Name: respiratory exam: lung sounds and percussion
Uploaded: 2023-04-30T06:35:14.000Z
Duration: 7 min 54 s
Channel: JoVE

K12 Standards

new-york-state-science-learning-standards

New York State Science Learning Standards

High School

Life Science

Structure and Function

HS-LS1-3.

respiratory-exam-ii-percussion-and-auscultation

Respiratory Exam II: Percussion and Auscultation

1. 定位
<ol>
	<li>确保患者脱去腰部以上的衣物。</li>
	<li>将患者置于检查台，身体与台面呈30至45度角，并从其右侧进行检查。检查肺部后侧时，需让患者向前倾斜或坐在床缘。</li>
</ol>
2. 叩诊
<ol>
	<li>从背部开始，先后在背部和前胸进行叩诊。</li>
	<li>将非优势手的中指（叩诊板指）紧贴并充分伸直，稳固地按压在患者右侧或左侧背部中段区域（肺下叶后部）。手指对胸壁按压越紧，叩诊音通常越响亮。</li>
	<li>确保其余手指及手掌不接触患者胸壁。</li>
	<li>用优势手的中指指尖（叩诊槌指）有力地叩击非优势手中指的上三分之一段（中节或远节指骨），至少叩击两次（建议保持指甲短而整齐）。叩击音应呈空响，代表含气正常的肺组织。</li>
	<li>在四个和五个水平层面重复叩诊，逐层比较两侧肺叶，从肺下界开始向上至胸壁。呼气时，肺下界在前胸部的锁骨中线平第六肋，腋中线平第八肋，背部大致相当于第10胸椎棘突水平。</li>
	<li>在前胸和后背进行叩诊，将手指置于肋间隙内。</li>
	<li>辨别叩诊音的性质。胸部正常叩诊音包括：
	<ol>
		<li>清音：在含气正常的肺组织上听到的叩诊音。</li>
		<li>浊音（在实质组织上听到的声音）：见于右前下胸部的肝脏区域和左前胸部的心脏区域。当肺部叩诊出现此音时，提示肺实变。</li>
		<li>鼓音（叩击空腔脏器时产生的类似鼓声的声音）：见于Traube区，即胃泡区上方，其边界为第六肋、前腋线和左侧肋缘。左侧胸腔积液时，Traube区可出现浊音。</li>
	</ol>
	</li>
	<li>注意是否存在病理性叩诊音。&#34;实音&#34;或绝对浊音比&#34;普通&#34;浊音更沉闷，类似叩击大腿时的声音，提示胸腔积液。过清音是一种病理性叩诊音，提示肺气肿、慢性阻塞性肺疾病（COPD）晚期或气胸所致的肺过度充气。</li>
</ol>
3. 听诊
<ol>
	<li>摆正患者体位：嘱患者向前倾斜或端坐，以便进行背部检查。嘱患者双臂交叉抱于胸前或双手置于对侧肩部，有助于充分暴露肺野。</li>
	<li>将听诊器的胸件置于患者胸部，要求患者通过口腔深呼吸。</li>
	<li>后部和前部共五个听诊部位，左右两侧逐一进行对比听诊。</li>
	<li>正常的呼吸音称为肺泡呼吸音，是一种低调的声音，在吸气时较响亮，呼气时较轻柔。在背部听诊时应呈对称分布。</li>
	<li>注意异常（附加）附加呼吸音的存在及其位置，例如爆裂音、哮鸣音、隆隆音、喘鸣音或胸膜摩擦音表1).</li>
	<li>注意记录任何异常呼吸音（如果存在）的以下特征：响度、音质、持续时间，以及是出现在吸气相还是呼气相即，呼吸周期中的时相）。许多异常呼吸音在让患者咳嗽后更易听到。</li>
	<li>听诊时嘱患者发音，评估支气管语音，即在肺实变区域声音传导增强的情况 &#34;99&#34; 或 &#34;1-2-1.&#34; 语音共振增强是指患者在发出声音时，通过听诊器听到的声音变得异常清晰、尖锐，如同“羊叫声”的一种体征。 &#34;E&#34; 声音变为一种 &#34;A&#34; 实变肺组织上方</li>
	<li>评估耳语音。听诊时，请患者低声耳语 &#34;99&#34; 或 &#34;1-2-1.&#34; 在实变的肺部，听诊器听到的声音实际上会更清晰、更明显。</li>
</ol>
<table>
	<tbody>
		<tr>
			<td>呼吸音</td>
			<td colspan="3">描述</td>
		</tr>
		<tr>
			<td>支气管呼吸音</td>
			<td colspan="3">粗糙或中空的呼吸音，类似于将听诊器置于气管或主支气管上方时所听到的声音。在其他区域出现时，可能提示存在肺实变</td>
		</tr>
		<tr>
			<td>支气管肺泡呼吸音</td>
			<td colspan="3">在大气道和胸骨区域为正常呼吸音，在其他区域则为异常</td>
		</tr>
		<tr>
			<td>细湿啰音、捻发音或啰音</td>
			<td colspan="3">由气道内液体引起，通常在吸气时于肺底更易听到。可进一步分为细湿啰音：声音柔和、短暂、高音调，类似&#34;爆裂声&#34;；或粗湿啰音：比细湿啰音更响亮、音调更低。细湿啰音可见于肺纤维化，粗湿啰音则见于慢性阻塞性肺疾病（COPD）和肺炎。注意啰音出现的时相。充血性心力衰竭通常产生晚期出现的啰音</td>
		</tr>
		<tr>
			<td>哮鸣音</td>
			<td colspan="3">在哮喘和慢性阻塞性肺疾病（COPD）中可听到的特征性高音调连续性声音</td>
		</tr>
		<tr>
			<td>鼾音</td>
			<td colspan="3">低音调的&#34;鼾声&#34;，可在任何引起气道反应性疾病的状况下听诊到，包括肺炎、慢性阻塞性肺疾病（COPD）和充血性心力衰竭（CHF）</td>
		</tr>
		<tr>
			<td>喘鸣音</td>
			<td colspan="3">一种异常的高音调声音，通常在吸气时由上呼吸道产生（常为医疗急症）</td>
		</tr>
		<tr>
			<td>摩擦音</td>
			<td colspan="3">由胸膜表面相互摩擦引起（胸膜摩擦音），在胸膜炎及其他疾病（如心包炎）中更易听到</td>
		</tr>
	</tbody>
</table>
表1. 肺部听诊过程中可能发现情况的汇总表。

