1. Human Norms

2. 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.

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

4. 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.

5. 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.

6. Feedback Loop

7. 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.

8. 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.

9. 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.

10. Blood Pressure Feedback Loop

11. 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.

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

13. Heart Rate As you get older your average heart rate drops.
Newborn-Infant 130 bpm.
Toddler bpm.
Child bpm.
Teens bpm.
Adults bpm.

14. 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.

15. Body Temperature Feedback Loop

16. 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 and usually decreases with age.

17. 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.

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