All of your body systems are dependent on each other. Any task that you complete as a human requires several body systems, including sleeping.
1. Your nervous system is involved with all aspects of human function. Circulation, digestion, endocrine and excretory systems are controlled by the autonomic nervous system. The autonomic nervous function is controlled by your body with out conscious thought. Imagine having to regulate your heart rate, rate of digestion, liver, and hormones with your mind. The brain and spinal cord work together to carry out these tasks.
2&3. To think about this in a more advanced fashion suppose you were to touch a hot stove. First skin (integumentary system) is filled with sensory neurons (nervous system) that transmit an impulse from your skin to your central nervous system (brain and spinal cord) signalling pain, the brain then sends the message back to the motor neurons which control the muscles (musculoskeletal system) which are attached to the bones. The motor neurons cause the muscles to contract and move away from the heat source. In response to the burn the blood vessels dilate (circulatory) in order to bring more fluid and materials to initiate the healing process.
Although your body is separated into many different systems, each individual system works with each other to maintain homeostasis. Homeostasis is the process of maintaining a constant internal environment even when there are changes in the external environment.
Normal body temperature is 98.6 degrees. Your body temperature is constant whether or not the outside temperature is 20, 70 or 110 degrees. When it is 20 degrees (cold) your body will shiver and you get goosebumps. Both of these actions help produce heat which will keep your internal temperature at 98.6 degrees. When it is 110 (hot) your body starts to sweat. Sweat evaporates from your skin (which is a cooling process) which will keep your temperature at 98.6 degrees.
In the example above, your nervous system notices that your body is hot/cold and tells your muscles (muscular system) to contract. Your circulatory system is also working with your immune system to bring fluids up to your skin (to sweat) and to circulate your blood to help keep you warm when it is cold.
Breathing is another example of your body systems working together. When you breathe, you think of the respiratory system. However, think about what the respiratory system does. It delivers oxygen (nutrients) and removes carbon dioxide (waste). However, the respiratory system only exchanges these gases through the lungs. These gases need to travel throughout the entire body. The circulatory system allows the gases (and blood) to travel everywhere. The skeletal and muscular systems are also involved because they help push the blood from one end of the body to the other.
A third example is when a pathogen enters the body. Your immune system is responsible for keeping invaders out. When you breath in a pathogen, it can sometimes cause you to cough. Your immune system recognizes the invader and communicates to your body that it is bad. Then your skeletal and muscular system is responsible for creating the contractions to create the cough.
The systems of the body are all linked together in very specific ways. Here are some examples:
- Say for example you have just eaten a very large meal. Because the digestive system is working very hard to digest the food it needs more blood, so the circulatory system jumps in. The blood vessels throughout the digestive system need to widen in order to pump more blood that the circulatory system sends. The nervous system is involved as well. The nervous system tells the body that it does not need any more food and less hunger is perceived
- Another example is the skeletal system and its interaction with the nervous system. For example, the skull protects the brain from injury. The brain also regulates the position of the bones by using the muscular system
- Neural processing (nervous system) is affected by hormones released by the endocrine system
The human body as a system interacts wit so many different environmental, social, biological and physical systems. It is almost impossible to compile a comprehensive list.
As part a social animal humans interact with other humans which are organized into so many different groups such friendship group, family, neighborhood, city, state nation, a market, employment system, educational system and so on. In addition, the individual is also am a member of transient social system like a person participating in a sports competition.
Then individuals also interact with other biological systems. A pet kept by a person, domestic animals to provide food milk, and farming are some very common example of such systems.
People also interact with various aspect of the environment. For example, the body is able to maintain a standard body temperature by responding appropriately. In addition, acts like wearing woolen clothes when it is cold also involves interaction with the environment.
Then we also interact with the various equipment we use. It is very common to talk about man and machine inter-phase in relation to computers and design of equipments like car which require skillful handling by people. However, things like the house we live in, as well as the physical infrastructure of the city we live in including things like traffic signal systems are all systems with which we interact.
The digestive system, the stomach takes in nutrients such as glucose out of the food we have eaten. This glucose is absorbed into our blood stream in the small intestine. These levels are controlled by the pancreas
The excretory system, The kidneys filter the blood and takes out wastes and things that we have in our blood, such as water and salt.
The endocrine system, nerves tell the brain when the body has too much or little of something. So when the there is too much or little of glucose, hormones will either increase or decrease the glucose. ( pancreas )