Exam 1 Flashcards
define tissue
a groups of similar cells that perform a common function
4 basic tissue types
- epithelial
- connective
- nervous
- muscle
role: epithelial tissue
a barrier/lining for protection
role: connective tissue
protein matrix that is layered by specialized cells to provide a supporting role
role: nervous tissue
responds to stimuli and initiate response from target cells
role: muscle tissue
initiate movement
define organ
consists of 2 or more primary tissues organized to perform a particular function
What does the common layering of tissues look like in the stomach?
lumen, epithelial, connective, muscle, nervous
What is a functional unit?
the unit within the organ that carries out an important function
define homeostasis
maintenance of nearly constant conditions in the internal environment
(despite exposures and changes in condition)
ECF
Extracellular Fluid
What is extracellular fluid?
it is in the internal environment and surrounds every cell in the body, all cells exist in the same ECF so that keeps the cells in a very similar environment
normal value: sodium ion
142 mmol/L
normal value: potassium ion
4.2 mmol/L
normal value: calcium ion
1.2 mmol/L
normal value: chloride ion
106 mmol/L
negative feedback
induces a response that is designed to OPPOSE the initial stimulus
examples of negative feedback
- sweating when hot to cool down
- lowering blood pressure when it is too high
positive feedback
induces a response that is designed to ENHANCE the initial stimulus
examples of positive feedback
- increasing oxytocin when giving birth
- increase platelets to seal a cut (blood clotting)
what is more common, negative or positive feedback?
negative feedback
Describe the phospholipid bilayer on microscopy
- dark line (phospholipids)
- light space
- dark line (phospholipids)
describe a phospholipid
- polar head (hydrophilic)
- nonpolar tails (hydrophobic)
integral proteins
goes through the entire phospholipid bilayer
peripheral proteins
they are only on one side (or leaflet) of the membrane
what is a carbohydrate chain linked to a protein called?
glycoprotein
what is a carbohydrate linked to a phospholipid called?
glycolipid
why is the phospholipid bilayer referred to as a fluid mosaic model?
- membranes are not static, there is fluidity
- there are many components that make up the membrane, making it mosaic
how is the cell membrane a selective barrier?
a few things can cross through but most cannot
molecules that can cross the cell membrane with little or no resistance
- dissolved gasses
- water
- non polar molecules
- some small polar molecules
molecules that cannot cross the cell membrane easily
- large polar molecules
- charged molecules/electrolytes
what are intracellular membranes?
organelles have membranes
(nuclear envelope, mitochondria, vesicles, ER, Golgi)
how does the cell membranes of organelles differ from the cell membrane?
protein composition
(although Golgi is almost identical)
organelles of the endomembrane system
- endoplasmic reticulum (ER)
- golgi apparatus
- endosomes
- lysosomes
- vesicles
what are the two forms of the endoplasmic reticulum?
- rough ER
- smooth ER
function of the rough ER
involved in protein synthesis
function of the smooth ER
contains enzymes for lipid synthesis
where is intracellular Calcium stored?
the endoplasmic reticulum
the rough ER is involved in the synthesis of only certain classes of proteins:
- destined to be secreted from the cell
- destined to be inserted in a membrane
- destined to be delivered to another membrane organelle
where would rough ER’s be prominent?
places that are responsible for secretion
(ex: pancreatic exocrine cell)
define post-translational modification
after translation a modification is made to the protein
where do proteins become glycosylated?
the rough ER
in what cells is the smooth ER prominent?
- adrenal cortex (steroids)
- liver (lipoprotein secretion)
- muscle cells (Calcium reservoir)
describe the endoplasmic reticulum
a system of membrane enclosed sacs and tubules in the cell that is next to the nucleus
describe the Golgi apparatus
a series of stacks separated from the nucleus
what is the cis face of the Golgi?
it retrieves material (near the ER)
what is the trans face of the Golgi?
it ships material (facing away from ER)
role of the Golgi
responsible for transporting, modifying (post translational modifications) and packaging proteins and lipids for delivery to targeted destinations
fate of substances leaving the Golgi
- targeting to other organelles
- secretory vesicles (regulated secretion)
- constitutive secretory (immediately released)
why are some secretions regulated?
