Name: homeostasis and body feedback control
Uploaded: 2023-04-30T10:08:28.000Z
Duration: 1 min 18 s
Channel: JoVE

K12 Standards

Louisiana Student Standards for Science

High School

Life Sciences

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

From Molecules To Organisms: Structures And Processes

HS-LS1-3

Positive and Negative Feedback Loops

Le funzioni biologiche come le vie metaboliche o le vie di segnalazione cellulare sono regolate da meccanismi di feedback, che comprendono cicli di feedback negativi e positivi.
Il feedback positivo si verifica quando il prodotto di un processo stimola un ulteriore aumento della sua produzione, portando a un aumento della risposta.
Il processo di coagulazione del sangue è uno degli esempi comuni di un ciclo di feedback positivo.
Un taglio nella parete dei vasi sanguigni agisce come uno stimolo che innesca i vasi e le piastrine vicine a rilasciare segnali chimici, attivando diversi fattori di coagulazione e attirando le piastrine nel sito della lesione, avviando un coagulo di sangue. Le piastrine secernono segnali chimici per attirare più piastrine nel sito fino a quando il coagulo in via di sviluppo sigilla completamente la ferita.
Un ciclo di feedback negativo si verifica quando il prodotto di una reazione riduce lo stimolo iniziale.
Ad esempio, quando i livelli di glucosio nel sangue aumentano, il pancreas rilascia insulina, che innesca l'assorbimento del glucosio da parte delle cellule del fegato, riducendo i livelli di glucosio nel sangue.
Una volta ripristinati i livelli di glucosio nel sangue, il pancreas interrompe la produzione di insulina.

circuiti di feedback positivi e negativi

Gli organi e i sistemi di organi animali si adattano costantemente ai cambiamenti interni ed esterni attraverso un processo chiamato omeostasi ("stato stazionario"). Esempi di questi cambiamenti includono la regolazione del livello di glucosio o di calcio nel sangue o le risposte interne alle temperature esterne. L’omeostasi richiede il mantenimento di un equilibrio dinamico interno:

Dinamico perché si adatta costantemente ai cambiamenti che i sistemi del corpo incontrano. 
Equilibrio perché le funzioni del corpo sono mantenute entro intervalli specifici. Anche un animale apparentemente inattivo mantiene questo equilibrio omeostatico.

Processo omeostatico

L'obiettivo dell'omeostasi è il mantenimento dell'equilibrio attorno a un punto o valore chiamato set point. Sebbene vi siano normali fluttuazioni rispetto al punto di regolazione, i sistemi del corpo solitamente tentano di tornare a questo punto. Un cambiamento nell'ambiente interno o esterno è chiamato stimolo e viene rilevato da un recettore; la risposta del sistema è quella di adeguare il parametro di deviazione verso il set point.

Controllo dell'omeostasi

Quando si verifica un cambiamento al di fuori dell'ambiente di un animale, è necessario apportare un aggiustamento. Il recettore percepisce il cambiamento nell'ambiente, quindi invia un segnale al centro di controllo (nella maggior parte dei casi, il cervello) che a sua volta genera una risposta che viene segnalata a un effettore. L'effettore è un muscolo (che si contrae o si rilassa) o una ghiandola che secerne. Questi segnali e risposte sono controllati da circuiti di feedback autonomi inconsci. I circuiti di feedback negativi mantengono l’omeostasi. I circuiti di feedback positivi spingono l’organismo ulteriormente fuori dall’omeostasi, ma possono essere necessari per le funzioni vitali. Pertanto, l'omeostasi è controllata dai sistemi nervoso ed endocrino dei mammiferi.

Punto di riferimento

È possibile modificare il setpoint di un sistema. Quando ciò accade, il ciclo di feedback funziona per mantenere la nuova impostazione. Un esempio di ciò è la pressione sanguigna: nel tempo, il valore normale o impostato per la pressione sanguigna può aumentare a causa dei continui aumenti della pressione sanguigna. Il corpo non riconosce più l'elevazione come anormale e non viene effettuato alcun tentativo di tornare al punto di riferimento inferiore. Il risultato è un aumento regolare della pressione sanguigna che può danneggiare il corpo. I farmaci possono abbassare la pressione sanguigna e ridurre il punto di regolazione del sistema a un livello più salutare. Questo è noto come processo di alterazione del set point in un circuito di feedback.

