6 - Nervous System Organisation Flashcards
Describe the levels of biological organisation
Atoms -> molecules -> organelle -> cell -> tissue -> organ -> organ system
-> organism
Describe response to picking up a glass of water
Stimulus (glass) -> sensory receptor (eye) -> sensory neuron -> relay neuron (in brain) -> motor neuron -> effector (bicep muscle) -> response (pick up glass)
What are the 2 subdivisions of the nervous system?
CNS and PNS
What is the CNS composed of?
Brain and spinal cord
What’s the PNS composed of?
Everything else
What’s a nerve?
Bundle of axons from multiple neurons
What do the parasympathetic and sympathetic divisions control?
Homeostasis and functions beyond voluntary control
Parasympathetic
Rest & digest
Sympathetic
Fight or flight
Rostral
Front/towards nose
Caudal
Back/towards tail
Dorsal
Top/towards back
Ventral
Bottom/towards belly
Lateral
Left/right
Medial
Middle
Coronal
Frontal
Sagittarius
Plane straight down nose
What are the key areas of CNS?
- Spinal cord connects brain w/ PNS
- Brain stem
- Cerebellum
- Diencephalon
- Cerebrum
- Spinal cord connects brain w/ PNS
Conduit for info — sends out motor info and receives sensory info
What’s the central gray matter of the spinal cord?
Cell bodies
What’s the peripheral white matter of spinal cord?
Myelinated axons
Where are the cell bodies of sensory neurons in spinal cord?
Dorsal root ganglion
Where do sensory neuron axons enter spinal cord?
Dorsal root
Where do sensory neurons synapse in spinal cord?
Dorsal horn
Where are motor neuron cell bodies in spinal cord?
Ventral horn
Where do motor neuron axons exit in spinal cord?
Ventral root
Where do motor neurons synapse?
on muscle fibres
What’s the brain stem composed of?
Medulla, pons and midbrain
- Cerebellum
Role in motor control — motor learning, coordination and incorporating sensory feedback
What cognitive functions is the cerebellum implicated in?
Attention and language
- Diencephalon
Contains thalamus, hypothalamus, pituitary gland, pineal gland and corpus callosum
Thalamus
Relay station and gateway controlling flow of sensory & motor signals to/from cerebrum. Regulates sleep, consciousness and alertness
Hypothalamus
Regulates metabolic processes
Pituitary gland
Endocrine gland critical for homeostasis
Pineal gland
Endocrine organ modulates sleep
Corpus callosum
Cut in extreme seizures — unable to transfer info between 2 sides of brain
- Cerebrum
Cerebral cortex, basal ganglia and limbic system
Cerebral cortex
Outermost sheet of neural tissue. Sensory perception, motor control, affect, cognition
Basal ganglia
4 internal nuclei form feedback circuits w/ cerebral cortex. Motor control, behaviour switching, learning, reward.
Limbic system
Collection of nuclei grouped for location. Hippocampus & amygdala
Hippocampus
Memory and spatial navigation
Amygdala
Emotional valence and importance of stimuli
What’s involved in protecting nervous system?
Meninges, CSF, blood-brain barrier
Meninges
3 membranes protecting CNS
What are the 3 membranes of the meninges?
Dura mater, arachnoid mater and Pia mater
Dura mater
Outermost membrane closest to skull, tough in elastic surrounding CNS, contains large blood vessels
Arachnoid mater
Appearance & consistency of spider web, no space between dura, impermeable to fluid
Pia mater
Thin membrane adheres close to brain surface
Separated from arachnoid by space filled w/ CSF
Many blood vessels
Cerebrospinal fluid is produced by what?
Choroid plexus
Where is choroid plexus?
In the ventricles
What space does CSF fill?
Sub-arachnoid space and ventricles
Functions of CSF
Cushions brain and carries metabolic waste from brain to bloodstream
Ventricles
4 interconnected cavities in core of brain continuous with central canal of spinal cord & sub-arachnoid space and filled with CSF
Blood-brain barrier
Restricts entry of macromolecules into brain and shields brain from abnormal variations in ionic composition and potentially toxic molecules
What can pass freely into brain?
Lipids and water
What do tight junctions between endothelial Cells & capillaries restrict?
Entry of macromolecules to brain
Are astrocytes involved w/ BBB?
No - but they regulate blood flow
T/F - brain has low metabolic demand
False
What supplies blood to brain and spinal cord?
Internal carotid and vertebral arteries
Circle of Willis
Arterial ring in blood supply to brain that helps maintain supply if major supplies blocked.
What distributes blood supply in brain?
Anterior cerebral artery
Middle cerebral artery
Posterior cerebral artery
What can cause local damage in brain tissue?
Stroke
How do we study single neuron extracellularly?
Electrode in extracellular space detects APs as spikes
Advantages of extracellular recordings
Invasive but little damage to cells
Easy to maintain stable recordings and can record for long periods
Disadvantages of extracellular recordings
Expensive equipment
Difficult to determine how many cells recording from
Difficult to determine exact cell type
Can’t get info about properties of individual cells
