Presentation on theme: "S TRESS Stressful Video. W HAT IS STRESS ? Stress has been defined as “the rate of wear and tear in the body” or, from Brainfacts any external stimulus."— Presentation transcript:
S TRESS Stressful Video
W HAT IS STRESS ? Stress has been defined as “the rate of wear and tear in the body” or, from Brainfacts any external stimulus that threatens homeostasis So what is homeostasis and give an example? The property of a system that regulates its internal environment and tends to maintain a stable, relatively constant condition of properties: ie blood sugar, temperature or pH
W HY STRESS ? Stress can help the body in the short term, Acute stress can provide extra strength and energy to cope with a challenge protects the body and brain Can increase memory during stressful situations helps reestablish homeostasis So is stress always good In the long term, no. Long term, or Chronic Stress can be very harmful.
N AME THE 3 SECTIONS OF THE NERVOUS SYSTEM ACTIVATED BY STRESS 1. Voluntary (Somatic) nervous system 2. Autonomic nervous system 3. Neuroendocrine system
T HE I MMEDIATE NS RESPONSE TO STRESS 1.) Somatic (voluntary) NS sends messages to muscles
T HE I MMEDIATE NS RESPONSE TO STRESS 2.) The Autonomic Nervous System What are the subgroups under this division of the NS? Sympathetic nervous system (fight or flight) & Parasympathetic nervous systems (calming, homeostatic) ( MEMORY HINT: I feel sympathetic toward you if you are chased by a bear and a PARAchute brings you down slowly)
Sympathetic NS triggers – Increased Increased blood flow to muscles arteries supplying blood to the muscles to relax Reduced blood flow to skin, kidney, digestive tract. Stress hormone epinephrine, aka adrenaline, is quickly released into the bloodstream. Epinephrine puts the body into a general state of arousal, enabling it to cope with the stressor. If this alarmed state lasts too long, it can be harmful. T HE I MMEDIATE NS RESPONSE TO STRESS
ONCE THE STRESSOR IS GONE: parasympathetic The parasympathetic branch helps regulate bodily functions and soothe the body Prevents the body from remaining in a state of high alert for too long. T HE I MMEDIATE NS RESPONSE TO STRESS
Maintains the body’s internal functioning. Various stress hormones travel through the blood and stimulate the release of other hormones, which affect bodily processes such as metabolic rate and sexual function. 3.) Neuroendocrine system T HE I MMEDIATE NS RESPONSE TO STRESS
3.) Neuroendocrine system What is the primary brain structure that communicates/influences with the endocrine system? The Hypothalamus What endocrine organ does the hypothalamus directly influence? The pituitary gland What are the 2 major stress hormones and what endocrine organ releases them? Epinephrine (adrenaline) and Cortisol (which is a type of glucocorticoid), both released by the adrenal gland. Epinephrine is released by the adrenal medulla, while Cortisol is released by the adrenal cortex
T HE I MMEDIATE NS RESPONSE TO STRESS 3.) Neuroendocrine system (still continues) Stress hormones: Epinephrine (also called adrenaline) Released quickly in response to stress Puts body in state of arousal (fight-or-flight) Cortisol Released more slowly in response to stress (5 min delay) Mobilizes energy and delivers it to muscles Increases Cardiovascular efficiency Turns Down immediate non-essentials such as feeding, digestion, growth, and reproduction Influenced by daily cycles – acts as “wake up” signal in the mornings. Both increase the activity of the immune system Both are released by the adrenal glands
T HE I MMEDIATE NS RESPONSE TO STRESS 3.) Neuroendocrine system Brain sends signal to glands to release stress hormones Hypothalamus releases CRF (corticotrophin-releasing factor) which stimulates the pituitary to release ACTH (adrenocorticotrophic hormone), which stimulates the release of stress hormones from the adrenal glands.
