Blood Vessels and Circulation – Practice Flashcards

Question-and-Answer flashcards covering major concepts from the Blood Vessels and Circulation lecture.

Which blood vessels collect blood from capillaries and return it to the heart?

Veins

Compared with arteries, veins are in diameter, have walls, and carry _ blood pressure.

larger; thinner; lower

What two mechanisms help propel blood through the venous system back to the heart?

(1) Venous valves that prevent back-flow, and (2) skeletal-muscle contractions that compress veins.

Capillary blood flow throughout the body is equal to what major cardiovascular parameter?

Total cardiac output (CO).

Which two variables determine cardiac output?

Stroke volume (SV) and heart rate (HR).

What vascular structures contract or relax to regulate blood flow into a capillary bed?

Pre-capillary sphincters.

How do water, ions, and small molecules such as glucose move across most capillary walls?

By diffusion between adjacent endothelial cells or through fenestrations.

Through what structures do Na⁺, K⁺, Ca²⁺, and Cl⁻ ions cross the capillary endothelium?

Ion channels in endothelial cell membranes.

How do large, water-soluble compounds pass through capillaries?

Via fenestrated capillaries.

Lipids, O₂, and CO₂ diffuse across capillary walls by passing through what part of the endothelial cells?

The lipid bilayer of endothelial cell membranes.

Plasma proteins can cross the endothelium only at what specialized capillaries?

Sinusoids.

At the arterial end of a capillary, fluid moves the capillary and the interstitial fluid.

out of; into

At the venous end of a capillary, fluid moves the capillary and the interstitial fluid.

into; out of

List the four main functions of the blood–lymph cycle.

(1) Maintains constant communication between plasma and interstitial fluid, (2) speeds distribution of nutrients, hormones, and gases, (3) transports insoluble lipids and tissue proteins that cannot cross capillary walls, and (4) flushes bacterial toxins and chemicals to immune tissues.

What systolic/diastolic values define hypertension?

140/90 mm Hg.

What systolic/diastolic values define hypotension?

< 90/60 mm Hg.

Name the three broad regulatory mechanisms that control cardiac output and arterial blood pressure.

Autoregulation, neural mechanisms, and endocrine mechanisms.

Autoregulation produces what kind of cardiovascular adjustments?

Immediate, localized homeostatic adjustments.

Give five examples of local vasodilator conditions or chemicals.

Low O₂ or high CO₂, low pH (acids), nitric oxide (NO), high K⁺ or H⁺, histamine or other inflammatory chemicals, and elevated local temperature.

During light exercise, what three cardiovascular changes occur?

(1) Extensive vasodilation increases circulation; (2) skeletal-muscle contractions increase venous return; (3) cardiac output rises via the Frank–Starling mechanism and atrial stretch.

Heavy exercise activates which division of the autonomic nervous system?

The sympathetic nervous system.

During heavy exercise, cardiac output can increase to about how many times its resting value?

Approximately four times resting level.

During heavy exercise, blood flow is restricted to which organs and redirected to which?

Restricted to nonessential organs (e.g., digestive tract) and redirected to skeletal muscles, lungs, and heart; cerebral blood flow remains unchanged.

What three short-term responses help prevent a dangerous drop in blood pressure after hemorrhage?

(1) Carotid and aortic reflexes raise CO and cause peripheral vasoconstriction; (2) sympathetic activation further constricts arterioles and causes venoconstriction; (3) hormones (epinephrine, norepinephrine, ADH, angiotensin II) raise CO and peripheral resistance.

Name four long-term mechanisms that restore blood volume after severe hemorrhage.

(1) Fluid recall from interstitial spaces, (2) aldosterone and ADH-mediated fluid retention, (3) increased thirst, and (4) erythropoietin-stimulated RBC production.

Why is blood flow to the brain considered top priority?

The brain has the body’s highest oxygen demand; when peripheral vessels constrict, cerebral vessels dilate to maintain brain perfusion.

What clinical event results from blockage or rupture of a cerebral artery?

A stroke, also called a cerebrovascular accident (CVA).

During increased cardiac activity, which two factors dilate coronary vessels and increase coronary blood flow?

Accumulation of lactic acid/low O₂ levels in cardiac tissue and the hormone epinephrine.

List three effects of epinephrine on the heart during stress or exercise.

Dilates coronary vessels, increases heart rate, and strengthens myocardial contractions.

Outline the basic path of blood through the pulmonary circuit.

Deoxygenated blood enters the right atrium → right ventricle → pulmonary trunk → pulmonary arteries → lung capillaries (CO₂ off-loaded, O₂ picked up) → pulmonary veins → left atrium, ready for systemic distribution.