Unit 5: Endocrine System

Signal transduction pathway

The process by which a signal on a cell’s surface is converted into a specific cellular response in a series of steps

Local regulator

Small water

Outside of body signaling

• Pheromones

• Quorum sensing

Pheromones

Chemicals produced to aid in communication with members of the same species

Quorum sensing

Used to react as a group (usually bacteria)

Inside of body signaling

• Short distance signaling

• Long distance signaling

• Direct contact communication

Direct contact communication

Cell junctions that allow molecules to pass readily between adjacent cells without crossing plasma membranes

• Gap junctions

• Plasmodesmata

Gap junctions

Protein channels between animal cells

Plasmodesmata

Holes between plant cells with a shared membrane

Short distance communication

• Paracrine

• Autocrine

Paracrine

Signals diffuse to and affect nearby cells

• Neurotransmitters

• Prostaglandins

Neurotransmitters

Released by a presynaptic cell move across the synapse and impact the post synaptic cell

Prostaglandins

• Promote fever and inflammation and intensify the sensation of pain

• Help regulate aggregation of platelets, an early step in formation of blood clots

Autocrine

Chemicals that affect the same cells that release them

Long distance communication

Endocrine hormones through the signal transduction pathway

Hormones

• Chemical signals

• Transported in tissue fluids

• Detected only by target cells

Secreting cell

Releases the signal