Name: feedback loops in body balance
Uploaded: 2023-06-23T15:38:43.000Z
Duration: 1 min 18 s
Channel: JoVE

K12 Standards

north-carolina-k-12-science-standard-course-of-study

North Carolina K-12 Science Standard Course of Study

9-12

Biology

from-molecules-to-organisms-structures-and-processes

From Molecules to Organisms- Structures and Processes

LS.Bio.3.1

Negative and Positive Feedback

Les fonctions biologiques telles que les voies métaboliques ou les voies de signalisation cellulaire sont régulées par des mécanismes de rétroaction, qui comprennent des boucles de rétroaction négative et positive.
La rétroaction positive se produit lorsque le produit d’un processus stimule une augmentation supplémentaire de sa production, ce qui entraîne une réponse accrue.
Le processus de coagulation sanguine est l’un des exemples courants d’une boucle de rétroaction positive.
Une coupure dans la paroi des vaisseaux sanguins agit comme un stimulus qui déclenche les vaisseaux et les plaquettes voisines pour libérer des signaux chimiques, activant plusieurs facteurs de coagulation et attirant les plaquettes vers le site de la lésion, initiant un caillot sanguin. Les plaquettes sécrètent des signaux chimiques pour attirer plus de plaquettes sur le site jusqu’à ce que le caillot en développement scelle complètement la plaie.
Une boucle de rétroaction négative se produit lorsque le produit d’une réaction réduit le stimulus initial.
Par exemple, lorsque la glycémie augmente, le pancréas libère de l’insuline, ce qui déclenche l’absorption du glucose par les cellules hépatiques, réduisant ainsi la glycémie.
Une fois que la glycémie est rétablie, le pancréas arrête la production d’insuline.

commentaires négatifs et positifs

Les différents systèmes au sein de l'organisme ainsi que les organes eux-mêmes s'adaptent constamment aux changements internes et externes grâce à un processus appelé homéostasie (« état d'équilibre »). Des exemples de ces changements incluent la régulation du niveau de glucose ou de calcium dans le sang ou les réponses internes aux températures externes. L'homéostasie nécessite le maintien d'un équilibre dynamique interne :

Dynamique car il s'adapte constamment aux changements que rencontrent les différents systèmes du corps; et équilibre car les fonctions corporelles sont maintenues dans des plages spécifiques. Même un animal apparemment inactif maintient cet équilibre homéostatique.

Processus homéostatique

Le but de l'homéostasie est le maintien de l'équilibre autour d'un point ou d'une valeur appelée point de consigne. Bien qu'il y ait des fluctuations normales par rapport à ce point de consigne, les systèmes du corps tentent généralement d’y revenir. Un changement dans l'environnement interne ou externe est appelé stimulus et est détecté par un récepteur ; la réponse du système est d'ajuster le paramètre à la cause de l’écart vers le point de consigne.

Contrôle de l'homéostasie

Lorsqu'un changement survient en dehors de l'environnement d'un animal, un ajustement doit être effectué. Le récepteur détecte le changement dans l’environnement, puis envoie un signal au centre de contrôle (dans la plupart des cas, le cerveau), qui génère à son tour une réponse signalée à un effecteur. L'effecteur est un muscle (qui se contracte ou se relaxe) ou une glande qui va sécréter une substance. Ces signaux et réponses sont contrôlés par des boucles de rétroaction autonomes inconscientes. Les boucles de rétroaction négative permettent de maintenir  l’homéostasie. Les boucles de rétroaction positive poussent l’organisme hors de l’homéostasie, mais peuvent être nécessaires aux fonctions vitales. Ainsi, l'homéostasie est contrôlée par les systèmes nerveux et endocrinien des mammifères.

Le point de consigne

Il est possible d'ajuster le point de consigne d'un système. Lorsque cela se produit, la boucle de rétroaction s’efforce de maintenir le nouveau paramètre. La pression artérielle en est un exemple : avec le temps, le point normal ou de consigne de la pression artérielle peut augmenter en raison d’une augmentation continue de la pression artérielle. Le corps ne reconnaît plus l'élévation comme anormale et aucune tentative n'est faite pour revenir au point de consigne inférieur. Le résultat est une pression artérielle régulièrement plus élevée qui peut nuire à l’organisme. Les médicaments peuvent abaisser la tension artérielle et réduire le point de consigne du système à un niveau plus sain. Dans une boucle de rétroaction c'est ce qu'on appellera un processus de modification du point de consigne.

