Organ Systems Working Together
As the world changes around you, your body must respond to those changes to continue to function
properly. Your body also has a range of chemical and physical conditions in which it can function
properly
For example:
blood pH, O2 level, body temperature, glucose level.
When the conditions within your body are in the appropriate ranges, it is in its steady-state (or
equilibrium).
HOMEOSTASIS: keeping the body’s conditions within their acceptable range
Each body system can be activated independently or working with other systems to help maintain
this steady-state. They are interdependent systems.
Some strongly interdependent systems include:
1. Circulatory and Respiratory System: Supply the body with Oxygen
• Circulatory system moves blood through the body providing O2 to cells and
carrying away CO2
• Respiratory system supplies the blood with O2 and gets rid of CO2
• connection is between alveoli and capillaries
• The body responds to changes in the steady state (e.g. exertion) by
 Heart rate changes to pump more or less oxygen to the cells
 Respiration rate changes to bring more oxygen into the lungs
2. Circulatory and Digestive System: Supply body with Glucose, minerals, vitamins
• Circulatory system moves blood through the body providing glucose to cells
• Digestive system supplies the blood with glucose
• connection is through the villi and capillaries
• The body responds to changes in the steady state by
 Heart rate changes to pump more or less glucose to the cells
 More or less sugar is release into the blood so it can be taken to the cells
3. Integumentary and skeletal systems: Help bone growth
 Sunlight on skin causes chemical reactions that produce vitamin D
 Vitamin D carried to bones (circulatory)
 Vitamin D helps bones absorb calcium (from digestive system)
Organs and Systems working together to maintain Homeostasis
Body Temperature Homeostasis
• Body temperature must be maintained within a few degrees of the normal 37 C
• Heat in the body is generated by cellular respiration
• hypothalamus (endocrine system - in brain) monitors body temperature and
regulates by changing the rate of cellular respiration reactions in skin
(integumentary).
• If the body becomes too hot
 blood vessels near skin dilate (open up), allows more heat loss from the
blood (circulatory)
 perspiration from the skin causes evaporative cooling
• When cold
 shivering uses rapid muscle action to produce heat
 blood vessels contract, less surface to lose heat
Glucose Level in Blood
•
When glucose levels are too high in the blood, a hormone called
the
pancreas
insulin is secreted by
(endocrine). Insulin stimulates the absorption of glucose by cells
•
causes liver’s conversion of glucose into glycogen (stored form of glucose)
•
If glucose levels are too low, hormone called glucagon is produced, which in turn causes
the liver to convert glycogen back to glucose.
Lactates in Muscles (tells you to stop exertion)
• When working hard, one of the chemical reactions that release energy produces
a chemical called lactate which builds up in the muscle.
• Lactates can cause muscle fatigue and pain, which triggers a signal from your muscles to your
brain to stop the exercise and allow more oxygen to reach the muscles.
• Once the exercise stops, lactates are carried away from muscles to the liver, and pain stops.
pH level ( acidity )
• regulated by lungs which controls amount of CO2 leaving blood (affects pH)
• kidneys get rid of excess acids or bases through urine
Water and mineral minerals: controlled by kidneys
Most of these organs are controlled by hormones secreted from the pituitary
gland, which in
turn is directed by the hypothalamus.
Homework: Read Section 2.3, Do Learning Checkpoint # 1 – 5 p. 83, and # 4, 6, 9, 15 p. 86