Neurons, PNS and CNS Flashcards
What does the peripheral nervous system consist of
Somatic and Autonomic nervous system
Somatic nervous system nerves
- Transmit messages for motor movement from the CNS to the body
- Convey sensory information to the CNS.
What does the autonomic nervous system
sends and receives messages that regulate automatic behaviours e.g. breathing
what does the autonomic nervous system split into
the sympathetic and parasympathetic
What is the CNS
consists of the brain and spinal cord
what are the three sections of the brain
forebrain, midbrain and hindbrain
what does the hindbrain consist of
medulla, pons and cerebellum
what does the medulla do
- -1. Regulates our cardiovascular and respiratory systems (heartbeat, blood circulation and breathing rate).
- Responsible for reflexes such as swallowing, coughing & sneezing, vomiting).
- Maintaining body balance by controlling head and limbs position with respect to gravity.
- Responsible for reflexes such as swallowing, coughing & sneezing, vomiting).
what does the pons do
- Integrates information from movements of and sensations from facial muscles, tongue, eye and ear.
2. Involved in regulating brain attentiveness levels and in initiating sleep and dreaming.
- Integrates information from movements of and sensations from facial muscles, tongue, eye and ear.
what does the cerebellum do
- Fine control and coordination of balance and movements using the information from muscles, joints and tendons. (it’s a big job, hence its size; it contains over 30 billion neurons.
what is the forebrain
- most anterior and prominent part of the brain - contains two cerebral hemispheres
- Consists of visible outer cortex and underneath those, subcortical regions
- Each hemisphere receives sensory information and controls motor movement from the opposite (contralateral) side of the body.
describe the cerebral cortex
- contains up to six thin layers that are parallel to the surface of the cortex.
Cells of the cortex are also divided into columns that lie perpendicular to the laminae
what lobes is the cortex divided into
occipital, parietal, temporal, and frontal.
what is the thalamus
contains a large number of relay centres conveying nearly all the sensory information to the cortex (e.g. from the eyes - LGN)
what is the hypothalamus
relatively small but important: 1) controls the autonomic nervous system and the endocrine system. 2) organises the basic behaviour for survival: fighting, feeding, fleeing
what is the limbic system
- This is an important set of interconnecting structures, surrounding the thalamus and lying just under the cortex.
- It includes structures such as the amygdala and the hippocampus and has neural links to the hypothalamus and the cortex.
It is involved in emotional and motivational activities as well as in some aspects of learning and memory
- It includes structures such as the amygdala and the hippocampus and has neural links to the hypothalamus and the cortex.
what are the primary projection areas
: The primary sensory projection areas serve as the receiving stations for information arriving from the body, eyes, ears, etc.
how do we get information from our sense to our brain
12 cranial nerves
explain the sizes of cortical areas
The size of any Cortical area is proportional to the complexity of the function it represents.
cell body
contains nucleus
axon
carries nerve impulse from soma to its terminal button
dendrites
branched structure attached to the soma of a neuron that receives info from the terminal button of another neuron
terminal button
the bud at the end of an axon which forms synapses with another neuron
synapse
- space between the axon of one neuron and the terminal button of another
neurotransmitter
a chemical released by a terminal button that can have an excitatory or inhibitory effect on another neuron
myelin sheath
surrounds axon and insulates it - prevents message from being spread between adjacent axons
nodes of ranvier
a naked portion of a myelinated axon - help to speed up conduction
why is myelin important
Damage to the myelin coating affects normal
brain functions
how do we record neural signals
- Microelectrodes are used to record from single neurons
- Recording electrode - inside nerve fibre
- Reference electrode - outside the fibre
Difference in measured charge between them is -70mv
sodium ions
positively charged
chlorine ions
negatively charged
potassium ions
positive charge
explain resting potential
- Proteins in the membrane pump out sodium ions and take potassium in
- 3 sodium outs for every 2 potassium ins
More positively charged outside the axon - sodium is positively charged
- 3 sodium outs for every 2 potassium ins
explain how an action potential is formed
- Sodium flows into axon is the beginning of an action potential - depolarisation
- This causes a change in voltage which opens more sodium channels
Potassium channels open and potassium flows out - repolarisation
- This causes a change in voltage which opens more sodium channels
refractory period
ensures action potential only flows in one direction - more negative than -70
- Neuron returns to resting state
what determines intensity of a signal
frequency
what is a neurotransmitter
- Released by presynaptic neuron
- Received by receptor sites on postsynaptic neuron
- Matched like a key and lock on specific receptor sites
Leads to a voltage change in postsynaptic neuron
how do neurotransmitters generate an action potential
- Neurotransmitters diffuse across synapse and bind to specific receptor sites
Causes sodium channels to open and generating action potential
excitatory neurotransmitter
makes the action potential likely to fire
inhibitory neurotransmitter
makes an action potential less likely to fire
what is hyperpolarisation
- makes the axon more negatively charged by releasing sodium - makes action potential less likely to fire