Des modifications peuvent être apportées aux systèmes du corps pour maintenir un point de consigne dans un autre système. C'est ce qu'on appelle l'acclimatation. Cela se produit, par exemple, lorsqu'un animal migre vers une altitude plus élevée que celle à laquelle il était initialement habitué. Afin de s'adapter à des niveaux d'oxygène plus faibles, le corps augmente le nombre de globules rouges circulant dans le sang pour assurer un apport adéquat d'oxygène aux tissus. Un autre exemple d'acclimatation, serait que certains animaux ont des changements saisonniers dans leur pelage : un pelage plus épais en hiver assure une rétention adéquate de chaleur, et un autre plus léger en été aide à empêcher la température corporelle d'atteindre des niveaux nocifs.

Ce texte est adapté de <a biology-2e="" books="" https:="" openstax.org="" pages="">Openstax, Biology 2e, Section 33.3: Homeostasis</a>

Commentaires négatifs et positifs

Les organes et les systèmes organiques des animaux s’adaptent constamment aux changements internes et externes par le biais d’un processus appelé homéostasie (« état d’équilibre »). Exemples...

Education

Enseignement

JoVE Core

Anatomy and Physiology

Anatomie et physiologie

Unit 1

Unité 1

Introduction to the Human Body

Introduction au corps humain

KEY TERMS AND CONCEPTS

TERMES ET CONCEPTS CLÉS

feedback loops in body balance

Negative and positive feedback help keep body conditions stable. These feedback loops control many body processes and support homeostasis, which is the maintenance of a steady internal environment.

Negative feedback reduces a change and brings a system back toward its normal state. Positive feedback increases a change and pushes a process further in the same direction. Together, they show how the body can fine-tune responses when conditions shift.

These control systems are important in many parts of biology. They help explain how the body responds to change and how certain processes stay balanced or move toward a clear outcome.

Feedback Loops in Body Balance

overview of anatomy and physiology

How Anatomy and Physiology Work Together

Human anatomy studies the structures of the body. Some body structures are so small that they can only be seen and examined with a microscope. Others are large enough to be viewed, handled, measured, and weighed. The word anatomy comes from a Greek root meaning “to cut apart.” Early study of the human body began with observing the outside of the body and the injuries seen in soldiers and other patients. Later, physicians were allowed to dissect dead bodies to learn more. Dissection means...

structural organization of the human body: an overview

structural-organization-of-the-human-body-an-overview

Levels of Organization in the Human Body

The human body is organized in levels that build from simple parts to a complete living being. These levels increase in complexity from subatomic particles, atoms, and molecules to organelles, cells, tissues, organs, organ systems, and the organism. At the chemical level, scientists study the smallest building blocks of matter. Matter is made of elements, which are pure substances such as hydrogen, oxygen, carbon, nitrogen, calcium, and iron. The smallest unit of an element is an atom, and...

functions of life

How the Human Body Keeps Going

Human life depends on metabolism, movement, development, growth, and reproduction. These functions help the body stay alive, maintain itself, and continue the species. Together, they show how the body uses energy and changes over time. Metabolism is the body’s use of energy and food molecules. It helps the body make fuel for movement, support body functions, and build and maintain body structures. Metabolism includes two kinds of reactions: anabolism and catabolism. Anabolism is the process...

requirements for human life

Human Survival Needs in the Body

Human survival depends on air, water, food, a narrow temperature range, and a narrow range of atmospheric pressure. The Earth and its atmosphere provide these conditions, but the body can only function well when they stay within limits. Oxygen is one of the most important needs. Atmospheric air is only about 20 percent oxygen, but that oxygen supports the chemical reactions that keep the body alive, including the reactions that make ATP. Brain cells are especially sensitive to a lack of oxygen...

what is homeostasis?

Homeostasis and Negative Feedback

Homeostasis keeps the body’s internal conditions stable. The body does this by holding each physiological condition near a set point. A set point is the value around which the normal range changes, and the normal range is the small group of values that is healthiest and most stable. Human body temperature is a common example. Its set point is about 37°C, or 98.6°F, and it can shift a little above or below that point while still staying in range. Negative feedback helps maintain homeostasis.

negative and positive feedback

Negative and positive feedback help keep body conditions stable. These feedback loops control many body processes and support homeostasis, which is the maintenance of a steady internal environment. Negative feedback reduces a change and brings a system back toward its normal state. Positive feedback increases a change and pushes a process further in the same direction. Together, they show how the body can fine-tune responses when conditions shift. These control systems are important in many...

