Topic 5: The brain Flashcards
how much of the bodies oxygen supply does the brain require
20%
how many minutes of lack of oxygen results in permanent damage
4mins lack of oxygen
the brain requires a continuous supply of?
glucose
What is the brain protected by?
The blood-brain barrier
Allows lipid soluble materials: O2, CO2, alcohol, anaesthetic agents but controls entry of other materials
What is the brain blood supply created by
Created by tight capillaries and glial cells: astrocytes
What does the brain stem consist of?
- continuous with spinal cord
Consists of Medulla oblongata, pons, midbrain
Brain stem: Medulla
Explain the structure, location and function of the medulla
- Found in inferior/lower part of brainstem
- Made up of white matter extending between spinal cord & other parts of brain
Contains several nuclei/clusters of cell bodies:
- 3 Vital Reflex Centres
- Cardiovascular centre (heart rate)
- Medullary rhythmicity area - (respiratory rhythm)
- Vasomotor –(vasoconstriction): Other sensory & reflex motor areas
e.g. sneezing, coughing and vomiting.
Brain stem: Pons
Explain the location/ structure/function of the pons
- Located above/superior to medulla oblongata
- Connects the spinal cord with the brain
- links one part of the brain with another by way of tracts/groups of nerve axons.
- Nerves tract cross here
- nerves supplying left side of body cross to right side of brain - and from right side of body to left side of brain.
Brain stem: Midbrain
Explain the location/ structure/function of the midbrain
- Connects pons to Diencephalon
- Conveys motor impulses from cerebrum to cerebellum and spinal cord
- Contains the substantia nigra: areas affected by Parkinson’s disease - dopamine
- Conveys sensory impulses from spinal cord to thalamus.
What does the Diencephalon consist of
Thalamus, Hypothalamus, pineal gland
Explain the function of the thalamus
- Critical relay for sensory input
- Transmits motor information from cerebellum & basal nuclei to cerebrum
Explain the function of the hypothalamus
- important for homeostasis
- Control of ANS-regulation of many activities
- Control of pituitary and hormone production
- Regulation of emotional & behaviour patterns
- Regulation of eating & drinking
- Control of body temperature
- Regulation of circadian rhythms & states of consciousness
Explain the function of the Pineal gland
- secretes melatonin which promotes sleep
Where is the cerebrum located in the brain
at the top and largest part of the brain
What is the surface of the cerebrum covered by and what is beneath
Surface covered with grey matter- cortex
Beneath is cerebral white matter
Describe structure of the cerebrum (6 points)
- Cerebral cortex: grey matter/cell bodies
- Internal white matter
- Surface folds: gyri – gyrus (singular)
- Grooves between sulci - sulcus
- Longitudinal Fissure: divides it into left & right hemispheres
- Connected by corpus callosum
Each cerebral hemisphere has 4 lobes: What are they
Frontal, parietal, temporal, occipital
What are the 3 function areas of the brain known as
- Sensory areas: receive input and responsible for perception
- Motor areas: Initiate movements
- Associative areas: complex integration: e.g. memory, emotion, reasoning, etc.
What is brain lateralisation
Left side receives input from & sends output to right side of body and vice versa
What is the left side of the brain more important for
- Spoken & written language
- numerical & scientific skills
- reasoning
What is the right side of the brain more important for
- more involved with spatial and pattern recognition and emotional content
Where is the cerebellum located?
back of brain stem
What does the Cranial meninges (continuous with spinal meninges) consist of?
dura mater, arachnoid mater & pia mater
Describe the structure of the cerebellum
- Two cerebellar hemispheres: posterior to medulla and pons, below cerebrum
- Cerebellar cortex: grey matter
- Interior: white matter & nuclei
- Attached to brain stem via cerebellar peduncles
Explain cerebellar function
- Receives wide range of sensory input
- Co-ordinates skeletal muscles: Maintenance of normal muscle tone, Regulates posture and balance
- Functions noticeable after excessive alcohol intake: ataxia/lack of muscle co-ordination
Explain the process of aging in the brain
- Rapid growth during first few years
- Size of neurons & proliferation of neuroglia
- Increases development of dendritic branches & synaptic contacts
- Decline in brain mass from early adulthood onwards.
