Lecture 3 - Excitable Membranes Flashcards
What is the structure of the plasma membrane?
fluid mosaic model
What makes up the fluid mosaic model?
-phospholipid bilayer
-cholesterol
-transmembranal proteins
What is the polar section of a phospholipid?
polar hydrophilic head
What is the non-polar section of a phospholipid?
non-polar hydrophobic fatty acid chains (tail)
peripheral membrane protein
-where
-what looks like
-function
-inside membrane
-small not across the full membrane
-attachment + shape changes
integral membrane proteins
-where
-what looks like
-function
-across the full membrane
-channel, pump…
-transport + communication
cytoskeleton
-where
-what looks like
-function
-underneath the plasma membrane
-small, attached to other proteins
-anchors + receptors
carbohydrates
-specific name
-where
-what looks like
-function
-glycocalyx
-outside of the cell
-thin, looks like little trees
-cell-cell recognition
cholesterol
-where
-what looks like
-function
-embedded in the membrane
-it looks like a steroid structure
-stabilization
4 functions of the plasma membrane
- communication
- selective
- physical barrier
- cell recognition
6 functions of the plasma membrane proteins?
- enzyme activity
- transport
- receptors
- cell-cell recognition
- intracellular joining
- attach to ECM
3 types of junctions formed between cells
- desmosomes
- gap junctions
- tight junctions
tight junctions + where
-impermeable
-no random diffusion
+ blood-brain barrier
desmosomes + where
-attach
-anchor
-structure
+ cardiac muscle tissue, bladder tissue, and epithelia
gap junctions + where
-channel
-communicate
-specialize
+ all cells of solid tissue
how much of the brain is used to maintain the Na+/K+ ATPases pump?
40%
How is the electrochemical gradient challenged? (2)
1) slow leaking ions
2) stimulation of muscle
3 types of endocytosis
1) pinocytosis
2) receptor-mediated
3) phagocytosis
what is the process of exocytosis?
t-snare on receptor + v-snare of vesicle attach on membrane to release outside
what molecules can travel past the membrane by simple diffusion?
O2 + CO2 + fats + urea + alcohol
state 5 features of facilitated diffusion
1) no ATP
2) specific
3) down conc. gradient
4) carrier saturation
5) can be inhibited
what and where is the biosynthetic centre?
- large spherical nucleus
-glandular cytoplasms
where is the term tract used?
nerve processes of the CNS
where is the term nerve used?
nerve processes of the PNS
what are the 3 special features of an axon?
1) extreme longevity
2) amitotic
3) high metabolic rate
look at the drawing on the 2nd page + names 1-4 regions
1) receptive
2) initial segment
3) conducting
4) secretory
receptive region of the axon
-the name of parts of the cell
-function
-dendrites + cell body
-receive graded potentials
initiail segment of the axon
-name parts
-function
-axon hillock
-where the action potential is reached
conducting region of the axon
-name parts
-function
-axon + myelin sheath
-propagate the electrical current down the axon
2 functional divisions of PNS
-sensory
-motor
how is the sensory PNS divided?
-somatic (skin/skeletal)
-visceral (visceral organs to the CNS)
how is the motor PNS divided?
-somatic (voluntary movement of muscles)
-autonomic (self-regulated organs)
What are the 2 principal cell types of nervous tissue and their definitions?
1) neuroglia
-small cells that wrap around axons
2) neurons
-excitable cells that transmit signals
what is the 4 main neuroglia that supports the CNS neurons?
1) astrocytes
2) oligodendrocytes
3) microglial
4) ependymal
astrocytes
-definition
-function
-highly branched that connect at capillaries and synaptic endings
-support, exchange, guide, control, respond, influence, process
microglial cells
-definition
-functions
-small cells that touch and monitor neurons
-help injury + phagocytize bad stuff
ependymal cells
-definition
-functions
-forms permeable membrane between the CSF and tissues
-layer the central cavities of the brain and spinal column
oligodendrocytes
-definitions
-functions
- a highly branched fatty cell that wraps around the CNS nerve fibres
-for conduction of electrical impulses
What is the 2 major neuroglia in the PNS?
1) Schwann cells
-surround nerve fibres
2) ganglion
-surround neuron cell body
What is vital to the regeneration of damaged PN fibres?
Schwann cells
What do conduction velocities depend on? (2)
-axon diameter
-myelin sheath
What is anterograde transport?
-transport away from the cell body toward the synapse
=mitos + cytoskeleton, membrane parts, nervous tissue
what is retrograde transport?
-transport towards the cell body
