Lecture 1.5 Flashcards
Stress and Physical Adaptation
What is Stress?
It is the body’s reaction to harmful forces (Stressors) that are capable of disturbing our homeostasis.
Characteristics include:
Real or perceived
Short or long-term
Isolated or recurrent
3 Manifestations of Stress
Routine Stress: everyday issues like work, school, etc.
Episodic Acute Stress: Transient, out-of-the-ordinary events such as loss of job, death in the family, major illnesses, etc.
Traumatic Stress: Life threatening events such as war, famine, assault, major accidents, etc.
Anxiety
The vague, uneasy feeling of discomfort or dread, which is often accompanied by an autonomic response (fight or flight)
Stressors
Any physical, physiological, or psychological force that is capable of disturbing our homeostasis equilibrium.
Homeostasis
A state of dynamic equilibrium of the internal body. It is maintained by the ever-changing processes of feedback and regulation in response to external or internal stimuli.
Adaptation
Response of an organism to stress to restore homeostasis and equilibrium.
What about an individual can affect their response to stress?
Age, General Health, Social Support, Genetic Influences, and Nurture Influences.
Stressor characteristics
The Type of Stressor: routine, episodic, traumatic
Persistence of Stressor: chronic or short
Perception of Stressor: How we perceive the stressor.
Origin of Stressor: Endogenous or Exogenous
How does stress affect the two ANS pathways?
Activates sympathetic, deactivates parasympathetic
Neurological Responses to Stress
Brainstem: Coordinates our body’s response
ANS: Coordinated by locus caeruleus (LC)
Increased: BP, HR, RR, pupil dilation, sweating, skeletal muscle, heart, and lung blood flow
Decreased: gastric function, peripheral blood flow and other viscera.
Cerebral Cortex: Regulates cognitive activities like focus, planning, attention, and persistence.
Limbic System: Regulates emotional activities and the reticular activating system (RAS).
Limbic includes fear, anxiety, anger, and excitement.
RAS includes alertness, muscle tension, and ANS stimulation.
Thalamus: Regulates and intensifies sensory input, such as our vision, hearing, or smell.
Hypothalamus: Regulates stress hormones and acts on the ANS.
Endocrine Response to Stress
Release of 4 hormones: Cortisol, Dopamine, Epinephrine, and Norepinephrine.
What is the pathway and effect of cortisol?
Corticotropin releasing hormone (CRH in the hypothalamus) -> adrenocorticotropic releasing hormone (ACTH in the pituitary) -> cortisol (adrenal glands)
Alters metabolism and increases blood glucose levels.
Decreases inflammatory response.
What is the effect of the 3 catecholamines?
Dopamine, Norepinephrine, and Epinephrine.
Increased blood flow to heart, lungs, brain, and skeletal muscles.
Decreased blood flow to nonvital organs such as skin and stomach.
What happens to our other hormones during stress?
Growth Hormone: suppressed in chronic stress.
Thyroid hormones: Decreased TSH and inhibited conversion of T4 to T3.
Reproductive Hormones: Anovulation and amenorrhea in females. Decreased spermatogenesis and testosterone in males.
Oxytocin: Released in stressful periods -> encourages social contact.
What happens to our immune system due to stress?
Cortisol - steroidal effects, hindering immune and inflammatory responses.
It inhibits the replication of T-cells and causes negative feedback to IL-1.
Prolonged stress can cause an increase in cytokines and cause illness-like symptoms.
