BMC L3 Flashcards
Cerebrum + Limbic System
DIAGRAM L3 - RECOGNISE THEM!!!
Embroyinic brain development
Brain + spinal cord start as an embroyonic structure known as the neural tube.
Neural tube has 3 primary brain vesicles (3 week embryo)
- Prosencephalon - Forebrain
- Mesencephalon - Midbrain
- Rhombencephalon - Hindbrain
These 3 primary brain vesicles develop into 5 secondary brain vesicles: (5 week embryo)
Prosencephalon - Telencephalon (endbrain)
Diencephalon (interbrain)
Mesencephalon - undivided
Rhombencephalon - metencephalon (after brain)
Mylencephalon (spinal brain)
5 secondary brain vesicles develop rapidly into major structures of adult brain:
Telencephalon- cerebrum
Diencephalon- Thalamus, hypothalamus, epithalamus, retina
Midbrain - remains undivided
Metencephalon- Pons, cerebellum
Mylencephalon - Medulla
Neural Tube Defects
- Spina Bifida
Leads to paralysis, issues with bladder + bowel control
NEURAL TUBE FAILS TO CLOSE PROPERLY
2. Anencephaly: born without head, brain, skull
Incompatible with life
Causes of Neural Tube Defects
1.(Maternal?) Folate deficiency
2. Maternal diabetes
3. Maternal obesity
4. (Maternal?) Smoking
How to test for neural tube defects?
Maternal alpha-foetal protein test
Level of maternal alpha foetal protein in blood
How to prevent neural tube defects?
0.4 mg folic acid before pregnancy
1 mg during pregnancy
4 mg if prioir neural tube defect (if neural tube defect has happened)
Organisation of the brain
DIAGRAM - RECOGNISE:
- CEREBRUM - FOREBAIN - ALL OF IT - THE 4 LOBES
-BRAINSTEM
-CEREBELLUM- HINDBRAIN
What is the cerebrum composed of?
1.Cerbral cortex
2.Basal Ganglia
3. Olfactory Bulb
4. Hippocampus
What is the frontal lobe responsible for?
Mood
Muscle movement
Aggression
Smell
MOTIVATION
What is the parietal lobe responsible for?
Touch
Temp
Taste
Balance
PAIN
What is the temporal lobe responsible for?
Hearing
Smell
Memory
Judgement
Abstract thoughts
What is the occipital lobe responsible for?
Vision
What happens if the frontal lobe is damaged?
Can lead to schizophrenia / psychotic episodes
What happens if the parietal lobe is damaged?
If one side is damaged, (trauma), leads to contralateral hemi spatial neglect
What happens if the temporal lobe is damaged?
Epilepsy
What happens if the occipital lobe is damaged?
Loss of vision
Describe the structure of the cerebral cortex
Gray matter surface of cortex - outer layer of cerebrum.
Consists of:
- Longitudinal fissure
- Gyri
- Sulci
- Corpus Callosum
Longitudinal fissure
Seperates the 2 cerebral hemispheres
Gyri (1 gyrus)
Outward folds
Sulci (1 sulcus)
Inward grooves
Corpus Callosum
Connects to cerebral hemispheres
3 areas of Cerebral Cortex
- Sensory area - processes sensory impulses
- Motor area - Controls muscular movement
- Association areas - processes emotions + intellect
Gyri of the cerebral cortex
Precentral Gyrus
-contains primary motor cortex
-located in frontal lobe
Postcentral Gyrus
-contains primary somatic sensory cortex
-located in parietal lobe
BE ABLE TO RECOGNISE IN DIAGRAM
What is the hippocampus responsible for?
