Neuroanatomy (L2) Flashcards
Central nervous system (two main features)
Brain and spinal cord
- Spinal cord is the primary means for transmitting messages between the brain and the rest of the body.
CNS - three main brain sections
Forebrain, midbrain, hindbrain
CNS forebrain (5)
Thalamus, hypothalamus, cerebrum, limbic system, corpus callosum.
CNS hindbrain (5)
Cerebellum, pons, medulla, brain stem, spinal cord.
PNS systems
Somatic system, automatic system
Somatic system (+ neuron activity)
Voluntary muscle activation.
- Sensory neurons carry messages from sensory organs (ears, eyes, skin) to CNS.
- Motor neurons carry messages from motor cortex to voluntary muscle fibres.
Automatic system (+ 2 key components)
Controls smooth muscles, cardiac muscles, and glands; basically involuntary.
1. Sympathetic: generally activates
2. Parasympathetic: generally inhibits.
Cross sections of the brain (3)
- Coronal (vertically ear to ear)
- Horizontal (through the jaw direction)
- Sagittal (mid) (spine to mouth)
- Mid sagittal means it was cut directly in the middle of the brain
Medulla functions (3)
- Heart rate
- Blood pressure
- Respiration
Pons functions (3)
- Sleeping and dreaming
- Breathing
- Arousal
Reticular formation functions (2)
- Consciousness
- Gating of incoming sensory information
Reticular formation + location
Begins at the level of the medulla and runs up through the midbrain to the forebrain.
- Located at the formation of the brainstem.
What is the cerebellum good for/what does it do?
- Important for fine motor coordination, learning and memory.
- Regulates movements requiring precise timing.
- Function is disrupted by alcohol consumption
Thalamus information
- ‘Switchboard’ of the CNS
- Relays incoming signals from sensory neurons to corresponding areas of the brain (mostly in the cerebrum).
What does the hypothalamus do?
- Role in motivation and emotion
- Controls the secretion of hormones into the bloodstream via the pituitary gland.
Pituitary gland information
- Brains portal to the neuroendocrine system.
- Releases hormones that regulate other glands.
- Hormones regulate sexual behaviour, metabolism, stress response, pleasure, pain.
Hippocampus information (2)
- Part of the limbic system
- Critical for: memory encoding and retrieval, spatial orientation, contextual mapping.
Amygdala information (3)
- Part of the limbic system
- Motivational and emotional response to environmental stressors.
- Aggression and fear.
Corpus callosum information (2)
- A region containing ‘white matter’ fibres (axons) connecting the two cerebral hemispheres.
- Dissection/agenesis leads to ‘split brain syndrome’.
Gyrus
The gyri are the ridges that appear on the wrinkled surface of the brain.
Sulcus
The sulci are the grooves that appear on the wrinkled surface of the brain.
What are the four lobes?
- Frontal lobe
- Parietal lobe
- Temporal lobe
- Occipital lobe
Association cortex
- Areas that, when stimulated, do not cause sensory or motor reactions.
- These regions process associations
(relationships) between one (unimodal) or multiple (multimodal) sensory and/or motor representations.
Grey matter
Contains the somata (cell bodies) or neurons.
White matter
Contains the axonal projections (axons) of neurons.
Cellular organisation (8)
- Cell membrane
- Dendrites
- Nucleus
- Myelin sheath
- Node of Ranvier
- Soma (cell body)
- Axon
- Axon terminals
Soma
The neuronal cell body, containing its nucleus and essential organelles.
Dendrites
Specialised receiving units that collect messages from neighbouring neurons and send them to the cell body.
Axon
Conducts electrical impulses from the soma to distal target regions, such as other neuron or muscle cells.
Myelin sheath
A layer of fatty tissue that surrounds and insulates the axon, improving its transmission efficiency.
Axon terminals
End points of the axon, where electrical impulses typically release chemical signals.
Resting membrane potential (2)
- Neuronal membranes regulate the flow of charged ionic particles or molecules into and out of a neuron.
- At rest, neurons use this mechanism to maintain a net negative interal charge of around -70 mV.
Action potential
When neurons are stimulated (typically by other neurons), the membrane potential becomes more positive (moves from -70 mV towards 0 mV).
- This is called depolarisation
- When the membrane potential reaches a particular value (called a threshold, typically -50 mV), a strong depolarisation occurs, driving the membrane potential rapidly to around +30mV.
