Brain Structure Flashcards
Describe structure and function of the cerebrum
- Largest part of brain, split into two hemispheres (left + right)
- Thin outer layer —> cerebral cortex, highly folded increasing SA
- Involved in conscious activities e.g. thought, emotions, memory, vision, speech
Describe structure and function of the hypothalamus
- Found at base of brain, above the pituitary gland
- role in control of homeostatic mechanisms, primarily thermoregulation
- Also stimulates pituitary gland to release hormones
Describe structure and function of medulla oblongata
- Found at base of brain stem
- Contains cardiovascular control centre + ventilation centre
- Regulates involuntary mechanisms like heart rate and breathing
Describe structure + function of cerebellum
- Located at back of the head, below visual cortex
- Controls muscular movement and balance
Describe how CT scans can be used to study the brain
Computerised tomography
- produce cross-section images of the brain using x-ray radiation
- Beam of x-rays aimed at a patient from multiple angles
- Digital x-ray detectors used to pick up x-rays as they exit the patient’s body
- Denser tissue absorbs more of the x-ray radiation so shows up as a lighter region on a scan
Give advantages and disadvantages of CT scans
Strengths
- shows physical structures of brain;allows visualisation of tissue damage (e.g blood less dense than brain tissue so bleeding can be identified)
- Possible to link visible symptoms with the location of any tissue damage —> help identify functions of different regions
Limitations
-Lower resolution than other techniques like MRI
- Uses x-ray radiation, less safe due to risk of mutations —> not used by pregnant women or children
- only structure not function (still image)
Describe how MRIs can be used to study the brain
Magnetic Resonance Imaging
- uses combination of magnetic field + radio waves to generate images through the body
- patient being scanned must remain very still while inside a large magnet
Give advantages and weaknesses of MRI
Strengths
- soft tissues can be seen clearly using MRI, higher resolution
- MRI is useful for identifying areas of abnormal or damaged tissue —> e.g tumours show up clearly in MRI scans
- low risk as no radiation used
Limitations
- more expensive than CT scans
- magnetic field can interfere with medical devices (pacemakers, implants) so inaccessible
- only structure not function (still image)
Describe how fMRI scans can be used to study the brain
Functional MRI
- also uses magnetic field + radio waves but allow brain function to be studied in real time
- fMRI scanner measures the ratio of oxygenated to deoxygenated haemoglobin —> oxyhemoglobin absorbs fewer radiowaves which appear as bright spots
- increased activity = increased demand for oxygen from oxyhemoglobin
Describe how PET scans can be used to study the brain
Positron Emission Tomography
- use radioactive tracers; collect in areas w/ increased activity
e.g. radioactively labelled glucose
- scanner detects gamma rays produced by tracer, can indicate whether that region is active or inactive (so both structure + function)
