Functional cell Ajith Sominanda Department of Anatomy Faculty of Medicine University 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 FunctionStructural adaptation/s of the cell These cells are called parenchymal cells in the tissue or the organ

Functions of the cell General functions 1.Multiplication and growth 2.Metabolism 3.Cellular homeostasis 4.Respond to the environmental stimuli Specific functions 1.epithelial cell 2.Connective tissue cell 3.Muscle cell 4.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’’

Metabolism Endoplasmic 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

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 ReceiverProcessor 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 Monosacharides Amino acids Fatty acids Nucleic acids Minerals Vitamins Drugs Poisons & chemicals Portal vein Hepatic artery Systemic blood Oxgenated blood Hepatic vein Gallbladder & gut Systemic blood Controlled release of materials Bile duct 80% 20%

Basic cellular arrangement Portal veinule Central vein Bile duct sinusoid Fenestrated, discontinuou s endothelium Space of Disse Hepatic arteriole Portal space

Liver is a factory Raw materials Electricity Product output, Storage

Conclusion Structural adaptations of the cell are for the function

Thank you