Cellular Functions 2 Flashcards
3 substances with higher concentration inside the cell than out
potassium, magnesium, and amino acids
3 substances with lower concentrations inside the cell than out
sodium, chloride, and calcium
passive membrane transport
does not require energy
molecules move down a concentration gradient
two types: diffusion and osmosis
diffusion
net movement of ions or molecules from areas of greater concentration to areas of lesser concentration
uses concentration gradient and kinetic energy
factors that influence diffusion
temp goes up, kinetic energy goes up, rate of diffusion goes up
big difference in concentration, faster rate of diffusion
simple diffusion
molecules move unassisted between phospholipid molecules
small and non polar solutes like gasses and urea
dependent on concentration gradient
facilitated diffusion
transport process for small charged or polar solutes
needs assistance from plasma membrane proteins
two types: channel-mediated diffusion and carrier-mediated diffusion
channel-mediated diffusion
movement of small ions through water filled protein channels
important for nerve and muscle cells
use leak and gated channels
carrier-mediated diffusion
small polar molecules assisted across membrane by carrier protein
substance binds which causes shape change in carrier protein
allows substance to move down gradient
3 types of gaited channels
voltage, chemically, and mechanically gated
osmosis
passive movement of water through the plasma membrane
does not allow solutes to move through
happens due to differences in water concentration on either side of membrane
can go between molecules of bilayer or through aquaporins
osmotic pressure
pressure exerted by movement of water across semipermeable membrane
due to different in solute concentration
hydrostatic pressure
pressure exerted by a fluid on the inside wall of its container
tonicity
ability of solutions to change the volume or pressure of a cell by osmosis
isotonic solution
cytosol and solution have same concentration of solutes
no net water movement
hypotonic solution
solution has lower concentration of solutes and more water in cytosol
cells will lyse as water goes inside the cell
hypertonic solution
solution has higher concentration of solutes and less water in cytosol
crenation: cells shrink
active transport
movement of solute against its concentration gradient
two types: primate and secondary active transport
primary active transport
type of transport that uses energy from breaking a phosphate bond in ATP
ex. ion pumps
secondary active transport
moves substances against gradient
first uses electrical chemical gradient energy then eventually will use ATP to rid the cell of built up ions
two types: symport and antiport
symport secondary active transport
two substances are moving in the same direction
antiport secondary active transport
two substances are moving in opposite directions
vesicular (bulk) transport
transporting large substance across the membrane in a vesicle
requires energy
exocytosis and endocytosis
exocytosis
large substances secreted from cell in a vesicle
vesicle fuses with plasma membrane and contents are released outside of the cell
requires ATP
endocytosis
cell uptake of large substances from external environment
pocket forms in membrane then pinches off with substances inside
phagocytosis
cellular eating
occurs when cell engulfs large particles external to cell
pinocytosis
cell drinking
internalization of droplets of interstitial fluid containing dissolved solutes
explain receptor-mediated endocytosis
ligand binds to surface receptors in clathrin coated pits
myosin and actin help pinch off the vesicle into the cell
enables the cell to obtain bulk quantities of substances
ex. transporting cholesterol from blood to inside the cell
explain familial hypercholestermia
inherited genetic disorder where there is a defect in the LDL receptor so cholesterol cannot be taken out of the blood as easily
results in too much cholesterol in the blood which can build up in the arteries and cause atherosclerosis
explain tight junctions
strands or rows of proteins that help link cells
prevents substances from passing between cells and requires them to move through the cells rather than between them
helps to maintain polarity of epithelia
ex. found in blood brain barrier
adheren junctions
join the actin filament of neighboring cell together
desmosomes
proteins that bind the intermediate filaments of neighboring cells
act like velcro to keep them from tearing apart
ex. found in heart muscle cells
hemidesmosomes
attach one cell’s intermediate filaments to the basal lamina (extracelullar molecules) of another cell
gap junctions
fluid-filled tunnels between adjacent cells that provide direct passageway for substances the travel between cells
allows small molecules and ions to move between cells
ex. found in heart cells and allow them to beat together
what is a signal transduction pathway
diverse sequence of events that like receptor activation to cellular response
explain lipid soluble chemical messengers
messengers can diffuse freely through the plasma membrane where they will bind to a receptor either in the cytoplasm or on the nucleus
binding triggers a genetic response
explain water soluble chemical messengers
first messengers bind to receptors on surface of the cell
