Neuronal Communication Flashcards
Define the nervous system
Electrical impulses which move through the CNS
Define the endocrine system
Release of hormones into blood
What are the 3 types of neurone?
Sensory
Motor
Relay
What is the role of aa Sensory receptor?
To detect stimuli and convert it into an electrical impulse
Why can receptors also be called a transducer?
Creates electrical signals
Name some features of Sensory neurones
Short axons
Long dendrites
What is the role of a motor neurone?
Create an electrical impulse from CNS to effectors in the muscles
Define homeostasis
Co ordination of organs to maintain optimum conditions needed to function
What is cell to cell signalling?
When a cell releases a chemical causing a change to another target cell
Name an example of co ordination I plants
Growing towards the light to maximise photosynthesis
Define a Sensory receptor
Cell which detects stimuli at receptors and turn into electrical impulse
Define a transducer
Changes a signal into another form
Name some properties of a pacinian corpuscles
Respond to pressure changes
Deep in skin
Wrapped in layers of tissue sperated by gel
Have channel proteins in membrane
Define a nerve impulse
Transmitted as an electrical impulse caused by movement of Na+ and K+ ions
Outline how ione move across the membrane
Ions move through gated channel proteins which cause a change in potential difference
What are the 2 pumps used in neurone membranes?
Na+ and K+ pump using ATP moves 3 Na+ ions out and 2 K+ ions in membrane
Voltage sensitive Channels open and close depending on voltage. Cytoplasm contains negatively charged ions
What does polarised mean?
Inside I cell is more negative than outside
What does depolarised mean?
Negative to positive
What does repolarised mean?
Positive to negative
What is propagation?
Current that reaches threshold potential
Outline an action potential
Neuron is polarised
Na ions move out
Action potential is reached
K ions move in
Hyperpolarisation occurs
How is a strong or weak stimulus identified?
Frequency of action potentials
What is the equation and unit for frequenc?
1 ÷ time (Hz)
How many milli seconds in one second?
1000
Where does diffusion of ions occur in a myelinated neurone?
Knodes of ranvier
What stops an action potential from going backwards?
Voltage gated calcium ions
What is the role of excitatory neurotransmitters?
Depolarise post synaptic neurone and creates an action potential if the threshold is met
What is the role of inhibitory neurotransmitters?
Hyperpolarisation to prevent action potential
Outline acetylcholine synaptic transmission
- Action potential causes calcium channels to open
- Vesicle binds to membrane to release acetylcholine in the synapse
- Acetylcholine docks and sodium channels to open. Sodium moves down steep concentration gradient
- New action potential
- Acetylcholine diffuses back preventing continuous action potential
- Ethanoic acid and choline form acetylcholine
Define temporal summation
Impulses arrive in quick succession causing action potential
Define spatial summation
Impulses arrive at many Synapses generating an action potential
What is grey matter?
Unmyelinated neurones
Whatbis a reflex arc?
Pathway of Neurones involved in reflex action
Outline the knee jerk reflex
Knee is tapped under knee cap which stretches the patella tendon this is the stimulus.
Reflex arc causes extensor muscle to contract.
Contraction and relaxation of muscles causes legs to kick
Outline the blinking reflex
Foreign body triggers stimulus response at Sensory neurone
Impulses travels down relay neurone at lower brain
Impulses sent across motor neurone to close eye
What causes the blinking reflex?
Stultaion of the cornea as a result of loud noise or bright light
Why are Reflexes important for survival?
Involuntary response
Don’t have to be learnt
Extremely quick
What does the medulla oblongata do?
Regulates autonomic functions
What does the cerebellum do?
Controls balance and posture
What does the cerebrum do?
Plans and thoughts and actions
What does the hypothalamus do?
Regulates hormones and homeostasis
What dies antagonist pair mean?
One muscle contractions the other relaxes
Whay are bundles of muscle fibre called within the membrane?
Sarcoleomma
What are the 2 proteins found in sacromeres?
Myosin and actin
What prevents acting from binding to myosin? What resolves this issue?
Tropomyosin
Calcium ions correct this
What is the A band in muscle?
Length of myosin
What happens to the H zone, Z line and I band when muscles contract?
Move closer together and gets shorter
What is the neuromuscular junction?
Space between presynaptic Neurones and muscle fibres
What causes muscles to contract?
Wave of depolarisation across T tubles causes calcium ions to be released by specialised reticulum which allows myosin to bind to ADP