homeostatic imbalance

How Feedback Failure Disrupts Homeostasis

Homeostasis keeps the body’s internal conditions stable so cells, tissues, organs, and organ systems can work properly. The body uses control systems to regulate temperature, blood pressure, pH balance, and fluid balance. These controls depend on feedback loops, which can be positive or negative. Homeostatic imbalance happens when those feedback loops fail and the body can no longer maintain a stable internal environment. Injury, disease, environmental changes, genetic mutations, and aging can...

anatomical terminology

Anatomical Terms and Body Position

Anatomical terms help describe the human body clearly in biology and medicine. Health care professionals and anatomists use this standard language to avoid confusion and to make descriptions more precise. Most anatomical words come from Greek and Latin roots, and these roots usually stay the same because the languages are rarely used in everyday conversation. Many anatomical words are built from a root plus a prefix or suffix. The root often names an organ, tissue, or condition. The prefix or...

anatomical positions

Body Positions Used in Anatomy

Body positions used in anatomy give a shared way to describe where body parts are and how they face. These standard references help people talk about anatomical structures with the same meaning. The anatomical position is the main reference point for body orientation. In anatomical position, the body stands upright and faces forward. The feet are parallel and flat on the floor. The arms rest at the sides with the palms facing forward, and the head and eyes point forward. The most common...

regional terms

Anatomy Regions and Body Landmark Terms

Anatomy regions and body landmark terms help identify specific parts of the human body. These regional terms divide the body into areas with structures that support similar functions. They also make it easier to describe the exact area affected by an injury or disease. The human body is organized into two major regions: the axial region and the appendicular region. The axial region includes the body from the head to the abdomen and forms the central body axis. The appendicular region includes...

directional terms

Anatomical Direction and Body Position

Anatomical direction and body position terms help describe where one body structure is located in relation to another. These terms use comparisons, such as one tissue being inferior to another or a tumor being superficial to a deeper structure. They are based on the standard anatomical reference position, which uses the body in an upright pose. Anterior and posterior are a common pair of directional terms. Anterior, also called ventral, means toward the front of the body. Posterior, also...

body planes

Anatomy Sections and Body Planes

Anatomy sections and body planes are imaginary flat surfaces used to divide the body for study. They help show the orientation, relationships, and spatial layout of anatomical structures. These reference planes are also useful for describing organs and body parts in a standard way. The sagittal plane divides the body or an organ vertically into right and left sides. When that cut goes through the middle and makes equal halves, it is called the midsagittal or median plane. When it makes unequal...

anatomical movements

Body Joint Motion Terms

Body joint motion terms describe how bones and muscles move at different joints. These standard names make it easier to talk about range of motion in the body. They are used to describe actions at the shoulder, hip, elbow, knee, wrist, fingers, toes, and spine. Flexion and extension are movements in the sagittal plane, also called the anterior-posterior plane. Flexion is the forward bending motion of the head or vertebral column. Extension is the backward movement or straightening of a joint,...

abdominal regions and quadrants

Abdominal Pain and Organ Location

The abdominal cavity is divided into quadrants and regions to help locate organs and describe pain clearly. Clinicians and anatomists use imaginary lines to mark the abdominopelvic cavity. This system makes it easier to communicate about a patient’s symptoms or a suspicious mass. The simpler method divides the area into four quadrants. One horizontal line and one vertical line cross at the umbilicus, or navel. These quadrants are the right upper quadrant, right lower quadrant, left upper...

key terms and concepts

Explore how negative and positive feedback help maintain body balance and homeostasis. Learn how these control loops change responses in biology.

Feedback Loops in Body Balance | JoVE K12

anatomy and physiology

JoVE Core Anatomy and Physiology showcases the anatomical and physiological details of the human body in comprehensive, clear, and engaging video animations. This collection of lessons focuses on the structures, components, functions, and requirements of the human body. It is complemented by scientist-in-action videos that demonstrate the application of this knowledge in real-world medical and research settings.

Pennsylvania State Academic Standards

Life Science

Structure and Function

3.1.9-12.C

Louisiana Student Standards for Science

High School

Life Sciences

From Molecules To Organisms: Structures And Processes

HS-LS1-3

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

Cells

Cell structure and function

Human Anatomy and Physiology

Levels Of Organization

Homeostasis

Virginia  Standards of Learning

HIgh School

BIO.2

BIO.2.a

Minnesota Academic Standards in Science

1.2.1 9L.1.2.1.1

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New Jersey Student Learning Standards for Science

From Molecules to Organisms: Structures and Processes

Arizona Science Standards

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Alabama Course of Study Science

9-12.B.1.4

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BIO.5

BIO.5.C

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South Carolina College and Career Ready Science Standards

B-LS1-3.

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New York State Science Learning Standards

HS-LS1-3.

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Feedback Loops in Body Balance

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