second messenger inside the cell will carry message throughout the cell and trigger a response (tell the cell what to do)
explain channel linked receptors
ligand will bind to membrane protein receptor
receptor changes shape with then allows ions to enter the cell
ex. used in muscle and nerve cells to initial electrical changes in the membrane potential
explain enzymatic receptors
two types: intrinsic and non intrinsic
intrinsic: enzyme is embedded into receptor
non-intrinsic: receptor has associated enzyme attached that will be activated upon activation of receptor
ligand binds to activate enzyme directly (intrinsic) or cause a shape change of reactor which activates associated enzyme (non-intrinsic)
explain overall G-coupled protein receptor pathway
ligand binds to receptor which causes it to change shape
shape change activates G protein
activate G protein leaves receptor and attaches to and activates an effector protein
effector protein (sometimes ion channel) allows ions to come into the cell
ions help to form second messengers
second messengers will activate kinases which will then phosphorylate other things downstream
explain the adenylyl cyclase and cyclic AMP pathway
ligand binds to receptor
Gs protein goes from GDP to GTP
adenylyl cyclase uses an ATP molecule to make cAMP (second messenger)
cAMP activates PKA which will then phosphorylate stuff
explain the DAG and IP3 pathway
ligand binds to receptor
Gq protein changes from GDP to GTP
effector protein changes PIP2 to IP3 and DAG
IP3 causes activation and release of calcium in the ER
DAG and calcium activate kinase C
kinase C helps to cause cell response
what is signal amplification
one messenger can cause millions of responses
how can we reduce activity of communication pathways or stop it all together?
decrease concentration of ligand
alter affinity of receptor
remove receptors
explain cell necrosis
cells are killed by harmful agents or mechanical damage
contents within cell are released once the cell ruptures
explain apoptosis
programmed cell death
cells are tagged with marker to cause them to kill themselves
cell breaks apart (blebs) into several apoptotic bodies
helps remove harmful cell
used for things like removing tissue between fingers of developing limbs
4 tissue types
epithelial
connective
muscle
nervous
where would you find epithelial tissue
body surfaces
body cavities
forming the majority of glands
4 functions of epithelial tissue
protection
selectively permeable
secretions
sensations
features of exocrine glands
connect to surface of epithelium by ducts
tube helps with secretion
ex. sweat glands and mammary glands
features of endocrine glands
no ducts
secrete hormones into the blood
ex. thyroid and adrenals
3 parts to connective tissue
cells
protein fibers
ground substance
2 cell types of connective tissue
resident cells and wandering cells
features of resident cells of connective tissue
stationary, housed in CT
support, maintain, and repair extracellular matrix
ex. adipocytes, fibroblasts, mesenchymal cells, and fixed macrophages
features of wandering cells of connective tissue
move throughout CT
repair damaged extracellular matrix
type of leukocytes
help protect the body from harmful agents
3 types of protein fibers of connective tissue
collagen fibers, reticular fibers, and elastic fibers
features of reticular fibers of connective tissue
like collagen but thinner
found in high amounts in the stroma of some organs like the lymph nodes
features of elastic fibers of connective tissue
made of elastin
stretch but mainly recoil
found in the skin and in walls of arteries
features of the ground substance of connective tissue
molecular material produced by connective tissue cells
houses connective tissue cells and protein fibers
can have different consistencies depending on where it’s found
what makes up the extracellular matrix
ground substance and protein fibers
glycosaminoglycans (GAGs)
large molecule found in the ground substance of connective tissue
charged which attracts cations and makes water follow
proteoglycans
a protein with an attached glycosaminoglycan (GAG)
glycoproteins
proteins with carbs attached
bound CT cells and fibers to ground substance
functions of connective tissue
protection
support and framework
binding of structures
storage
transport
immune protection
4 types of body membranes
mucous, serous, cutaneous, and synovial
functions of skeletal muscle tissue
moves skeleton and helps to thermoregulate the body
functions of cardiac muscle tissue
pumps blood through the heart and blood vessels
functions of smooth muscle tissue
moves and propels materials through internal organs
also controls size of lumens
function of glial cells
protect, nourish, and support neurons
do not transmit nerve impulses
function of neurons
receive, process, and transmit nerve impulses
features of intracellular fluid
fluid within cells
makes up 2/3rds of our body fluid
allows some substances to pass
features of extracellular fluid
fluid outside cells
made up of interstitial fluid and blood plasma
makes of 1/3rd of out body fluid
features of interstitial fluid
extracellular fluid around cells
makes of 2/3rds of extracellular fluid
features of blood plasma
extracellular fluid within blood vessels
permeable
makes up 1/3rd of extracellular fluid
