Topic 73 - Communication among cells, Intracellular receptor signaling

Question 1

Words to include in communication among cells

Answer 1

• Hypothalamus
• Signaling regulation
• Central integrating role
• Intracellular communication
  
  • Direct communication
    
    • Gap junctions
    • Ionic transportation
    • Cytoplasm
  • Contact communication
    
    • Cell membrane
    • Immune system
  • Communication by secretion
    
    • Immune system
    • Nervous system
    • Endocrine
    • Paracrine
      
      • Local chemical mediators
    • Autocrine
    • Neurotransmitted
      
      • Synaptic transmission
      • Neurotransmitters
      • CNS
        
        • Myoneural junction
      • ANS
        
        • Perpiheral junction
  • Cytoskeletal communication

Question 2

Words to include in intracellular receptor signaling

Answer 2

• Cytoplasm
• Lipophilic hormones
• Cell membrane
• Cytoplasmic receptor
• Nucleus
• Receptor-ligand complex
• DNA segment
• HRE’s
• Protein (enzyme)
• Aldosterone
• N⁺/Na⁺ ATPase pump
• K⁺ secreting channel
• Na⁺ reabsorbing channel
• Protein synthesis
• Nuclear receptor
  
  • Variable domain
    
    • NH₂
  • DNA-binding domain
  • Ligand binding domain
    
    • -COOH (carboxyl terminal

Aldosterone

• Regulator
• N-terminal
• Amino acid segments
• Hormone receptor complex (DBD)
• Promotor region
• Receptor DNA complex

Question 3

Communication among cells

Which organ is most important in cell signaling regulation?

Answer 3

Hypothalamus

Due to central integrating role

Question 4

Communication among cells

Name the different types of IC communication

Answer 4

1. Direct communication
2. Contact communication
3. Communication by secretion
   
   1. Endocrine secretion
   2. Paracrine secretion
   3. Autocrine secretion
   4. Neurotransmitted secretion
4. Cytoskeletal communication

Question 5

Communication among cells

Direct communication

Answer 5

• Transporting substances via gap junctions
• This is ionic transportation between the cytoplasm of one cell to another (requires cells to be close)

Question 6

Intracellular communication

Contact communication

Answer 6

• Information processing by molecules integrated in the cell membrane
• This is a typical method in the immune system (requires cells to be close)

Question 7

Intracellular communication

Communication by secretion

Answer 7

• Secreting molecules between cells that are not so close
• Important for the function of both the immune and the nervous system
• Different types of secretion:
  
  1. Endocrine secretion
     
     • Specialized cells will secrete hormones that will reach the recipient cells through the bloodstream
  2. Paracrine secretion
     
     • Local chemical mediators that will be broken down, immobilized or taken up by cells close to the producer very quickly, therefore this secretion will not use the bloodstream for transport
  3. Autrocrine secretion
     
     • When the cells own signal will affect it, this is a type of paracrine effect
  4. Neurotransmitted secretion
     
     • When a synaptic transmission causes the cells to secrete neurotransmitters, this type of secretion can be found in the CNS (myoneural junction) and in the ANS (peripheral junctions)

Question 8

Intracellular communication

Cytoskeletal communication

Answer 8

Processing mechanical information that will influence the cell by the cytoskeletal system

Question 9

IC receptor signaling

Answer 9

Receptors in the cytoplasm of the cell

1. Lipophilic hormones can pass the cellular membrane and bind to cytoplasmic receptors
2. Then they reach the nucleus and exert the effect
3. The receptor-ligand complex is able to enter the nucleus, and the DNA-binding domain of receptor “finds” DNA segments, called HRE`s
4. Then it activates the structure gene downstream to HRE and a biological response is initiated trough a protein (enzyme)

Question 10

IC receptor signalis

Fine structure of the nuclear receptor

Answer 10

• Variable domain
  
  • NH₂
• DNA-binding domain
• Ligand binding domain
  
  • -COOH (carboxyl terminal)

Question 11

IC receptor signaling

Role of aldosterone

Answer 11

1. Binds to regulator
2. On the receptor the hormone binding site is close to carboxyl terminal
3. When it enters the nucleus, a short segment of receptor complex close to N-terminal finds basis pair segments on DNA, they are called HRE
4. HRE binds to few amino acid segments of the hormone receptor complex called DBD (DNA-binding domain??)
5. The promotor region is activated by the receptor DNA complex
6. Expression

Question 12

Overview of receptor families

Answer 12