Nervous System Flashcards
What are the Divisions of the nervous system
central nervous system
peripheral nervous system
somatic nervous system
autonomic nervous system
sympathetic nervous system
parasympathetic nervous system
Cerebrum
largest part of the brain
2 hemispheres - connected by the corpus callosum
Frontal Lobe
Motor cortex
Broca’s area in the dominant hemisphere
intellectual and emotional behaviour
thinking and memory
Parietal Lobe
sensory cortex
language and touch
Temporal Lobe
auditory cortex
learning
judgement
feelings
Occipital Lobe
Visual cortex
Brainstem
contains medulla oblongata
responsible for breathing, HR and temperature
pons lies between the midbrain and medulla oblongata
Cerebellum
contains half the brains neurons
responsible for posture, balance and coordination
Blood Brain Barrier
protects brain cells from pathogens and harmful substances.
There is an extra layer of endothelial cells around the capillaries preventing blood from leaking from them, also a thick basement membrane and astrocytes
What protects the spinal cord?
spinal vertebrae, tough connective tissue and meninges
Spinal Cord Overview
extends from medulla to the superior border of the second lumbar vertebrae
two enlargements: cervical (nerves for upper limbs: C4-T1) lumbar (nerves for lower limbs: T9-T12)
Grey matter is arranged in a H shape with white matter surrounding it
31 pairs of spinal nerves
Layers of the spinal cord and brain
Dura mater: durable, fibrous and dense connective tissue. green in colour
subdural space
Arachnoid mater: vascular but no muscles. pink in colour
subarachnoid space
Pia mater: thin and transparent connective tissue that adheres to the surface of the spinal cord and brain. red in colour
Neuroglia
cells that support and protect nerve cells
Parts of a nerve cell and their function
Cell body: contains everything that keeps the cell alive (mitochondria, nucleus etc)
Dendrites: receive impulses and transmit them along the neuron
Axon: transmit impulses away from the cell body
Myelin Sheath: protects the axon and provides electrical insulation. gaps in the myelin sheath are called the nodes of ranvier
Axon terminals: where an axon ends and action potentials are passed on to adjacent neurons via synapses.
SAME acronym
Sensory Afferent
Motor Efferent
how many pairs of cranial nerves are there
12
Brief overview on how the somatic nervous system works
stimuli is picked up by receptors which stimulates afferent sensory neurones. impulse travels to the CNS and then efferent motor neurons cause a gland or effector to react.
Functions of the enteric nervous system
controls gut function
monitors chemical changes in the GI tract
controls smooth muscle
governs secretions
functions of the autonomous nervous system
regulates and maintains homeostasis
blood pressure, HR, temperature, breathing, digestion, metabolism and elimination.
sympathetic nervous system
fight or flight, expenditure of energy
parasympathetic nervous system
relaxation, conservation of energy
How is the resting potential formed
most sodium is outside the cell and most potassium is inside.
3 sodium leave and 2 potassium enter via the sodium potassium pump = outside of the cell is more positive
potential difference is around -5mV but it needs to be around -70mV
there are potassium channels in some nerve and muscle cells so some diffuses out
How is an action potential created?
excitatory neurotransmitters bind to receptors which results in sodium diffusing into the neuron - making that part of the neuron more positive
-55mV is the threshold for voltage gated sodium channels to open further down the axon
when the voltage reaches 30mV the voltage gated sodium channels close but voltage gated potassium channels open so potassium ions diffuse out
so much potassium diffuses out that the voltage goes lower than the resting potential in a process called hyperpolarisation (-90mV) and another impulse cannot be sent during this time
3 facts about action potentials
either generated or not “all or nothing principle”
which means all action potentials are the same size (more painful stimulus = higher frequency of action potentials)
always travel in the same direction
Schwann Cells
Surrounds the axons of neurons in the peripheral nervous system forming the myelin sheath
this speeds up conduction of action potentials as they jump along the nodes of Ranvier
Factors that can affect the rate of saltatory conduction
The condition of the myelin sheath
temperature
diameter of axon
What happens at synapses?
Vesicles containing neurotransmitters come towards the axon terminals of the presynaptic neuron
neurotransmitters enter the synaptic cleft via exocytosis after calcium enters
receptors receive the neurotransmitters on the dendrite of the post synaptic neuron (which are also sodium channels - so sodium also enters the neuron)
action potential continues in this neuron
What type of synpase is acetylcholine used at?
Cholinergic
How does ipratropium bromide link to synapses?
ipratropium bromide is anti cholinergic, so it stops acetylcholine having it’s effect (muscle contraction) - so in cases of COPD it relaxes the airways