È possibile apportare modifiche a un gruppo di sistemi di organi del corpo per mantenere un punto impostato in un altro sistema. Questo si chiama acclimatazione. Ciò si verifica, ad esempio, quando un animale migra ad un'altitudine superiore a quella a cui era originariamente abituato. Per adattarsi ai livelli di ossigeno più bassi ad un'altitudine più elevata, il corpo aumenta il numero di globuli rossi circolanti nel sangue per garantire un adeguato apporto di ossigeno ai tessuti. Come altro esempio di acclimatazione, alcuni animali presentano cambiamenti stagionali nel loro mantello: un mantello più pesante in inverno garantisce un'adeguata ritenzione del calore e un mantello più leggero in estate aiuta a mantenere la temperatura corporea dall'innalzamento a livelli dannosi.

Circuiti di feedback positivi e negativi

Gli organi e i sistemi di organi animali si adattano costantemente ai cambiamenti interni ed esterni attraverso un processo chiamato omeostasi ("stato stazionario"). Esempi...

Education

Didattica

JoVE Core

Cell Biology

Biologia cellulare

Unit 1

Unità 1

Introduction to Metabolism

Introduzione al metabolismo

KEY TERMS AND CONCEPTS

TERMINI E CONCETTI CHIAVE

homeostasis and body feedback control

Homeostasis keeps body conditions in a steady range through feedback control. Animal organs and organ systems constantly adjust to internal and external changes. This balance is called a dynamic equilibrium because the body keeps adapting while still staying within specific ranges.

The goal of homeostasis is to stay near a set point, which is the value the body tries to maintain. A change in the internal or external environment is a stimulus. A receptor detects that change and sends a signal to a control center, which is usually the brain. The control center then sends a response to an effector.

Effectors are muscles that contract or relax, or glands that secrete. These signals and responses are managed by unconscious autonomic feedback loops. Negative feedback loops help maintain homeostasis. Positive feedback loops push the organism farther from homeostasis, but they may still be necessary for life functions.

Homeostasis in mammals is controlled by the nervous system and the endocrine system. Even an animal that seems inactive is still maintaining this internal balance. The system keeps working to return body functions toward the set point after small changes.

A set point can also change over time. Blood pressure is one example. If blood pressure stays high for a long time, the normal set point can rise. The body then treats the higher pressure as normal and does not try to return to the lower level. This can harm the body, but medication can lower blood pressure and shift the set point to a healthier level.

Groups of body systems can also adjust to help maintain a set point in another system. This is called acclimatization. It can happen when an animal moves to a higher altitude. To deal with lower oxygen levels, the body increases the number of red blood cells in the blood so tissues still get enough oxygen. Some animals also change their coats with the seasons. A heavier winter coat helps retain heat, and a lighter summer coat helps prevent body temperature from rising too high.

Homeostasis and Body Feedback Control

overview of metabolism

Metabolism in Plants, Animals, and Microbes

Metabolism is the set of chemical reactions that keep living cells working. These reactions are linked through many pathways. Together, they support the normal function of cells in plants, animals, and microbes. In plants, sunlight is the main energy source. Chlorophyll pigments in the leaves absorb this light. The plant then uses that energy for photosynthesis. During photosynthesis, water is oxidized to oxygen and carbon dioxide is reduced to glucose. Glucose then serves as a starting...

carbohydrate metabolism

Carbohydrates, Digestion, and Blood Sugar

Carbohydrates are an important source of energy and a key part of human nutrition. They are made of carbon, hydrogen, and oxygen. One gram of carbohydrate provides four kilo-calories of energy, so carbohydrates are the body’s most efficient instant fuel. Starch makes up about 60% of the carbohydrates people eat. It is broken down by amylase enzymes, but amylase cannot work in the stomach’s acidic environment. That is why starch digestion happens in the mouth and the small intestine. Simple...

