Cellular Responses to Environmental Signals and Stress Flashcards
(29 cards)
What is chemotaxis?
Directed movement of a cell toward or away from a diffusible chemical (chemoattractant).
Which receptor type detects chemotactic signals?
G-protein-coupled receptors (GPCRs).
How do neutrophils establish polarity during chemotaxis?
Binding of a chemotactic peptide to a GPCR triggers PI3K activation and local accumulation of PIP3.
What role do cytoskeletal filaments play in chemotaxis?
They reorganize to allow directed movement and changes in cell shape.
What organs detect pheromones in mammals?
The Main Olfactory Epithelium (MOE) and the Vomeronasal Organ (VNO).
What is the function of olfactory GPCRs?
They detect specific odor molecules and pheromones.
What is the Flehmen response?
A behavior in some animals to expose the VNO to pheromones.
What defines a pheromone?
A chemical released by one organism that affects the behavior or physiology of another organism of the same species.
What are mechanoreceptors?
Receptors that detect mechanical stimuli like touch or pressure
What do TRP channels do?
Act as environmental sensors and regulate calcium signaling; some are thermosensitive.
What is an example of a thermosensitive TRP channel?
TRPV4 in alligators, which may influence sex determination.
What happens to blood vessels during local heat exposure?
Arteriolar vasodilation increases blood flow.
What happens to blood vessels during cold exposure?
Arteriolar vasoconstriction reduces blood flow.
What are Heat Shock Proteins (HSPs)?
Molecular chaperones that assist in protein folding and are upregulated in response to stress.
How are HSPs activated?
Sudden temperature elevation leads to HSF-1 trimerization and transcription of hsp genes.
What is the role of Hsp60?
It encloses misfolded proteins to refold them in an ATP-dependent manner.
Can other stressors induce HSPs?
Yes—heavy metals, ischemia, alcohol, and UV light can also trigger HSP expression.
What is a physical stressor?
An external factor like trauma, cold, or injury that challenges homeostasis.
What is a psychological stressor?
The perception or anticipation of a threat to homeostasis.
What biological system mediates stress responses?
The Hypothalamic-Pituitary-Adrenal (HPA) axis.
What are glucocorticoids?
Stress hormones that prepare the body for emergency action and regulate gene expression.
How do glucocorticoids affect gene expression?
They bind to the glucocorticoid receptor (GR), which regulates transcription of multiple genes.
How does early life stress affect gene expression?
Through epigenetic mechanisms like DNA methylation of the GR gene promoter.
What behavioral differences were observed in rat pups based on maternal care?
Offspring of high-grooming mothers were less fearful and had better stress regulation.