每次进行完整的呼吸系统检查时，叩诊和听诊应始终按顺序进行。掌握正确的叩诊方法需要时间和练习（可以在自己身上或其他表面如桌子进行练习）。注意叩诊音在含气肺组织、肋骨以及心脏等实质性器官上的自然变化。
必须对每个肺区进行听诊，以便医生最大程度地识别任何肺部病变的病灶。异常呼吸音在患者中出现时应易于辨认。应留出足够的时间对呼吸音进行分类。如有必要，在一个区域倾听数个呼吸周期，以准确听清爆裂音、哮鸣音、隆隆音或其他病理性发现的具体特征。区分某些呼吸音有时可能看似主观，但随着实践会变得更容易，从而对许多肺部疾病实现&#34;即刻诊断&#34;。

呼吸系统检查 ii：叩诊与听诊

来源：<a href="https://www.jove.com/author/Suneel_Dhand">Suneel Dhand</a>，医学博士，内科主治医师，贝斯以色列女执事医疗中心
掌握呼吸系统叩诊和听诊的正确技术至关重要，这需要通过在真实患者身上的实践来学习。叩诊是一项有用的技能，在日常临床实践中常被省略，但如果操作得当，可帮助医生识别潜在的肺部病变。听诊能够为多种急性肺部疾病提供几乎即时的诊断，包括慢性阻塞性肺疾病（COPD）、哮喘、肺炎和气胸。
听诊肺部的区域对应于肺区。在叩诊和听诊期间，每个肺叶均可在胸壁下方进行定位（图1）。右肺有三个肺叶：上叶、中叶和下叶。左肺有两个肺叶：上叶和下叶。左肺的上叶还有一个独立的区域，称为舌叶。
<img alt="肺部解剖图；标有上叶、中叶、下叶及裂隙，用于教学。" src="/files/ftp_upload/10041/10041fig1.jpg" data-altupdatedat="1761830439000" data-alt="图3"> 
图1. 肺与胸壁关系的解剖结构。 肺及其裂隙和肺叶在胸前壁的大致投影。RUL — 右上叶；RML — 右中叶；RLL — 右下叶；LUL — 左上叶；LLL — 左下叶。

