Different levels of structural organization in Human anatomy and physiology for bachelor in pharmacy first semester. according to PCI syllabus.

1. By – Devendra Kumar Rawat
Assistant Professor
M.Pharm (Pharmacology)
B.M.S. College Of Pharmacy, Nasratpur, Tiloi, Distt.
Amethi
(Chapter – 1)
(Lecture – 2)

2. Levels of Structural Organization
The human body contains multiple levels of structural
organization :
1. Chemical level
2. Cellular level
3. Tissue level
4. Organ level
5. Organ system level
6. Organism level

5. 1. Chemical level
 The simplest level of structural organization of living
organisms is the chemical level.
 Atoms of various elements combine to form larger, more
complex structures termed Molecules.
 Organic molecules aggregate to form cellular organelles.
 Certain atoms such as Carbon, hydrogen, oxygen,
nitrogen, phosphorus, calcium, and sulfur, are essential for
maintaining life.
 Two familiar molecules found in our body are DNA and
Glucose.

6. 2. Cellular level
 The cellular level is made up of the smallest unit of living
matter, i.e. cell.
 Molecules combine to form cells, the basic structural and
functional unit of an organism.
 Cells are building blocks of the human body.

7. 3. Tissue level
 Cells of similar structure and function congregate to form
tissues.
 There are 4 principle types of tissues in the human
organism :
i. Epithelial tissue
ii. Connective tissue
iii. Muscular tissue
iv. Nervous tissue

8. 4. Organ level
 Two or more types of tissues are combine within the same
structure to form an organ.
 Organs have specific functions and usually have
recognizable shapes.
 Examples of organs are the stomach, skin, bones, heart,
liver, lungs, and brain.
 Complex functions begin to emerge at this level.
 Most organs contain all 4 of the principle types of tissues.

9. 5. Organ system level
 Individual organs that function cooperatively to
accomplish a common purpose are grouped together into
organ system.
 An example of the system level is the Digestive system,
which breaks down and absorbs food.
 Digestive system includes many organs such as mouth,
salivary glands, pharynx, oesophagus, stomach, intestine,
liver, gallbladder, and pancreas.
 Other organ system of the body are integumantary system,
skeletal system, nervous system, muscular system,
endocrine system, respiratory system, lymphatic system,
urinary system and reproductive system.

11. 6. Organism level
 An organism is any living individual, like microorganism
or human body. All the parts of the human body
functioning together constitute the whole organism.
 The organism level is the highest level of the organization.
It is the sum total of all structural levels working together.
 In short, it is the human being or organism as a whole.
 An organism is a living being that has a cellular structure
and that can independently perform all physiologic
functions necessary for life.
 In multi-cellular organisms, including humans, all cells,
tissues, organs, and organ systems of the body work
together to maintain the life and health of the organism.