Lec 02 Flashcards
By what means cells are grouped?
Physically and functionally
By what materials cell are grouped?
-Extracellular matrix
-Special cell adhesion proteins
ECM has variable —————?
Consistency
ECM different consistency
1- Bone
2- Blood
Cell junction types
1- Gap junction — heart contract as a whole
2- Tight junction — lumen, making a barrier
3- Anchoring junction — anchor cells to ECM or to each others
Gap junction example
Connexin proteins
Tight junction example
Claudin and Occludin proteins
Anchor junction example
Desmosome: cell-to-cell anchoring Ex:
Cadherin proteins
Hemidesmosomes: cell-to-ECM anchoring
Four major tissue types of body
1- Epithelial
2- Connective tissue cells
3- Muscle
4- Neural
Epithelial tissue
-Found at surfaces
-Protect internal environment of the body AND regulate exchange of materials
Epithelial cell types
Exchange, protective, ciliated, transporting, secretory
Connective tissue
MADE:
Cells and collagen
FUNCTION:
Structural support AND physical barriers
Connective cell types
Blood cell, bone cell, fibroblast
Muscle tissue function
Generate contractile force
Muscle cell type
Smooth, skeletal, cardiac
Neural tissue function
NEURONS:
Info transfer (chemical/electrical)
GLIAL CELLS:
Support for neurons
Epithelial tissue types
1– exchange: lungs gas transport
2- protective: epidermis
3- ciliated: protection upper airways
4- secretory: secret oil/sweat
5- transporting: small instestine
Apical
Faces out of body
Basolateral
Faces ECM and ECF membrane
Connective tissue types
1- loose — beneath the skin — fibroblasts
2- dense — strength and flexibility — smooth muscles
3- adipose tissue
4- blood — rbc/wbc
5- cartilage — fat cells
6- bone
Only excitable cells
Muscle and neural tissue
Membrane transport
Across cell membrane (physical barrier)
Selectively permeable (small and hydrophobic can pass)
Membrane: hydrophobic bilayer
Transport depends on lipid/protein composition
Membrane permeability
Lipid solubility/molecular size
HIGHLY PERMEABLE: gases, small lipophilic
Membrane permeability can be enhanced
-May need membrane proteins/vesicular transport
-May need energy
-Endocytosis/exocytosis
Non facilitated transport
Simple diffusion
Facilitated transport
Protein-mediated transport
(Channels vs transporters)
Passive vs active
Vesicular transport
Endocytosis
Exocytosis
Phagocytosis
Diffusion
From higher to lower concentration (down chemical concentration)
Passive — no energy
Simple diffusion: across phospholipid bilayer — lipophilic molecules
Facilitated diffusion: protein-mediated transport
Fick law diffusion
Rate of diffusion:
Surface area * concentration gradient * membrane permeability
(All have positive effects)
Membrane permeability will increase by:
Lipid solubility increases
Or
Molecular size decrease
Protein roles
Structural: connect to cytoskeleton, form cell junction
Enzymes: catalyze reaction
Membrane transport: channels and carriers
Receptors: cell signaling
Protein-mediated membrane transport
Large or lipophobic atoms and molecules
Protein-mediated transport types
Facilitated/passive diffusion:
move down the concentration gradient towards equilibrium
Active transport/need energy:
move against the concentration gradient and away from equilibrium
Facilitated diffusion example
Ions
Active transport ex.
Glucose
Channels
-Water filled pore connecting ecf and icf
- Facilitated diffusion—always passive transport (only down the gradient)
Allow to pass: small/water/ion (na/k/ca/cl)
- most have gates
- transport is fast
Carriers/transporters
-Open to one side or the other
-Facilitated diffusion or active transport
-may be selective
-can carry larger molecules
-Slower than channels
-might be down or up the gradient
-might need ATP
Type of channels
1-Passive/leak channels
2-Voltage-gated channels
3-Ligand-gated channels
4-Mechanically-gated channels
Passive/leak channels
Always open
Potassium ion
Voltage-gated channel
Open and close in response to change in membrane voltage
Ligand-gated channel
Open when specified chemical molecules binds to channel protein
-Drug/Hormone
Mechanically-gated channel
Open and close due to physical disturbance of membrane
Selective depends on:
1- diameter of the pore
2- electrical charge of amino acid lining
Membrane carriers proteins
Sodium-Glucose Transporter
Facilitated or active transport
Inward-facing vs outward-facing
Carrier proteins types
1-Uniport carriers —only one kind of substrate
2-Symport carries —move two substrates in the same direction
3-Antiport carriers —move substrates in opposite directions
Antiport carriers energy usage
Not all of them require energy
Active transport
Move away from eq
Requires energy
2 types
-primary active transport
Directly uses ATP
-secondary active transport
Uses potential energy stored in concentration gradient
Symport/antiport mechanism
ATP
Adenosine triphosphate
ATP
1- metabolic product of glycolysis, citric cycle, electron transport
2- Release energy when phosphate bond is broken
Na/K pump
Primary
3 Na out
2 K in
Make inside the cell negative
Sodium-glucose transporter
Symport
Secondary transport
Uses sodium gradient energy to transport glucose
Larger molecules transport
Endocytosis and Exocytosis
For neurotransmitters and vesicular transport
Transcellular Transport
Transport through the cell
Ion/molecule cross apical and basolateral membranes
Paracellular Transport
Molecules pass between adjacent cells
Regulated by presence of tight junction
