Additional Material on Homeostasis and Taxonomy


Introduction to Biomedical Science

Man and Environment

Principles of Taxonomy

Taxonomy is a science of classification of organism. The naming of the organism is based on a system called binominal.

Binominal name

In binominal name, there are 2 parts : Apis mellifera

What does that name mean?

  • The first word, Apis
    • It means that Apis is the genus of the organism
    • The first letter of the word must be capitalized
  • The second word, mellifera
    • It means that mellifera is the species of the organism
    • The first letter of the second word must not be capitalized
  • Remember:
    • In the binominal naming, the name must be italized

So, what is genus and species? the term we are talking about?

Taxonomic Hierarchy

Taxonomy classified organism into categories. Organism that shares similar characteristics are grouped into smaller classification.

The hierarchy of the organism is as following:

Kingdom-Phylum-Class-Order-Family-Genus-Species

We can remember that hierarchy with the following:

Kindly Pay Cash Or Furnish Good Security

This hierarchy means that an organism which have the less same characteristic is grouped in the same “kingdom”, organism which have the same “species” have the most characteristic shared.

The Five Kingdom

From Molecules to Homeostasis

The concept of homeostasis in one-celled organism and multi-celled organism

What is the different between the concept of homeostasis in one-celled organism and multi celled organism?

In one celled organism(for example: amoeba) the organism has direct contact to the external environment. In this context the organism can take material for example Oxygen and nutrition directly from the environment. but, in multi-celled organism for example: human the cell does not have direct contact with the external environment. For example, the muscle cell in the human does not have any direct contact with the external environment. How can they exchange material which they very need?? It is through the presence of watery internal environment called Internal Environment which is a fluid surrounds the cell and with this, the cells makes life-sustaining exchanges.

Body cells are in contact with a privately maintained internal environment

There are 2 fluids contained near the cells:

  • Intracellular fluid : Fluid that is contained within the cells
  • Extracellular fluid : fluid that is contained within the body and outside the cells
    • Interstitial fluid        :    Fluid that surrounds the cell
    • Plasma            :    Fluid portion of the blood

How does cell make this life-sustaining exchanges?

The cells are surrounded by extracellular fluid which consisted of interstitial fluid and blood plasma. This 2 substances have very important function in maintaining the internal environment of the cells.

For example, when we breaths, the O2 from external environment is carried out by blood of our body into the capillary. In the capillary there will be exchange between the interstitial fluid with the plasma. The O2 will be transferred into the interstitial fluid where the body picks and use that O2. The body than release waste products such as CO2. The waste products than enter plasma then transported to organ that eliminate that waste products. For example, CO2 is eliminated in the lung.

The different between the concept of Homeostasis in human and amoeba, in human each body cell must maintain the composition of the internal environment so that the fluid can be continuously remain suitable to support the existence of all the body cells. Amoeba need not worry for such thing and does nothing to regulate it’s surrounding

Principles of Homeostasis

Body system maintain homeostasis, a dynamic steady state in the internal environment

Homeostasis is : Maintenance of a relatively stable internal environment

The cell can only survive only if Extracellular Fluid is compatible with the cell’s survival, so the chemical composition and physical state of the internal environment must be maintained. For example, if the cells takes up O2 from their environment, the O2 must be replenished quickly and also if the cells produced waste, the waste must also be eliminated quickly before they reach toxicity level.

Homeostasis is essential for the survival of each cell, and each cell, through its specialized activities, contributes as part of a body system to the maintenance of the internal environment shared by all cells

Homeostasis is dynamic and steady state, in this context means that change that are occurring to the body are minimized through physiological response. Dynamic means that each homeostatic regulated factor are marked with continous change. Steady means that these changes do not deviate much from the constant or steady level.

Some homeostasis mechanism is immediate and other are long term reaction. For example, immediate one is when we are exposed to a hot environment, the internal environment temperature increase, our body reacts to this increase of the temperature by sweating in order to reduce the body temperature to normal stage. In long term reaction, for example, if someone exercise athletic often, the capacity of the lung will increase significantly in order to meet the demand of the athletic challenges.

