Homeostasis: Introduction to Homeostasis and Internal Environment

len Alfred Ajibola - Thu, 21st March, 2019 @ 1:55 PM

Topics in Biology

Tropical savanna explained with its characteristics Ecological pyramid explained with its importance and limitations Hindbrain: Medulla Oblongata and its features Food web explained with examples Biology Scheme of Work, SS1, First Term Biology Scheme of Work, SS1, 2nd Term Biology Scheme of Work, SS1, 3rd Term Male accessory sex organs: Seminal vesicles and bulbourethral glands Scrotum and its contents: Testicles Brain: Introduction to the human brain Forebrain: Lobes of the cerebrum and their functions Cerebellum: Parts and functions of the cerebellum Midbrain: Division and functions of the midbrain Negative feedback mechanism in homeostasis Arterial disorders explained with their causes Types of desert and their characteristics Characteristics of tropical rainforest Swamp forest: What are swamp forests? Characteristics of swamp forests Savanna biome: Concept of the savanna

Academic Questions in Biology

Please click here to see all Questions and Answers

In a food chain, the primary consumers are classified under trophic level  _____.

  • A. Zero

  • B. One

  • C. Two

  • D. Three

  • E. Four

  • F. Five

Cold blooded animals are referred to as _____.

  • A. Homeotherms

  • B. Endotherms

  • C. Poilokitherms

  • D. Ectotherms

  • E. Thermotherms

  • F. None of the above

All reptiles are vertebrates.

  • A. True

  • B. False

_____ cells are responsible for the formation of osteoblasts.

  • A. Osteocytes
  • B. Chondrocytes
  • C. Chondroblasts
  • D. Osteoclasts
  • E. Osteoprogenitor cells
  • F. Osteoblastic

_____ is a bone that constitute the axial skeleton.

  • A. Clavicle
  • B. Scapula
  • C. Patella
  • D. Radius
  • E. Sternum
  • F. Femur

Which of the following is false concerning cartilages and bones?

  • A. Cartilage does not have a direct blood supply while bones have direct blood supply
  • B. The process of ossification replaces a cartilage to bone
  • C. The protein that makes up cartilage is called chondrin while that that makes up bone is called ossein
  • D. Cartilage grows from both ends while bones grow from one of its epiphysis
  • E. They both have living cells within them
  • F. Haversian system is absent in cartilage but present in bones

A diagram showing the movement of energy through a food chain is called a _____.

  • A. Food Chain
  • B. Food Web
  • C. Food Energy
  • D. Food Link
  • E. Food Flow
  • F. Food Pyramid

Which of the following is NOT a part of the wrist bones (or carpal bones)?

  • A. Cuboid
  • B. Scaphoid
  • C. Hamate
  • D. Triquetral
  • E. Pisiform
  • F. Trapezium

What is Homeostasis?

Have you ever wondered why on a sunny day you drink a lot of water and tend to produce lesser urine? On the contrary, think about how likely you will produce more urine on a cold day and drink less water too. This is so because some processes are constantly ongoing inside your body and they are necessary for your survival.

Please read on the basic characteristics of life here.

Now, let's imagine that someone has a fever. His or her temperature will be abnormally high as a result of the fever. The person may sweat abnormally or even urinate abnormally. On your part, you will suspect that some processes are not working right inside the person.

Please read on vectors of diseases here.

Medically speaking, for a person to be physiologically healthy, the conditions and processes within his or her body must be carefully and properly controlled. This internal control is what homeostasis entails.

Homeostasis can be defined as the regulation and maintenance of a constant (or nearly constant) internal environment.

Understanding Internal Environment

Recall that your environment comprises of everything that surrounds you; for instance air, water, your phone, shoes and anything around you right now. This concept of environment is your external environment.

In physiology, we have another concept of environment called the internal environment; and it is this environment that the bodily homeostatic organs constantly regulate to it's best optimum conditions.

Now let's think of it this way: If for instance, the external environment is very dirty and unhealthy (from lack of environmental sanitation, cleanliness and healthy living), children will suffer from illnesses and diseases like cholera, typhoid and dysentery. This is true because the respective causative organisms (of such diseases) will find their way into the child's body systems and invariably, the environment inside their body (internal environment).

Please read on microorganisms causing food, water and air borne diseases here.

As living organisms, human beings are composed of trillions of cells. These cells aren't just stacked upon one another (like a pack of cards); instead, they are separated by a fluid filled space.

ICF and ECF - Len Academy
The above diagram illustrates the various fluids seen within and around the cell

The fluid filled space present outside all the cells of any multi-cellular organism is termed the Extracellular fluid (or ECF).

Note: Blood plasma present inside the blood vessels (that is, arteries, veins and capillaries) is a component of the ECF because it is present outside the body cells. The same is true for the interstitial fluid which is also another component of the ECF.

Please read on various disorders of the artery here.

The ECF accounts for about 35% (one-third) of the Total Body Water (TBW) in healthy adults.

You can read on immunization here.

Similarly, inside each of the cells is another kind of fluid called the Intracellular Fluid or ICF.

The ICF comprises of the cytoplasm of each cell's organelle which contains water, proteins and electrolytes.

About 65% (two-third) of the TBW is ICF. For this reason, the volume of ICF is greater than that of ECF with regards to the Total Body Water.

The TBW accounts for about 65% of the body weight of an average man although this value will vary with age. For instance, children will have a higher percentage of TBW value while that of the aged will be lower.