some material is only needed at certain times, but it can be kept waiting in a vesicle so that it can be released when needed (and for some released in greater amounts)
endosomes
vesicles that pinch off from the cell’s plasma membrane (by endocytosis) and merge to form endosomes
lysosomes
(the recycling center)
formed by the fusion of vesicles, they are membrane bound organelles that are full of hydrolytic enzymes to break down materials brought in and can be used by the cell
why is the lumen of a lysosome more acidic (5)?
the cytoplasm is more neutral, so if the hydrolytic enzymes were to escape the lysosome they would not be able to function and eat away the cell
the membrane lipids and proteins that are synthesized in the ER must be transported through the network in _____________?
vesicles
What are the 4 processes to move material through the end-membrane system?
- vesicles created (correct material)
- vesicles must be marked
- vesicles must be moved
- vesicles must be bound and fused to the target
function: coat proteins
assist in the formation of vesicles
(they are specific to the organelle and the vesicle being created)
function: snares
complementary proteins on vesicles and targets that interact to provide specific docking/tethering
v-snare
the snare on the vesicle
t-snare
the snare on the target
how are vesicles moved for short distances?
diffusion
how are vesicles moved for long distances?
microtubules on motor proteins
define “fusion complex” with vesicles
fusion proteins are assembled at the sire of docking with v and t snares
function: endocytosis
movement of material from the extracellular environment into the cell
functions of cytoskeleton
- transport material around the cell
- anchor organelles to certain locations of the cell
three types of cytoskeleton
- microtubules
- actin filaments
- intermediate filaments
describe the makeup of microtubules
made up of alpha and beta tubulins that connect to make dimers, the dimers string together to make long strands, about 13 come together to form hollow filaments of microtubules, they have a + end and a - end (the largest cytoskeleton)
why are microtubules dynamic?
they can bind to GTP and hydrolyze it for energy to be changed and modified
define MTOCS
microtubule organizing center
function of the microtubule organizing center/centrosome
- the minus end anchors to the structure
- assist in cell division
function: protein motors
link to ‘cargo’ (like vesicles) and move the bound material along the microtubule or actin filaments
why are actin filaments and microtubules closely associated?
so they can pass ‘cargo’ back and forth
microtubule motor proteins
- kinesins
- dynein
which direction does kinesins move?
toward the + end of the microtubule (away from the cell)
which direction does dynein move?
toward the - end of the microtubule (toward the cell)
how do motor proteins move?
hydrolyze ATP
describe actin filaments
they are the smallest cytoskeleton that is associated with the cell membrane
what are actin filaments made up of?
actin monomer proteins (arranged in a long spiral chain with a + and - end)
if actin monomer is bound to ATP it is more likely to __________________
polymerize
if actin monomer is bound to ADP it is more likely to __________________
depolymerize
motor protein for actin
myosin
function of myosin
transports intracellular organelles and other cellular material
describe intermediate filaments
they are structural/mechanical, middle size, many different types that are specific to cell types
function of anchor points
cytoskeleton can be bound to proteins in the cell membrane to provide stability and anchor points (help cells change shape, migrate, and divide)
actin filament anchor points
- adherens junctions
- tight junctions
intermediate filaments anchor points
- desmosomes
- hemi-desmosomes
why would cytoskeletons need to reconstruct?