glycolysis: preparatory phase

Glycolysis: Energy Investment Steps

Glycolysis begins with energy investment steps in the cytoplasm of both prokaryotic and eukaryotic cells. It is the first step in cellular metabolism, which is the complete breakdown of glucose to extract energy. In heterotrophic cells, glucose enters by secondary active transport or through GLUT proteins, which are glucose transporter proteins that help glucose diffuse into the cell. The pathway starts with one six-carbon, ring-shaped glucose molecule and ends with two three-carbon molecules...

glycolysis: pay-off phase

Glycolysis: ATP and NADH Output

The pay-off phase of glycolysis turns the two three-carbon sugar molecules into ATP, NADH, and pyruvate. By this stage, the cell has already spent two ATP molecules. The remaining reactions recover that investment and add two more ATP molecules and two high-energy NADH molecules. The sixth step oxidizes glyceraldehyde 3-phosphate, a three-carbon sugar made earlier in glycolysis. High-energy electrons are transferred to NAD+, which becomes NADH. A second phosphate group is then added to form...

fates of pyruvate

Pyruvate Pathways in Fermentation

Pyruvate is a key product of glycolysis and can follow different pathways depending on oxygen availability. During glycolysis, glucose is oxidized to pyruvate, NAD+ is reduced to NADH, and two ATP are made by substrate-level phosphorylation. In aerobic organisms, pyruvate then enters the citric acid cycle, which helps produce the reduced coenzymes NADH and FADH2. These coenzymes are later oxidized in the electron transport chain to make ATP and regenerate NAD+ and FAD. When oxygen is absent,...

role of reduced coenzymes nadh and fadh&#8322;

Electron Carriers in Cellular Energy

Electron carriers help store and move energy during nutrient breakdown. Cells can save released energy by reducing these carriers or by making ATP, the cell’s main energy molecule. These mobile electron carriers bind high-energy electrons and shuttle them between compounds in metabolic pathways. The main carriers discussed here come from the B vitamin group and are nucleotide derivatives. They include nicotinamide adenine dinucleotide, nicotinamide adenine dinucleotide phosphate, and flavin...

overview of nitrogen metabolism

Nitrogen Cycle in Soil and Plants

Nitrogen moves through soil, plants, animals, and microbes in a cycle that keeps this macronutrient available for life. It is a major part of proteins and nucleic acids, so cells need it to build both amino acids and nucleotides. In nature, nitrogen is recycled from organic compounds and stored in several forms, including ammonia, ammonium ions, nitrate, nitrite, and nitrogen gas. Many of the key steps in this cycle are carried out only by prokaryotes. The largest nitrogen pool in terrestrial...

overview of fatty acid metabolism

Fatty Acids: Energy, Membranes, and Cholesterol

Fatty acids help cells store and use energy, and they also support important cell structures. Lipids are nonpolar and hydrophobic, so they do not mix well with water. Major lipid types include fats and oils, waxes, phospholipids, and steroids. Cells break down fatty acids by beta-oxidation. This process happens in the matrix of the mitochondria and cuts fatty acid chains into two-carbon acetyl groups. CoA picks up these groups to form acetyl CoA, which then enters the citric acid cycle. Extra...

sugars as energy storage molecules

Glucose Storage in Plants and Animals

Glucose storage in plants and animals helps cells manage energy for metabolism. Sugar is a simple carbohydrate, and cells use it because a lot of energy is stored in its bonds. Consumed carbohydrates often come from photosynthesizing organisms, especially plants. Plants make glucose during photosynthesis by using sunlight to convert carbon dioxide into sugar molecules. Because this builds a larger, energy-storing molecule, the process needs an energy input. Glucose can then be stored for later...

fats as energy storage molecules

How Triglycerides Fuel ATP Production

Triglycerides store long-term energy in fats. A triglyceride is built from glycerol and three fatty acids. When the body needs energy, these molecules are broken down first. This breakdown is called lipolysis, and it happens in the cytoplasm by hydrolysis. Lipolysis splits triglycerides into fatty acids and glycerol. The glycerol then enters glycolysis as DHAP, which connects fat breakdown to the cell’s main energy pathway. The fatty acids are then oxidized by beta-oxidation into acetyl-CoA.

