Chapter 5(Mechanisms of inter cellular communication) Flashcards
What is a gap junction? What about coupling ?
link adjacent cells and are formed by plasma membrane proteins called connexins. Electrical impulse directly to the other cell. Direct electrical and metabolic coupling
Where are gap junction common?
smooth and cardiac muscle
How do chemical messengers work?
When one cell releases a chemical into the interstitial fluid and another cell called the target cell responds to it.
Explain Paracrines and give an example.
Released by cell, moves to target cell by diffusion
Paracrines- act on neighboring cells. Histamine.
What are autocrines?
Act on the cell that releases it.
What is a neurotransmitter? Two properties of it.
Messenger of nervous system.
Diffuses to very close target cell
Released from neuron by exocytosis
What is the site called where junction occurs between neurotransmitter and cell?
Synapse.
Give an example of neurotransmitter and how it works?
Acetylcholine, causes contraction of skeletal muscle.
What are hormones? Two properties of them.
Chemical messenger of the endocrine system.
Released from endocrine gland into blood
Transported in blood to target
What are the target cells for hormones?
cells in body with receptors specific to the hormone
What are neurohormones?
Released from neuron into blood where it acts in manner similar to hormones
What are cytokines classified as
peptide/ protein
4 characteristics of cytokines
Can be transported in blood
Released by most cell types
Involved in cell development, differentiation, and immune response
Often act on a wide range of targets
What is the most important chemical characteristic?
Whether or not the messenger can dissolve in water or cross the lipid bilayer in the plasma membrane.
Two classifications and why?
Lipophillic. Lipid soluble and can cross plasma membrane- do not dissolve in water.
Hydrophilic. water soluble and do not cross plasma membrane.
Name the chemical classes of messengers. 5.
Amino acids Amines Peptides Steroids Eicosanoids
What do amino acids function as? What are the 4? Lipophillic or hydrophillic?
Neurotransmitters. Glutamate Aspartate Glycine GABA (gamma-amino butyric acid) Hydrophillic.
What are amines derived from? What group do they include?
Amino acids. Catecholamines, derived from tyrosine.
Examples of amines.
Dopamine, norepinephrine, epinephrine
Serotonin derived from? Histamine? Thyroid hormones?
Tryptophan, histadine, tyrosine
Amines except for thyroid hormones are all?
Lipophobic.
What is Most abundant class of chemical messengers Lipophobic?
peptide/ protein. Yes.
Peptide usually refers to what?
Chains smaller than 50 amino acids.
proteins are usually what?
more than 50 amino acids.
Steroid messenger derived from what?
Cholesterol.
All of the steroid messengers function as what?
Hormones
Steroid lipophillic or lipophobic?
Lipophillic.
Lipophillic messengers released how? How is release regulated?
Diffusion. By regulating rate of synthesis
Lipophobic messengers released how
Exocytosis
How many amino acids are essential? How many produced by body? How many of those are neurotransmitters
9,11,3
After amino acid synthesis, neurotransmitters transported into where?
Secretory vesicles.
What is synthesized from glucose ?
Glutamate and aspartate
What is GABA synthesized from
glutamate
All amines derived from Synthesized where?
Amino Acids. In the cytosol.
Which chemicals diffuse through interstitial fluid?
Paracrines, autocrines,most Ctyokines and neurotransmitters
Which chemical are transported in blood?
Hormones, neurohormones and some cytokines
To be transported in dissolved form, messenger must be?
Hydrophillic
How long a hormones persists in the blood depends on?
The half-life of that hormone
