced perfusion to lower limbs (Slide 29, Supplemental application)
A patient’s histological sample shows abnormal thickening of the tunica intima across multiple vessels. What condition might this represent, and why does it compromise circulation?
→ Atherosclerosis; narrowed lumen increases resistance and reduces blood flow (Supplemental—discussion, not directly in slides)
A patient develops widespread inflammation that disrupts tight junctions in continuous capillaries. Predict the consequences at the tissue level.
→ Increased permeability → leakage of plasma proteins → edema and impaired tissue function (Supplemental—discussion, tied to Slide 11)
A patient with chronic obstructive pulmonary disease (COPD) has impaired thoracic pressure changes. How will this affect venous return and cardiac output?
→ Reduced effectiveness of respiratory pump → decreased venous return → lower preload → reduced cardiac output (Slide 17, integrated application)
A patient with severe liver disease presents with widespread edema. Explain how impaired protein synthesis leads to this outcome using bulk flow principles.
→ Decreased albumin → reduced osmotic pressure → reduced reabsorption → net fluid accumulation in interstitial space (Slides 24, integrated application)
A cancer therapy drug inhibits VEGF (vascular endothelial growth factor). Predict the effect on tumors and normal tissues.
→ Reduces tumor blood supply and growth; but may also impair angiogenesis in normal tissues, leading to side effects (Slide 28, integrated reasoning)