lecture 2 Flashcards
ECM consistency
- proteoglycans
- insoluble protein fibres (collagen, laminin, elastin)
3 types of cell junctions
Gap junctions
Tight junctions
Anchoring junctions
Gap junctions
communicating junctions (between cytoplasms of adjacent cells)
proteins: connexin proteins
Tight junctions
occluding junctions. adjacent membranes are partly fused together to make a barrier
protein: claudin and occludin proteins
Anchoring junctions
anchor cells to each other or ECM. provides strength when tissue is under mechanical stress
protein: cadherin proteins
anchor junctions:
cell-cell
cell-ECM
desmosome= cell-cell
hemidesmosome= cell-ECM
4 major tissue types in the body
Epithelial
Connective tissue cells
Muscle
Neural
Epithelial tissue: function, cell types
protects internal environment of the body, regulates exchange of materials between internal/external environment
cell types: exchange, protective, ciliated, transporting, secretory
Connective tissue cells
provides structural support and physical barriers
- found in extracellular matrix networs
cell types: blood cells, bones cells, fibroblasts
Muscle tissue
generates contractile force
cell type: smooth, skeletal, cardiac
Neural
Neurons –> information transfer (chemical/electrical)
Glial cells –> support for neurons
5 functions of epithelial cells
- exchange
- protective
- ciliated
- transporting
- secretory
what does the consistency of tissue depend on?
the type of tissue
6 types of connective tissue
- loose connective tissue
- dense connective tissue
- adipose tissue
- blood
- cartilage
- bone
what is the difference between loose and dense connective tissue?
loose= elastic tissue beneath the skin and between some cells
dense= provides strength and flexibility
(tendons and ligaments)
what 2 tissue types are excitable?
Muscle tissue and Neural tissue
(able to generate and transmit electrical signals. minimal extracellular matrix)
cell membrane permeability
selectively permeable
transport depends on composition of lipid/protein
increased membrane cholesterol = decreased h2O permeability
membrane permeability is directly correlated to
lipid solubility/molecular size
facilitated transport of a substance
may require a channel or transporter
may require use of ATP
different membrane transport mechanisms
Non faciliated transport
(simple diffusion)
Facilitated transport
–> protein mediated transport (channels, transporters)
active, passive
–> vesicular transport (endocytosis, exocytosis, phagocytosis)
simple diffusion
directly across a phospholipid bilayer.
small lipophilic molecules
facilitated diffusion is a type of
protein-mediated transport
Fick’s law of diffusion
rate of diffusion is directly related to:
surface area x concentration gradient x membrane permeability
membrane permeability equation
membrane permeability is directly related to lipid solubility/molecular size
8 roles of proteins in the body
- structure
- enzymes
- membrane transporter
- receptors
- signal molecules
- binding proteins
- immunoglobulins
- regulatory proteins
2 main types of protein-mediated transport
facilitated diffusion (passive)= down conc gradient
active transport (ATP input)= against conc gradient, system moves away from equilibrium
Channels
facilitated diffusion, ALWAYS passive
selective: small molecules, water channels, ions channels
fast transport
can have gates
Carriers or transporters
open to either one side of the membrane or the other
facilitated diffusion OR active transport
can be selective
slower than channels
4 types of channels
- passive/leak channels
- voltage gated
- ligand gated
- mechanically gated
what does channel selectivity depend on?
the diameter of the pore
the electrical charge of amino acids lining the pore
3 types of carrier proteins
Uniport= one substrate in one direction
Symport= two substrate in one direction
Antiport= substrates in opposite directions
Transcellular transport
transport through simple diffusion, facilitated diffusion, active transport, endo/exocytosis
ions or molecules cross both apical and basolateral membranes
Paracellular transport
molecules pass between adjacent cells to get to or from lumen
regulated by the presence of tight junctions