The above explanations on TBW affirms that humans are composed more of water (liquid) than solids.

You can read on some amazing facts in biology here.

The two compartments accounting for the TBW are the ICF and ECF respectively; and both make up the internal environment. It is these internal environments that are regulated via homeostasis.

You can read on the red blood cells and hemoglobin here.

Understand that the concentration of substances within the internal environment must be at a very narrow range, else the organism becomes sick and may eventually die. Most of the medical drugs function by restoring the internal environment to it's normal composition and pH.

You can read on types and functions of drugs here.


Systems Coordinating Homeostasis

In humans, homeostasis is achieved via two systems; these are:

  1. Nervous System: It comprises of the brain and spinal cord.
    Please read an introduction to the human brain Man here.

  2. Endocrine System: It has every thing to do with hormones. The pituitary gland is serves as the master endocrine gland. This implies that it regulates the homeostatic functions of other endocrine glands (or glands that produces hormones).

For now, think of endocrine glands as the producers of hormones.

These two systems (nervous and endocrine systems) coordinates all homeostatic processes by regulating the respective homeostatic organs in the body.

Homeostatic Organs

Below are some homeostatic organs alongside a summary of their homeostatic functions:

  • Hypothalamus: It regulates the body temperature, sleep, appetite and thirst.

  • Kidneys: It regulates water, salts and electrolytes through the formation and elimination of urine.

  • Skin: Regulates water, salts and electrolytes via sweat formation.

  • Liver: It regulates the storage of glucose, storage of blood, production of bile, breakdown of proteins, cleansing of the body and much more.

  • Pancreas: It regulates blood glucose and glycogen.

  • Lungs: Regulates oxygen and carbon(IV)oxide intake through breathing.

The diagram below shows the various homeostatic organs and their locations.

Endocrine Glands - Len Academy

The nervous and endocrine systems regulate the above homeostatic organs through a mechanism called the negative feedback mechanism.

Please read more on negative feedback mechanism in homeostasis here.

Need more answers to this topic? Please enter your search below:

Kindly share this article via the links below:


Please contact Alfred via the above whatsapp link for a comprehensive online academic coaching in Biology, Chemistry, Basic Science and ICT

Click here to read the amazing features of the Len Academy Smart School Software. However, contact Alfred through the above whatsapp link if you require a standard website for your business or school at an affordable price

Please click here to follow Len Academy on Google News.

Please like and follow our official facebook page here for great educational write-ups.

You can follow Len Academy on twitter here.Thank you.

Please Register here or Login here to contribute to this topic by commenting in the box below.

Amazing facts in Biology

Cockroach is the fastest land animal on six legs

Laughing ape - Len Academy

Like humans, all apes laugh when tickled

Ostrich eye and brain - Len Academy

An ostrich's eye is bigger than its brain

The upper front teeth are missing in giraffes. Meanwhile, like an adult human, a fully grown giraffe has 32 teeth but most are positioned at the back of their mouth

Slugs have four noses

Most insects hatch from egg but aphids give birth to their young alive

Bats aren't birds, rather, they are mammals. Infact, they are the second largest order of mammals after rodents. We have over 1,400 species of bat. Globally, they make up about 20% of all classified mammal species

Panda eating bamboo - Len Academy

99% of a panda's diet is bamboo. They may eat fish or other small animals occasionally

When attacked by insects, lima beans plant will often command parasitic wasps to their defence.

When the leaves of the lima bean's leaves are eaten by insects, the plant gives off a substance that signals parasitic wasps to swam in, destroying its enemies (the leaf-eating insects) in the process

Frogs drink water through their skin


For a thing to be considered living, it must possess all the basic characteristics of life. These include:

  1. Movement

  2. Respiration

  3. Nutrition

  4. Irritability or Sensitivity

  5. Growth

  6. Excretion

  7. Reproduction

  8. Death

  9. Adaptation

  10. Competition

Please read the explanations on all the basic characteristics of life here

During strenuous exercises like sprinting or running, your body may actually work in the shortage of oxygen. During this time, your body owes oxygen (called oxygen debt) and it must be replenished or repayed after the exercise is stopped. This is why you breathe excess of oxygen after you stopped the exercise.

This is the concept of anaerobic respiration

Food Chain - Len Academy

A food chain is a diagram that shows the relationship between plants and animals within a habitat on the basis of how they rely on each other for food.

Note: Habitat is a place where an organism live. It is of three types:

  • Terrestrial (Land)
  • Aquatic (Water)
  • Arboreal (Treetops)

You can read on food chain here

The term Biology originated from two Greek words. They are:

  • Bios: means life.

  • Logos: means knowledge or to study.

Biology can therefore be defined as the study of life

Anything that has life is generally considered as a living organism (or organism). All living organisms must be able to carry the following activities:

  1. Movement

  2. Respiration

  3. Nutrition

  4. Irritability or Sensitivity

  5. Growth

  6. Excretion

  7. Reproduction

  8. Death

  9. Adaptation

  10. Competition

The above listed points are often regarded as the basic characteristics of life. You can memorize them using the acronym -> MR. NIGER DAC.

You can read on the introduction to biology and the basic characteristics of life here

The gas used in the manufacture of food by plants is Carbon dioxide or Carbon(IV)oxide or CO2

Plants manufacture food through a process called photosynthesis.

Please read on photosynthesis here

It is noteworthy to state that plants are the only orgnisms that take away CO2 from the atmosphere