Tissue Types and Membrane Transport Flashcards
Gap junctions
enable communications between cytoplasms of adjacent cells
connexin proteins
tight junctions
adjacent cell membranes are partly fused together, making a barrier
claudin and occludin proteins
anchoring junctions
anchor cells to each other or ECM. Cell-cell anchoring junction. Hesmidesmosomes anchor cells to ECM
provide strength when the tissue is under mechanical stress
cadherin proteins
epithelial tissue function
protect the internal environment of the body and regulate exchange of materials between internal/external environment
minimal matrix, basal lamina
no direct blood supply
has microvilli and cilia
covers body surface lines cavities and hollow organs and tubes, secretory glands
variable number or layers, from one to many; cells flattened, cuboidal or columnar
types of epithelial tissue
exchange, protective, ciliated, transporting, secretory
connective tissue cells function
provides structural support and physical barriers
found within extensive extracellular matrix networks
matrix is varied - protein fibers in ground substance that ranges from liquid to gelatinous to firm to calcified
cartilege has no blood supply
supports skin and other organs
cells not in layers; usually scattered in matrix; cell shape irregular to round
types of connective tissue
loose
dense
adipose
blood cartilege bone
what are the main tissue types in the body
epithelial
connective
muscle
neural
muscle tissue function
generate contratile force
minimal matrix, external lamina
makes up skeletal muscles, hollow organs and tubes
cells linked in sheets or elongated bundles; cells shapes in elongated, thin cylinders; heart muscle cells may be branched
muscle tissue types
smooth, skeletal and cardiac
neural tissue
neurons - info transfer (chemical/electrical)
glial cells - support for neurons, physical and biophysical support
minimal matrix; external lamina
are located throughout body, concentrated in brain and spinal cord
cells isolated or networked; cell appendages highly branched and/or elongated
which types of tissues are excitable
neural and muscle
apical
faces lumen or external environment
basolateral
faces ECM and ECF membranes
what is connective tissue made up of
cells and extensive extracellular matrix
proteoglycans and insoluble protein fibers
consistency (liquid, gel, solid) depends on tissue type
loose connective tissue
elastic tissues beneath skin and between some cells
very flexible
ie/ fibroclasts
dense connective tissue
provides strength and flexibility. collagen fibers of tendons densely packed
e.g. tendons and ligaments
excitable cells in muscle and neural tissue
can generate and transmit electrical signals
minimal extracellular matrix
what is membrane permeability proportional to
lipid solubility/ size
what is highly permeable in a membrane
gases small lipophilic (hydrophilic) molecules, water
what is impermeable to cell membrane
ions, lipophobic (hydrophilic, polar) and large molecules
diffusion
movement of molecules from an area of higher concentration to lower concentration
passive
no energy input needed
theres both simple and facilitated
equation for fick’s law of diffusion
rate of diffusion is proportional to SA x concentration gradient x membrane permeability
function of structural proteins
connect to cytoskeleton, ECM, form cell junctions
function of enzymes
catalyze reactions, involved in signaling/communication
function of membrane transporters
move things across membranes
- channels and carrier proteins
functions of receptors
cell signaling/communication, vesicular transport
facilitated diffusion
passive transport
molecules move down their concentration gradients towards equilibrium
active transport
requires energy input
molecules move against their concentration gradients and move away from equilibrium
channels
facilitated diffusion
usually only allow one thing through at a time
selective
carriers (transporters)
flip/flop
slow - because of conformation change
facilitated diffusion or active transport
open to one side of the membrane or the other (inward and outward conformations)
may be selective, can carry large molecules than channels
passive/leak channels
are always open and conducting
ie/ potassium leak channel
voltage gated channels
open and close in response to changes in membrane voltage, sodium and potassium
ligand gated channels
open when a specific chemical molecule binds to the channel protein
ie/ neurotransmitter gated channels
mechanically gated channels
open and close in response to physical disturbance/stress of membrane
stress/ stretch gated
what does channel selectively depend on
diameter of pore
electrical charge of amino acids lining the pore
uniport carriers
transport only one kind of substrate
one molecule, one direction
symport carriers
move two or more substrates in the same direction across the membrane
two molecules, same directions
antiport carriers
move substrates in opposite direction
require ATP
two substances, opposite directions
primary active transport
directly uses ATP as its energy source (ATPases)
secondary active transport
uses potential energy stored in concentration gradients from other molecules
either symport or antiport
ATP
metabolic product of glycolysis, the citric acid cycle and the electron transport system
releases energy when phosphate bonds are broken
sodium potassium pump
- sodium high in ECF. 3 sodiums from ICF bind to high affinity sites. Sodium is low on inside. Inward facing conformation
- ATPase is phosphorylated with Pi from ATP. Protein changes conformation
- Sodium binding sites lose their affinity for sodium and release 3 sodium into ECF. High affinity binding sites for potassium appear
- 2 potassium from ECF bind to high-affinity sites. Potassium concentration low on the ECF.
- Potassium binding sites lose their affinity for potassium and release two potassium into ICF. High affinity sites for sodium appear.
Sodium-glucose transporter
secondary active transport
1. sodium binds to carrier. Sodium high in ECF, glucose low.
2. sodium binding creates a high affinity site for glucose.
3. glucose binding changes carrier conformation so that binding sites now face ICF
4. sodium is released into cytosol, where sodium concentration is low. Release changes glucose-binding site to low affinity. Glucose is released.
trancellular transport
transport through cells via simple diffusion, facilitated diffusion, active transport, endo/exocytosis
ions or molecules cross both apical and basolateral membranes
paracellular transport
molecules pass between adjacent cell to get to or from lumen
regulated by the presence of tight junctions
