Exercise Physiology: Homeostasis, Cell Signaling, and Protein Synthesis

Flashcards covering key definitions and mechanisms of homeostasis, steady state, biological control systems, cell signaling pathways, extracellular vesicle dynamics, and exercise-induced gene transcription and protein synthesis.

How is homeostasis defined?

Homeostasis is defined as the maintenance of a constant or unchanging "normal" internal environment during unstressed conditions.

How is steady state defined?

Steady state is defined as a constant internal environment, but this does not necessarily mean that the internal environment is normal.

What is an example of a physiological variable that remains relatively constant during steady state?

Heart rate.

How does steady state differ from homeostasis regarding the condition of the internal environment?

Homeostasis refers to a normal internal environment during unstressed conditions, whereas steady state refers to a constant internal environment that is not necessarily normal.

What does the gain of a biological control system describe?

The gain describes the accuracy of the control system to maintain homeostasis.

To what does "gain" refer regarding physiological changes?

Gain refers to how precisely a control system can correct physiological changes away from a homeostatic "set point."

How does a control system with high gain compare to one with low gain?

A control system with high gain has a greater ability to maintain homeostasis when faced with changes in the internal environment compared to a low gain system.

How is physiological adaptation defined?

Adaptation refers to a change in the structure and function of a cell or an organ system that results in an improved ability to maintain homeostasis during stressful conditions.

What role do regular bouts of exercise play in skeletal muscle adaptation?

Regular bouts of exercise serve as an intermittent stress that promotes biochemical adaptations within active skeletal muscle fibers.

Exercise-induced adaptation in cells is an example of which process?

Hormesis.

What is acclimation?

Acclimation is an environmental adaptation involving the improved function of an existing homeostatic system.

How is hormesis defined?

Hormesis refers to a process in which low-to-moderate doses of a potentially harmful stress (i.e., chemical agent or environmental factor) result in a beneficial adaptive effect on the cell or organism.

What stress factors can induce a hormetic response according to the text?

Chemical agents or environmental factors.

How is cell signaling defined?

Cell signaling refers to a system of communication between cells that coordinates cellular activities.

What is intracrine signaling?

Intracrine signaling occurs when a chemical messenger is produced inside a cell that triggers a signaling pathway within the same cell that leads to a specific response.

Where is the chemical messenger produced and where does it act in intracrine signaling?

It is produced inside a cell and triggers a signaling pathway within that exact same cell.

What is juxtacrine signaling?

Juxtacrine signaling is communication by cell-to-cell contact, in which the cytoplasm of one cell is in contact with the cytoplasm of another through small junctions that connect the two cell membranes.

How do cytoplasms connect between adjacent cells in juxtacrine signaling?

Through small junctions that connect the two cell membranes.

What is autocrine signaling?

Autocrine signaling occurs when a cell produces and releases a chemical messenger into the extracellular fluid that acts upon the cell producing the signal.

Into what medium is an autocrine signal released before acting on the producing cell?

Extracellular fluid.

What is paracrine signaling?

Paracrine signaling occurs when cells produce chemical messengers (signals) that act locally on nearby cells to bring about a coordinated response.

What is synaptic signaling?

Synaptic signaling is a type of paracrine signaling that occurs in the nervous system.

In which body system does synaptic signaling occur?

The nervous system.

What unique signaling mechanism uses both paracrine and endocrine signaling to convey cellular messages?

Extracellular vesicles (EVs).

Which two modes of signaling are combined by extracellular vesicles?

Paracrine signaling and endocrine signaling.

What type of chemical signals are released into the blood to be transported throughout the body?

Hormones.

Which specific tissues are mentioned as releasing chemical signals (hormones) into the blood?

Pancreas, adrenal glands, and skeletal muscles.

What initial stimulus begins the pathway leading to protein synthesis during exercise?

The "stress" of exercise stimulating a specific cell signaling pathway.

What molecule is activated as a result of an exercise-stimulated cell signaling pathway?

A transcriptional activator.

What are transcriptional activators responsible for?

They are responsible for "turning on" specific genes to synthesize new proteins.

Where is a transcriptional activator initially activated during exercise?

In the sarcoplasm.

Where does a transcriptional activator move after being activated in the sarcoplasm?

Into the nucleus.

To which region of a gene does a transcriptional activator bind in the nucleus?

The promoter region of the gene.

What message is formed as a result of transcription?

Messenger RNA (mRNA).

What information is contained within messenger RNA (mRNA)?

The genetic information for a specific protein's amino acid sequence.

What path does mRNA take after leaving the nucleus?

It travels through the sarcoplasm to the ribosome.

What is the ribosome defined as in the process of protein synthesis?

The site of protein synthesis.

What happens to mRNA once it reaches the ribosome?

It is translated into a specific protein.

Which tissues/cells promote the release of extracellular vesicles (EVs) during exercise?

Skeletal muscles, epithelial cells, white fat cells, and other tissues.

What type of signaling occurs when extracellular vesicles enter nearby cells?

Paracrine signaling.

What type of signaling occurs when extracellular vesicles are transported via circulation to organs?

Endocrine signaling.

How is the cellular stress response defined?

A biological control system in cells that battles homeostatic disturbances by manufacturing proteins designed to defend against stress.

How does the cellular stress response battle homeostatic disturbances?

By manufacturing proteins designed to defend against stress.

What is a stress protein?

A family of proteins manufactured in cells in response to a variety of stresses (e.g., high temperature).

What is one of the most important families of stress proteins?

Heat shock proteins.

Besides high temperature, what is one type of stress that triggers production of heat shock proteins involving free radicals?

Free radical production.

Besides high temperature, what acidity-related stress triggers production of heat shock proteins?

Low pH.

Besides high temperature, what tissue-response stress triggers production of heat shock proteins?

Inflammation.

What is the set point in a biological control system?

The homeostatic target value from which physiological changes away are corrected by the control system.

What process translates mRNA into a specific protein at the ribosome?

Translation.