- Spatial navigation
- Consolidation of info
- Short term + long term memory
PART OF LIMBIC SYSTEM
Limbic System
Hippocampus with a HAT:
- Hippocampus
- Hypothalamus
- Amygdala
- Thalamus
RECOGNISE THESE ALL ON DIAGRAM
Thalamus
Responsible for:
Sleep
Wakefulness
Alertness
Also, relays sensory and motor signals
Hypothalmus
Controls + intergrates autonomic nervous system
Controls pituitary gland and links the endocrine system to the nervous systems
Recieves sensory impulses from internal body organs
Brain Stem
- Midbrain
- Pons
- Medulla
Midbrain
Sensory + Motor function
Responsible for reflex movement of head, eyeball + trunk
Pons
Connect brain + spinal cord
Connect different parts of brain
Helps control breathing
Medulla
Connect brain + spinal cord
Helps control breathing / ventilation (respiratory centre)
Cardiovascular centre (sympathetic + parasympathetic NS) - regulation of cardiac output/ heart rate
Reflex centre - vomiting, coughing, sneezing, swallowing
Motor fibres
Vasomotor centre - barrorecetprs - regulation of heart rate
Hemispheric Lateralisation
The right side of brain controls left side of body and left side of brain controls right side of bod
Lateralisation - division of labour between the two hemisphere
Left Hemisphere
Responsible for:
- General interpretation and speech centres (Wenricke, Broca)
- Language skills
- Cerebral dominance is left in 80% of people
Right hemisphere
Responsible for:
Spatial awareness
Analysis
Language formation areas
Broca’s area
Wenricke’s area
Found in left hemisphere of right handed individuals
Lesions to Broca’s area or Wenricke’s area
These are language formation areas in the left hemisphere of right handed individuals.
Therefore, lesions can lead to failure to comprehend or speaking disorders
Corrosponding areas (to language formation areas) in the right hemisphere
Responsible for emotional responses to language.
Lesions can lead to
- Emotionless speech
- Failure to understand jokes
Corpus Callosum
Sevral interconnecting neurones linking the two cerebral hemispheres.
Majority of these neurones are found in corpus callosum
Corpus Callosum cut as treatment for epilepsy
This leads to split brain personality
Example of hemispheric assymetry
Superior motor coordination of right hand
Most CNS structures are
- Bilateral
- Symmetrical
Split Brain Patient
- If you show them image in left field of view they cannot name it:
-Image seen on left field of view is only sent to right side of brain
- Speech centre is in left side of brain
-Communication between hemispheres inhibited
If they touch an object with left hand without seeing it, they cannot name it:
-Each cerebral hemisphere has a tactile representation of the opposite side of body
-Speech centre is in left side of brain
-Communication between hemispheres is inhibited
Alpha Waves
8-13 Hz
- Regular + ryhtmic
-Low amplitude
-Synchronous
Represent “idling” brain, wake but relaxed. Resting with eyes closed
Beta Waves
14-30 Hz
- Less regular
-Awake, alert, concentrating, anxious
Theta waves
4-7 Hz
-Very irregular
-Common in children, uncommon in adults
- Trying to supress an action
Delta Waves
Less than 4 Hz
HIGH AMPLITUDE WAVES
“D” for Deep Sleep
- Deep sleep
- Reticular activating system = damped
-Brain Damage
-Anesthesia
State how brain waves are shown and studied
Scalp electrodes used on patient, produce
EEG - electroencephalogram - measure brain wave activity
Brain waves classed into groups based on frequency (alpha, beta, theta, delta)
State what a flat EEG indicates
Death
State which factors affect brain waves
- Age
- Sensory stimuli
- Brain disease
- Chemical state of the body
Explain consciousness
Consciouss perception of sensation
Higher mental processing - judgement, memory
Volunrary movement etc
What does a loss of conscious indicate?
Brain impairment / brain damage
Loss of conscious is:
-syncope (fainting)
State the effects of sleep deprivation
-reduces immune function
-moody
-depressed
Describe 3 sleep disorders
Narcolepsy
-lapsing abrubrlt into sleep from the awake state
Insomnia
-chronic inability to obtain the amount of quality sleep needed
Sleep apnoa
-temporary cessation of breathing during sleep
