W8 The Neural System Flashcards
What is the Neural System responsible for?
- It’s responsible for all memories, behaviours and movements
What’s the disease called that deteriorates your nervous system with age?
- Alzheimer’s disease
- Parkinson’s disease
There are two main parts of the nervous system.
- What are they called?
- What body parts are included in each part?
- Central Nervous System (CNS)
- Brain
- Spinal cord - Peripheral Nervous System (PNS)
- Cranial Nerves (12 pairs)
- Spinal Nerves (31 pairs)
Can you name the four sections of the brain and describe what each does?
- Cerebrum - 4 lobes (frontal, pariental, temporal & occipital)
- Cerebellum - Little Brain (coordinates movement)
- Diencephalon - Thalamus, hypothalamus & pituitary gland (sensory integration & homeostasis regulation)
- Brain stem - connects brain to spinal cord (CV & respiratory control)
How many cranial nerves are there?
- There are 12 pairs of cranial nerves
How many spinal nerves are there?
- There are 31 pairs of spinal nerves
PNS Devision:
- What is an Afferent nerve?
- Can you give an example of an Afferent nerve?
- An Afferent nerve conducts signals inwards or impulses from receptors to CNS (from skin to spinal cord)
- E.g. Sensory neurons
PNS Devision:
- What is an Efferent nerve?
- Can you give an example of an Efferent nerve?
- An Efferent nerve conducts signals outwards or impulses from CNS to effectors
- E.g. Motor neurons
What is an interneuron?
- A neuron that sends impulses between other neurons, especially as part of a reflex arc
Interneurons:
- Describe what happens during a reflex arc or Myotatic.
- The afferent nerve receives the pain impulse which gets carried to spinal cord
- This by passes the brain (as spinal cord can make simple motor reflexes) straight to the efferent nerve which creates a response
Can you give a step by step process for what happens during a Myotatic or reflex arc? (5 steps)
- Stretch sensed by muscle spindles
- Afferent signal to spinal cord
- Sensory signals transmit signal
- Motor neurons
- Interneurons - Motor neurons send efferent impulses to agonist muscle to contract
- Interneurons block motor neurons signalling antagonist muscle to not contract
- What are the two types of efferent division?
- Autonomic nervous system
- Involuntary response (SNS & PNS) - Somatic nervous system
- Motor neurons (Skeletal muscle)
What is sensory function?
- To sense change through internal & external environments using sensory receptors (afferent neurons)
What is Integrative function?
- To analysis the sensory information and store some aspects to make decisions (interneurons)
What is motor function?
- To respond to stimuli by initiation of action (efferent neurons)
What makes up the Pain Neural Response (Reflex arc/Myotatic)?
- Sensory function
- Integrative function
- Motor function
- This is the response from a pain stimulus that needs a fast reaction so doesn’t go back to the brain.
What are the four nervous system tissues and what do they do?
- Neuron(e)s
- Converts stimuli to impulses - Neuroglia (microglia)
- Do not conduct or generate nerve impulses
- They are protective & supportive - Oligodendrocytes
- Supports cells in CNS - Astrocytes
- Regulates electrical transmission in brain
Motor units have two components and three types can you name them?
Components 1. Alpha-motor neurons (AMN) 2. Muscle fibres innervated by the AMN Types 1. Slow - Type 1 fibres 2. Fatigue resistant - Type 2a fibres 3. Fast fatiguing - Type 2x fibres
Anatomy of a neuron:
- Can you name the four parts of a neuron?
- Dendrites
- Little trees, they pick up signals - Axon Hillock
- Generates nerve impulse - Axon
- Carries electrical signal away from cell body - Synapses
- Contacting point
Anatomy of a neuron:
What does the word Myelinated mean?
- It describes the myelin sheath (outside layer) that surrounds most neurons
- This myelin sheath is an insulting fatty layer
Anatomy of a neuron:
What are Nodes of Ranvier?
- Nodes of ranvier are periodic breaks in-between the myelin sheath
Anatomy of a neuron:
- How do nerve impulses move so quickly through neurons?
- The way impulses are able to move so quickly through neurons is because of the myelin sheath.
