1. Human Anatomy & Physiology
Introduction
Panda Wilson

2. Maintenance of Life
Vital signs (temperature, pulse, respiration, & blood pressure) indicate that a person’s health status. Vital signs can also be helpful in forming a diagnosis on a patient.
Panda Wilson

3. Maintenance of Life Homeostasis
Maintenance of a stable internal environment is called homeostasis. The body maintains homeostasis through a number of self-regulating control systems (called homeostatic mechanisms); all of which share 3 components.
Receptors provide information about the internal environment
A control center that includes a set point which is the value to be maintained.
Effectors produce changes necessary to maintain the set point value
Panda Wilson

4. Maintenance of Life – Homeostasis Example
Body Temperature Thermoreceptors are constantly monitoring the body’s temperature & sending the information to the control center (in this case the hypothalamus). The control center compares the information to the set point for body temperature and signals the effectors when a correction in body temperature is required.
Panda Wilson

5. Maintenance of Life – Homeostasis Example
Body Temperature
The set point for a human’s body temperature is 98.6°F. When temperature deviates from the set point the control center detects the deviation from the set point and effectors are stimulated to cause changes to occur in the body which will bring the temperature back to the set point.
Panda Wilson

6. Maintenance of Life – Homeostasis Example
Body Temperature (set point 98.6°F )
When temperature falls below the set point the following changes occur in the body:
vasoconstriction (blood vessels constrict) to conserve body heat & protect core temperature) and
shivering which produces heat
These processes continue until the body temperature returns to the set point.
Panda Wilson

7. Maintenance of Life – Homeostasis Example
Body Temperature (set point 98.6°F )
When temperature rises above the set point the following changes occur in the body:
vasodilation (blood vessels dilate) allowing more blood to move into vessels close to the body’s surface where heat can be lost to the environment
sweat glands secrete sweat; as the sweat evaporates, the skin cools; further cooling the blood.
These processes continue until the body temperature returns to the set point.
Panda Wilson

8. VI. Maintenance of Life Homeostasis
Negative feedback vs Positive feedback
In a negative feedback system, the deviation from the set point causes a response which leads to a return to the set point (reducing the difference / deviation between the set point & the actual condition of the body)
for example: body temperature
A positive feedback system causes the deviation between set point and actual condition to increase.
For example: nursing an infant – a loss of milk to a nursing infant leads to an increase in milk production
Panda Wilson

9. Body Sections, cont
Sometimes a cylindrical organ (a long bone, the trachea) must be sectioned; in such cases:
1. A cut across the structure is called a cross-section.
2. An angular cut across the structure is called an oblique section.
3. A lengthwise cut on the structure is called a longitudinal section.
Panda Wilson