呼吸系统检查 II：叩诊与听诊

来源：Suneel Dhand，医学博士，内科主治医师，贝斯以色列女执事医疗中心  
学习正确的叩诊及……技巧

掌握呼吸系统叩诊和听诊的正确技术对于床旁诊断肺部疾病至关重要。叩诊是一项简单但非常有用的技术，若操作得当，可帮助医生识别潜在的肺部病理变化。另一方面，听诊能够为多种肺部疾病提供几乎即时的诊断，包括慢性阻塞性肺疾病、哮喘、肺炎和气胸。在另一段视频中，我们介绍了如何对呼吸系统进行视诊和触诊。本视频将重点介绍该检查中的叩诊和听诊步骤。在深入讲解临床检查的细节之前，让我们先回顾一下肺叶的解剖结构和呼吸音。这将有助于我们更好地理解叩诊和听诊的解剖学位置及其结果。肺部叩诊和听诊的区域对应于肺叶，每个肺叶均可在胸壁下方定位。右肺较左肺大，分为三个肺叶：上叶、中叶和下叶。水平裂将上叶与中叶分隔开，而右斜裂则将中叶与下叶分隔开。左肺仅有两个肺叶：上叶和下叶，由左斜裂分隔。由于肺内大部分充满吸入的空气，因此在大部分肺区进行叩诊时会产生共鸣音，即一种低音调、空旷的声音。因此，任何浊音或过清音均提示可能存在肺部病变，分别见于胸腔积液或气胸等情况。听诊时通过听诊器听到的呼吸音也具有特殊特征。正常呼吸时可听到两种呼吸音，即支气管呼吸音和肺泡呼吸音。支气管呼吸音较为管状、空旷，在前胸部的大气道区域可听到；而肺泡呼吸音则柔和、低音调并带有沙沙声，可在大部分肺组织区域听到。异常呼吸音包括湿啰音（又称水泡音），提示小气道内有液体存在。另一方面，哮鸣音或鼾音提示气道狭窄或肿胀，导致部分气道阻塞。胸膜摩擦音发生在呼吸过程中发炎的胸膜表面相互滑动时；最后，喉喘鸣由上呼吸道阻塞引起。了解了在进行呼吸叩诊和听诊时应关注的部位和要点后，接下来讨论具体操作步骤，首先从叩诊开始。请患者坐直或向前倾斜。先从背部区域的叩诊开始，将非优势手的中指紧贴并充分伸直，稳固地放置于患者背部中线区域。用优势手的中指指尖，有力地叩击按压手的中指末节指骨的上三分之一处，每次至少叩击两下。在四到五个不同水平位置重复此操作，并进行左右两侧的对比。在前胸壁以相同方法进行叩诊，从肺下界开始操作。无论前胸壁还是后胸壁，均应确保叩诊手的中指置于肋间隙内，而非肋骨上。注意辨别叩诊音的音质。正常含气肺组织区域的叩诊音应为清音。相反，叩击实性组织（如肝脏或心脏）时，应产生浊音。而叩击空腔结构（如Traube腔）时，则应产生鼓音，即类似击鼓的声音。最后，我们进行听诊，即使用听诊器听取呼吸音。开始时，指导患者向前倾斜或直坐，以便进行背部听诊。请患者将双手放在对侧肩上，以充分暴露肺区。将听诊器的膜型胸件置于患者背部中线区域，要求患者通过口腔进行深呼吸。在背部五个水平位置进行听诊，然后在前胸部重复相同步骤，并进行左右对比。正常的呼吸音在背部和前胸部均应对称；任何不对称情况都可能是肺部疾病的潜在征象。听诊的最后三个步骤是用于识别肺实变的检查。第一个检查是评估支气管语音（bronchophony）。听诊胸部区域时，请患者说出“99”。声音传导增强提示存在肺实变。第二个检查是评估羊鸣音（egophony）。请患者发出“E”的声音。当通过听诊器听到的“E”音变为“A”音时，提示存在肺实变。最后，评估 whispered pectoriloquy（ whispered pectoriloquy）。请患者低声说“99”。在肺实变的情况下，通过听诊器反而能更清晰地听到该声音。所有这些步骤还应在背部不同位置进行，以覆盖整个肺区。检查结束时，向患者表示感谢，并让其恢复着装。您刚刚观看了 JoVE 关于呼吸系统评估中叩诊与听诊的视频。在检查的这一部分中，区分所听到的各种声音有时可能看似主观，但通过练习，评估会变得更加清晰和容易，从而对许多肺部疾病实现“即刻诊断”。一如既往，感谢您的观看！

Education

教育

JoVE Science Education

Clinical Skills

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Physical Examinations I

体格检查 I

呼吸道考试 II: 打击乐和听诊

respiratory exam: lung sounds and percussion

Respiratory exam skills include percussion and auscultation of the lungs. These techniques help identify lung problems during a physical exam. Percussion uses tapping to assess the chest, and auscultation uses a stethoscope to listen for breath sounds.

