University:
University of Cincinnati
Course:
BIOL 1081 | Biology I
Academic year:

2023
Views:

153

Pages:

3
Author:

pin4ta4xqct

Cell Communication Forms of Signalling Paracrine signals occur between cells that are close together. Example: Synaptic signals between neurotransmitters. The animation shows how neurotransmitters are affected by cocaine. Cocaine blocks reuptake channels for dopamine. The increased amount of dopamine makes a person feel good. Endocrine Signals Originate from endocrine cells (within the endocrine system) and send signals to distant cells. These signals are in the form of chemical messengers known as hormones. Hormones only act on TARGET cells. Hormones help maintain homeostasis Hormones help maintain homeostasis By returning the body back to a set point. This is called NEGATIVE FEEDBACK Examples: Maintaining temperature Blood glucose levels Positive Feedback Loops - increase activity Oxytocin increases uterine contractions in response to cervix stimulation Oxytocin also plays a role in bonding Climate change is a positive feedback loop also. Autocrine Signalling Signalling and target cell are the same or similar. Example: A cell that is infected with a virus can signal APOPTOSIS (cell death) in itself and neighboring cells. Direct Signalling Gap junctions between plant cells share small molecules via connectors: Gap Junctions (animals) Plasmodesmata (plants) Endocrine | Paracrine | Autocrine