T HE R OLE OF G LUCOCORTICOIDS – I MMEDIATE R ESPONSE glucocorticoids In response to signals from the hypothalamus, the adrenal glands secrete the stress hormone glucocorticoids ( secreted by adrenal cortex). Cause energy mobilization (breakdown of fatty acids and proteins) increasing cardiovascular tone and delaying non-essential processes during a crisis, such as feeding, digestion, growth, and reproduction.
T HE R OLE OF G LUCOCORTICOIDS Some of the actions of glucocorticoids help mediate the stress response Previous slide for examples Other, slower actions counteract the primary response to stress and help re-establish homeostasis. The immediate release of epinephrine (secreted by adrenal medulla) mobilizes energy and delivers it to muscles for the body’s response. The glucocorticoid cortisol, however, promotes energy replenishment (glucose glycogen) and efficient cardiovascular function.
L ETS GET T HIS FIGURED OUT A stress is detected and requires your body to respond. The first thing you could do is move, this requires your _____________ nervous system. At the same time, your body is preparing for a stressful situation, which requires the ______________ nervous system. In order for your body to coordinate a uniform response, the nervous system links up to the endocrine system (neuroendocrine system) using the nervous system structure known as the _____________, which directly communicates the endocrine structure known as the _____________. More specifically, the _____________ releases signals called _________________________________ to the anterior _________________ and causes it to release a hormone known as ___________________________. The hormone ____________ released from the anterior ________ then signals the _______________ to release _____________. The two types of _______________ are _______________ & ________________. somatic autonomic hypothalamus Pituitary gland hypothalamus pituitary gland CRF (corticotrophin-releasing factor) ACTH (adrenocorticotrophic hormone) ACTH pituitary Adrenal glandStress hormones Epinephrine Cortisol (a type of glucocorticoid)
W HAT ELSE DO G LUCOCORTICOIDS DO ? Glucocorticoids also affect food intake during the sleep-wake cycle. Cortisol levels, which vary naturally over a 24-hour period, peak in the body in the early-morning hours just before waking. Helps to produce a wake-up signal, turning on appetite and physical activity. May help explain disorders such as jet lag, which results when the light-dark cycle is altered by travel over long distances, causing the body’s biological clock to reset itself more slowly. Until that clock is reset, cortisol secretion and hunger, as well as sleepiness and wakefulness, occur at inappropriate times of day in the new location.
Acute stress also enhances the memory of earlier threatening situations and events, increases the activity of the immune system, and helps protect the body from pathogens. Cortisol and epinephrine facilitate the movement of immune cells from the bloodstream and storage organs, such as the spleen, into tissue where they are needed to defend against infection. This is only an immediate increase in immunity, and will eventually have the opposite effect. T HE I MMEDIATE NS RESPONSE TO STRESS
R EVIEW What stress hormone is made by the adrenal cortex? What major stress hormone is made by the adrenal medulla? Explain how glucocorticoids both enhance, and bring down the stress response. Explain how the brain directs the release of glucocorticoids. If observing cortisol levels during a sleep study, what would one expect to occur just before the subject awakens? Cortisol (a type of glucocorticoid) Epinephrine The glucocorticoid cortisol, promotes fatty acids and protein breakdown to increase energy in blood stream, however, it also promotes energy replenishment (glucose glycogen). Hypothalamus –Corticotrophin Releasing Factor (CRF) Pituitary – Adrenalcorticotrophic Hormone (ACTH ) Adrenal glands -( Glucocorticoids) A sharp spike in cortisol
Take a look at the bodies response to stress. How are these beneficial?
C HRONIC S TRESS How is stress today different from the stress of our Nomadic ancestors? Modern stressors often do not require that we respond with muscular activities (running or fighting). How could this be bad? Our system is has evolved so that exertion would help to return your body to homeostasis. Instead, your body may stay roused up, long after the initial stressor is gone.
Take a look at the bodies response to stress. How could these be harmful in response to modern stressors?
