Module 2 - Nerves Flashcards
Three states of information processing in the nervous systems?
- Sensory input
- integration
- motor output
Two types of signalling?
Local vs Distance
Two types of local signalling?
Paracrine and Synaptic signalling
Three stages of cell signalling?
Reception, Transduction, Response
What is paracrine signalling?
A signalling cell acts on nearby target cells by secreting molecules of a local regulator (a growth factor, for example)
What is Synaptic signalling?
A nerve cell releases neurotransmitter molecules into a synapse, stimulating the target cell, such as a muscle or another nerve cell
What is a form of long distance signalling?
Endocrine (hormonal) signalling
What is endocrine signalling?
Specialised endocrine cells secrete hormones into body fluids, often blood. Hormones reach most body cells, but are bound by and affect only some cells.
Two main types of receptors?
Plasma membrane receptors and intracellular receptors
What is an intracellular receptor?
A steroid receptor
Three types of plasma membrane receptors?
Ion channel linked receptors:-Na+channel opened by ligand
G protein-coupled receptors: 7 TM-spanning regions- all aspects of physiology and pharmacology
Tyrosine kinase linked receptors:
Example of ion channel linked receptors
nicotinic receptors, glutamate receptors
Where would G protein-coupled receptors be found?
all aspects of physiology and pharmacology
Example of Tyrosine kinase linked receptors?
metabolism, cell growth, cell reproduction
What energy is used in G-protein receptors?
ATP (adenlyl) and GTP (g protein)
Four main proteins in a G-protein receptor?
G protein-couple receptor (GPCR)
G protein
Adenlyl cyclase
Protein kinase A
What can activate a G-protein couple receptor?
light, ions (eg. Ca2+), odourants, gustative molecules,neurotransmitters, hormones, peptides, proteins.
What do GPCRs interact with? For what cause?
Heterotrimeric G proteins to control the activity of enzymes, ion channels, and instracellular signal trasnduction pathways
What enzymes mediate transfer of phosphates in Tyrosine kinase linked receptors?
Kinases
What is a phosphate?
PO4-
What occurs during Tyrosine kinase linked receptors?
Phosphorylation cases are mediated by Kinase - these enzymes transfer phosphate and activate or inactive target proteins
Three structural vetebrate neurons?
What are cells that support nerve cells?
Glia cells
Two types of glia cells?
Astrocytes and Oligodendrocyes & Schwann Cells
How many more glia cells than neurons in mammalian brain?
10-50 times
Where are astrocytes found?
The CNS
What do astrocytes do? (3)
Structural support
Regulate extracellular concentration of ions and neurotransmitters
Formation of blood-brain barrier
Where are Oligodendrocyes found?
CNS
Where are Schwann cells found?
PNS
What do Oligodendrocytes and Schwann Cells do? (2)
Form myelin sheaths around axons
Lipid membranes: insulator
What concentration of Na+ and K+ does ATPase pump?
3 NA+ out of the cell
2 K+ into the cell
What are the numbers of Na+ and K+ in the resting membrane potential? What about calcium?
IS the membrane potential voltage gated?
Nah, that’s for action potentials
What is the membrane potential?
Voltage of inside of membrane relative to outside - equilibrium
What is depolarisation?
Inside of membrane becomes more positive
What channels open during depolarisation?
Opening of voltage-gated Na+ channels, letting Na+ in
When does the all or nothing response of an action potential occur?
Round 50mV
How fast is an action potential all or ntohing response?
1-2 ms
How fast are each voltage-gated channel? How many steps in each channel?
What is a stimulus, resting state, undershoot and repolarisation?
Four stages of an action potential?
Resting state, stimulus, repolarisation and undershoot
What happens to Na+ channels during repolarisation?
They become inactivated
What happens to K+ channels during repolarisation?
They open
What are the two refractory periods?
Absolute RP and Relative RP
What happens during absolute repolarisation?
No action potential can be activated, and the Na+ channels open then are inactivated
What happens during rekative repolarisation?
Action potential only happens if you apply a large stimulus, because some Na_ channels are closed again
Two stages of refractory period in order?
How many directions can the action potential travel?
1
How do anaesthetics work?
They prevent action potentials by blocking voltage-gated Na+ channels between the inactivated and closed stages
At what stage in the action potential do anaesthetics work?
Factors affecting action potential
Axon diameter
Temperature
Degree of myelination
How does axon diameter effect action potential?
The larger the diameter, the less resistance and faster conduction speed
How does temperature affect the action potential?
Any chemical reaction occurs faster at warmer temperatures
How does the degree of myelination affect the action potential?
Myelin insulates the axon membrane in vertebrates - faster conduction speed
What is the depolarised region between each myelin sheath called?
Node of Ranvier
What is the conduction process in myelinated sheathed nerves called?
