Concept explainers
To review:
Whether the following statements are true or false:
a. Arteries are the exchange vessels of the cardiovascular system.
b. The tunica intima is composed of a sheet of endothelium, connective tissue, and the internal elastic lamina.
c. The tunica media consists of smooth muscle cells innervated by vasomotor nerves.
d. Muscular arteries control blood flow at the tissue level.
e. Veins have smaller lumens, more elastic fibers, and more smooth muscles than arteries.
Introduction:
The cardiovascular system contains a billion blood vessels, which transport blood to tissues and so carry it back to the heart. It involves the exchange of gases, nutrients, and wastes. These blood vessels involve arteries, veins, and capillaries. They also regulate blood flow to tissues and control blood pressure.

Explanation of Solution
a. The statement “Arteries are the exchange vessels of the cardiovascular system” is false. The arteries carry blood away from the heart and supply blood to the various organs and tissues. The pulmonary artery carries the deoxygenated blood and the systemic artery carries oxygenated blood. The exchange vessels of the cardiovascular system are capillaries. So, the correct statement would be “Arteries are distribution system of the cardiovascular system.”
b. The statement “The tunica intima is composed of a sheet of endothelium, connective tissues, and the internal elastic lamina” is true. Tunica intima is the innermost layer of the blood vessels. Endothelium provides a smooth surface for blood flow. Deep in the endothelium, the internal elastic lamina is present, which consists of a thin layer of subendothelial connective tissues and a layer of elastic fibers. This layer has the ability to restore the original shape of the blood vessels after stretching.
c. The statement “The tunica media consists of smooth muscle cells innervated by vasomotor nerves” is true. Tunica media is the middle layer of the blood vessel wall. It consists of two components—a layer of smooth muscle cells and a layer of elastic fibers called the external elastic lamina. The smooth muscles of tunica media are supplied with nerves from a sympathetic nervous system called the vasomotor nerves. These nerves enable the action of vasodilation and vasoconstriction of blood vessels.
d. The statement “Muscular arteries control blood flow at the tissue level” is false. Muscular arteries contain well-developed tunica media, which consist of smooth muscle cells. Due to the presence of smooth muscle cells, muscular arteries can change their diameter with vasoconstriction and vasodilation. This helps in the regulating the blood flow to different organs. So, the correct statement would be “Muscular arteries control the blood flow at the organ level.”
e. The statement “Veins have smaller lumens, more elastic fibers, and more smooth muscles than arteries” is false. Veins act as the blood reservoirs of the body. Blood can be diverted from veins to other parts of the body when needed. The arteries are circular, whereas veins appear collapsed, so they have much thinner walls. The correct statement is “Veins have fewer elastic fibers, less smooth muscles, and a larger lumen that arteries.”
Thus, it can be concluded that the statements (b) and (c) are true and the statements (a), (d), and (e) are false.
Want to see more full solutions like this?
Chapter 18 Solutions
HUMAN A+P MOD.MASTERING
- Ch.21 What causes patients infected with the yellow fever virus to turn yellow (jaundice)? A. low blood pressure and anemia B. excess leukocytes C. alteration of skin pigments D. liver damage in final stage of disease — What is the advantage for malarial parasites to grow and replicate in red blood cells? A. able to spread quickly B. able to avoid immune detection C. low oxygen environment for growth D. cooler area of the body for growth — Which microbe does not live part of its lifecycle outside humans? A. Toxoplasma gondii B. Cytomegalovirus C. Francisella tularensis D. Plasmodium falciparum — explain your answer thoroughlyarrow_forwardCh.22 Streptococcus pneumoniae has a capsule to protect it from killing by alveolar macrophages, which kill bacteria by… A. cytokines B. antibodies C. complement D. phagocytosis — What fact about the influenza virus allows the dramatic antigenic shift that generates novel strains? A. very large size B. enveloped C. segmented genome D. over 100 genes — explain your answer thoroughlyarrow_forwardWhat is this?arrow_forward
- Molecular Biology A-C components of the question are corresponding to attached image labeled 1. D component of the question is corresponding to attached image labeled 2. For a eukaryotic mRNA, the sequences is as follows where AUGrepresents the start codon, the yellow is the Kozak sequence and (XXX) just represents any codonfor an amino acid (no stop codons here). G-cap and polyA tail are not shown A. How long is the peptide produced?B. What is the function (a sentence) of the UAA highlighted in blue?C. If the sequence highlighted in blue were changed from UAA to UAG, how would that affecttranslation? D. (1) The sequence highlighted in yellow above is moved to a new position indicated below. Howwould that affect translation? (2) How long would be the protein produced from this new mRNA? Thank youarrow_forwardMolecular Biology Question Explain why the cell doesn’t need 61 tRNAs (one for each codon). Please help. Thank youarrow_forwardMolecular Biology You discover a disease causing mutation (indicated by the arrow) that alters splicing of its mRNA. This mutation (a base substitution in the splicing sequence) eliminates a 3’ splice site resulting in the inclusion of the second intron (I2) in the final mRNA. We are going to pretend that this intron is short having only 15 nucleotides (most introns are much longer so this is just to make things simple) with the following sequence shown below in bold. The ( ) indicate the reading frames in the exons; the included intron 2 sequences are in bold. A. Would you expected this change to be harmful? ExplainB. If you were to do gene therapy to fix this problem, briefly explain what type of gene therapy youwould use to correct this. Please help. Thank youarrow_forward
- Molecular Biology Question Please help. Thank you Explain what is meant by the term “defective virus.” Explain how a defective virus is able to replicate.arrow_forwardMolecular Biology Explain why changing the codon GGG to GGA should not be harmful. Please help . Thank youarrow_forwardStage Percent Time in Hours Interphase .60 14.4 Prophase .20 4.8 Metaphase .10 2.4 Anaphase .06 1.44 Telophase .03 .72 Cytukinesis .01 .24 Can you summarize the results in the chart and explain which phases are faster and why the slower ones are slow?arrow_forward
- Can you circle a cell in the different stages of mitosis? 1.prophase 2.metaphase 3.anaphase 4.telophase 5.cytokinesisarrow_forwardWhich microbe does not live part of its lifecycle outside humans? A. Toxoplasma gondii B. Cytomegalovirus C. Francisella tularensis D. Plasmodium falciparum explain your answer thoroughly.arrow_forwardSelect all of the following that the ablation (knockout) or ectopoic expression (gain of function) of Hox can contribute to. Another set of wings in the fruit fly, duplication of fingernails, ectopic ears in mice, excess feathers in duck/quail chimeras, and homeosis of segment 2 to jaw in Hox2a mutantsarrow_forward
- Human Biology (MindTap Course List)BiologyISBN:9781305112100Author:Cecie Starr, Beverly McMillanPublisher:Cengage LearningHuman Physiology: From Cells to Systems (MindTap ...BiologyISBN:9781285866932Author:Lauralee SherwoodPublisher:Cengage Learning


