1. INTERCELLULAR COMMUNICATION
بسم الله الرحمن الرحيم
INTERCELLULAR COMMUNICATION
Dr.Mohammed Sharique Ahmed Quadri
Assistant prof. Physiology
Al Maarefa College

2. INTERCELLULAR COMMUNICATION
Direct intercellular communication
Gap junction
Transient direct linkup of surface makers
Indirect intercellular communication
Through extracellular chemical messengers or signal molecules
Paracrine
Neurotransmitters
Hormones
Neurohormones

3. Direct intercellular communicationF

4. Direct intercellular communication..
(complementary surface markers)

5. Indirect intercellular communication
extracellular chemical messengers or signal molecules
Paracrine
Neurotransmitters
Hormones
Neurohormones
Source
Distance
Means by which get to target cells
differs

6. Paracrines Local chemical messengers
Exert effect only on neighboring cells in immediate environment of secretion site .

7. Neurotransmitters Short-range chemical messengers
Diffuse across narrow space to act locally on adjoining target cell (another neuron, a muscle, or a gland)

8. Hormones Long-range messengers
Secreted into blood by endocrine glands in response to appropriate signal
Exert effect on target cells some distance away from release site

9. Neurohormones Hormones released into blood by neurosecretory neurons
Distributed through blood to distant target cells

10. Hormones
Two distinct groups of hormones based on their solubility properties
Hydrophilic hormones
Highly water soluble
Low lipid solubility
Lipophilic hormones
High lipid solubility
Poorly soluble in water

11. Extracellular chemical messengers bring about cell responses primarily by signal transduction
Process by which incoming signals are conveyed to target cell’s interior

12. Binding of extracellular messenger (first messenger) to matching receptor brings about desired intracellular response by either
Opening or closing channels
By activating receptor enzymes
Activating second-messenger systems
Activated by first messenger
Relays message to intracellular proteins that carry out dictated response

13. Opening of receptor-channel when an extracellular messenger binds

15. Tyrosine kinase pathway.

16. Activation of second messenger pathway via G-Protein couples receptors

19. Amplification of the initial signal by a second-messenger pathway

21. RECEPTORS AND THEIR REGULATION
The receptors on target tissues are not static. They are dynamic and mobile and their number also changes during the process of regulation.
Up Regulation of Receptors –
The number of receptors is increased on the target tissue. This happens when there is less concentration of ligand in the ECF
Down Regulation of Receptors
The number of receptors is decreased on the target tissue. This happens when ligand concentration is more in the ECF

23. References Human physiology by Lauralee Sherwood, seventh edition
Text book physiology by Guyton &Hall,11th edition
Text book of physiology by Linda .s contanzo,third edition