Saltatory conduction (refers to the hop)
where does generation of action potential occur?
At the hillock
What releases the neurotransmitters at the synapse?
Presynaptic neuron
Via what process is neurotransmitter released from neurons?
Via exocytosis,
What does EPSP and IPSP stand for?
Excitatory postsynaptic potential and inhibitory postsynaptic potential
When does EPSP occur?
If depolarisation at postsynaptic membrane occurs
When does IPSP occur?
If hyperpolarisation at posysynaptic membrane occurs
What happens to most potentials before they reach an axon hillock?
They decline
What is temporal summation?
Several EPSPs from the same synapse just after one another
What is spatial summation?
Two or more EPSPs from different synapses
l,
What does the subthreshold (no summation) of action potential look like?
What does a temporal summation of EPSPs look like?
What does a spatial summation of EPSPs look like?
What does a spatial summation of EPSP + IPSP look like?
Characteritstics of action potential? (5)
Depolarisation
“All or nothing”
Excutatory postsynaptic potentials can add up and cause an action potential
Generated at the axon hillock
Travels along the axon
What is a direct synaptic transmission?
Neurotransmitter opens ion channels on the postsynaptic membrane
Action via ligand-gated ion channels
What is an indirect synaptic transmission?
Neurotrasmitter binds to a receptor on the post synaptic membrane
Activates a signal transduction pathway
Involves a second messenger
What type of receptors are neurotransmitters? What is direct and what is indirect?
Ion channel linked receptors (direct)
G-protein-coupled receptors (indirect)
What does a direct synaptic transmission look like at a chemical synapse?
What does a neurotrasmitter, when opening ion channels on the postsynaptic membrane, lead to?
A postsynaptic potential - graded0
What are three amino acid neurotransmitters?
Glutamate
Glycine
GABA (gamma-aminobutryic acid)
What are amine neurotransmitters?
Acetylcholine
Biogenic amines
What are Biogenic Amine Neurotrasmitters?
Nonadrenaline, dopamine and seratonin
What does indirect synaptic transmittion look like at the chemical synapse?
At an indirect synaptic transmission, what does the G-protein activate?
A signal transduction pathway
How are chemicals in the synaptic cleft recycled? What breaks them down? What takes them up?
Broken down by enzymes such as acetylcholinesterase
Recycled by selective uptake by transporters (NET, SERT)
Taken up by astrocytes
How many cranial nerves in the PNS in mammals?
12 pairs
How many spinal nerves in the PNS in mammals?
31 pairs
Two types of nervous systems in the peripheral nervous system?
Somatic nervous system and autonomic nervous system
Three types of autonomic nervous systems?
Sympathetic, parasympathetic and enteric divisions
During what nervous system does glycogen to glucose occur?
The sympathetic division
What main neurotransmitter does the parasympathetic division release?
Acertylcholine
Four main sections of the human cerebtral cortex (four lobes)?
What regions of the brain control the brain and spinal cord?
What fluid protects the CNS in the spinal cord?
Cerebrospinal fluid
What condition occurs with blocked flow of cerebrospinal fluid?
Gydrocephalus
Main tree types of matter in the brain?
Grey and whie matter + ventricles
What is gray matter?
Dendrites, unmyelinated axons and cell bodies
What is white matter?
Myelinated axons in tracts
What are the three parts of the brain stem?
Pons, midbrain and medulla oblongata
What does the reticular formation do?
Selectivity filter that determines arousal and sleep
What does the cerebellum do?
Motor function, cognitive and perceptual functions and coordination
Three main parts of the diencephalon?
Epithalamus, thalamus and hypothalamus
What does the pineal gland produce?
Sleep
Where is the pineal gland?
In the epithalamus
What does the epithalamus do?
Connects limbic system (“emotional center”) to the rest of the brain
What does the thalamus do?
Receives input from sensory neurones and outputs via motor neurons
What does the hypothalamus do?
Homeostatic regulation (hormones)
Biological block
Temperature regulation
Survival (hunger, thirst)
What weight of brain does neocortex take?
80%
What are the main components of the cerebrum?
Cerebral cortex, corpus callosum and basal nuclei
What is the basal nuclei important for?
Movement
What does the corpus callosum do?
Communicates between left and right sides of the body
What is the area responsible for generating speech?
Broca’s area
What is the area of the brain used for deciphering speech?
Wernicke’s area
Where are language and speech activated in the brain?
Where does short term memory occur?
Hippocampus
Where is long term memory stored? How is it reactivated?
Cerebral cortex - sent to hypothalamus to “re-remember” short term
What is the long term potential in vertebrates dictated by?
High frequency transmission of glutamate
What is a conjugate base?
A conjugate base is what is left over after an acid has donated a proton during a chemical reaction
