Brain anatomy Flashcards
What are iontropic receptors?
Ligand-gated ion channels
What are metabolic receptors?
G-protein coupled receptors
What three things make a neurotransmitter a neurotransmitter?
- Molecule must be synthesised and stored in the presynaptic neurone to be released
- Molecule must be released upon stimulation
- Once released, it must produce a response in the postsynaptic cell
What are the stages of neurotransmission?
- Action potential arrives at presynaptic neurone
- Voltage gated calcium channels open
- Calcium increase leads to fusion between the synaptic vesicle and pre-synaptic membrane
- Neurotransmitters released due to exocytosis
- Diffuses across synaptic cleft and binds
- Action is terminated
How do ligand-gated ion channels work?
Bind to receptor, leading to opening of ion channel
Sodium ions flow into the cell causing an action potential response
How do g-protein coupled receptors work?
Bind to receptor, g-proteins activate effector protein, effector protein opens ion channels
What does GABA do?
Inhibitory neurotrasmitter leading to hyperpolarisation
What does glutamate do?
Excitatory neurotransmitter, with an important role in learning and memory
What does acetylcholine do?
Important for the neuromuscular junction and memory
What does dopamine do?
Important role in motivation, reward and movement
What does serotonin do?
Important role in sleep, mood, and emotional behaviours
What does noradrenaline do?
Important for ‘fight or flight response’, attention, arousal and sleep
What is the role of the frontal lobe?
Voluntary movement, expressive language, and executive function
What is the role of the parietal lobe?
Sensory input, emotion, and association
What is the role of the temporal lobe?
Auditory processing and memory encoding
What is the role of the occipital lobe?
Processing of visual input, and interpretation of visual data
What is the role of the basal ganglia?
Motor tasks and reward processing
What is the role of the thalamus?
Relays information (sensory and motor)
What is the hypothalamus?
Releases hormones to maintain the body
What does corticotropin do?
Releases adrenocorticotropic hormone (ACTH)
What two inhibitory hormones are produced by the hypothalamus?
Dopamine and somatostatin
What hormone is released by the pituitary gland?
Melatonin to regulate the sleep cycle
What can blockages in CSF ventricles lead to?
Backup of CSF leading to enlarged ventricles that press on the brain leading to obstructive hydrocephalus
What three things make up the meninges of the brain?
Pia mater, dura mater, and arachnoid mater
What are the three main areas of the brainstem?
Midbrain, pons, and medulla
What is the role of the midbrain?
Movement and processing
How does the substantia nigra create movement?
Full of dopaminergic neurones
What is the role of the pons?
Movement
What is the role of the medulla?
Autonomic processes and reflexes
What are the symptoms of 3rd nerve palsy?
Eye looks down and out
Unable to adduct eye
What are the symptoms of 4th nerve palsy?
Eye turns upwards
No obvious squint
What are the symptoms of 6th nerve palsy?
Can’t abduct eye
Eye turns inwards
What are the symptoms of 7th nerve palsy?
Drooping face
Asymmetric smile
What are the symptoms of 8th nerve damage?
Impaired swallowing, taste, and neuralgia
What is the role of the neocerebellum?
Planning movements and motor learning
What is the role of the vestibulocerebellum?
Controlling balance and ocular reflexes
What is the role of the spinocerebellum?
Regulates body movements and receives proprioception information
What symptoms can cerebellum lesions lead to?
Unclear speech, jumping eyes, abnormal movement and posture
What are cerebellum peduncles?
Connects the cerebellum and the brainstem
What are cerebellum tracts?
Connect the cerebellum and parts of the brain stem and contain fibres
What arteries is the anterior circulation supplied by?
Carotid arteries
What arteries is the posterior circulation supplied by?
The vertebrals, forming the basilar
What arterial circulation is the frontal lobe supplied by?
Anterior cerebral artery
What is the main vein that blood from the brain drains into?
The jugular vein
What are spinal tracts?
Run up and down the spinal cord carrying neural pathways
descending and ascending tracts
What are the names of the two ascending spinal tracts?
Dorsal columns and spinothalamic tract
What is the name of the descending spinal tracts?
Corticospinal tract
What sensations does the spinothalamic tract carry?
Pain and temperature sensations to the peripheral nervous system
What is the route of the spinothalamic tract?
1st order neurone in the dorsal root ganglion, to the second order neurone, where it crosses over to the thalamus and third order neurone
What is the route of the corticospinal tract?
Axon goes down internal capsule to the brain stem, crosses over at the medulla, decussation happens at the pyramidal tract, and synapses at the lower motor neurone on the anterior horn
What sensations does the dorsal column carry?
Fine touch and proprioception
What is the somatic nervous system?
Carries motor and sensory information
What is the autonomic nervous system?
Regulates body functions
What is the role of the spinal nerves?
Sends signals from the body to the spine
What is the neuromuscular junction?
Communication between the muscles and nerves
What is used to help muscles contract?
Acetylcholine
What is the spinal reflex arc of pain?
e.g. if you step on a pin, interneurones send the sensation straight back to the muscle so they flex
What is the spinal reflex arc for stretch?
Either goes to the brain or not, muscles contract, then information goes to the brain to tell it it happened
An issue with the brainstem will lead to issues on what side of the body?
The same side as the lesion
A lesion to half of the spinal cord might lead to what?
Change in sensory in one side, and pain and temperature issues on the other side
An issue with the frontal spinal cord might lead to what?
Changes in motor function and temperature
What does central cord syndrome lead to?
CSF canal expands and pushes on tissues leading to pain and temperature disruption
What is the role of oligodendrocytes?
Produce myeline
What is the role of astrocytes?
Metabolic support
What is the role of microglial cells?
Immune system
What is the role of vascular cells?
Provide the brain with blood and oxygen
What are the stages of the innate immune system?
- Macrophages identify the pathogen
- wrap around pathogen
- release cytokines, leading to inflammation
- opsonins make pathogens more digestible
What does interleukin 1 lead to?
Fever, low appetite, and lethargy
What does interleukin 6 lead to?
Sent to the liver to produce acute phase proteins
What is the complement immune system?
Works alongside the innate and specific immune systems to help destroy pathogens
What types of cells are involved in the specific immune system?
T and B cells
What are T cells?
Have receptors specific to a type of antigen
What are B cells?
Have antibodies on their cell membranes specific to a type of antigen
What are CD4 cells?
T helper cells, help trigger the immune system and fight infection