Percussion is a useful skill that is often skipped in routine clinical practice. When it is done correctly, it can help a physician detect underlying lung pathology. Auscultation can also give an almost immediate clue to several acute pulmonary conditions, including chronic obstructive pulmonary disease (COPD), asthma, pneumonia, and pneumothorax.

The lung zones used for auscultation match the areas of the lungs beneath the chest wall. The right lung has three lobes: superior, middle, and inferior. The left lung has two lobes: superior and inferior. The superior lobe of the left lung also has a separate projection called the lingula, which is part of the lung map used during exam.

Respiratory Exam: Lung Sounds and Percussion

respiratory-exam-lung-sounds-and-percussion

general approach to the physical exam

Why Physical Exams Still Matter

Physical examination remains an important part of medicine. Doctors have used the body exam for centuries to connect changes in body function with disease. Even with modern imaging and lab tests, the bedside exam still helps clinicians understand what may be happening in the patient. Physical examination is not a replacement for tests, and it does not answer every question. Some maneuvers that were once highly valued may have limited usefulness. Still, many conditions can only be found through...

observation and inspection

Clinical Observation in Physical Exam

Clinical observation is the starting point of a physical examination and begins at the first contact with a patient. Observation is a broad term for using the senses carefully to gather information. Inspection is a narrower term. It refers to what can be seen with the eyes, especially on the surface of the body, rather than to behavior. Skilled clinicians use more than sight when they examine a patient. They also rely on touch, through palpation and percussion, and on hearing, through...

palpation

How Hand Position Guides Palpation

Palpation uses touch to collect diagnostic information during the physical exam. It is one of the ways a healthcare provider uses the senses to learn more about a patient. The part of the hand used for palpation changes depending on the body area being examined. Finger pads are best for fine detail. Their dense sensory nerves help the examiner feel small features, such as the borders of masses or lymph nodes. The back of the hand, also called the dorsal surface, gives a rough sense of relative...

percussion

Clinical Percussion and Body Sound

Clinical percussion uses tapping to create sound and help assess what lies beneath the body surface. It is a simple bedside technique that depends on the way sound changes when it travels through different tissues. The method began with Leopold Auenbrugger, an Austrian inn-keeper's son, who found that tapping beer barrels could help him take inventory. He later applied the same idea to patients in Vienna and published the first description of its diagnostic use in 1761. Jean-Nicolas Corvisart...

auscultation

Stethoscope Sounds in Clinical Exam

Auscultation is a clinical exam method that lets a provider listen to sounds inside the body. Doctors use it to gather important diagnostic information from the chest, heart, abdomen, and blood vessels. For many years, auscultation meant immediate auscultation. In that method, the examiner placed an ear directly on the patient's skin. This approach was used for centuries, but it became less useful in nineteenth-century France because of social norms and poor diagnostic yield. René Laënnec...

proper adjustment of patient attire during the physical exam

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Draping for a Better Physical Exam

Draping is an important part of a careful physical exam. It helps the provider examine the right body area while also protecting patient modesty. Good draping takes practice because the examiner must balance exposure with comfort. Correct technique also improves the accuracy of the exam. Skin lesions can be missed if inspection is done through clothing. Lung crackles may be reported by mistake when the chest is examined through a T-shirt, and subtle heart findings can be missed when...

blood pressure measurement

Manual Blood Pressure Reading Steps

Blood pressure reading uses an indirect method to measure the pressure of blood against vessel walls. Blood pressure, or BP, is a vital sign that is checked routinely in hospital and outpatient settings. It is one of the most common medical assessments performed around the world. The indirect method is non-invasive, safe, and easily reproducible, so it is used most often. BP can be measured automatically by oscillometry or manually by auscultation. Auscultation uses a sphygmomanometer, which...

