Ion Channels + Cellular Homeostasis Flashcards
What is a cell?
Basic structural + functional unit of living organism
What is a tissue?
Group of cells with similar structures, working together to perform a shared function
What is an organ?
Structure made up of group tissues, working together to perform specific functions
What is an organ system?
Group of organs with related functions, working together to perform body functions
What is organism?
Living thing performing all 7 life processes
What is cytoplasm?
Consists of contents of the cell, enclosed within cell membrane
Includes cytosol + organelles
What is cytoplasm mainly composed of?
H2O
What is cytoskeleton?
Network of fibres that maintain cell’s shape + give it support
What is nuclear envelop?
Double membrane that separates nucleus contents from cytoplasm
What is function of nuclear envelop?
Maintains shape of nucleus + regulates in + out of nuclear pores
What is nucleolus?
Place where ribosomes synthesised
What is the chromosomal DNA in form of?
Chromatin
How is proteins produced at ER?
Ribosomes attached to cytoplasmic side mRNA translated into protein Enters ER lumen Passes through SER Post translational modification
What is ER major reserve of?
Ca2+
What are the sacs in golgi?
Cisternae
What happens in golgi?
Molecules move between cisternae by budding
Vesicle formation
Proteins packaged in vesicles + “shipped” to other sacs
What does size of mitochondria depend on?
Metabolism required
What does lysosomes contain?
Hydrolytic enzymes = digest cellular macromolecules
What is lysosomes main function?
Degraded newly synthesised proteins
What is autophagy?
Intracellular structures + proteins engulfed by lysosomes for degradation
What is structure of centriole?
Made up of 9 sets of triplet microtubules
How many centrioles does each cell contain?
2
Where are centrioles found?
In centrosome (near nucleus)
What is function of centrioles?
Provide framework for membranes of ER + golgi
Important in cell division
What is function of physical barrier of plasma membrane?
Establishes boundary, protects + supports structure too
What is function of selective permeability of plasma membrane?
Regulates entry + exit
What is function of electrochemical gradient of plasma membrane?
Maintains electrical charge difference
What is function of communication of plasma membrane?
Contains receptors that recognise + respond to molecular signals
What does plasma membrane form?
Forms lipid bilayer-fluid + dynamic structure with proteins floating through lipid
Where are globular proteins embedded?
Bilayer
Where are helical proteins embedded?
Span membrane
Where does hydrophilic face?
OUTWARDS
Where does hydrophobic face?
INWARDS
What is structural protein?
Cell support + shape
What is receptor protein?
Help communicate with external environment
What is channel protein?
Allow H2O, ions + proteins flow positively through bilayer
What is transport protein?
Transport molecules cross cell membrane
What are glycoproteins?
Carbohydrate chain attached to protein
Embedded into cell membrane + help cell communication + adhesion
How do hydrophobic molecules pass through membrane?
Passive diffusion
How do hydrophilic molecules pass through membrane?
Need protein carriers
How does H2O cross the membrane?
Diffuses
Aquaporin provide membrane pores
What is osmosis?
The diffusion of H2O from less concentrated to more concentrated solution through selectively permeable membrane
What is hypotonic?
Swells
H2O moves in
What is hypertonic?
Shrinks
H2O moves out
How is permeability determined?
No. of ion channels
What does Na-K pump do?
2K+ in
3Na+ out
How can Na-K pump be inhibited?
Cell swells
How does Na+ move in the cell?
Na-K pump establishes + maintains conc gradient for Na+
Na+ go down conc gradient
= inwardly-directed , chemical driving force on Na+
-70mV
Inside slightly more negative
Na+ = positive = attracted inwards
= inward-directed electrical driving force
Na+ co-transport = cells take up sugars + amino acids
Electrochemical gradient maintains Na-K pump
How does K+ move in the cell?
Na+ pump maintains high internal K+
= chemical driving force outwardly directed
Electrical still inward = K+ positive
Net electrochemical force on K+ = outwardly directed
How does Ca2+ move in the cell?
Ca 2+ extruded by Ca2+ pump Active transport by ATP Ca2+ binds to proteins in cytoplasm [Ca2+] low in cytoplasm = chemical + electrical gradient Membrane impermeable to Ca2+
What do drugs do?
Activate ion channels
= allow ions to flow down conc gradient
= evoke cellular response
What does activation of nicotinic receptors allow?
Na+/Ca2+ to cross membrane + enter cell
What are ionotropic receptors?
Ones that allow ions to cross + enter membrane when activated