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Ch. 21 Blood Vessels and Circulation
Martini - Fundamentals of Anatomy and Physiology 12th Edition
Martini, Nath, Bartholomew12th EditionFundamentals of Anatomy and PhysiologyISBN: 9780137854011Not the one you use?Change textbook
All textbooksMartini, Nath, Bartholomew 12th EditionCh. 21 Blood Vessels and CirculationProblem 7
Chapter 21, Problem 7

The local control of blood flow due to the action of precapillary sphincters is:
(a) Vasomotion
(b) Autoregulation
(c) Selective resistance
(d) Turbulence

Verified step by step guidance
1
Step 1: Understand the role of precapillary sphincters. These are small muscular rings located at the entrance of capillary beds that regulate blood flow into the capillaries by contracting or relaxing.
Step 2: Define the term 'vasomotion'. Vasomotion refers to the rhythmic contraction and relaxation of precapillary sphincters, which causes intermittent blood flow through capillaries.
Step 3: Review the other options: 'Autoregulation' refers to the ability of tissues to regulate their own blood flow based on metabolic needs; 'Selective resistance' is not a standard term in this context; 'Turbulence' refers to irregular blood flow patterns, not controlled by sphincters.
Step 4: Connect the concept of local control of blood flow by precapillary sphincters to the term that best describes this action, which is the rhythmic opening and closing of these sphincters.
Step 5: Conclude that the correct term describing the local control of blood flow by precapillary sphincters is 'vasomotion'.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Precapillary Sphincters and Local Blood Flow Control

Precapillary sphincters are rings of smooth muscle located at the entrance of capillary beds. They regulate blood flow into capillaries by contracting or relaxing, thus controlling the distribution of blood to tissues based on local metabolic needs.
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Vasomotion

Vasomotion refers to the rhythmic contraction and relaxation of precapillary sphincters and small blood vessels. This process causes intermittent blood flow through capillary beds, allowing fine-tuned local regulation of blood supply.

Autoregulation

Autoregulation is the ability of tissues to maintain a relatively constant blood flow despite changes in arterial pressure. It involves mechanisms like myogenic responses and metabolic factors but is broader than the specific action of precapillary sphincters.
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Related Practice
Textbook Question

Identify the major veins in the following diagram.

a. ___

b. ___

c. ___

d. ___

e. ___

f. ___

g. ___

h. ___

i. ___

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Textbook Question

Blood is transported through the venous system by means of:

(a) Skeletal muscle contractions

(b) Decreasing blood pressure

(c) The respiratory pump

(d) A and C

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Textbook Question

Baroreceptors that function in the regulation of blood pressure are located in the:

(a) Left ventricle

(b) Brainstem

(c) Carotid sinus

(d) Common iliac artery

(e) Pulmonary trunk

Textbook Question

Large molecules such as peptides and proteins move into and out of the bloodstream by way of:

(a) Continuous capillaries

(b) Fenestrated capillaries

(c) Thoroughfare channels

(d) Venules

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Textbook Question

The most important factor in vascular resistance is:

(a) The viscosity of the blood

(b) The diameter of the lumen of blood vessels

(c) Turbulence due to irregular surfaces of blood vessels

(d) The length of the blood vessels

Textbook Question

Cardiovascular function is regulated by all of the following except:

(a) Local factors

(b) Neural factors

(c) Endocrine factors

(d) Venous return

(e) Conscious control

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