Factors Homeostatically regulated

Many factors of the internal environment must be homeostatically maintained including:

  1. Concentration of nutrient
    1. Why ? Because cell need nutrient for energy production which is used for supporting life sustaining and specialized cell activities
  2. Concentration of O2 and CO2
    1. Why ? O2 are needed to produce energy-yielding chemical reaction, CO2 are a waste product that must be removed
  3. Concentration of waste product
    1. Why? Some chemical reaction produce end product that have a toxic effect on the body cel
  4. pH
    1. Why? Changes in pH of the external cell fluid adversely affect nerve cell function and wreak havoc with the enzyme activity of the cell
  5. Concentration of water, salt and other electrolytes
    1. Why ? the cells perform best when the water that enters the cell is appropriate, the relative concentration of salt (NaCl) and water in the ECF influence how water enters or leave the cells.
    2. Why electrolytes ? Some electrolytes perform variety of vital function, for example the rhythmic beating of the heart depends on a relatively constant concentration of potassium (K+) in the ECF
  6. Volume and preassure
    1. Why ? Maintained at an adequate pressure and volume in order that bodywide distribution of this important link between external environment and the cells
  7. Temperature
    1. Why? One of the things determined the chemical reaction velocity is temperature, if the temperature is too low then body function will slow down, if the temperature is too high then the enzyme will be damaged

Homeostatic control system

Connected network of body components that operates to maintain a given factor in the internal environment constant around an optimal level. To maintain homeostasis, control system must be able to:

  1. Detect change from the normal value from the environment of the factor that must be held in the narrow limit
  2. Integrate this information with other information
  3. Make appropriate adjustment in the activity of the body part responsibly for restoring the value to the normal

There are 2 types of homeostatic control system: intrinsic control system and extrinsic control system.

Intrinsic control system means that the control system is built inside the organ. For example, an exercising skeletal muscle rapidly uses up O2 to generate energy to support its contractile activity, the O2 concentration within the muscle fails. This local chemical change acts directly on the smooth muscle in the walls of the blood vessels that supply the exercising muscle, causing the smooth muscle to relax so that the vessel dilate or open widely. Increased blood flows through the dilated vessels into the exercising muscle, bringing more O2, this local mechanism helps maintain an optimal level of O2 in the fluid immediately around the exercising muscle’s cell

Extrinsic or systemic control, accomplished by nervous and endocrine systems. This regulatory systems coordinated regulation of several organs toward a common goal in contrast with intrinsic control which only serve the organ in which they occur. Coordinated, overall regulatory mechanism are crucial for maintaining the dynamic steady state in the internal environment as a whole. For example to restore blood pressure to the proper level when it falls too low, the nervous sytem acts simultaneously on the heart and blood vessels throughout the body to increase the blood pressure to normal.

To stabilize the physiological factor being regulated, there are 2 mechanism to response to change the first one is feedback which means responses made after a change have been made and feedforward is the responses made in anticipation of a change.

Application of Homeostasis principle in Clinical Situation

Stomach flu

Jennifer R. has the”stomach flu” that is going around campus and has been vomiting profusely for the past 24 hours. Not only has she been unable to keep down fluids or food but she has also lost the acidic digestive juices secreted by the stomach that are normally reabrobed back into the blood farther down the digestive tract. In what ways might this condition threaten to disrupt homeostasis in Jennifer’s internal environment? That is, what homeostatically maintained factors are moved away from normal by her profuse vomiting? What body systems respond to resist that change?

Aldo’s Answer:

In this case, Jennifer R. was identified to have the disease “stomach flu” which has several symptoms including vomiting profusely for the last 24 hours. This vomiting decrease the amount of fluids, food and acidic digestive juice in the stomach that should have been reabsorbed back into the blood farther down the digestive tract.

This condition might threaten the internal environment by changing the pH of the digestive system. As pH is important as a condition for the food which it can be absorbed by the intestine this change is very dangerous to the body.

To counter this challenge, the body will try to find a way to decrease the pH of the digestive tract.

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