Week 5: Nervous System Flashcards
The 2 basic cell types of nervous tissue
Neurons (electrical conduits)
- sensory
- motor
- inter-neurons
Glial cells (supporting cells)
- Phagocytes (immune cells)
- insulation (myelin)
- support and protect neurons
- produce growth factors
- Do not transfer information
What does amitotic mean
The can’t divide or repair
The 4 components of the synapse
- Synaptic vesicles (containing neurotransmitter)
- pre-synaptic neuron
- synaptic cleft
- post-synaptic membrane`
What are the 2 biogenic amines: potent neurotransmitters
Catcholamines
-Norepinephrine, Dopamine
Indolamines
-Seratonin
(More info on slides (chemical synapses and neurotransmitters)
Difference between chemical and voltage gated channels
Chemical:
-Open in response to binding of appropriate neurotransmitter
Voltage:
-Open in response to changes in membrane potential
What is Depolarisation and Hyperpolarisation relative to the Resting membrane potential
- depolarization = membrane potential becomes less
negative than -70mV (up to +30mV) - hyperpolarization = membrane potential becomes more
negative than -70mV
Two types of signals
- Graded potential: short distance
- Action potential: long distance signals of axons
Generating the action potential
An action potential is a brief reversal of membrane
potential (in nerves also called a ‘nerve impulse’
• Resting state: All gated Na+ and K+ are closed.
• Depolarisation: Na+ channels open, at threshold becomes self generating
– Positive feedback
• Repolarisation: Na+ are inactivating, K+ channels open
• Hyperpolarisation: Some K+ remain open, Na+ channels reset.
The action potential
• Stimulus must initially reach a “trigger” potential (- 55mV).
• Large change in membrane potential then spreads down entire length of
axon (all or nothing “domino” effect).
• Magnitude is sustained with time and distance.
Structural region of the brain
- Ventricles
- Cerebrum
- Diencephalon
- Brain stem
- Cerebellum
Structure of the cerebrum
- Largest brain component (83%)
- Cerebral cortex
- Cerebral white matter
- Basal nuclei
Functions of the cerebral cortex
Consciousness voluntary movement communication understanding intelligence/reasoning/logical thought memory personality morals, beliefs, values social behaviour
Cerebral cortex - functional domains
- Comprised of gray matter
- 2-4mm thick containing billions of nerve cells arranged in 6 layers
- 40% of total brain mass
- all neurons in the cortex are interneurons
3 functional domains
- motor
- sensory
- associated
Sensory cortex function
- Somatory (skin, proprioceptors, feeling)
- visual
- auditory
- vestibular (balance)
- olfactory (smell)
- Gustatory (taste)
- Visceral (sensations)
Multimodal association areas function
Anterior association area (prefrontal cortex)
- Working memory (comprehension of abstract ideas, judgement, reasoning, persistence, planning)
- Maturation dependent on social environment feedback
Posterior association area
- Combines temporal, parietal and occipital lobes
- pattern and face recognition
- spatial awareness
- combining sensory inputs
- comprehension of written and spoken language
Limbic association area
- Emotional impact
- Memories