Textbook Question
Explain why the skin and lips of fair-skinned individuals may 'turn blue' in very cold weather.
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Ch. 18 The Cardiovascular System II: The Blood Vessels
Amerman2nd EditionHuman Anatomy & PhysiologyISBN: 9780136873822
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Table of contents
- Ch. 1 Introduction to Anatomy and Physiology26
- Ch. 2 The Chemistry of Life38
- Ch. 3 The Cell55
- Ch. 4 Histology47
- Ch. 5 The Integumentary System30
- Ch. 6 Bones and Bone Tissue36
- Ch. 7 The Skeletal System40
- Ch. 8 Articulations19
- Ch. 9 The Muscular System36
- Ch. 10 Muscle Tissue and Physiology29
- Ch. 11 Introduction to the Nervous System and Nervous Tissue28
- Ch. 12 The Central Nervous System42
- Ch. 13 The Peripheral Nervous System41
- Ch. 14 The Autonomic Nervous System and Homeostasis31
- Ch. 15 The Special Senses39
- Ch. 16 The Endocrine System42
- Ch. 17 The Cardiovascular System I: The Heart30
- Ch. 18 The Cardiovascular System II: The Blood Vessels43
- Ch. 19 Blood32
- Ch. 20 The Lymphatic System and Immunity45
- Ch. 21 The Respiratory System27
- Ch. 22 The Digestive System27
- Ch. 23 Metabolism and Nutrition7
- Ch. 24 The Urinary System39
- Ch. 25 Fluid, Electrolyte, and Acid-Base Homeostasis39
- Ch. 26 The Reproductive System10
- Ch. 27 Development and Heredity5
Chapter 18, Problem L3.1
You are babysitting two children who are having a contest to see who can hang upside-down for the longest time. At the end of the contest, both children feel dizzy and are worried they are sick. Explain to them why they feel this way and why the effect is only temporary. (Hint: Consider how the baroreceptor reflex responds when a person hangs upside-down.)
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Explain to the children that when they hang upside-down, gravity causes blood to pool in the upper part of their body, particularly in the head. This increases the pressure in the blood vessels of the brain and face.
Introduce the concept of baroreceptors, which are specialized sensors located in the walls of certain blood vessels, such as the carotid arteries and aortic arch. These sensors detect changes in blood pressure and send signals to the brain to regulate it.
Describe how the baroreceptor reflex works: When the blood pressure in the head increases due to being upside-down, the baroreceptors signal the brain to lower the heart rate and dilate blood vessels to reduce the pressure. This is the body's attempt to maintain homeostasis.
Explain that the dizziness they feel is a temporary effect caused by the sudden changes in blood pressure and the body's adjustment process. Once they return to an upright position, the baroreceptor reflex helps normalize blood pressure, and the dizziness subsides.
Reassure them that this is a normal physiological response and not a sign of illness. Their bodies are simply adapting to the unusual position, and the effect will pass as their blood pressure stabilizes.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Baroreceptor Reflex
The baroreceptor reflex is a physiological mechanism that helps regulate blood pressure. Baroreceptors, located in the carotid arteries and aorta, detect changes in blood pressure and send signals to the brain to adjust heart rate and blood vessel diameter. When hanging upside-down, blood pools in the head, causing increased pressure, which the body must quickly adapt to in order to maintain stable blood flow and pressure.
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Stretch Reflex
Vestibular System
The vestibular system is responsible for maintaining balance and spatial orientation. It consists of structures in the inner ear that detect changes in head position and motion. When the children hang upside-down, the fluid in the inner ear shifts, leading to confusion in the brain about their orientation, which can cause dizziness and a sensation of imbalance.
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Temporary Effects of Dizziness
The dizziness experienced by the children is temporary because the body has mechanisms to quickly adapt to changes in position. Once they return to an upright position, the baroreceptor reflex and vestibular system recalibrate, restoring normal blood flow and balance. This adaptation process helps prevent prolonged dizziness and allows the body to recover from the effects of hanging upside-down.
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Related Practice
Textbook Question
Which of the following factors would increase peripheral resistance?
a. Increased blood viscosity
b. Shorter vessel
c. Vasodilation
d. An increase in vessel radius
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Textbook Question
The carotid sinus contains:
a. Baroreceptors
b. Chemoreceptors
c. Metabolic controls
d. Smooth muscle cells
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Textbook Question
Predict the effects of each of the following on systemic arterial blood pressure:
Caffeine consumption, which increases heart rate and causes vasoconstriction
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Textbook Question
Match the following terms with the correct definition.
____ Auricle
____ Aorta
____ Coronary sinus
____ Papillary muscle
____ Fossa ovalis
____ Pectinate muscle
____ Venae cavae
____ Pulmonary trunk
____ Chordae tendineae
____ Pulmonary veins
a. Drainage point for the coronary veins
b. Extensions that attach papillary muscles to valves
c. Remnant of a hole present in the fetal interatrial septum
d. Two largest veins of the systemic circuit
e. Flaplike extension from the right or left atrium
f. Finger-like projections of ventricular muscle
g. Main artery of the pulmonary circuit
h. Veins that drain the pulmonary circuit
i. Largest artery of the systemic circuit
j. Ridges of muscle in the atria
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Textbook Question
Ms. Rodgers has been diagnosed with secretion of inappropriate ADH syndrome (SIADH). What effect will SIADH have on the amount of water in her body? What symptoms would you expect from this condition? How would it affect her blood pressure and net filtration pressure?
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