- It is wrapped around the axon which increases the speed of transmission
There are three different nerve fibre groups, can you name them?
- Alpha or Beta or Gamma
- All at myelinated (fast signal) - B-nerve fibres
- Moderate myelinated (moderate speed) - C-never fibres
- Unmyelinated (slow signal)
What three factors affect the velocity of action potential?
- Amount of myelination
- faster in myelin - Axon diameter
- Faster as diameter increases - Temperature
- Faster as temperature increases
What does Action Potential mean?
- A difference of rapidly occurring events that reverse the membrane potential and then restore it to a resting rate
There are two types of potential can you name both and describe them?
- Physics Potential
- Separation of charge - Membrane Potential
- Difference in amount of electrical charge inside and outside the cell
Resting membrane potential
- What type of particle will you look at to find the membrane potential?
- Give two examples of the type of partials that we would be looking at:
- ions
- Sodium (Na+) & Potassium (K+)
Name two extracellular ions that we use to compare membrane potential:
- Na+
2. Cl-
Name two Cytosol (intracellular) ions that we use to compare membrane potential:
- K+
2. AA (-)
How does a cell get the term polarised?
- A cell with a membrane energy difference is termed as polarised
- When a cell is polarised it has a negative charge compared to outside the cell
What are the three membrane ion channels?
- Leakage channels
- Voltage gated channels
- Ligand-gated ion channels
When does depolarisation occur?
- It occurs when sufficient stimulus depolarises the cell
- So Sodium rushes into the cell making it more positive than outside the cell
E.g. - Voltage gate Na+ opens (-55 mV) and sodium floods in
- Delayed closing of the sodium channels
- Delaying opening of potassium channels
What is repolarisation?
- Repolarisation is when the cell returns to resting membrane potential
- Potassium (K+) rushes out of the cell making the cell more negative again
What is hyperpolarisation?
- Delay in closing of voltage gated K+ channels
- The repolarisation over shoots the normal charge of the cell and goes into hyperpolarisation
- It’s the opposite of depolarisation
If a neuron was flat would a transmission travel faster or slower down it than a neuron with myelin on it?
- Myelin makes the transmission travel faster down the neuron
- So, it would travel slower
Action potentials speed is affect by different fibre types.
Can you name all three and why they affect speed of action potential?
- A fibres are the largest
- these are the most myelinated which makes action potential faster - B fibres are moderately sized
- These have moderate levels of myelin & speed for action potential - C fibres which are the smallest
- They have the least myelin so have the slowest action potential
- What are the purpose of synapses?
- How are synapses connected to one another?
- Communication occurs via synaptic transmission. Can you name both types?
- They are a way for neurons to communicate with each other or target cells
- Membranes do not touch they are separated by the synaptic cleft which is where communication occurs
1. Chemical synapse
2. Electrical synapse
- What is exocytosis?
- Exocytosis is the process synaptic vesicles use to release…
- It is a process of moving materials from within the cells to the extracellular fluid
- …neurotransmitters
What is an excitatory postsynaptic potential (EPSP)?
What is an inhibitory postsynaptic potential (IPSP)?
- An excitatory postsynaptic potential is a kind of synaptic potential that is more likely to generate action potential
- An Inhibitory postsynaptic potential is a kind of synaptic potential that is less likely to generate action potential
- Is excitatory postsynaptic potential (EPSP) depolarised?
- Is inhibitory postsynaptic potential (IPSP) depolarised?
- Yes, EPSP is depolarised via ligand-gated Na+ channels
- No, IPSP is hyperpolarised via ligand-gated K+ (or Cl-) channels
If depolarisation occurs is there an increase in sodium (Na+) or potassium (K+) inside the cell?
- There is an increase in sodium (Na+) within the cell which causes depolarisation
What charge will the cell be when action potential can occur?
- It will be at +30 mV
What charge is the cell at when its polarised?
- When its polarised (normal) a cell is at -70 mV
When a cell is in the process of repolarisation what will be happening to the potassium (K+)?
- During repolarisation a cell gets rid of its potassium (K+)
