PHYL 2066 Intercellular communication

What are the types of plasma membrane receptors?

Chemically gated channels, receptor enzymes and G-protein coupled receptors.

What are the types of extracellular messengers?

Paracrine secretion, neurotransmitter secretion, Hormonal secretion, Neurohormone secretion.

What are Paracrine secretions?

They are short range chemical messengers, which only effect neighbouring cells in immediate environment.

What are neurotransmitters?

They are short range chemical messengers secreted by neuron’s in response to an action potential. They will act locally on neurons, muscles or glands.

What are hormones?

They are long-range chemical messengers, secreted into the blood by endocrine glands.

What are neurohormones?

Neurohormones are hormones released into the blood by neurons. Thye are distributed by blood to the far away target cells.

How do extracellular receptors work?

A target cell will detect a signal when the extracellular messenger binds to a receptor. Extracellular messengers have a specific shape that will only bind to a specific receptor. The receptor cell will change shape and will activate when the messenger binds to it.

Where can cellular receptors be found?

They can be found in the cell membrane, or inside of the cell itself.

What are the three mechanisms an extracellular messenger can have an affect on a cell, and what is the most common way for receptors to bind?

The most common way for an extracellular messenger to bind, is to receptors in the cell membrane. When these messengers bind, they cause an effect through three mechanisms, these are: opening/closing a chemically gated receptor channel, activating receptor enzymes or activating a second messenger pathway through a G-protein coupled receptor.

How do extracellular messengers affect chemically gated receptor channels?

The binding of the messenger to a chemically gated channel will cause the channel to open or close. This will change the movement of ions that cross the plasma membrane.

What is signal transduction?

Signal transduction is when a signal outside of a cell is converted to a signal inside of the cell. This process usually involves protein kinases, which are enzymes that transfer phosphates from ATP to other proteins, and those proteins may transfer the phosphate to other proteins again.

How do receptor enzymes work?

When the extracellular messenger binds to the receptor enzyme in the plasma membrane, it causes the receptor enzyme to be activated, which will they activate other proteins may transfer kinases. The last kinase in the cascade alters the designated protein which in turn will cause a cellular response.

How do G protein coupled receptors work?

The receptor is linked to a G protein. The binding of the messenger causes the G protein to activate. The G protein will travel along the plasma membrane until it stimulates an effector protein, which will produce a second messenger. Which in turn activates a cascade of protein kinases, which will alter the designated protein leading to a cellular response.

What is an intracellular receptor?

An intracellular receptor is found inside of the cytoplasm, or nucleus. They are messengers that bind to intracellular receptors produce an effector protein by activating genes.

How does an intracellular receptor work?

Once the messenger binds to a receptor (usually very small and will penetrate the plasma membrane, and a hormone(maybe)), is will then penetrate the nucleus and bind to a specific region of DNA. Once bound to the DNA, it will activate a specific gene, will then transcribe an mRNA, a new protein will then be produced, which carries out the desired response.

What are the 7 major ways in which the endocrine and nervous system.

1. The way they’re linked (wired vs wireless)

2. Type of chemical messenger (neuron transmitters vs hormones)

3. Distance of action

4. Specificity of action (some cells responding but not others)

5. Speed of response

6. Duration of action

7. Major function (fast, precise responses vs long duration activities)