cell signalling Flashcards
what is Homeostasis?
what is it regulated by?
physiological processes that are regulated between ranges
regulated by + and - feedback loops
how do cells communicate with other cells?
via cell signalling
most cells signals are what?
chemical
what is the characteristics of direct cell signalling?
signaling cell and target cell are connected by gap junctions
signal is passed directly from one cell to another
What are the characteristics of indirect cell signalling? (5)
Signaling cell releases chemical messenger
Chemical messenger carried in extracellular fluid
Chemical messenger binds to a receptor on target
cell
Activation of signal transduction pathway or ion
channel
Response in target cell
Gap junctions:
what are the specialized protein complexes called and what do they do?
called connexins
create an aqueous pore between adjacent cells
Gap junctions:
what do gap junctions transport?
what does this do?
Movement of ions between cells
Changes in membrane potential
Chemical messengers can travel
through the gap junction
Example: cAMP
Opening and closing of gap junction
can be regulate
Indirect signalling:
Short distance
What is Paracrine
what is Autocrine
Paracrine:
chemical messenger diffuses to nearby cell
Autocrine:
chemical message diffuses back to signalling cell
Indirect signalling:
Short distance uses what?
paracrine and autocrine
indirect signalling doing long distances uses what?
Endocrine system and the Nervous system
indirect signalling:
how does the endocrine system work?
uses chemical messengers (hormones) that are transported by circulatory system
Indirect signalling:
how does the Nervous system work?
it uses electrical signals that travel along neurons and a chemical messanger (NT) is released
What are the three steps in indirect signalling?
Three steps
Release of chemical messenger from signaling cell
(gland)
Transport of messenger through extracellular
environment to target cell
Communication of signal to target cell
what are the classes of chemical messengers (7)
Classes of chemical messengers
Peptides (insulin, glucagon, atrial natriuretic peptide, vasopressin)
Steroids (testosterone, estrogen, aldosterone, cortisol)
Amines (norepinephrine, epinephrine, triiodothyronine, thyroxine)
Lipids (eicosanoids: prostaglandin, leukotrienes)
Purines (AMP, ATP, GMP)
Gases (nitric oxide)
Amino Acids (glutamate, aspartate, glycine, GABA)
the structure of the chemical messenger affects what?
what structural change has the largest affect?
affects signalling mechanism
hydrophilic and hydrophobic
Peptide Protein Hormones:
what are they composed of?
composed on AA
Peptide Protein Hormones:
Where are they synthesized?
On the rough ER often as larger preprohormones
Peptide Protein Hormones:
where are they stored?
Stored in vesicles as prohormones
Peptide Protein Hormones:
how are they secreted?
secreted by exocytosis
Peptide Protein Hormones:
what is their chemical structure?
Hydrophilic
soluble in aqueous solutions
travel to target cell and dissolve in extracellular fluid
Peptide Protein Hormones:
where to they bind?
bind to transmembrane receptors
signal transduction
have rapid effects on target cells
Steroid Hormones:
what are they derived from?
Cholesterol
Steroid Hormones:
what are they synthesized by?
The smooth ER OR mitochondria
Steroid Hormones:
What are the three classes?
Mineralocorticoids (aldosterone)
- Electrolyte balance
Glucocorticoides (cortisol, cortisone, corticosterone)
- Stress hormones
Reproductive hormones (estrogen, progesterone, testosterone) -Regulate sex-specific characteristics
Molting hormone (ecdysone) - Insects shed hard exoskeleton during molting
What are some characteristics of steroid hormones? (8)
Hydrophobic
Can diffuse through plasma membrane
Cannot be stored in the cell
Must be synthesized on demand
Transported to target cell by carrier proteins
Example: albumin
Bind to intracellular or transmembrane receptors
Slow effects on target cell (gene transcription)
Stress hormone cortisol has rapid non-genomic effects
What are amine hormones?
Chemicals that possess amine group
- some true hormones, some neurotransmitters, some both
- most hydrophilic (thyroid hormones are hydrophobic)
What is paracrine signalling?
form of cell to cell communication in which a cell produces a signal to induce change in nearby cells, altering the behaviour of cells
