Module 10: Cell Signaling Flashcards
(17 cards)
Why do cells communicate with each other?
- To regulate their development and growth into tissues
- Control their growth and division
- Coordinate other activities
How do cells communicate?
3 main ways:
1. Secreting chemical signals to targets at a distance
2. Displaying molecules on their plasma membranes
3. Forming gap junctions to allow for direct communication between cells
Different methods cells use to send signals
Cells can send signals via:
1. Chemical mediators that act locally,
2. Hormones that travel through the bloodstream via the endocrine system,
3. Neurotransmitters at the synapses between 2 neurons
Local chemical mediators→ methods of action
- Paracrine = adjacent/nearby cells
- Autocrine= the cell sends a signal to itself
- Contact-dependent communication = through gapjunctions
Different methods of the release of cell signals
Aka modes of secretion:
1. Merocrine
2. Holocrine
3. Apocrine
Merocrine secretion
The cell secretes the signal by exocytosis, without any damage to the cell itself
Example: sweat glands, mammary glands
Holocrine secretion
The whole cell is expelled during the process of secretion and the ruptured cell becomes part of the secretory product
Example: sebaceous glands
Apocrine secretion
Only the apical part of the cell (the cell’s apex) is shed in the secretory product
Example: sweat glands in the armpit
Cell signaling types
3 main types = autocrine, paracrine, and endocrine
All 3 types involve the secretion of some kind of chemical signal from a cell that binds to a receptor and causes a downstream effect.
Autocrine signaling
A cell releases a signal that acts on itself, binding to receptors on the plasma membrane, and causing an effect within the same cell
Example: the release of the cytokine IL-2 from T cells
The release of cytokine IL-2 from T cells
An example of autocrine signaling
This cytokine promotes the proliferation and differentiation of the same T cells → to protect our bodies via our immune system
Paracrine signaling
The cell releases a signal that acts on nearby cells, causing a downstream effect in these target cells
Example: At the neuromuscular junction, where a neuron meets a muscle cell.
The neuromuscular junction = junction where a neuron meets a muscle cell
An example of paracrine signaling
The neuron releases a signal onto the muscle cell → causes a downstream effect in the muscle cell once the signal has bound to the receptor in the muscle cell
Example: if the signal is acetylcholine, the downstream effect in the muscle cell leads to muscle contraction
Endocrine signaling
A cell releases a signal that must travel through the bloodstream to reach its target cell, which is often very far away
General example: associated with the endocrine system →
Specific example: cascade of events that originates at the hypothalamus and ends in the testicles
The endocrine system
One of the physiological systems in the body that controls hormones
Via the actions of these hormones, this system influences just about every other system of the body
How the hypothalamus communicates to cells in the testicles
An example of endocrine signaling → a cascade of events:
1. The hypothalamus releases GnRH (gonadotropin releasing hormone)
2. GnRH acts on the anterior pituitary → releases LH (luteinizing hormone)
3. LH acts on the Leydig cells in the testicles → produces testosterone
Neurotransmitter signaling
A very well-known form of cell signaling
Involves the chemical messages sent between 2 neurons at a synapse (the point where the processes of I neurons meet)
