Module 5: Neuornal communication Flashcards
What is the nervous pathway
Receptor Sensory neurone CNS (via relay neurone) Motor neurone Effector (muscles)
What is the function of a dendron
Sends impluse to cell body
What is the function of the cell body
realeses neurotransmitters
What is the function of the axon
Sends impulse away from cell body
Axon (A , away)
What is the mylein sheath
layers of plasma membranes
What is the function of the mylein sheath
Acts as an insulating layer
Speeds up nerve impulses transmission
at nodes of ranvier
What makes the mylein sheath
Schwann cells
What is the function of the nodes of ranvier
signal is transmitted across nodes of ranvier
Draw the sensory neurone and label the parts
Go check google
labels cell body with nucleus dendrites cell body in the middle axon
Draw a motor neurone and label it
Check google
Labels
Dendrites
Cell body with nucleus
axon
Draw a relay neurone
Check google
Labels
Cell body with nucelus in the middle with dendrites and axons surrounding
Dendrites
Axons
What is the resting potential of a neurone
-70 milivolts
Give the names of different sensory receptors
Mechanoreceptors
thermoreceptors
chemoreceptors
photoreceptor
Why do sensory receptors act as transducers
able to convert kinetic energy, thermal energy, light and chemical energy into electrical impulses
What is saltatory conduction
When impulse jumps from node of Ranvier to node of Ranvier
What is a generator’s potential
Change in potential difference due to a stimulus,
when stimulus is detected the cell membrane gets excited and becomes more permeable allowing more ions to move in and out of cell
if the generator potential is large enough an action potential will happen
How does the panicnium corpuscle work
Pressure to skin
causes lamellae to deform
stretch mediated sodium ion channels open
so sodium ions move in through sodium channels down electrochemical gradient
which depolarises the membrane
creates a generator potential
if generator potential is large enough it can cause an action potential
How does an action potential work
Stimulus: Excites the membrane, so Na channels open. This causes membrane to be more permeable to NA+ ions so Na+ ions move into cell, down Na ion electrochemical gradient
Depolarisation: If resting potential reaches threshold, voltage-gated sodium ion channels open, so there is a rapid influx of Na+ ions diffuse in (positive feedback),
Repolarisation: at 30mv the Na channels close, and voltage-gated K+ ions open. Membrane more permeable to K+, so K+ ions diffuse out of neurone down potassium ion conc gradient (negative feedback)
Hyperpolarisation: k+ ions channels slow to close, causing a k+ to pump out of neurone. To get to the resting potential k+/Na+ pump returns to membrane potential back to normal
What is the refactory period
Can’t be excited straight away as ion channels are recovering
acts as a time delay between one action potential and the next, so action potentials don’t overlap
Also makes sure action potential only travels one way (unidirectional)
What is a synapse
junction between 2 neurones
Name an excitory neurotransmotter
Acetylcholine
Name an inhibitory neurotransmitter
GABA
Describe synaptic transmission to a cholinergic synapse
- Action potential arrives at presynaptic knob
- Action potential stimulates ligand-gated channels in presynaptic neurone to open
- Calcium ions diffuse into presynpatic neurone down electrochemical gradient
- Influx of Ca+ ions causes vesicles to fuse with presynaptic membrane
- Vesicles release ACh into synaptic cleft via exocytosis
- ACh diffuses across synaptic cleft
- ACh binds onto cholinergic receptors
- This causes Na+ channels to open, Na+ diffuses in which causes depolarisation
- If threshold is reached another action potential will be generated
How is ACh removed from the synaptic cleft
broken down by acetylcholinesterase (AChe) into choline and acetate (ethanoic acid)
This diffuses back to presynaptic neurone
ATP can be used to combine Acetate and choline back to acetylcholine
Outline the roles of synapses in nervous system
allows , neurones to communicate / cell signalling ;
2 ensure transmission (between neurones)
in one direction (only) ;
3 allows , convergence / impulses from more than one
neurone to be passed to a single neurone ;
4 allows , divergence / impulses from a single neurone
to be passed to more than one neurone ;
5 idea that filters (out) , ‘background’ / low level , stimuli
or
ensures that only stimulation that is strong enough
will be passed on ;
6 prevents fatigue / prevents over-stimulation ;
7 allows many low level stimuli to be amplified ;
8 idea that presence of inhibitory and stimulatory
synapses allows impulses to follow specific path ;
9 permits , memory / learning / decision making ;
What is spatial summation
Multiple neurones that are connected on one single synapse
they will release neurotransmitters into synapse which will trigger an action potential if it reaches the threshold
allows signals from multiple stimuli to be coordinated into a single response
What is temporal summation?
multiple high-frequency impulses over time are released from the same presynaptic neurone to trigger another action potential in postsynaptic neurone
What is synaptic convergence
When multiple neurones all connect to a single neurone, causing the action potentials from multiple neurones to converge and become amplified
What is synaptic divergence
When one neurone connects to many neurones so information can be dispersed to different parts of the body
How is the nervous system organsised
Split into central and peripheral nervous system
Central: Brain and spinal cord
Peripheral: somatic and autonomic
autonomic: parasympathetic and sympathetic
How is the nervous system organsised
Split into central and peripheral nervous system
Central: Brain and spinal cord
Peripheral: somatic and autonomic
autonomic: parasympathetic and sympathetic
What does the somatic nervous system do
- conscious control (running etc)
- skeletal muscles
What does the autonmic nervous system do
controls unconscious activities
like heart rate, breathing, digestion
What does the parasymapthetic nervous system do
rest and digest
What does the symapthetic nervous system do
Fight or flight
What are the different parts of the brain
Cerebrum Hypothalamus Medulla oblongata Cerebellum Pituraity gland
What function does the cerebrum have
controls:
voluntary actions
personality
learning, hearing and thinking
What function does the cerebellum do
Coordinates muscle movement
particularly balance and posture
What function does the medulla obolongata have
autonomic control
Controls heart rate, breathing rate
What function does the hypothalamaus have
Automatically maintains body temperature
monitors blood glucose level
produces hormones that control the pituitary gland
What function does the pituitary gland have
Split into anterior (produces hormones like FSH) and posterior glands (stores hormones made by hypothalamus like ADH)
Releases hormones to stimulate other glands
