NUR 339 Exam 2
- Homeostasis
level of constancy maintained by body during time of change
- Control Systems
used to maintain homeostasis—the human body has thou- sands of intricate control systems Examples Temperature control, blood glucose control, BP control, fluid balance
- Feedback mechanisms/loops
-Self-regulating mechanisms which control homeostasis
-3 components
Sensor mechanism - senses disruption in homeostasis Control center - regulates response in the body, regulated in CNS Effector mechanism - acts to restore homeostasis.
- Negative vs positive feedback
-Negative reverses the original change; positive increases the original change.
Negative ex. --> increased blood sugar, increased blood osmolarity (dehydration) Positive ex. --
> labor contractions. Uncommon feedback loop
- Adaptation 1 / 3
Ability to respond and maintain stability during rapidly changing conditions in internal and external environment.
Responses are efficient and effective.
Ex. CHF. Short term response --> Elevates BP, HR, retain fluid. Long term response --> heart vessel enlarge
- Stress response
Stress is a state manifested by a specific syndrome of the body developed in response to any stimuli that made an intense systemic demand on it.
Stressor = event or agent responsible for initiating stress response
When stress occurs, individuals react by either adapting successfully or by failing to adapt
- Selye's General Adaptation Syndrome (GAS) --> Alarm stage
Alarm stage
Body senses stress, CNS is aroused, body releases chemicals to initiate fight-or-flight Chemicals released
catecholamines (epinephrine and norepinephrine) and cortisol
S/S
increased HR & SV, increased mental acuity, sweaty, shaky, dilated pupils, increased RR 2 / 3
- Selye's General Adaptation Syndrome (GAS) --> Resistance stage
Resistance stage
Body responds to stressor and attempts to return to homeostasis, utilizes coping mechanisms Chemicals released
cortisol, glucagon, thyroid hormone, aldosterone S/S
Decreased lymphocytes, immune suppression can result in infection
- Selye's General Adaptation Syndrome (GAS) --> Exhaustion stage
Occurs if stressor is prolonged or overwhelms ability of body to defend itself.
Resources are depleted and signs of systemic damage appear. Severe immunodeficiency due to prolonged stress.End-organ dysfunction (renal failure, heart failure) due to prolonged stress & SNS stimulation.Onset of disease.
- Adaptive (positive) vs. maladaptive (negative) responses
Adaptive re- sponses
regulate blood glucose, fluid balance, temp control, cardiac output Maladaptive responses
PTSD, alcoholism, depressive disorders, hypertension, gastric issues, headaches, insomnia
- Examples of stressors
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