Nervous System Flashcards
(48 cards)
Neuron
nerve cell
Nerve fibre
Any long extension of cytoplasm from a nerve cell body (axon)
Nerve
A bundle of nerve fibres surrounded by connective tissue
Multipolar Neurons
1 axon, multiple dendrites
Motor Neurons
Bipolar Neurons
1 axon, 1 Dendrite
Ear, Eye, Nose
Unipolar Neurons
Cell body to one side of the axon
Sensory Neurons
Central Nervous System
Brain and spinal cord
Peripheral Nervous System
Nerves, Receptors, Muscles, Glands
Synapse
Gap between the end of one neurons dendrite and another neurons axon or cell body
Outline the steps in the transmission across a synapse
- A nerve impulse reaches the axon terminal, activating voltage gated sodium ion channels.
- There is a higher concentration of calcium ions in the extracellular fluid, which flow into the cell at the presynaptic axon terminal.
- Synaptic Vessicles fuse to the membrane releasing neurotransmitters via exocytosis
- THe neurotransmitters diffuse across the gap attaching to the next neurons membrane
- Ligand-gated portein channels are stimulated open, allowing an influx of sodium ions and intiates an action potential in the postsynaptic axon terminal. Neurotransmitters are reabsorbed via enzyme degregation or diffusion.
Outline the steps in the transmission of impulses
- Positive outside, negative inseide (-70mv) at rest in the nodes of ranvier
- A stimulus large enough to break the threshold (15mv) causes voltage gated sodium channels to open allowing soidum ions to move into the neuron
- Depolarisation occurs at the nodes of ranvier
- Sodium channels in the next node are triggered open
- Repolarisation occurs as sodium channels close, potassium channels open and potassium ions move out of the neuron.
- Hyperpolarisation occurs as a potassium channels close and sodium/potassium pumps work to bring the membrane back to resting potential (-70mv)
- Action potential jumps from node to node (a saltatory conduction occurs)
Unmyelinated Nerves
-Depolarisation causes the action potential to flow onto the membrane immediately adjacent to the stimuus
- Nerve impulse travels the whole length of the axon
- Lower concentration gradient of ions on either side of the membrane
-Nerve impulse is slower
Myelinated Nerves
Depolarisation causes the action potential to jump from node to node
- Nerve impulse only occurs at nodes of ranvier
- Higher concentration gradient of ions on either side of the membrane
Nerve impulse is faster
Afferent (Sensory): Somatic
Carries impulses from receptors around skin and muscles to the CNS
Afferent (Sensory): Visceral
Carries impulses from internal organs to the CNS
Efferent (Motor): Somatic
Carries impulses from CNS to skeletal muscles
- 1 nerve fibre
- No synapse or ganglion
- Acetylcholine at the neuromuscular junction
- Always excitation
Efferent (Motor): Autonomic
Carries impulses from CNS to the heart and other involuntary muscles
- 2 nerve fibres
- Synapse and Ganglion
- Sympathetic (Noradrenaline)
- Parasympathetic (Acetylcholine)
- Excitation or Inhibition
Sympathetic
Flight or fight response (prepares body for strenuous activity)
Parasympathetic
Rest or digest (rest and quiet situations)
How many cranial nerve pairs are there?
12 pairs
How many spinal nerve pairs are there?
31 pairs
Cerebral Cortex
Outer surface of the cereberum
made of grey matter
In charge of higher order functions
Frontal Lobe
Thinking, problem solving, personality, emotions, movement control
Temporal Lobe
Processing memories, linking them to senses, auditory information