measuring vital signs

Vital Sign Ranges and Patient Status

Vital signs are objective measurements that show a patient’s clinical status. The commonly accepted vital signs are blood pressure, heart rate, temperature, respiratory rate, and oxygen saturation. In many practices, pain is also treated as the sixth vital sign and is documented with the others. Pain is different from the other vital signs because it is a subjective measurement. That means the pain scale can vary from one patient to another. A vital signs assessment includes heart rate, blood...

respiratory exam i: inspection and palpation

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Checking Breathing Distress by Exam

Respiratory exam starts with looking for breathing distress and feeling the chest. Shortness of breath is a common reason for both outpatient and inpatient evaluation. Early inspection can reveal fast breathing or cyanosis, which is a bluish color change that can signal low oxygen. If a patient shows respiratory distress, the situation needs urgent attention and oxygen therapy. In many cases, careful clinical examination can help identify lung problems without relying only on tests. This is...

respiratory exam ii: percussion and auscultation

Respiratory exam skills include percussion and auscultation of the lungs. These techniques help identify lung problems during a physical exam. Percussion uses tapping to assess the chest, and auscultation uses a stethoscope to listen for breath sounds. Percussion is a useful skill that is often skipped in routine clinical practice. When it is done correctly, it can help a physician detect underlying lung pathology. Auscultation can also give an almost immediate clue to several acute pulmonary...

cardiac exam i: inspection and palpation

Cardiac Exam I: Checking the Chest First

Cardiac exam inspection and palpation are the first steps in a careful heart assessment. These steps help a physician gather useful information before using a stethoscope. They are part of the core examination performed when a patient is first seen. Heart and circulatory disorders are common reasons for hospital admission. They can include conditions such as myocardial infarction and congestive heart failure. Because of this, learning a complete cardiac examination is important for any...

cardiac exam ii: auscultation

Listening for Normal and Abnormal Heart Sounds

Heart auscultation uses a stethoscope to listen to heart sounds and check for normal and abnormal patterns. For physicians, knowing how to hear these sounds and tell them apart is an essential skill. The sound heard at each spot on the chest relates to the closing of specific heart valves. The heart has two main sounds, called S1 and S2. S1 happens when the mitral and tricuspid valves, which are the atrioventricular valves, close after blood enters the ventricles. This marks the start of...

cardiac exam iii: abnormal heart sounds

Heart Murmurs and Gallop Sounds

Heart murmurs and gallop sounds are abnormal heart sounds that can be heard during auscultation, or listening to the heart with a stethoscope. A good understanding of normal heart sounds is the first step in telling normal sounds apart from abnormal ones. Murmurs usually have a swishing quality and point to turbulent blood flow across a heart valve. Murmurs can happen because a valve is too narrow, which is called stenosis, or because blood leaks backward across the valve, which is called...

peripheral vascular exam

Assessing PAD and Venous Signs

Peripheral vascular disease can affect blood flow in the arms and legs, and careful exam steps help reveal signs of disease. Peripheral artery disease (PAD) is linked to cardiovascular and cerebrovascular complications. Risk factors include diabetes, hyperlipidemia, hypertension, and tobacco use. Symptoms may appear as limb claudication, which is cramp-like muscle pain that gets worse with activity and better with rest. Chronic venous insufficiency (CVI) can cause lower extremity swelling,...

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peripheral-vascular-exam-using-a-continuous-wave-doppler

Bedside Doppler for Leg Blood Flow Checks

Peripheral vascular disease affects the arteries and veins outside the heart, and it is common in older adults. History and physical exam can suggest the diagnosis, but Doppler ultrasound is now a routine part of the bedside vascular exam. This lesson focuses on bedside assessment of peripheral arterial disease and chronic venous insufficiency with a handheld continuous wave Doppler. A handheld Doppler is a simple tool that sends and receives ultrasound at the same time. It detects changes in...

physical examinations i

本系列为进行体检提供了基础;从测量血压或生命体征, 到关键的肺和心血管物理检查的技术不等。

Learn how percussion and auscultation are used in a respiratory exam to assess lung zones and spot signs of COPD, asthma, pneumonia, and pneumothorax.

Respiratory Exam: Lung Sounds and Percussion | JoVE K12

Suneel Dhand

Beth Israel Deaconess Medical Center

Overview

Lung Lobes and Breath Sounds

Respiratory Percussion Procedure

Respiratory Auscultation Procedure

Summary

Characteristics of Life

Biology is a natural science that studies life and living organisms, including their structure, function, development, interactions, evolution, ...

https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/10647.jpg

Cell Structure

Background
Cells represent the most basic biological units of all organisms, whether it be simple, single-celled organisms like bacteria, or large, ...