to help the cell move in response to a signal
define adhesion
Describes how some integral and peripheral membrane proteins physically interact with intracellular cytoskeletal filaments, with other cells, and with the extracellular matrix
characteristics of epithelia
- orientation (polarity)
- specialized contacts (sheets)
- supported by connective tissue
4 membrane protein complexes involved in the connections between a cells and the extracellular matrix
- tight junctions
- adhesion junctions
- desmosomes
- gap junctions
integral proteins contribute to…
- heme-desmosomes
- focal adhesions
function: tight junctions
- close contact between cells (good barrier)
- define apical vs basolateral surfaces
epithelial apical surface
the top of the cell, doing interactions
epithelial basolateral surface
the bottom of the cell
function: adherens junction
linked to the actin cytoskeleton across cells to create an adhesion belt (band that encircles the cell)
function: desmosomes
usually found in cells subjected to shear or pulling forces, interact with intermediate filaments
function: gap junctions
creates pores between cells so that small ions can move through
function: integrins
function as dimers that bind to the extracellular matrix proteins to anchor cells to the matrix
actin filaments integrin
focal adhesion
intermediate filaments integrin
hemi-desmosome
function: cell surface receptor
bind to an external ligand molecule and convert an extracellular signal into an intracellular signal
3 general cell surface receptors
- ion channel receptors
- enzyme linked receptors
- g-protein-linked receptors
ion channel receptor
channels that open or close to regulate ion movement
enzyme linked receptors
activate enzymes that can alter intracellular proteins to modify their function
g-protein-linked receptors
initiate the release or formation of second messengers
steps of the ion channel receptor
- ligand binds to the channel protein
- the gate opens (ions flow following the concentration gradient)
- ligand disengages and the shape changes back
define a “g-protein”
a complex of three proteins: alpha, beta, and gamma
understand how all three receptors work!!
too much to type out lol
what are the two enzymes used to create second messengers in the g-protein-linked receptors?
- phospholipase C
- adenylyl cyclase
which enzyme converts ATP to cAMP
adenylyl cyclase
understand cAMP, IP3, and DAG
you’ve got this!!
function: cAMP
activates protein kinase A which them phosphorylates inactive proteins
phosphatidyl-inositol diphosphate (PIP2) is hydrolyzed by Phospholipase C to create which second messengers?
- inositol 1,4,5, triphosphate (IP3)
- diacylglycerolw (DAG)
function: IP3
responsible for mobilizing intracellular calcium (from the ER)
what is calmodulin?
a calcium binding protein
function: DAG
activate protein kinase C
why do we see second messenger receptors so often?
ligand binding to a G protein-coupled receptor allows signals to be passed along and amplified in cells
diffusion
molecules moving from an area of high concentration to an area of low concentration until reaching equilibrium
what dictates how fast diffusion occurs?
concentration
function: channel proteins
allows passage of ions in and out of cells (concentration gradient)
are channel proteins specific?
yes, channels have specific substances that they transport
define leak protein
a channel protein that is open all the time
define gated protein
a channel protein that can be induced to be open (numerous types)
voltage gated channel
charges accumulate due to the resistance of the bilayer (negative on the inside and positive on the outside), changes in this will open or close it
stretch gated channel
on the cytoskeleton and it will stretch to open
phosphorylation gated channel
based on the state of phosphorylation, it will open or close
ligand gated channel
needs a ligand to open or close
aquaporin
a group of water channels that allows water to diffuse through the cell membrane even though its polar
carrier proteins/transporters
- movement of polar organic solutes (glucose, amino acids, etc.) through the membrane
- (electrolytes are also moved)
facilitated diffusion
NO ATP, but it increases the speed of transit by providing a way to move down the concentration gradient
why is there a max rate of diffusion for facilitated diffusion?
the proteins can only work so fast, carrier proteins alter between confirmations where the binding site is accessible to one side of the membrane or the other
what determines the rate of diffusion for simple diffusion?
concentration difference (if the concentration difference increases, the rate of diffusion increases)
3 types of transporters
- uniporter
- symporter
- antiporter
uniporter
carries one specific ion or molecule
symporter
carries two different ions or molecules, both in the same direction
antiporter
carries two different ions or molecules in different directions
active transport
integral membrane proteins convert energy directly via hydrolysis of ATP to transport a solute (can move against the gradient)
function: sodium potassium pump
- moves 2 K+ into the cell
- moves 3 Na+ out of the cell
- helps control cell volume (not hyperosmotic)
active or passive transport: sodium potassium pump
active transport
electrogenic pump
creates a charge imbalance in the membrane (example is the sodium potassium pump)
hyperosmotic
not enough water in the cell (water follows solutes)
parietal cell
produces acid in the stomach, lowers ph by releasing hydrogen ions
proton K pump in the parietal cell
- 2 H+ going out
- 2 K+ going in
why is a proton K pump NOT electogeneic?
the charges moving in and out of the cell are equal
when is potential energy high in simple diffusion?
when concentration is high
when is there no potential energy in simple diffusion?
when the cell reaches equilibrium
