What is Stress?

1
What is Stress?
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• A state of physiological or psychological strain
  caused by adverse stimuli (physical, mental,
  internal or external) that tend to disturb the
  functioning of an organism.

2
Physiological Stress Response
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• Sudden and severe stress generally produces
• Increase in heart rate
• Alterations in digestive activity
• Skin becomes pale
• Sweating increases
• Muscular tremors
• These responses are produced by the
  Hypothalamic-Pituitary-Adrenal Axis (HPAA)

3
Physiological Stress Response
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The stress response occurs when we are exposed to
some sort of threat. It involves co-ordinated
responses from a number of different systems and
structures
Hypothalamus
Pituitary gland
Sympathetic ganglia
Adrenal cortex
Adrenal Medulla
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4
The Hypothalamus
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The hypothalamus is in charge of the stress
response. When a stress response is triggered, it
sends signals to two other structures the
pituitary gland, and the sympathetic ganglia.
Hypothalamus
Pituitary gland
Sympathetic ganglia
Adrenal cortex
Adrenal Medulla
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5
The Pituitary Gland
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The pituitary gland controls the glands of the
endocrine system. When activated by the
hypothalamus it releases ACTH, which activates
the adrenal cortex.
Hypothalamus
Pituitary gland
Sympathetic ganglia
Adrenal cortex
Adrenal Medulla
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6
The Sympathetic Ganglia
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The sympathetic ganglia are connected to the
internal organs. When activated they affect the
functioning of the lungs, heart and digestive
system. They are also connected to the adrenal
medulla
Hypothalamus
Pituitary gland
Sympathetic ganglia
Adrenal cortex
Adrenal Medulla
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7
The Adrenal Cortex
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The adrenal cortex releases chemicals called
corticosteriods. These have a number of functions
including releasing stored glucose and
controlling swelling after injury.
Hypothalamus
Pituitary gland
Sympathetic ganglia
Adrenal cortex
Adrenal Medulla
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8
The Adrenal Medulla
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The adrenal medulla releases adrenaline. This
hormone stimulates the sympathetic ganglia,
keeping their activity at a high level.
Hypothalamus
Pituitary gland
Sympathetic ganglia
Adrenal cortex
Adrenal Medulla
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9
Fight or Flight Response
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Increase oxygen intake
Release stored glucose
Divert resources away from digestion
10
The Fight or Flight Response
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• An early evolutionary adaptation that is useful
  in dealing with physical threats
• Helps us deal with short-term problems that can
  be solved by fighting or running
• Unfortunately, many of the threats we face in our
  society do not fall into these categories