Visualizing Onion and Cheek Cells
ExpandImmediately before the experiment, wash and peel onion bulbs for the class.
Remove the entire brown outer skin and ...

Visualizing Onion and Human Cells
ExpandIn this experiment you will prepare different types of cells from a plant and animal, onion and human ...

What are Cells?

Cell Diversity

The concept of a cell started with microscopic observations of dead cork tissue by Robert Hooke in 1665. Hooke coined the term &#34;cell&#34; based on the ...

Cytoplasm

The cytoplasm consists of organelles and a framework of protein scaffolds called the cytoskeleton suspended in an aqueous solution, the cytosol. The ...

The Nucleus

The nucleus is a membrane-bound organelle that acts as a control center in a eukaryotic cell. It contains chromosomal DNA, which controls gene expression ...

The Central Dogma

The DNA Helix

Nucleic Acids

DNA as a Genetic Template

Structure of a Gene

A gene is the fundamental unit of heredity. Every individual has two copies of each gene, one inherited from each parent. Although most people contain the ...

Chromosome Structure

Base-pairing and DNA Repair

What is Gene Expression?

A gene is a stretch of DNA that serves as the blueprint for functional RNAs and proteins. Since DNA is comprised&#160; of nucleotides and proteins are ...

RNA Structure

The basic structure of RNA consists of a string of ribonucleotides attached by phosphodiester bonds. Although most RNA is single-stranded, it can form ...

Types of RNA

Three main types of RNA are involved in protein synthesis: messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). These RNAs perform diverse ...

Transcription

Transcription is the synthesis of RNA from a DNA sequence by RNA polymerase. It is the first step in producing a protein from a gene sequence. ...

Translation

Translation is the process of synthesizing proteins from the genetic information carried by messenger RNA (mRNA). Following transcription, it constitutes ...

Ribosomes

Ribosomes translate genetic information encoded by messenger RNA (mRNA) into proteins. Both prokaryotic and eukaryotic cells have ribosomes. Cells that ...

Protein and Protein Structures

Proteins: From Genes to Degradation

From DNA to Protein

The flow of genetic information in cells from DNA to mRNA to protein is described by the central dogma, which states that genes specify the sequence of ...

Protein Folding

Proteins are chains of amino acids linked together by peptide bonds. Upon synthesis, a protein folds into a three-dimensional conformation, critical to ...

An Overview of Gene Expression

Gene expression is the complex process where a cell uses its genetic information to make functional products. This process is regulated at multiple ...

an-introduction-to-caenorhabditis-elegans

An Introduction to Caenorhabditis elegans

Caenorhabditis elegans is a microscopic, soil-dwelling roundworm that has been powerfully used as a model organism since the early 1970&rsquo;s.  It was ...

An Overview of Genetic Analysis

An organism&#8217;s physical traits, or phenotype, are a product of its genotype, which is the combination of alleles (gene variants) inherited from its ...

An Introduction to Cell Death

Necrosis, apoptosis, and autophagic cell death are all manners in which cells can die, and these mechanisms can be induced by different stimuli, such as ...

An Overview of Genetic Engineering

Genetic engineering &#8211; the process of purposefully altering an organism&#8217;s DNA &#8211; has been used to create powerful research tools and model ...

An Introduction to Cell Division

Cell division is the process by which a parent cell divides and gives rise to two or more daughter cells. It is a means of reproduction for single-cell ...

An Overview of Genetics and Disease

Many human diseases are associated with mutations or variations in genetic sequences. Some of these genetic variants are heritable, passed down from ...

an-introduction-to-cellular-and-molecular-neuroscience

An Introduction to Cellular and Molecular Neuroscience

Cellular and molecular neuroscience is one of the newest and fastest growing subdisciplines in neuroscience. By investigating the influences of genes, ...

Annexin V and Propidium Iodide Labeling

Staining with annexin V and propidium iodide (PI) provides researchers with a way to identify different types of cell death&#8212;either necrosis or ...

an-introduction-to-developmental-genetics

An Introduction to Developmental Genetics

Development is the complex process through which a single-celled embryo transforms into a multicellular organism. Developmental processes are guided by ...

