Keystone Anchor

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Keystone Anchor

• BIO.A.4.2 Explain mechanisms that permit
  organisms to maintain biological balance between
  their internal and external environments.
• In other words - ______________________________
  _________________ ________________________________
  __________________________________________________
  __________________________________________
• BIO.A.4.2.1 Explain how organisms maintain
  homeostasis (e.g., thermoregulation, water
  regulation, oxygen regulation).
• In other words - _______________________________
  ________________ _________________________________
  __________________________________________________
  _________________________________________

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KEY CONCEPT Homeostasis - regulation and
maintenance of a CONSTANT environment in the body
The term homeostasis is derived from two Greek
words Homeo which means unchanging and Stasis
which means standing
It is an organisms internal environment which
stays the same
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Type 1 Think about this persons body, describe
the factors that need to remain in homeostasis.

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• Control systems in the body.

• Sensors -gather data and detect changes
• Control center - receives data, sends messages,
  usually the brain
• -Communication system - delivers messages in
  form of nerve impulses and hormones to target
  organs, tissues
• Targets organ, tissue or cell that responds to
  change

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Negative feedback loops are necessary for
homeostasis.

• Feedback compares current conditions to set
  ranges.
• Negative feedback- counteracts change.
• Reverses any change and returns body to set point

Negative Feedback Loop

Keep athlete running
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KEY CONCEPT Systems interact to maintain
homeostasis.
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Each organ system affects other organ systems.

• Organ systems must also work together to keep the
  organism healthy.

There is no specific organ which controls
homeostasis. The skin, kidneys, liver,
endocrine system, nervous system and sensory
system all play a part in maintaining the
internal environment within narrow limits. The
hypothalamus is involved to a degree in each of
these regulations
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Type IDescribe how this picture of an automotive
race team is similar to the systems of a body.
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• Body cells work best if they have the correct
• Temperature
• Glucose concentration, (sugar)
• Water levels
• Homeostasis involves keeping the internal
  environment within set ranges

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Organs and involved

• Water - kidneys
• regulate water mineral salts concentration
• Thermoregulation skin and muscles
• regulate body temperature
• Glucose - liver pancreas
• regulate blood glucose level

skin
kidney
liver

pancreas
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Thermoregulation process of maintaining a
steady body temperature

• Sweating
• When your body is hot, sweat glands are
  stimulated to release sweat.
• The liquid sweat turns into a gas (it evaporates)
• To do this, it needs heat.
• It gets that heat from your skin.
• As your skin loses heat, it cools down.

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Thermoregulation process of maintaining a
steady body temperature

• Shivering
• Hypothalamus signals skin and muscular,
  respiratory, and circulatory systems
• Blood vessels constrict to reduce blood flow to
  prevent loss of heat
• Muscles contract around pores
• Muscles contract causing shivering
• Thyroid releases hormones that increase
• metabolism

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Controlling Glucose levels

• Your cells also need an exact level of glucose in
  the blood.
• Excess glucose gets turned into glycogen in the
  liver
• This is regulated by 2 hormones (chemicals) from
  the pancreas called Insulin and Glucagon
• In this way, the concentration of glucose in the
  blood is kept within narrow limits

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The glucose concentration in the blood is
controlled by the pancreas
The pancreas contains cells which produce
digestive enzymes but it also produces the
hormones insulin and glucagon
If the glucose concentration rises, the pancreas
releases insulin
If the glucose concentration falls, the pancreas
releases glucagon
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Insulin stimulates the liver and muscles to
remove excess glucose from the blood and store
it as glycogen
Glucagon stimulates the liver to convert its
stored glycogen into glucose which is then
released into the bloodstream
In this way, the concentration of glucose in the
blood is kept within narrow limits
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Water Regulation

• After having a very salty meal
• produce concentrated urine to remove excess salts
  in solution form
• extra water is needed to be excreted along with
  the excess salts
• sensation of thirst (drink more water to
  compensate for the water loss)

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Water Regulation

• The amount of water in the blood must be kept
  more or less the same all the time to avoid cell
  damage as a result of osmosis.
• There has to be a balance between the amount of
  water gained (from your diet though drinks and
  food and the water produced by cellular
  respiration) and the amount of water lost by the
  body (in sweating, evaporation, feces and urine).
• This is achieved by the action of the hormone ADH
  (anti-diuretic hormone).

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Water Regulation

• Part of the brain, the hypothalamus, detects that
  there is not enough water in the blood. The
  hypothalamus sends a message to the pituitary
  gland which releases ADH.
• This travels in the blood to your kidneys and as
  a result you make a smaller volume of more
  concentrated urine. The level of water in your
  blood increases until it is back to normal.
• If the level of water in your blood goes up the
  hypothalamus detects the change and sends a
  message to the pituitary. The release of ADH into
  the blood is slowed down or even stopped. Without
  ADH the kidneys will not save as much water and
  you produce large volumes of dilute urine.
• This is an example of negative feedback.

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• There are 11 major organ systems in the human
  body.

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TYPE I

• Name 3 systems that help maintain homeostasis and
  describe how they work to maintain homeostasis.
• 1.
• 2.
• 3.