regulation of metabolism

How Cells Control Metabolic Enzymes

Cells control metabolic enzymes to match changing needs and conditions. Different cells use different enzymes and energy levels, and those needs can also change within the same cell over time. Stomach cells, fat storage cells, skin cells, blood cells, and nerve cells do not all need the same metabolic activity. A digestive cell also works harder soon after a meal than it does many hours later. As cell needs change, the amount and activity of enzymes change too. Enzymes lower activation energy,...

positive and negative feedback loops

Homeostasis keeps body conditions in a steady range through feedback control. Animal organs and organ systems constantly adjust to internal and external changes. This balance is called a dynamic equilibrium because the body keeps adapting while still staying within specific ranges. The goal of homeostasis is to stay near a set point, which is the value the body tries to maintain. A change in the internal or external environment is a stimulus. A receptor detects that change and sends a signal...

key terms and concepts

Learn how receptors, control centers, and effectors work in homeostasis. Compare negative and positive feedback loops, set points, and acclimatization.

Homeostasis and Body Feedback Control | JoVE K12

cell biology

JoVE Core Cell Biology illustrates complex cellular processes in easy-to-understand yet comprehensive animated video lessons. This collection focuses on the essential components and functions of cells, including organelles and membranes, cellular transport, and cell energetics. It is complemented by scientist-in-action videos that demonstrate the application of cell biology in real-world research experiments.

Alabama Course of Study Science

9-12

Human Anatomy and Physiology

From Molecules to Organisms: Structures and Processes

9-12.HA.1.6

Next Generation Science Standards

Life Science

Texas Essential Knowledge and Skills

Biology

BIO.12

BIO.12.A

Nucleic Acids and Nucleotides

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Nucleic Acid Structure

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DNA Base Pairing

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The DNA Helix

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The Central Dogma

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RNA is the Missing Link Between ...

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Genomic DNA in Eukaryotes

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Overview

Deoxyribonucleic acid, or DNA, is the genetic material responsible for passing traits from generation to generation in all organisms and most ...

DNA Packaging

Overview

Eukaryotes have large genomes compared to prokaryotes. In order to fit their genomes into a cell, eukaryotes must pack their DNA tightly inside ...

RNA Structure

Overview
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Overview
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What is Gene Expression?

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Transcription

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Translation

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Ribosomes

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tRNA Activation

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...

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chromatin-position-affects-gene-expression

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The centromere is a DNA ...

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HS-LS1-1

Characteristics of Life

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Taxonomy

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Phylogeny

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HS-LS1-2

Overview of Metabolism

Living cells constantly carry out various chemical reactions which are necessary for their proper functioning. These reactions are interlinked to one ...

Regulation of Metabolism

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Animal organs and organ systems constantly adjust to internal and external changes through a process called homeostasis (&#34;steady state&#34;). Examples ...

Functions of Life

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Requirements for Human Life

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What is Homeostasis?

Maintaining homeostasis requires that the body continuously maintain its internal conditions. Each physiological condition has a particular set point, ...

Negative and Positive Feedback

Homeostatic Imbalance

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pH Homeostasis

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homeostatic-imbalances-in-body-temperature

Homeostatic Imbalances in Body Temperature

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...

Regulation of Food Intake

The hypothalamus releases peptides influencing feeding behavior.
Two hypothalamic neuronal groups participate in this process.
Neuropeptide Y (NPY) and ...

Plan and conduct an investigation to provide evidence that feedback mechanisms maintain homeostasis in living organisms. Examples of investigations could include heart rate responses to exercise, stomate responses to moisture and temperature, root development in response to water levels, or cell response to hypertonic and hypotonic environments.

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Interphase

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The Cell Cycle Control System

Positive Regulator Molecules

Inhibition of CDK Activity

Use a model to illustrate the role of the cell cycle and differentiation in producing and maintaining complex organisms. Emphasis is on conceptual understanding that mitosis passes on genetically identical materials via replication, not on the details of each phase in mitosis.

HS-LS1-4

Homeostasis and Body Feedback Control

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