Human Norms

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Human Norms
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Vital Signs

• Humans have four vital signs, that if out of
  their normal range, could signify a problem has
  or is about to occur.
• Those four vital signs are blood pressure, heart
  rate, body temperature and breathing rate.

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Feedback Loops

• Your body uses what are known as feedback loops
  to check on and maintain a normal range in these
  vital signs.

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Feedback Loops

• A feedback loop consists of three parts.
• A monitor/sensor that indicates a change in a
  vital sign.
• A control center that recognizes the change and
  issues a response.
• An effector/regulator that restores the vital
  sign back to its normal range.

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Feedback Loops

• Feedback loops can be either positive or
  negative.
• A positive feedback loop recognizes a change and
  amplifies it.
• A negative feedback loop recognizes a change and
  brings it back to normal.

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Feedback Loop
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Blood Pressure

• It is the most irregular of the vital signs.
• It falls during sleep and then rises sharply
  after wake-up.
• It changes quite dramatically during the day
  based on the amount of activity we are undergoing.

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Blood Pressure

• It is measured using a sphygmomanometer.
• It measures the arterial pressure in mm of Hg.
• This is an old unit of pressure, but has carried
  over due its universality.

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Blood Pressure

• Blood pressure usually averages around 115/70 mm
  of Hg.
• 115 is the systolic pressure, the peak pressure
  of the blood in the arteries.
• 70 is the diastolic pressure, the minimum
  pressure of blood in the arteries.

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Blood Pressure Feedback Loop
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Heart Rate

• Heart Rate also changes throughout the day, but
  not as much as blood pressure.
• During sleep it drops, but once awake it stays
  pretty consistent save for periods of high
  activity.
• Heart rate can also be called a pulse.

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Heart Rate

• The pulse is commonly taken at the wrist where
  the brachial artery is located.
• You can feel this with your fingers or hear it
  here (or in your chest) with a stethoscope.

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Heart Rate

• As you get older your average heart rate drops.
• Newborn-Infant 130 bpm.
• Toddler 100-120 bpm.
• Child 90-110 bpm.
• Teens 80-100 bpm.
• Adults 50-80 bpm.

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Body Temperature

• Your core body temperature various the least of
  the vital signs.
• It hovers around 37 degrees Celsius and only
  various slightly.
• This goes for every age and body type.
• Elevated body temperature usually means
  infection.

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Body Temperature Feedback Loop
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Respiratory Rate

• The least accurate of the vital signs because it
  has the most variation amongst a population.
• This makes it hard to tell if a change is because
  someone is sick.
• The average breaths per minute can be anywhere
  from 12-30 and usually decreases with age.

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Pain

• Pain is sometimes referred to as the 5th vital
  sign.
• It is depends on who you ask as some perceive
  pain as a subjective symptom.
• There is even a pain scale which goes from 1-10.
• Pupil size has also been argued.

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Homework Questions

1. For each of the four main vital signs, indicate
   your norms based on your age or your own
   readings.
2. Which of the four vital signs are most likely
   interlinked? Why do you think that is so?
3. What is the difference between a negative
   feedback loop and a positive feedback loop?
4. Draw a feedback loop and indicate the monitor(s),
   control center and effector(s).
5. What do you think happens to breathing rate when
   you sleep? Why?