The multicellular organism

Dr. Ajith Sominanda (MBBS, MPhil, PhD)Department of AnatomyFaculty of Medicine-Peradeniya

Objectives for SBM-1/2

b. The multicellular organism

1. understand the levels of organization of the multicellular organism from cells, tissues, organs and systems and their integration in to human being

2. understand the terms “totipotent” and “pluripotent” 3. understand that the functional unit of the

multicellular organism is the tissue 4. state the basic systems of the body and their

functions

Where to find the objectives

http://www.pdn.ac.lkhttp://www.pdn.ac.lk/uop/main/faculty_centers.htmlhttp://www.med.pdn.ac.lkhttp://www.med.pdn.ac.lk/curriculum/coursemap.htmlhttp://www.med.pdn.ac.lk/groups/1/y1s1/foundation.html

http://www.med.pdn.ac.lk/groups/1/y1s1/foundation.html

Living versus Non-living things

@ First School YearsSort the pictures into living and non-living things.

Living Things Non-Living Things

Living versus Non-living things

Features Living Non-living

Consists of physical matter

yes Yes

Consumption of energy

Yes Yes

Changes in quantity Yes Yes

Can multiply Yes ?

Propagate characteristics

Yes no

An attempt to describe a living thing

A something capable of • Growing• Using energy for its activities• Formation of its copies / offspring appears to be a living thing

Scientific term for living thing is ORGANISM

Copies

Living versus Non-living things

Life at molecular level

Inorganic molecules

organic moleculesbiomolecules

Are Prion protein and virus organisms ?

Prion = ‘Protein’ + ‘infectious’Infectious proteins

The scientific definition

An organized thing or a system capable of self 1.Growth2.Synthesis and degradation of materials by utilizing or releasing energy-Metabolism3.Keep a balance of the activities and conditions - Homeostasis4.Response to the environmental stimuli5.Reproduction

What is a cell

• The cell is considered as the basic structural unit of the living things (organism)

Unicellular Versus Multicellular organisms

• OrganismsMulticellular organism

Unicellular organism

Process of Unicellular to multi cellular organization

The long process -The evolution The short process – The Embryogenesis,

growth & Development

Ability (Potential) of a cell to change (differentiate) into different cell types during embryogenesis

1. Totipotent - cells having total (full) potential to differentiate into another cell

2. Pluripotent- cells having some potential to develop into another cells

3. Unipotent cells - cells having no potential to develop into another cell

Germinal cell layers

Organization of cells to form specific functions

group of cells that is aggregated to perform a specific function/s are called TISSUES

Tissue is the functional unit of multi cellular organism

Four basic types of tissues

1. Epithelial Tissue2. Connective tissue3. Muscle Tissue4. Nerve or Nervous tissue

Epithelial tissues

Connective tissue

Muscle tissue

Nervous tissue

Functions of tissues

Type of tissue Function Principle Cell types

1. Epithelial tissue Covering, secretion

Epithelial cells

2. Connective tissue1.Loose (areolar) connective tissue2.Dense connective tissue

Support Fibroblasts

Special connective tissue 1.Adipose tissue2.Cartilage3.Bone4.Hematopoietic tissue

SupportPackingProtectionmetabolism

AdipocytesChondrocytesOsteocytesBlood progenitor cells

3. Muscle tissue Contractility / movement

Muscle fibers

4. Nervous tissue communication

Neurons and glial cells,

Levels of organization of multicellular organism

Level 1 CellLevel 2 TissueLevel 3 OrganLevel 4 SystemLevel 5 Organism; the human

Organs of the human body

Tissues form the organs

Tissues form the organs

What are the tissues that compose this organ

A

B

C

D

Tissues and organs form the systems

List the functions of the systems in our body

• Circulatory system• Respiratory system• Alimentatory (Digestive) system• Nervous system• Endocrine system• Excretory system• Reproductive system• Lymphatic system

Summary

New Terms

1. Cell2. Embryo3. Totipotent ,pluripotent4. Tissue5. Organ6. System7. Epithelium, Epithelia8. Muscle9. Nerve10. Glia11. Bone12. Cartilage13. Fibroblast14. Chondroblast15. Osteoblast16. Osteoclast

17. Evolution18. Circulation19. Respiration20. Digestion21. Excretion22. Reproduction23. Lymph, Lymphatic24. Haematopoietic tissue

References

• Molecular Cell Biology by Harvey Lodish

• Basic Histology by Carlos Junqueira• WWW.

Thank you