Homeostasis and Cell Function Flashcards
Describe the regulation of homeostasis at the cellular, tissue, and organ system levels.
Cells: genes, operons, repressor proteins, transcription factors, membrane transport
Tissues: autocrines, paracrines
Organ sys: nervous and endocrine
Describe negative feedback. Give an example.
Oppose inciting stimulus
Decrease art pressure–> Increase SNS–> Increase HR and Vasoconstriction->Increase in Art. Pressure
Describe feed forward. Give an example.
Learned anticipatory response to known cues. Muscle memory when touching a hot burner, so bypass going all the way to brain–> quicker response
How do you measure the effectiveness of a feedback system?
Gain= Correction/Error Ex: drop in bp from 100 to 60--> Neg Feedback brings it back up to 90 Correction= 90-60= 30 Error= 100-90=10 Gain= 3 Higher gain= more effective
Describe Positive Feedback. Give an example of positive feedback working for and against.
Enhance inciting stimlulus
Positive: cervical stretching leads to more stretching in labor and influx of Na in Ap leads to more Na moving into cell
Negative: Lose so much blood that negative feedback cannot recover–> decrease in venous return–>decrease CO, bp–>coronary blood flow–>decrease cardia contractility
What is a cell composed of? In what proportions?
Water highest Proteins 10-20% Fat 2-95% CHO 1-6% Ions
What types of molecules does the lipid bilayer keep out?
Hydrophilic…Ions->glucose–>H2O, urea
Lets through gasses, alcohols
What types of proteins are in the lipid bilayer?
Integral- channels, pores, carriers, enzymes
Peripheral- enzymes, intracellular signal mediator, receptors
Where is CHO found in the cell? What is the role of CHO in the lipid bilayer?
Mostly in lipid bilayer: Glycoproteins (mostly protein) and Proteoglycans (mostly CHO)…
- Glycocalyx traps cells as they flow through the blood stream for intracellular signaling with proteins
- Negative to repel
What role does cholesterol play in the lipid bilayer?
Decrease membrane fluidity and therefore permeability.
Increase flexibility and stability.
What are the types of ER? What is its function?
- Rough-ribosomes. Smooth.
- Rough process new proteins: Crosslink, Glycosylated, Cleaved, Folded
- Smooth- lipid synthesis…buds to transport in vesicles to Golgi
What is the role of the Golgi?
Further proecssing..more glycosylation and phosphorylation.
Sorted, Packaged for secretion.
What are lysosomes?
Formed from budding Golgi
Hydolases
Fuse with pino/phagocytic vesicles to digest
How are cells affected by defects in the lysosome system?
Hydrolases not working properly means the lysosome becomes engorged with undigested substances.
What is I-cell disease (non-specific) aka mucolipidosis?
Deficiency of phospho-N-acetylglucosamine-transferase..gene ok but enzyme not transported properly
Leads to CHO storage= abnormal skeletal development, coarse facial features, hepatomegaly, splenomegaly, claw shaped hands, short trunk dwarfism
