week 1 Flashcards
define homeostasis + give 3 examples of variables under homeostatic control
maintenance of stable internal environment.
examples: plasma glucose, body temp, blood pressure
describe components needed to maintain homeostasis (5)
1 regulated variable
2 sensor
3 control center 4 set-point
5 effector
what is negative feedback loop? why is it called negative?
- turning back to normal set-point.
- called negative bc response of system is opposite direction of change that set it in motion.
what is positive feedback loop? why is it called positive?
- turning back to normal set-point.
- called positive bc response of system is same direction of change that set it in motion.
define moving DOWN a concentration gradient vs moving UP
- down: high to low concentration
- up: low to high concentration.
diff between chemical vs electrical driving force
chemical: higher concentration of molecules moves to lower.
electrical: movement of charged molecules (opposites attract and likes repel).
resting membrane potential is what charge?
negative (~70mV)
intracellular fluid is what charge? extracellular?
iNtra = Negative
extra = positive
if equilibrium potential is larger than membrane potential, the electrochemical force acts in same direction as the ___ force.
if membrane potential is larger than equilibrium potential, the electrochemical force acts in same direction as the ___ force.
chemical
electric
diff between hydrophobic and hydrophilic?
hydrophobic: not water-loving. cross phospholipid bilayer. ex lipids.
hydrophilic: water-loving. use membrane proteins for transport. ex ions, glucose.
which category does water fall into?
both
2 types of passive transport
simple diffusion
facilitated diffusion
diff between simple and facilitated diffusion
simple = thru phospholipid bilayer
facilitated = carriers or channels
which membrane would have higher net flux: high permeability or low permeability?
high! low perm = resistance
diff between carriers and channels for facilitated diffusion?
carriers: binds molecules on one side of a membrane and transports them to the other side.
channels: transports molecules via a passageway or pore in membrane.
why does facilitated diffusion reach a maximum/level off?
because the carrier proteins become 100% saturated at high concentrations.
most water diffuses across cell membranes through what membrane transport protein?
aquaporins
diff between active and passive transport re: electrochemical gradients
active: up
passive: down
diff between primary and secondary active transport regarding mechanisms
primary: pumps use ATP
secondary: carriers
ions/molecules inside (5) vs outside (4) cell
inside: potassium (+), amino acids, protein, phosphate, HCO3
outside: sodium (+), calcium (+), chlorine, HCO3
diff between primary and secondary active transport regarding electrochemical gradients
primary: both substances (ie Na and K) move AGAINST the ec gradient
secondary: one substance (ie Na) moves down while another substance (ie H or glucose) moves against the ec gradient
when discussing cotransport and countertransport, are we talking about primary or secondary active transport?
secondary
diff between cotransport and countertransport?
cotransport: both substances moving same direction (ie in or out of cell)
countertransport: substances moving in opposite directions (ie in and out)
how does endocytosis work? (2)
- phagocytosis: cell extends membrane around matter in extracellular fluid. when membrane surrounds particle, pinch together to form phagosome, which fuses with lysosome to breakdown.
- receptor-mediated: specific receptor at cell membrane, pinch together corresponding substance into cell (can be used or broken down).
how does exocytosis work?
secretory vesicles fuse with plasma membrane and release contents
what is transcytosis?
- combo of endo and exocytosis
- ex you ingested something, gets endocytosis into one side and then exits via exocytosis
T or F: osmosis is ALWAYS passive
true
water moves from ___ to ___ water concentration
water moves from ___ osmolarity to ___ osmolarity
high to low
low to high
define osmolarity. typical osmolarity inside cells is ___?
osmolarity = concentration of particles in 1L solution
~300 mOsm
1 liter of a solution containing 0.1 mole of glucose has an osmolarity of ___
0.1 osmolar
1 liter of a solution containing 0.1 mole of NaCl has an osmolarity of ___
0.2 osmolar
define isotonic solution. what happens to a cell placed in isotonic solution?
solution with same tonicity as inside cell (~300mOsm)
cells neither shrink nor swell.
define hypotonic and hypertonic solutions. what happens to cells placed in such solutions?
hypotonic: lower tonicity than inside cell (cell swells).
hypertonic: higher tonicity than inside cell (cell shrinks).
4 types of cells?
- neurons
- muscle cells
- epithelial cells
- connective tissue cells
what type of cells are skeletal, smooth, and cardiac cells?
muscle cells
what do epithelial cells do?
line where there is an interface bw outside and inside body (skin, lungs)
blood cells, bone cells, and fibroblasts are what type of cells?
connective tissue cells
diff between direct and indirect cell-to-cell communication?
direct: connexons between 2 close cells create gap junction which allow ions to move bw cells.
indirect: secretory cell releases chem messenger and binds to receptor on target cell
name 3 types of chem messengers
- paracrines (2 cells close together)
- neurotransmitters (released by axon and synapse)
- hormones (travel thru blood)
give the proper term for each of the following:
(a) all the water that is contained into the body,
(b) fluid that is contained within cells,
(c) fluid that is located outside the cells,
(d) fluid that is located outside of the cell and found in the blood,
(e) fluid that is located outside of the cell and found outside of the blood
a) TBW
b) intracellular
c) extracellular
d) plasma
e) interstitial fluid
vault (3)
- barrel-shaped structures comprising proteins and vault RNA (vRNA).
- most in cytoplasm, some in nucleus
- assist in intracellular transport + chemical signals
polysome (2)
- made of multiple ribosomes
- translate mRNA into polypeptide chains (proteins)
microtubule (3)
- long hollow tubes
- constantly undergo assembly/disassembly
- provide strength to cytoskeleton
nucleus / nucleolus / chromatin
nucleus: contains cell’s genetic info
nucleolus: makes ribosomes and rRNA
chromatin: thin threads of DNA
mitochondrion (2)
- inner membrane houses proteins + electron transport chain
- produce ATP
rough + smooth ER / ribosomes
rough ER: looks like flattened sacs with ribosomes on it. produces proteins
smooth ER: produces and moves lipids
ribosomes: free ribosomes can remain in cytosol or enter mitochondrion, nucleus, or peroxisome. ribosomes on rough ER packaged into vesicles by the golgi apparatus and directed to their destination
centriole (3)
- short cylindrical structures
- each cell has 2 centrioles perpendicular to each other
- direct development of mitotic spindle during cell division
lysosome (1)
degrade debris
peroxisome (2)
- perform oxidation, and thereby degradation, of molecules such as amino acids, fatty acids, and toxic foreign matter.
- contain catalase to counteract H2O2
golgi apparatus (1)
- packaging ribosomes into vesicles and directing to the appropriate location
cytoplasm (2)
- the cytosol (the gel-like intracellular fluid)
- the organelles.
plasma membrane (2)
- provides protection for cell
- helps move substances in/out of cell
