Functional cell

Ajith SominandaDepartment of AnatomyFaculty of MedicineUniversity of Peradeniya

Multi cellular organism and the cell

CELL is the basic structural functional unit of life

However, in multicellular organism, cells with specific function aggregate to form a tissue.

Therefore the functional unit of multi cellular organism is TISSUE

Aim of this lecture

Function Structural adaptation/s of the cell

These cells are called parenchymal cells in the tissue or the organ

Functions of the cell

General functions1.Multiplication and growth2.Metabolism3.Cellular homeostasis4.Respond to the environmental stimuli

Specific functions1.epithelial cell2.Connective tissue cell3.Muscle cell4.Nerve cell

Multiplication and growth of the cell

• Depend on the stimulation (signal), cell starts to multiply and grow– These stimulations can be normal

physiological or pathological

Cell cycle

Normal Multiplication and growth of the cell

Pathological Multiplication and growth of the cell

‘Neoplasms’ ‘Tumors’ ‘’Cancers’’

MetabolismEndoplasmic reticulum (ER), Golgi apparatus & vescicles - The factory of life

the scavengers or recycling system Endo-lysosomal system

Cell membrane and cellular homeostasis

Specific cellular functions

• Cell structures change from its basic form (differentiate) to a specialized form to perform specific functions– Covering and lining– Secretion– Absorption– Support– Contractility and movement– Communication and response to stimuli

Covering and lining by epithelial cell

• Shape and form of the cell contributes to the function

• Cellular adhesions and basement membrane is critical for the integrity of the epithelium

Covering and lining by epithelial cell

• Presence of several cell layers to enhance the covering or lining function

Covering and lining by epithelial cell

• (Protein) synthetic machinery is fully functional • Nucleus is active• ER is active

Secretory cells

Glands (exocrine)

Glands (endocrine)

Cells with absorptive function

• Intestinal epithelial cells are adapted to increase the surface area

Cells adapted to supportive function

• Fibroblasts secretes fibers and maintain the cellular matrix

Contractility and movements

• Cilia are cell surface specializations that moves the substances on the cell surface

Contractility and movements

Contractility and movements

•Muscle fibers are arranged in longitudinal orientation•Fibers are arranged in bundles•Contractile elements are central and nuclei are peripheral

Communication and response

• Environment information transfer Information processing response

Receiver Processor

Effector

• Neuron has short and long processes

• Long processes are often covered with myelin to insulate the fiber to prevent short circuiting (effective nerve impulse transmission)

• Active nucleus and protein synthetic machinery for synthesis of neurotransmitters

Communication and response

Hepatocytes (liver), the interface between

GUT & the systemic circulation

Gut

MonosacharidesAmino acidsFatty acidsNucleic acidsMineralsVitaminsDrugsPoisons & chemicals

Portal vein

Hep

atic

ar

tery

Systemic bloodOxgenated blood

Hepatic

vein

Gallbladder & gut Systemic blood

Controlled release of materials

Bile

d

uct

80%20%

Basic cellular arrangement

Portal veinule

Central vein

Bile duct

sinusoid

Fenestrated, discontinuous endothelium

Space of Disse

Hepatic arteriole

Portal space

Liver is a factory

Raw materialsElectricity

Product output, Storage

Conclusion

Structural adaptations of the cell are for the function

Thank you