Brain physiology Flashcards
Layers of the head (8)
Skin Periosteum Bone Dura mater Arachnoid (fibrous membrane) Pia mater Gray matter White matter
Which 3 layers are bathed in CSF?
Dura mater, arachnoid, and pia mater
Cerebrospinal fluid (CSF) is produced in…
the choroid plexus, located along the ventricles
Functions of CSF (4)
- Cushions the brain
- Prevents pressure on the brain stem by keeping the brain floating in the cranium
- CSF flow washes waste materials from the brain into the venous system
- Helps maintain intercerebral pressure
Flow of CSF
Bathing brain and spinal cord
Absorbed via arachnoid granulations in subarachnoid spaces into venous system
Intracranial pressure is governed by…
Blood flow and CSF flow
Cerebral perfusion pressure =
Mean arterial pressure - intracranial pressure, and is needed to force blood into the brain tissues
Therefore blood pressure needs to be greater than intracranial pressure (BP will adjust to this)
Monroe-Kellie hypothesis
Increase in volume of one of the intracranial components (CSF, blood or brain) must be accopanied by a reciprocal decrease in another component
Intracranial compliance is…
the relationship between changes in intracranial pressure and volume.
If compliance is low, small changes in volume can result in high increase in pressure
Regions of the hind brain (3)
Medulla
Pons
Cerebellum
Medulla
Connects spinal cord to pons
Centre of autonomic control
Homeostatic control
Respiratory and cardiovascular systems
Pons
Bridges the cerebrum and the cerebellum
Relays movement signals from forebrain to cerebellum
Cerebellum
Important in coordination and balance
Handles walking and posture
Mid brain
Posture and walking Reflexes of eye movement Motivation and habituation Input from the eyes and ears Sensory input from the spinal cord
Regions of the forebrain (2)
Telencephalon - cerebral cortex (frontal, temporal, parietal and occipital lobes), limbic system
Diencephalon - thalamus, hypothalamus
Frontal lobe
Contains olfactory and motor cortices
Language production
Memory
Higher cognitive function
Temporal lobe
Auditory processing
Memory
Understanding language
Parietal lobe
Somatosensory
Spatial processing
Attention
Occipital lobe
Vision V1 - contrast V2 - colour and shape V3 - motion V4 - colour V5 - motion and eye movement
Homunculus man
Each side of the central sulcus has a ‘map’ of the body for motor area (frontal cortex) and sensory area (parietal cortex)
Each hemisphere controls the opposite side of the body
Wernicke’s aphasia
Can’t understand content words or produce meaningful sentences
Broca’s aphasia
Can use content words but can’t form a grammatical sentence
Limbic system
Emotion processing
Amygdala - fear, socialisation, mating
Hippocampus - short- and long-term memory and spatial orientation
Thalamus
Primary ‘gate’ between sensory and motor neurons in the PNS and cerebral hemispheres in the CNS - directs signals to where they’re needed