Bacterial Transformation: Electroporation

The term &#x201C;transformation&#x201D; refers cellular ingestion of foreign DNA.  In nature, transformation can occur in certain types of bacteria.  In ...

an-introduction-to-molecular-developmental-biology

An Introduction to Molecular Developmental Biology

Molecular signals play a major role in the complex processes occurring during embryonic development. These signals regulate activities such as cell ...

bacterial-transformation-the-heat-shock-method

Bacterial Transformation: The Heat Shock Method

Transformation is the process that occurs when a cell ingests foreign DNA from its surroundings. Transformation can occur in nature in certain types of ...

an-introduction-to-saccharomyces-cerevisiae

An Introduction to Saccharomyces cerevisiae

Saccharomyces cerevisiae (commonly known as baker&rsquo;s yeast) is a single-celled eukaryote that is frequently used in scientific research.  S. ...

Cell Cycle Analysis

Cell cycle refers to the set of events through which a cell grows, replicates its genome, and ultimately divides into two daughter cells through the ...

An Introduction to Transfection

Transfection is the process of inserting genetic material, such as DNA and double stranded RNA, into mammalian cells. The insertion of DNA into a cell ...

Chromatin Immunoprecipitation

Histones are proteins that help organize DNA in eukaryotic nuclei by serving as &#8220;scaffolds&#8221; around which DNA can be wrapped, forming a complex ...

An Overview of Epigenetics

Since the early days of genetics research, scientists have noted certain heritable phenotypic differences that are not due to differences in the ...

community-dna-extraction-from-bacterial-colonies

Community DNA Extraction from Bacterial Colonies

Source: Laboratories of Dr. Ian Pepper and Dr. Charles Gerba - The University of Arizona
Demonstrating Author: Luisa Ikner
Traditional methods of analysis ...

Cytogenetics

Cytogenetics is the field of study devoted to chromosomes, and involves the direct observation of a cell&#8217;s chromosomal number and structure, ...

embryonic-stem-cell-culture-and-differentiation

Embryonic Stem Cell Culture and Differentiation

Culturing embryonic stem (ES) cells requires conditions that maintain these cells in an undifferentiated state to preserve their capacity for self-renewal ...

DNA Gel Electrophoresis

DNA gel electrophoresis is a technique used for the detection and separation of DNA molecules. An electric field is applied to a gel matrix comprised of ...

Enzyme Assays and Kinetics

Enzyme kinetics describes the catalytic effects of enzymes, which are biomolecules that facilitate chemical reactions necessary for living organisms. ...

DNA Ligation Reactions

In molecular biology, ligation refers to the joining of two DNA fragments through the formation of a phosphodiester bond.  An enzyme known as a ligase ...

explant-culture-for-developmental-studies

Explant Culture for Developmental Studies

Explant culture is a technique in which living cells or tissues are removed from an embryo for continued development outside of the organism. This ex vivo ...

DNA Methylation Analysis

Methylation at CpG dinucleotides is a chemical modification of DNA hypothesized to play important roles in regulating gene expression. In particular, the ...

Expression Profiling with Microarrays

Microarrays are important tools for profiling gene expression, and are based on complementary binding between probes that are attached to glass chips and ...

Density Gradient Ultracentrifugation

Density gradient ultracentrifugation is a common technique used to isolate and purify biomolecules and cell structures. This technique exploits the fact ...

F&#246;rster Resonance Energy Transfer (FRET)

F&#246;rster resonance energy transfer (FRET) is a phenomenon used to investigate close-range biochemical interactions. In FRET, a donor photoluminescent ...

detecting-environmental-microorganisms-with-polymerase-chain-reaction

Detecting Environmental Microorganisms with the Polymerase Chain Reaction and Gel Electrophoresis

Source: Laboratories of Dr. Ian Pepper and Dr. Charles Gerba - Arizona University
Demonstrating Author: Bradley Schmitz
Polymerase chain reaction (PCR) is ...

Gel Purification

Gel purification is used to recover DNA fragments after electrophoretic separation. DNA recovery from an agarose gel includes three basic steps: binding, ...

Detecting Reactive Oxygen Species

Reactive oxygen species are chemically active, oxygen-derived molecules capable of oxidizing other molecules. Because of their reactive nature, there are ...

Gene Silencing with Morpholinos

Morpholino-mediated gene silencing is a common technique used to study roles of specific genes during development. Morpholinos inhibit gene expression by ...

Construct an explanation based on evidence for how the structure of DNA determines the structure of proteins which carry out the essential functions of life through systems of specialized cells.

HS-LS1-1.

Respiratory Exam: Lung Sounds and Percussion

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