C HRONIC S TRESS Overexposure to cortisol and epinephrine can lead to: Impaired memory weakened muscles suppression of immune system hypertension (high blood pressure) abdominal obesity (“belly fat”) atherosclerosis (hardening of arteries) Arthritis Accelerated aging
C HRONIC S TRESS Stress also can contribute to sleep loss. Elevated levels of glucocorticoids can delay the onset of sleep, and sleep deprivation raises glucocorticoid levels, setting off a vicious cycle.
C HRONIC S TRESS Stress-related disorders include: colitis, (swollen colon) hypertension, clogged arteries, impotency, loss of sex drive, irregular menstrual cycles, diabetes, and maybe cancer
C HRONIC S TRESS Overexposure to glucocorticoids also increases the number of neurons damaged by stroke. Prolonged exposure to glucocorticoids before or immediately after birth can cause a decrease in the normal number of brain neurons and smaller brain size. What might cause this? For some reason, the adrenal is producing too much cortisol. Could be a tumor in the pituitary, cuasing too much ACTH to be relased, signalling the release of too much cortisol, or a tumor in the adrenal itself, causing too much cortisol to be created.
R ANDOM RELATED DISEASE Cushing’s syndrome: Rapid weight gain-Central obesity Moon Face Hyperhydrosis (sweat a lot) Hirsutism (male pattern hair growth) Muscle & Bone weakness Hypertension Immune suppression… Can be caused by overmedication of steroids, or by tumors in the pituitary or adrenal.
G LUCOCORTICOIDS AND THE IMMUNE RESPONSE Hydrocortisone is a synthetic (man-made) glucocorticoid. What does it do? Hydrocortisone suppresses the immune response. So it stops inflamation. How does this make sense in relation to natural glucocorticoids influence over the immune system during stress. While stress initially increases or promotes the immune system, glucocorticoids will work as immunosuppressors, reversing the initial stress response, and ensuring there is not an over- response by the immune system.
ChronicStress and the immune system
What is the Brainfacts definition for stress? Any external stimulus that threatens homeostasis The somatic nervous system responds to stress by sending signals to ______. Muscles In response to stress, how does the Sympathetic Nervous System affect skin, the kidneys, and the digestive tract, and why? parts of the body that blood decreases is the Blood flow to these areas is decreased and prioritized to ‘essential organs for the ‘fight or flight’ response The two major stress hormones are Epinephrine (adrenaline and Glucocorticoids (Cortisol) Of the two stress hormones named above, which is ‘fast-acting’ compared to the other Epinephrine is a more immediate response while the glucocorticoids could take up to 5 minutes to respond
PERCEIVED DANGER -P SYCHOLOGICAL STRESS Physical stressors typically are not chronic, although they may be reoccurring (very hard manual labor, athletics…) Social & Psychological stressors No physical outlet to return body to normal May be chronic Give examples
PERSONALITY OR BEHAVIOR How we deal or perceive event in our lives affects our stress hormone level. Hostile and irritable people are at higher risk for heart attacks. Case study: Researchers studied two groups of men categorized as having high or low hostility. Both were subjected to harassment. Scientists found that harassed men with high hostility scores had larger increases in levels of stress hormones, muscle blood flow, and blood pressure. Thus, for those people with personality traits that include high levels of hostility, learning to reduce or avoid anger could be important to avoid cardiovascular damage.
R EVIEW OF S TRESS When stress occurs, the sympathetic nervous system is triggered. Norepinephrine is released by nerves, and epinephrine is released by the adrenal medulla. By activating receptors in blood vessels and other structures, these substances ready the heart and working muscles for action. Acetylcholine Acetylcholine is released in the parasympathecalming effectstic nervous system, producing. The neuroendocrine system also maintains the body’s normal internal functioning. Corticotrophin releasing hormone CRh ) is released from the hypothalamus and travels to the pituitary gland, where it triggers the release of adrenocorticotropic hormone (ACTh). ACTh travels in the blood to the adrenal glands (adrenal cortex), where it stimulates the release of the glucocorticoid hormone, cortisol.