Stress Physiology Flashcards
What is stress
Stress is a physiological and psychological response to a perceived threat or challenge. It is a natural and necessary response that helps animals (including humans) adapt to their environment by mobilizing resources to cope with the situation. Stress can be caused by both internal and external factors, such as physical or emotional trauma, chronic illness, relationship problems, financial difficulties, or work-related stressors.
What happens when an individual is faced with stressful situation
When an individual is faced with a stressful situation, the body responds by releasing stress hormones such as cortisol and adrenaline. These hormones trigger a “fight or flight” response, which prepares the body for action by increasing heart rate, blood pressure, and respiration. At the same time, the body redirects energy away from non-essential functions such as digestion and towards the muscles and brain, in preparation for action.
If the stressful situation is short-lived, the body’s stress response will return to normal once the threat has passed. However, if the stress is chronic or prolonged, it can lead to physical and psychological health problems such as anxiety, depression, high blood pressure, heart disease, and immune system dysfunction.
What is the autonomic nervous system
The autonomic nervous system (ANS) is a division of the peripheral nervous system (PNS) that controls and regulates involuntary functions in the body. It is responsible for maintaining the internal environment of the body in a balanced and stable state, known as homeostasis. The ANS consists of two branches: the sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS).
What is the sympathetic nervous system responsible for
The SNS is responsible for the body’s “fight or flight” response, which prepares the body for action in response to a perceived threat or stressor. It increases heart rate, blood pressure, and respiration, while decreasing digestion and other non-essential functions.
What is the parasympathetic nervous system for
The PNS, on the other hand, is responsible for the body’s “rest and digest” response. It slows down heart rate and breathing, while increasing digestion and other bodily processes that promote relaxation and recovery.
What is the hypothalamic pituitary adrenal axis
The hypothalamic-pituitary-adrenal (HPA) axis is a complex neuroendocrine system that plays a key role in the body’s response to stress. It involves a series of hormonal signals that originate in the hypothalamus, a region of the brain that regulates many bodily functions, including hunger, thirst, body temperature, and sleep.
I’m response to stress what does the hypothalamus release
In response to stress or other perceived threats, the hypothalamus releases a hormone called corticotropin-releasing hormone (CRH) into the bloodstream. This hormone then stimulates the pituitary gland, located at the base of the brain, to release adrenocorticotropic hormone (ACTH) into the bloodstream.
What does adrenocorticotropic hormone do
ACTH then travels to the adrenal glands, located on top of the kidneys, and stimulates the release of cortisol, a stress hormone. Cortisol plays a critical role in the body’s stress response, helping to mobilize energy stores and suppress inflammation.
Once threat has passed what happens
Once the threat has passed, cortisol levels typically return to normal as the HPA axis is downregulated. However, chronic stress or other factors can lead to dysregulation of the HPA axis, resulting in overproduction or underproduction of cortisol. This can lead to a variety of health problems, including anxiety, depression, obesity, and immune system dysfunction.
What are glucocorticoids
Glucocorticoids are a class of steroid hormones that are produced in the adrenal gland ( released by adrenal cortex ) in response to stress or inflammation.
The primary glucocorticoid in humans is cortisol, also known as hydrocortisone.
Glucocorticoids play a crucial role in the body’s stress response by mobilizing energy stores and suppressing inflammation. They also help to regulate blood sugar levels, blood pressure, and immune system function.
In addition to their natural production in the adrenal gland, glucocorticoids are also used therapeutically to treat a variety of medical conditions, including autoimmune disorders, allergies, asthma, and certain types of cancer. Synthetic glucocorticoids, such as prednisone and dexamethasone, are commonly prescribed for these purposes.
Difference between glucocorticoids between species
There are differences in the regulation and function of glucocorticoids between different species. While cortisol is the primary glucocorticoid in humans and many other primates, other species may have different primary glucocorticoids, such as corticosterone in rodents, reptiles and birds.
How do glucocorticoids work
Glucocorticoids work by binding to specific receptors inside cells to modulate gene expression and other cellular processes.
In response to stress, the hypothalamus in the brain releases corticotropin-releasing hormone (CRH), which triggers the release of adrenocorticotropic hormone (ACTH) from the pituitary gland. ACTH then stimulates the adrenal gland to release glucocorticoids, primarily cortisol in humans.
Once in the bloodstream, glucocorticoids can enter cells and bind to glucocorticoid receptors (GRs) in the cytoplasm. This binding causes a conformational change in the GR, allowing it to translocate to the nucleus and bind to specific DNA sequences known as glucocorticoid response elements (GREs).
The binding of the GR to GREs can have a range of effects on gene expression, depending on the specific target genes involved. Glucocorticoids can upregulate the expression of genes involved in the stress response, such as those involved in glucose metabolism, while downregulating the expression of genes involved in inflammation and immune responses.
Glucocorticoids can also have non-genomic effects, such as altering ion channel activity and modulating neurotransmitter release, which can contribute to their physiological effects.
Overall, the actions of glucocorticoids are complex and multifaceted, with a wide range of effects on cellular and physiological processes throughout the body.
Benefit of HPA activity
One major benefit of HPA activity is its role in maintaining blood glucose levels during periods of stress or fasting. Glucocorticoids, which are released by the adrenal gland in response to ACTH from the pituitary gland, stimulate the liver to convert glycogen into glucose and promote glucose release into the bloodstream. This can help provide the body with energy during times of increased demand.
The HPA axis is also involved in regulating immune function and inflammation. Glucocorticoids can have anti-inflammatory effects by inhibiting the production and activity of pro-inflammatory cytokines and other immune cells. This can help prevent excessive inflammation and tissue damage in response to infection or injury.
Additionally, HPA activity can play a role in modulating mood and behavior. Studies have shown that stress-induced activation of the HPA axis can lead to changes in neurotransmitter levels and altered behavior in animals, including increased anxiety and depression-like behaviors. However, the precise mechanisms underlying these effects are not yet fully understood.
Disadvantages of HPA axis
Increased risk of psychiatric disorders: Chronic HPA axis activation has been associated with an increased risk of mood and anxiety disorders, including depression and post-traumatic stress disorder (PTSD).
Suppressed immune function: While acute HPA activation can help regulate immune function and inflammation, chronic or excessive HPA activation can lead to suppression of immune function. This can increase the risk of infection and other health problems.
Increased risk of metabolic disorders: Chronic HPA axis activation has been linked to an increased risk of metabolic disorders, including insulin resistance, obesity, and type 2 diabetes.
Cognitive impairment: Chronic HPA axis activation has been associated with impaired cognitive function and memory.
Cardiovascular disease: Chronic HPA axis activation has been linked to an increased risk of cardiovascular disease, including hypertension and atherosclerosis.
Digestive problems: Chronic HPA activation has been associated with digestive problems, including decreased appetite, nausea, and diarrhea.
Consequences of stress
Physical health problems: Chronic stress has been linked to a number of physical health problems, including cardiovascular disease, high blood pressure, diabetes, gastrointestinal problems, and immune system dysfunction.
Emotional problems: Chronic stress can contribute to the development of mood disorders, such as anxiety and depression.
Behavioral problems: Stress can lead to unhealthy coping behaviors, such as overeating, substance abuse, and social withdrawal.
Sleep problems: Stress can disrupt sleep patterns, leading to difficulty falling asleep or staying asleep.
Cognitive problems: Chronic stress can impair cognitive function, including memory, attention, and decision-making.
Interpersonal problems: Stress can lead to interpersonal problems, including conflict with others, social isolation, and relationship difficulties.
